com.unity.netcode.gameobjects@1.0.0-pre.9

The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/) and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).

Additional documentation and release notes are available at [Multiplayer Documentation](https://docs-multiplayer.unity3d.com).

## [1.0.0-pre.9] - 2022-05-10

### Fixed

- Fixed Hosting again after failing to host now works correctly (#1938)
- Fixed NetworkManager to cleanup connected client lists after stopping (#1945)
- Fixed NetworkHide followed by NetworkShow on the same frame works correctly (#1940)

CHANGELOG.md

@@ -6,6 +6,152 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/)
 
 Additional documentation and release notes are available at [Multiplayer Documentation](https://docs-multiplayer.unity3d.com).
 
+## [1.0.0-pre.9] - 2022-05-10
+
+### Fixed
+
+- Fixed Hosting again after failing to host now works correctly (#1938)
+- Fixed NetworkManager to cleanup connected client lists after stopping (#1945)
+- Fixed NetworkHide followed by NetworkShow on the same frame works correctly (#1940)
+
+## [1.0.0-pre.8] - 2022-04-27
+
+### Changed
+
+- `unmanaged` structs are no longer universally accepted as RPC parameters because some structs (i.e., structs with pointers in them, such as `NativeList<T>`) can't be supported by the default memcpy struct serializer. Structs that are intended to be serialized across the network must add `INetworkSerializeByMemcpy` to the interface list (i.e., `struct Foo : INetworkSerializeByMemcpy`). This interface is empty and just serves to mark the struct as compatible with memcpy serialization. For external structs you can't edit, you can pass them to RPCs by wrapping them in `ForceNetworkSerializeByMemcpy<T>`. (#1901)
+
+### Removed
+
+- Removed `SIPTransport` (#1870)
+- Removed `ClientNetworkTransform` from the package samples and moved to Boss Room's Utilities package which can be found [here](https://github.com/Unity-Technologies/com.unity.multiplayer.samples.coop/blob/main/Packages/com.unity.multiplayer.samples.coop/Utilities/Net/ClientAuthority/ClientNetworkTransform.cs) (#1912).
+
+### Fixed
+
+- Fixed `NetworkTransform` generating false positive rotation delta checks when rolling over between 0 and 360 degrees. (#1890)
+- Fixed client throwing an exception if it has messages in the outbound queue when processing the `NetworkEvent.Disconnect` event and is using UTP. (#1884)
+- Fixed issue during client synchronization if 'ValidateSceneBeforeLoading' returned false it would halt the client synchronization process resulting in a client that was approved but not synchronized or fully connected with the server. (#1883)
+- Fixed an issue where UNetTransport.StartServer would return success even if the underlying transport failed to start (#854)
+- Passing generic types to RPCs no longer causes a native crash (#1901)
+- Fixed a compile failure when compiling against com.unity.nuget.mono-cecil >= 1.11.4 (#1920)
+- Fixed an issue where calling `Shutdown` on a `NetworkManager` that was already shut down would cause an immediate shutdown the next time it was started (basically the fix makes `Shutdown` idempotent). (#1877)
+
+## [1.0.0-pre.7] - 2022-04-06
+
+### Added
+- Added editor only check prior to entering into play mode if the currently open and active scene is in the build list and if not displays a dialog box asking the user if they would like to automatically add it prior to entering into play mode. (#1828)
+- Added `UnityTransport` implementation and `com.unity.transport` package dependency (#1823)
+- Added `NetworkVariableWritePermission` to `NetworkVariableBase` and implemented `Owner` client writable netvars. (#1762)
+- `UnityTransport` settings can now be set programmatically. (#1845)
+- `FastBufferWriter` and Reader IsInitialized property. (#1859)
+- Prefabs can now be added to the network at **runtime** (i.e., from an addressable asset). If `ForceSamePrefabs` is false, this can happen after a connection has been formed. (#1882)
+- When `ForceSamePrefabs` is false, a configurable delay (default 1 second, configurable via `NetworkConfig.SpawnTimeout`) has been introduced to gracefully handle race conditions where a spawn call has been received for an object whose prefab is still being loaded. (#1882)
+
+### Changed
+
+- Changed `NetcodeIntegrationTestHelpers` to use `UnityTransport` (#1870)
+- Updated `UnityTransport` dependency on `com.unity.transport` to 1.0.0 (#1849)
+
+### Removed
+
+- Removed `SnapshotSystem` (#1852)
+- Removed `com.unity.modules.animation`, `com.unity.modules.physics` and `com.unity.modules.physics2d` dependencies from the package (#1812)
+- Removed `com.unity.collections` dependency from the package (#1849)
+
+### Fixed
+
+- Fixed in-scene placed NetworkObjects not being found/ignored after a client disconnects and then reconnects. (#1850)
+- Fixed issue where `UnityTransport` send queues were not flushed when calling `DisconnectLocalClient` or `DisconnectRemoteClient`. (#1847)
+- Fixed NetworkBehaviour dependency verification check for an existing NetworkObject not searching from root parent transform relative GameObject. (#1841)
+- Fixed issue where entries were not being removed from the NetworkSpawnManager.OwnershipToObjectsTable. (#1838)
+- Fixed ClientRpcs would always send to all connected clients by default as opposed to only sending to the NetworkObject's Observers list by default. (#1836)
+- Fixed clarity for NetworkSceneManager client side notification when it receives a scene hash value that does not exist in its local hash table. (#1828)
+- Fixed client throws a key not found exception when it times out using UNet or UTP. (#1821)
+- Fixed network variable updates are no longer limited to 32,768 bytes when NetworkConfig.EnsureNetworkVariableLengthSafety is enabled. The limits are now determined by what the transport can send in a message. (#1811)
+- Fixed in-scene NetworkObjects get destroyed if a client fails to connect and shuts down the NetworkManager. (#1809)
+- Fixed user never being notified in the editor that a NetworkBehaviour requires a NetworkObject to function properly. (#1808)
+- Fixed PlayerObjects and dynamically spawned NetworkObjects not being added to the NetworkClient's OwnedObjects (#1801)
+- Fixed issue where NetworkManager would continue starting even if the NetworkTransport selected failed. (#1780)
+- Fixed issue when spawning new player if an already existing player exists it does not remove IsPlayer from the previous player (#1779)
+- Fixed lack of notification that NetworkManager and NetworkObject cannot be added to the same GameObject with in-editor notifications (#1777)
+- Fixed parenting warning printing for false positives (#1855)
+
+## [1.0.0-pre.6] - 2022-03-02
+
+### Added
+- NetworkAnimator now properly synchrhonizes all animation layers as well as runtime-adjusted weighting between them (#1765)
+- Added first set of tests for NetworkAnimator - parameter syncing, trigger set / reset, override network animator (#1735)
+
+### Fixed
+- Fixed an issue where sometimes the first client to connect to the server could see messages from the server as coming from itself. (#1683)
+- Fixed an issue where clients seemed to be able to send messages to ClientId 1, but these messages would actually still go to the server (id 0) instead of that client. (#1683)
+- Improved clarity of error messaging when a client attempts to send a message to a destination other than the server, which isn't allowed. (#1683)
+- Disallowed async keyword in RPCs (#1681)
+- Fixed an issue where Alpha release versions of Unity (version 2022.2.0a5 and later) will not compile due to the UNet Transport no longer existing (#1678)
+- Fixed messages larger than 64k being written with incorrectly truncated message size in header (#1686) (credit: @kaen)
+- Fixed overloading RPC methods causing collisions and failing on IL2CPP targets. (#1694)
+- Fixed spawn flow to propagate `IsSceneObject` down to children NetworkObjects, decouple implicit relationship between object spawning & `IsSceneObject` flag (#1685)
+- Fixed error when serializing ConnectionApprovalMessage with scene management disabled when one or more objects is hidden via the CheckObjectVisibility delegate (#1720)
+- Fixed CheckObjectVisibility delegate not being properly invoked for connecting clients when Scene Management is enabled. (#1680)
+- Fixed NetworkList to properly call INetworkSerializable's NetworkSerialize() method (#1682)
+- Fixed NetworkVariables containing more than 1300 bytes of data (such as large NetworkLists) no longer cause an OverflowException (the limit on data size is now whatever limit the chosen transport imposes on fragmented NetworkDelivery mechanisms) (#1725)
+- Fixed ServerRpcParams and ClientRpcParams must be the last parameter of an RPC in order to function properly. Added a compile-time check to ensure this is the case and trigger an error if they're placed elsewhere (#1721)
+- Fixed FastBufferReader being created with a length of 1 if provided an input of length 0 (#1724)
+- Fixed The NetworkConfig's checksum hash includes the NetworkTick so that clients with a different tickrate than the server are identified and not allowed to connect (#1728)
+- Fixed OwnedObjects not being properly modified when using ChangeOwnership (#1731)
+- Improved performance in NetworkAnimator (#1735)
+- Removed the "always sync" network animator (aka "autosend") parameters (#1746)
+- Fixed in-scene placed NetworkObjects not respawning after shutting down the NetworkManager and then starting it back up again (#1769)
+
+## [1.0.0-pre.5] - 2022-01-26
+
+### Added
+
+- Added `PreviousValue` in `NetworkListEvent`, when `Value` has changed (#1528)
+
+### Changed
+
+- NetworkManager's GameObject is no longer allowed to be nested under one or more GameObject(s).(#1484)
+- NetworkManager DontDestroy property was removed and now NetworkManager always is migrated into the DontDestroyOnLoad scene. (#1484)'
+
+### Fixed
+
+- Fixed network tick value sometimes being duplicated or skipped. (#1614)
+- Fixed The ClientNetworkTransform sample script to allow for owner changes at runtime. (#1606)
+- Fixed When the LogLevel is set to developer NetworkBehaviour generates warning messages when it should not (#1631)
+- Fixed NetworkTransport Initialize now can receive the associated NetworkManager instance to avoid using NetworkManager.Singleton in transport layer (#1677)
+- Fixed a bug where NetworkList.Contains value was inverted (#1363)
+
+## [1.0.0-pre.4] - 2021-01-04
+
+### Added
+
+- Added `com.unity.modules.physics` and `com.unity.modules.physics2d` package dependencies (#1565)
+
+### Removed
+
+- Removed `com.unity.modules.ai` package dependency (#1565)
+- Removed `FixedQueue`, `StreamExtensions`, `TypeExtensions` (#1398)
+
+### Fixed
+- Fixed in-scene NetworkObjects that are moved into the DDOL scene not getting restored to their original active state (enabled/disabled) after a full scene transition (#1354)
+- Fixed invalid IL code being generated when using `this` instead of `this ref` for the FastBufferReader/FastBufferWriter parameter of an extension method. (#1393)
+- Fixed an issue where if you are running as a server (not host) the LoadEventCompleted and UnloadEventCompleted events would fire early by the NetworkSceneManager (#1379)
+- Fixed a runtime error when sending an array of an INetworkSerializable type that's implemented as a struct (#1402)
+- NetworkConfig will no longer throw an OverflowException in GetConfig() when ForceSamePrefabs is enabled and the number of prefabs causes the config blob size to exceed 1300 bytes. (#1385)
+- Fixed NetworkVariable not calling NetworkSerialize on INetworkSerializable types (#1383)
+- Fixed NullReferenceException on ImportReferences call in NetworkBehaviourILPP (#1434)
+- Fixed NetworkObjects not being despawned before they are destroyed during shutdown for client, host, and server instances. (#1390)
+- Fixed KeyNotFound exception when removing ownership of a newly spawned NetworkObject that is already owned by the server. (#1500)
+- Fixed NetworkManager.LocalClient not being set when starting as a host. (#1511)
+- Fixed a few memory leak cases when shutting down NetworkManager during Incoming Message Queue processing. (#1323)
+- Fixed network tick value sometimes being duplicated or skipped. (#1614)
+
+### Changed
+- The SDK no longer limits message size to 64k. (The transport may still impose its own limits, but the SDK no longer does.) (#1384)
+- Updated com.unity.collections to 1.1.0 (#1451)
+- NetworkManager's GameObject is no longer allowed to be nested under one or more GameObject(s).(#1484)
+- NetworkManager DontDestroy property was removed and now NetworkManager always is migrated into the DontDestroyOnLoad scene. (#1484)
+
 ## [1.0.0-pre.3] - 2021-10-22
 
 ### Added

Components/Interpolator/BufferedLinearInterpolator.cs

@@ -4,13 +4,11 @@ using UnityEngine;
 
 namespace Unity.Netcode
 {
-
     /// <summary>
     /// Solves for incoming values that are jittered
     /// Partially solves for message loss. Unclamped lerping helps hide this, but not completely
     /// </summary>
-    /// <typeparam name="T"></typeparam>
+    public abstract class BufferedLinearInterpolator<T> where T : struct
-    internal abstract class BufferedLinearInterpolator<T> where T : struct
     {
         private struct BufferedItem
         {
@@ -24,6 +22,10 @@ namespace Unity.Netcode
             }
         }
 
+        /// <summary>
+        /// There’s two factors affecting interpolation: buffering (set in NetworkManager’s NetworkTimeSystem) and interpolation time, which is the amount of time it’ll take to reach the target. This is to affect the second one.
+        /// </summary>
+        public float MaximumInterpolationTime = 0.1f;
 
         private const double k_SmallValue = 9.999999439624929E-11; // copied from Vector3's equal operator
 
@@ -69,6 +71,19 @@ namespace Unity.Netcode
 
         private bool InvalidState => m_Buffer.Count == 0 && m_LifetimeConsumedCount == 0;
 
+        /// <summary>
+        /// Resets Interpolator to initial state
+        /// </summary>
+        public void Clear()
+        {
+            m_Buffer.Clear();
+            m_EndTimeConsumed = 0.0d;
+            m_StartTimeConsumed = 0.0d;
+        }
+
+        /// <summary>
+        /// Teleports current interpolation value to targetValue.
+        /// </summary>
         public void ResetTo(T targetValue, double serverTime)
         {
             m_LifetimeConsumedCount = 1;
@@ -82,7 +97,6 @@ namespace Unity.Netcode
             Update(0, serverTime, serverTime);
         }
 
-
         // todo if I have value 1, 2, 3 and I'm treating 1 to 3, I shouldn't interpolate between 1 and 3, I should interpolate from 1 to 2, then from 2 to 3 to get the best path
         private void TryConsumeFromBuffer(double renderTime, double serverTime)
         {
@@ -179,7 +193,14 @@ namespace Unity.Netcode
 
                     if (t < 0.0f)
                     {
-                        throw new OverflowException($"t = {t} but must be >= 0. range {range}, RenderTime {renderTime}, Start time {m_StartTimeConsumed}, end time {m_EndTimeConsumed}");
+                        // There is no mechanism to guarantee renderTime to not be before m_StartTimeConsumed
+                        // This clamps t to a minimum of 0 and fixes issues with longer frames and pauses
+
+                        if (NetworkLog.CurrentLogLevel <= LogLevel.Developer)
+                        {
+                            NetworkLog.LogError($"renderTime was before m_StartTimeConsumed. This should never happen. {nameof(renderTime)} is {renderTime}, {nameof(m_StartTimeConsumed)} is {m_StartTimeConsumed}");
+                        }
+                        t = 0.0f;
                     }
 
                     if (t > 3.0f) // max extrapolation
@@ -191,14 +212,16 @@ namespace Unity.Netcode
                 }
 
                 var target = InterpolateUnclamped(m_InterpStartValue, m_InterpEndValue, t);
-                float maxInterpTime = 0.1f;
+                m_CurrentInterpValue = Interpolate(m_CurrentInterpValue, target, deltaTime / MaximumInterpolationTime); // second interpolate to smooth out extrapolation jumps
-                m_CurrentInterpValue = Interpolate(m_CurrentInterpValue, target, deltaTime / maxInterpTime); // second interpolate to smooth out extrapolation jumps
             }
 
             m_NbItemsReceivedThisFrame = 0;
             return m_CurrentInterpValue;
         }
 
+        /// <summary>
+        /// Add measurements to be used during interpolation. These will be buffered before being made available to be displayed as "latest value".
+        /// </summary>
         public void AddMeasurement(T newMeasurement, double sentTime)
         {
             m_NbItemsReceivedThisFrame++;
@@ -211,6 +234,8 @@ namespace Unity.Netcode
                 {
                     m_LastBufferedItemReceived = new BufferedItem(newMeasurement, sentTime);
                     ResetTo(newMeasurement, sentTime);
+                    // Next line keeps renderTime above m_StartTimeConsumed. Fixes pause/unpause issues
+                    m_Buffer.Add(m_LastBufferedItemReceived);
                 }
 
                 return;
@@ -223,17 +248,25 @@ namespace Unity.Netcode
             }
         }
 
+        /// <summary>
+        /// Gets latest value from the interpolator. This is updated every update as time goes by.
+        /// </summary>
         public T GetInterpolatedValue()
         {
             return m_CurrentInterpValue;
         }
 
+        /// <summary>
+        /// Method to override and adapted to the generic type. This assumes interpolation for that value will be clamped.
+        /// </summary>
         protected abstract T Interpolate(T start, T end, float time);
+        /// <summary>
+        /// Method to override and adapted to the generic type. This assumes interpolation for that value will not be clamped.
+        /// </summary>
         protected abstract T InterpolateUnclamped(T start, T end, float time);
     }
 
-
+    public class BufferedLinearInterpolatorFloat : BufferedLinearInterpolator<float>
-    internal class BufferedLinearInterpolatorFloat : BufferedLinearInterpolator<float>
     {
         protected override float InterpolateUnclamped(float start, float end, float time)
         {
@@ -246,7 +279,7 @@ namespace Unity.Netcode
         }
     }
 
-    internal class BufferedLinearInterpolatorQuaternion : BufferedLinearInterpolator<Quaternion>
+    public class BufferedLinearInterpolatorQuaternion : BufferedLinearInterpolator<Quaternion>
     {
         protected override Quaternion InterpolateUnclamped(Quaternion start, Quaternion end, float time)
         {

Components/NetworkAnimator.cs

@@ -1,12 +1,12 @@
+#if COM_UNITY_MODULES_ANIMATION
 using Unity.Collections;
 using Unity.Collections.LowLevel.Unsafe;
-
 using UnityEngine;
 
 namespace Unity.Netcode.Components
 {
     /// <summary>
-    /// A prototype component for syncing animations
+    /// NetworkAnimator enables remote synchronization of <see cref="UnityEngine.Animator"/> state for on network objects.
     /// </summary>
     [AddComponentMenu("Netcode/" + nameof(NetworkAnimator))]
     [RequireComponent(typeof(Animator))]
@@ -14,32 +14,27 @@ namespace Unity.Netcode.Components
     {
         internal struct AnimationMessage : INetworkSerializable
         {
-            public int StateHash;      // if non-zero, then Play() this animation, skipping transitions
+            // state hash per layer.  if non-zero, then Play() this animation, skipping transitions
-            public float NormalizedTime;
+            internal int StateHash;
-            public byte[] Parameters;
+            internal float NormalizedTime;
+            internal int Layer;
+            internal float Weight;
+            internal byte[] Parameters;
 
             public void NetworkSerialize<T>(BufferSerializer<T> serializer) where T : IReaderWriter
             {
                 serializer.SerializeValue(ref StateHash);
                 serializer.SerializeValue(ref NormalizedTime);
-                serializer.SerializeValue(ref Parameters);
+                serializer.SerializeValue(ref Layer);
-            }
+                serializer.SerializeValue(ref Weight);
-        }
-
-        internal struct AnimationParametersMessage : INetworkSerializable
-        {
-            public byte[] Parameters;
-
-            public void NetworkSerialize<T>(BufferSerializer<T> serializer) where T : IReaderWriter
-            {
                 serializer.SerializeValue(ref Parameters);
             }
         }
 
         internal struct AnimationTriggerMessage : INetworkSerializable
         {
-            public int Hash;
+            internal int Hash;
-            public bool Reset;
+            internal bool Reset;
 
             public void NetworkSerialize<T>(BufferSerializer<T> serializer) where T : IReaderWriter
             {
@@ -49,8 +44,6 @@ namespace Unity.Netcode.Components
         }
 
         [SerializeField] private Animator m_Animator;
-        [SerializeField] private uint m_ParameterSendBits;
-        [SerializeField] private float m_SendRate = 0.1f;
 
         public Animator Animator
         {
@@ -58,61 +51,35 @@ namespace Unity.Netcode.Components
             set
             {
                 m_Animator = value;
-                ResetParameterOptions();
             }
         }
 
-        /* 
+        private bool m_SendMessagesAllowed = false;
-         * AutoSend is the ability to select which parameters linked to this animator 
-         * get replicated on a regular basis regardless of a state change. The thinking
-         * behind this is that many of the parameters people use are usually booleans 
-         * which result in a state change and thus would cause a full sync of state. 
-         * Thus if you really care about a parameter syncing then you need to be explict
-         * by selecting it in the inspector when an NetworkAnimator is selected.
-         */
-        public void SetParameterAutoSend(int index, bool value)
-        {
-            if (value)
-            {
-                m_ParameterSendBits |= (uint)(1 << index);
-            }
-            else
-            {
-                m_ParameterSendBits &= (uint)(~(1 << index));
-            }
-        }
-
-        public bool GetParameterAutoSend(int index)
-        {
-            return (m_ParameterSendBits & (uint)(1 << index)) != 0;
-        }
 
         // Animators only support up to 32 params
-        public static int K_MaxAnimationParams = 32;
+        private const int k_MaxAnimationParams = 32;
 
-        private int m_TransitionHash;
+        private int[] m_TransitionHash;
-        private double m_NextSendTime = 0.0f;
+        private int[] m_AnimationHash;
-
+        private float[] m_LayerWeights;
-        private int m_AnimationHash;
-        public int AnimationHash { get => m_AnimationHash; }
 
         private unsafe struct AnimatorParamCache
         {
-            public int Hash;
+            internal int Hash;
-            public int Type;
+            internal int Type;
-            public fixed byte Value[4]; // this is a max size of 4 bytes
+            internal fixed byte Value[4]; // this is a max size of 4 bytes
         }
 
-        // 128bytes per Animator 
+        // 128 bytes per Animator
-        private FastBufferWriter m_ParameterWriter = new FastBufferWriter(K_MaxAnimationParams * sizeof(float), Allocator.Persistent);
+        private FastBufferWriter m_ParameterWriter = new FastBufferWriter(k_MaxAnimationParams * sizeof(float), Allocator.Persistent);
         private NativeArray<AnimatorParamCache> m_CachedAnimatorParameters;
 
-        // We cache these values because UnsafeUtility.EnumToInt use direct IL that allows a nonboxing conversion
+        // We cache these values because UnsafeUtility.EnumToInt uses direct IL that allows a non-boxing conversion
         private struct AnimationParamEnumWrapper
         {
-            public static readonly int AnimatorControllerParameterInt;
+            internal static readonly int AnimatorControllerParameterInt;
-            public static readonly int AnimatorControllerParameterFloat;
+            internal static readonly int AnimatorControllerParameterFloat;
-            public static readonly int AnimatorControllerParameterBool;
+            internal static readonly int AnimatorControllerParameterBool;
 
             static AnimationParamEnumWrapper()
             {
@@ -122,25 +89,6 @@ namespace Unity.Netcode.Components
             }
         }
 
-        internal void ResetParameterOptions()
-        {
-
-            if (NetworkLog.CurrentLogLevel <= LogLevel.Developer)
-            {
-                NetworkLog.LogInfoServer("ResetParameterOptions");
-            }
-
-            m_ParameterSendBits = 0;
-        }
-
-        private bool sendMessagesAllowed
-        {
-            get
-            {
-                return IsServer && NetworkObject.IsSpawned;
-            }
-        }
-
         public override void OnDestroy()
         {
             if (m_CachedAnimatorParameters.IsCreated)
@@ -153,25 +101,36 @@ namespace Unity.Netcode.Components
 
         public override void OnNetworkSpawn()
         {
+            if (IsServer)
+            {
+                m_SendMessagesAllowed = true;
+                int layers = m_Animator.layerCount;
+
+                m_TransitionHash = new int[layers];
+                m_AnimationHash = new int[layers];
+                m_LayerWeights = new float[layers];
+            }
+
             var parameters = m_Animator.parameters;
             m_CachedAnimatorParameters = new NativeArray<AnimatorParamCache>(parameters.Length, Allocator.Persistent);
 
-            m_AnimationHash = -1;
-
             for (var i = 0; i < parameters.Length; i++)
             {
                 var parameter = parameters[i];
 
                 if (m_Animator.IsParameterControlledByCurve(parameter.nameHash))
                 {
-                    //we are ignoring parameters that are controlled by animation curves - syncing the layer states indirectly syncs the values that are driven by the animation curves
+                    // we are ignoring parameters that are controlled by animation curves - syncing the layer
+                    //  states indirectly syncs the values that are driven by the animation curves
                     continue;
                 }
 
-                var cacheParam = new AnimatorParamCache();
+                var cacheParam = new AnimatorParamCache
+                {
+                    Type = UnsafeUtility.EnumToInt(parameter.type),
+                    Hash = parameter.nameHash
+                };
 
-                cacheParam.Type = UnsafeUtility.EnumToInt(parameter.type);
-                cacheParam.Hash = parameter.nameHash;
                 unsafe
                 {
                     switch (parameter.type)
@@ -199,115 +158,100 @@ namespace Unity.Netcode.Components
             }
         }
 
+        public override void OnNetworkDespawn()
+        {
+            m_SendMessagesAllowed = false;
+        }
+
         private void FixedUpdate()
         {
-            if (!sendMessagesAllowed)
+            if (!m_SendMessagesAllowed || !m_Animator || !m_Animator.enabled)
             {
                 return;
             }
 
-            int stateHash;
+            for (int layer = 0; layer < m_Animator.layerCount; layer++)
-            float normalizedTime;
-            if (!CheckAnimStateChanged(out stateHash, out normalizedTime))
             {
-                // We only want to check and send if we don't have any other state to since
+                int stateHash;
-                // as we will sync all params as part of the state sync
+                float normalizedTime;
-                CheckAndSend();
+                if (!CheckAnimStateChanged(out stateHash, out normalizedTime, layer))
-
-                return;
-            }
-
-            var animMsg = new AnimationMessage();
-            animMsg.StateHash = stateHash;
-            animMsg.NormalizedTime = normalizedTime;
-
-            m_ParameterWriter.Seek(0);
-            m_ParameterWriter.Truncate();
-
-            WriteParameters(m_ParameterWriter, false);
-            animMsg.Parameters = m_ParameterWriter.ToArray();
-
-            SendAnimStateClientRpc(animMsg);
-        }
-
-        private void CheckAndSend()
-        {
-            var networkTime = NetworkManager.ServerTime.Time;
-            if (sendMessagesAllowed && m_SendRate != 0 && m_NextSendTime < networkTime)
-            {
-                m_NextSendTime = networkTime + m_SendRate;
-
-                m_ParameterWriter.Seek(0);
-                m_ParameterWriter.Truncate();
-
-                if (WriteParameters(m_ParameterWriter, true))
-                {
-                    // we then sync the params we care about
-                    var animMsg = new AnimationParametersMessage()
-                    {
-                        Parameters = m_ParameterWriter.ToArray()
-                    };
-
-                    SendParamsClientRpc(animMsg);
-                }
-            }
-        }
-
-        private bool CheckAnimStateChanged(out int stateHash, out float normalizedTime)
-        {
-            stateHash = 0;
-            normalizedTime = 0;
-
-            if (m_Animator.IsInTransition(0))
-            {
-                AnimatorTransitionInfo tt = m_Animator.GetAnimatorTransitionInfo(0);
-                if (tt.fullPathHash != m_TransitionHash)
-                {
-                    // first time in this transition
-                    m_TransitionHash = tt.fullPathHash;
-                    m_AnimationHash = 0;
-                    return true;
-                }
-                return false;
-            }
-
-            AnimatorStateInfo st = m_Animator.GetCurrentAnimatorStateInfo(0);
-            if (st.fullPathHash != m_AnimationHash)
-            {
-                // first time in this animation state
-                if (m_AnimationHash != 0)
-                {
-                    // came from another animation directly - from Play()
-                    stateHash = st.fullPathHash;
-                    normalizedTime = st.normalizedTime;
-                }
-                m_TransitionHash = 0;
-                m_AnimationHash = st.fullPathHash;
-                return true;
-            }
-            return false;
-        }
-
-        /* $AS TODO: Right now we are not checking for changed values this is because
-        the read side of this function doesn't have similar logic which would cause
-        an overflow read because it doesn't know if the value is there or not. So 
-        there needs to be logic to track which indexes changed in order for there 
-        to be proper value change checking. Will revist in 1.1.0.
-        */
-        private unsafe bool WriteParameters(FastBufferWriter writer, bool autoSend)
-        {
-            if (m_CachedAnimatorParameters == null)
-            {
-                return false;
-            }
-
-            for (int i = 0; i < m_CachedAnimatorParameters.Length; i++)
-            {
-                if (autoSend && !GetParameterAutoSend(i))
                 {
                     continue;
                 }
 
+                var animMsg = new AnimationMessage
+                {
+                    StateHash = stateHash,
+                    NormalizedTime = normalizedTime,
+                    Layer = layer,
+                    Weight = m_LayerWeights[layer]
+                };
+
+                m_ParameterWriter.Seek(0);
+                m_ParameterWriter.Truncate();
+
+                WriteParameters(m_ParameterWriter);
+                animMsg.Parameters = m_ParameterWriter.ToArray();
+
+                SendAnimStateClientRpc(animMsg);
+            }
+        }
+
+        private bool CheckAnimStateChanged(out int stateHash, out float normalizedTime, int layer)
+        {
+            bool shouldUpdate = false;
+            stateHash = 0;
+            normalizedTime = 0;
+
+            float layerWeightNow = m_Animator.GetLayerWeight(layer);
+
+            if (!Mathf.Approximately(layerWeightNow, m_LayerWeights[layer]))
+            {
+                m_LayerWeights[layer] = layerWeightNow;
+                shouldUpdate = true;
+            }
+            if (m_Animator.IsInTransition(layer))
+            {
+                AnimatorTransitionInfo tt = m_Animator.GetAnimatorTransitionInfo(layer);
+                if (tt.fullPathHash != m_TransitionHash[layer])
+                {
+                    // first time in this transition for this layer
+                    m_TransitionHash[layer] = tt.fullPathHash;
+                    m_AnimationHash[layer] = 0;
+                    shouldUpdate = true;
+                }
+            }
+            else
+            {
+                AnimatorStateInfo st = m_Animator.GetCurrentAnimatorStateInfo(layer);
+                if (st.fullPathHash != m_AnimationHash[layer])
+                {
+                    // first time in this animation state
+                    if (m_AnimationHash[layer] != 0)
+                    {
+                        // came from another animation directly - from Play()
+                        stateHash = st.fullPathHash;
+                        normalizedTime = st.normalizedTime;
+                    }
+                    m_TransitionHash[layer] = 0;
+                    m_AnimationHash[layer] = st.fullPathHash;
+                    shouldUpdate = true;
+                }
+            }
+
+            return shouldUpdate;
+        }
+
+        /* $AS TODO: Right now we are not checking for changed values this is because
+        the read side of this function doesn't have similar logic which would cause
+        an overflow read because it doesn't know if the value is there or not. So
+        there needs to be logic to track which indexes changed in order for there
+        to be proper value change checking. Will revist in 1.1.0.
+        */
+        private unsafe void WriteParameters(FastBufferWriter writer)
+        {
+            for (int i = 0; i < m_CachedAnimatorParameters.Length; i++)
+            {
                 ref var cacheValue = ref UnsafeUtility.ArrayElementAsRef<AnimatorParamCache>(m_CachedAnimatorParameters.GetUnsafePtr(), i);
                 var hash = cacheValue.Hash;
 
@@ -340,24 +284,12 @@ namespace Unity.Netcode.Components
                     }
                 }
             }
-
-            // If we do not write any values to the writer then we should not send any data
-            return writer.Length > 0;
         }
 
-        private unsafe void ReadParameters(FastBufferReader reader, bool autoSend)
+        private unsafe void ReadParameters(FastBufferReader reader)
         {
-            if (m_CachedAnimatorParameters == null)
-            {
-                return;
-            }
-
             for (int i = 0; i < m_CachedAnimatorParameters.Length; i++)
             {
-                if (autoSend && !GetParameterAutoSend(i))
-                {
-                    continue;
-                }
                 ref var cacheValue = ref UnsafeUtility.ArrayElementAsRef<AnimatorParamCache>(m_CachedAnimatorParameters.GetUnsafePtr(), i);
                 var hash = cacheValue.Hash;
 
@@ -391,28 +323,20 @@ namespace Unity.Netcode.Components
             }
         }
 
-        [ClientRpc]
+        /// <summary>
-        private unsafe void SendParamsClientRpc(AnimationParametersMessage animSnapshot, ClientRpcParams clientRpcParams = default)
+        /// Internally-called RPC client receiving function to update some animation parameters on a client when
-        {
+        ///   the server wants to update them
-            if (animSnapshot.Parameters != null)
+        /// </summary>
-            {
+        /// <param name="animSnapshot">the payload containing the parameters to apply</param>
-                // We use a fixed value here to avoid the copy of data from the byte buffer since we own the data
+        /// <param name="clientRpcParams">unused</param>
-                fixed (byte* parameters = animSnapshot.Parameters)
-                {
-                    var reader = new FastBufferReader(parameters, Allocator.None, animSnapshot.Parameters.Length);
-                    ReadParameters(reader, true);
-                }
-            }
-        }
-
         [ClientRpc]
         private unsafe void SendAnimStateClientRpc(AnimationMessage animSnapshot, ClientRpcParams clientRpcParams = default)
         {
             if (animSnapshot.StateHash != 0)
             {
-                m_AnimationHash = animSnapshot.StateHash;
+                m_Animator.Play(animSnapshot.StateHash, animSnapshot.Layer, animSnapshot.NormalizedTime);
-                m_Animator.Play(animSnapshot.StateHash, 0, animSnapshot.NormalizedTime);
             }
+            m_Animator.SetLayerWeight(animSnapshot.Layer, animSnapshot.Weight);
 
             if (animSnapshot.Parameters != null && animSnapshot.Parameters.Length != 0)
             {
@@ -420,11 +344,17 @@ namespace Unity.Netcode.Components
                 fixed (byte* parameters = animSnapshot.Parameters)
                 {
                     var reader = new FastBufferReader(parameters, Allocator.None, animSnapshot.Parameters.Length);
-                    ReadParameters(reader, false);
+                    ReadParameters(reader);
                 }
             }
         }
 
+        /// <summary>
+        /// Internally-called RPC client receiving function to update a trigger when the server wants to forward
+        ///   a trigger for a client to play / reset
+        /// </summary>
+        /// <param name="animSnapshot">the payload containing the trigger data to apply</param>
+        /// <param name="clientRpcParams">unused</param>
         [ClientRpc]
         private void SendAnimTriggerClientRpc(AnimationTriggerMessage animSnapshot, ClientRpcParams clientRpcParams = default)
         {
@@ -438,11 +368,22 @@ namespace Unity.Netcode.Components
             }
         }
 
+        /// <summary>
+        /// Sets the trigger for the associated animation
+        ///  Note, triggers are special vs other kinds of parameters.  For all the other parameters we watch for changes
+        ///  in FixedUpdate and users can just set them normally off of Animator. But because triggers are transitory
+        ///  and likely to come and go between FixedUpdate calls, we require users to set them here to guarantee us to
+        ///  catch it...then we forward it to the Animator component
+        /// </summary>
+        /// <param name="triggerName">The string name of the trigger to activate</param>
         public void SetTrigger(string triggerName)
         {
             SetTrigger(Animator.StringToHash(triggerName));
         }
 
+        /// <inheritdoc cref="SetTrigger(string)" />
+        /// <param name="hash">The hash for the trigger to activate</param>
+        /// <param name="reset">If true, resets the trigger</param>
         public void SetTrigger(int hash, bool reset = false)
         {
             var animMsg = new AnimationTriggerMessage();
@@ -451,18 +392,40 @@ namespace Unity.Netcode.Components
 
             if (IsServer)
             {
+                //  trigger the animation locally on the server...
+                if (reset)
+                {
+                    m_Animator.ResetTrigger(hash);
+                }
+                else
+                {
+                    m_Animator.SetTrigger(hash);
+                }
+
+                // ...then tell all the clients to do the same
                 SendAnimTriggerClientRpc(animMsg);
             }
+            else
+            {
+                Debug.LogWarning("Trying to call NetworkAnimator.SetTrigger on a client...ignoring");
+            }
         }
 
+        /// <summary>
+        /// Resets the trigger for the associated animation.  See <see cref="SetTrigger(string)">SetTrigger</see> for more on how triggers are special
+        /// </summary>
+        /// <param name="triggerName">The string name of the trigger to reset</param>
         public void ResetTrigger(string triggerName)
         {
             ResetTrigger(Animator.StringToHash(triggerName));
         }
 
+        /// <inheritdoc cref="ResetTrigger(string)" path="summary" />
+        /// <param name="hash">The hash for the trigger to activate</param>
         public void ResetTrigger(int hash)
         {
             SetTrigger(hash, true);
         }
     }
 }
+#endif // COM_UNITY_MODULES_ANIMATION

Components/NetworkRigidbody.cs

@@ -1,80 +1,102 @@
+#if COM_UNITY_MODULES_PHYSICS
 using UnityEngine;
 
 namespace Unity.Netcode.Components
 {
     /// <summary>
     /// NetworkRigidbody allows for the use of <see cref="Rigidbody"/> on network objects. By controlling the kinematic
-    /// mode of the rigidbody and disabling it on all peers but the authoritative one.
+    /// mode of the <see cref="Rigidbody"/> and disabling it on all peers but the authoritative one.
     /// </summary>
     [RequireComponent(typeof(Rigidbody))]
     [RequireComponent(typeof(NetworkTransform))]
     public class NetworkRigidbody : NetworkBehaviour
     {
+        /// <summary>
+        /// Determines if we are server (true) or owner (false) authoritative
+        /// </summary>
+        private bool m_IsServerAuthoritative;
+
         private Rigidbody m_Rigidbody;
         private NetworkTransform m_NetworkTransform;
-
-        private bool m_OriginalKinematic;
         private RigidbodyInterpolation m_OriginalInterpolation;
 
-        // Used to cache the authority state of this rigidbody during the last frame
+        // Used to cache the authority state of this Rigidbody during the last frame
         private bool m_IsAuthority;
 
-        /// <summary>
-        /// Gets a bool value indicating whether this <see cref="NetworkRigidbody"/> on this peer currently holds authority.
-        /// </summary>
-        private bool HasAuthority => m_NetworkTransform.CanCommitToTransform;
-
         private void Awake()
         {
-            m_Rigidbody = GetComponent<Rigidbody>();
             m_NetworkTransform = GetComponent<NetworkTransform>();
+            m_IsServerAuthoritative = m_NetworkTransform.IsServerAuthoritative();
+
+            m_Rigidbody = GetComponent<Rigidbody>();
+            m_OriginalInterpolation = m_Rigidbody.interpolation;
+
+            // Set interpolation to none if NetworkTransform is handling interpolation, otherwise it sets it to the original value
+            m_Rigidbody.interpolation = m_NetworkTransform.Interpolate ? RigidbodyInterpolation.None : m_OriginalInterpolation;
+
+            // Turn off physics for the rigid body until spawned, otherwise
+            // clients can run fixed update before the first full
+            // NetworkTransform update
+            m_Rigidbody.isKinematic = true;
         }
 
-        private void FixedUpdate()
+        /// <summary>
+        /// For owner authoritative (i.e. ClientNetworkTransform)
+        /// we adjust our authority when we gain ownership
+        /// </summary>
+        public override void OnGainedOwnership()
         {
-            if (NetworkManager.IsListening)
+            UpdateOwnershipAuthority();
-            {
-                if (HasAuthority != m_IsAuthority)
-                {
-                    m_IsAuthority = HasAuthority;
-                    UpdateRigidbodyKinematicMode();
-                }
-            }
         }
 
-        // Puts the rigidbody in a kinematic non-interpolated mode on everyone but the server.
+        /// <summary>
-        private void UpdateRigidbodyKinematicMode()
+        /// For owner authoritative(i.e. ClientNetworkTransform)
+        /// we adjust our authority when we have lost ownership
+        /// </summary>
+        public override void OnLostOwnership()
         {
-            if (m_IsAuthority == false)
+            UpdateOwnershipAuthority();
-            {
+        }
-                m_OriginalKinematic = m_Rigidbody.isKinematic;
-                m_Rigidbody.isKinematic = true;
 
-                m_OriginalInterpolation = m_Rigidbody.interpolation;
+        /// <summary>
-                // Set interpolation to none, the NetworkTransform component interpolates the position of the object.
+        /// Sets the authority differently depending upon
-                m_Rigidbody.interpolation = RigidbodyInterpolation.None;
+        /// whether it is server or owner authoritative
+        /// </summary>
+        private void UpdateOwnershipAuthority()
+        {
+            if (m_IsServerAuthoritative)
+            {
+                m_IsAuthority = NetworkManager.IsServer;
             }
             else
             {
-                // Resets the rigidbody back to it's non replication only state. Happens on shutdown and when authority is lost
+                m_IsAuthority = IsOwner;
-                m_Rigidbody.isKinematic = m_OriginalKinematic;
-                m_Rigidbody.interpolation = m_OriginalInterpolation;
             }
+
+            // If you have authority then you are not kinematic
+            m_Rigidbody.isKinematic = !m_IsAuthority;
+
+            // Set interpolation of the Rigidbody based on authority
+            // With authority: let local transform handle interpolation
+            // Without authority: let the NetworkTransform handle interpolation
+            m_Rigidbody.interpolation = m_IsAuthority ? m_OriginalInterpolation : RigidbodyInterpolation.None;
         }
 
         /// <inheritdoc />
         public override void OnNetworkSpawn()
         {
-            m_IsAuthority = HasAuthority;
+            UpdateOwnershipAuthority();
-            m_OriginalKinematic = m_Rigidbody.isKinematic;
-            m_OriginalInterpolation = m_Rigidbody.interpolation;
-            UpdateRigidbodyKinematicMode();
         }
 
         /// <inheritdoc />
         public override void OnNetworkDespawn()
         {
-            UpdateRigidbodyKinematicMode();
+            m_Rigidbody.interpolation = m_OriginalInterpolation;
+            // Turn off physics for the rigid body until spawned, otherwise
+            // non-owners can run fixed updates before the first full
+            // NetworkTransform update and physics will be applied (i.e. gravity, etc)
+            m_Rigidbody.isKinematic = true;
         }
     }
 }
+#endif // COM_UNITY_MODULES_PHYSICS

Components/NetworkRigidbody2D.cs

@@ -1,3 +1,4 @@
+#if COM_UNITY_MODULES_PHYSICS2D
 using UnityEngine;
 
 namespace Unity.Netcode.Components
@@ -32,7 +33,7 @@ namespace Unity.Netcode.Components
 
         private void FixedUpdate()
         {
-            if (NetworkManager.IsListening)
+            if (IsSpawned)
             {
                 if (HasAuthority != m_IsAuthority)
                 {
@@ -74,8 +75,8 @@ namespace Unity.Netcode.Components
         /// <inheritdoc />
         public override void OnNetworkDespawn()
         {
-            m_IsAuthority = false;
             UpdateRigidbodyKinematicMode();
         }
     }
 }
+#endif // COM_UNITY_MODULES_PHYSICS2D

Components/NetworkTransform.cs

@@ -15,9 +15,10 @@ namespace Unity.Netcode.Components
     [DefaultExecutionOrder(100000)] // this is needed to catch the update time after the transform was updated by user scripts
     public class NetworkTransform : NetworkBehaviour
     {
-        public const float PositionThresholdDefault = .001f;
+        public const float PositionThresholdDefault = 0.001f;
-        public const float RotAngleThresholdDefault = .01f;
+        public const float RotAngleThresholdDefault = 0.01f;
-        public const float ScaleThresholdDefault = .01f;
+        public const float ScaleThresholdDefault = 0.01f;
+
         public delegate (Vector3 pos, Quaternion rotOut, Vector3 scale) OnClientRequestChangeDelegate(Vector3 pos, Quaternion rot, Vector3 scale);
         public OnClientRequestChangeDelegate OnClientRequestChange;
 
@@ -38,7 +39,7 @@ namespace Unity.Netcode.Components
             // 11-15: <unused>
             private ushort m_Bitset;
 
-            public bool InLocalSpace
+            internal bool InLocalSpace
             {
                 get => (m_Bitset & (1 << k_InLocalSpaceBit)) != 0;
                 set
@@ -49,7 +50,7 @@ namespace Unity.Netcode.Components
             }
 
             // Position
-            public bool HasPositionX
+            internal bool HasPositionX
             {
                 get => (m_Bitset & (1 << k_PositionXBit)) != 0;
                 set
@@ -59,7 +60,7 @@ namespace Unity.Netcode.Components
                 }
             }
 
-            public bool HasPositionY
+            internal bool HasPositionY
             {
                 get => (m_Bitset & (1 << k_PositionYBit)) != 0;
                 set
@@ -69,7 +70,7 @@ namespace Unity.Netcode.Components
                 }
             }
 
-            public bool HasPositionZ
+            internal bool HasPositionZ
             {
                 get => (m_Bitset & (1 << k_PositionZBit)) != 0;
                 set
@@ -80,7 +81,7 @@ namespace Unity.Netcode.Components
             }
 
             // RotAngles
-            public bool HasRotAngleX
+            internal bool HasRotAngleX
             {
                 get => (m_Bitset & (1 << k_RotAngleXBit)) != 0;
                 set
@@ -90,7 +91,7 @@ namespace Unity.Netcode.Components
                 }
             }
 
-            public bool HasRotAngleY
+            internal bool HasRotAngleY
             {
                 get => (m_Bitset & (1 << k_RotAngleYBit)) != 0;
                 set
@@ -100,7 +101,7 @@ namespace Unity.Netcode.Components
                 }
             }
 
-            public bool HasRotAngleZ
+            internal bool HasRotAngleZ
             {
                 get => (m_Bitset & (1 << k_RotAngleZBit)) != 0;
                 set
@@ -111,7 +112,7 @@ namespace Unity.Netcode.Components
             }
 
             // Scale
-            public bool HasScaleX
+            internal bool HasScaleX
             {
                 get => (m_Bitset & (1 << k_ScaleXBit)) != 0;
                 set
@@ -121,7 +122,7 @@ namespace Unity.Netcode.Components
                 }
             }
 
-            public bool HasScaleY
+            internal bool HasScaleY
             {
                 get => (m_Bitset & (1 << k_ScaleYBit)) != 0;
                 set
@@ -131,7 +132,7 @@ namespace Unity.Netcode.Components
                 }
             }
 
-            public bool HasScaleZ
+            internal bool HasScaleZ
             {
                 get => (m_Bitset & (1 << k_ScaleZBit)) != 0;
                 set
@@ -141,7 +142,7 @@ namespace Unity.Netcode.Components
                 }
             }
 
-            public bool IsTeleportingNextFrame
+            internal bool IsTeleportingNextFrame
             {
                 get => (m_Bitset & (1 << k_TeleportingBit)) != 0;
                 set
@@ -151,12 +152,12 @@ namespace Unity.Netcode.Components
                 }
             }
 
-            public float PositionX, PositionY, PositionZ;
+            internal float PositionX, PositionY, PositionZ;
-            public float RotAngleX, RotAngleY, RotAngleZ;
+            internal float RotAngleX, RotAngleY, RotAngleZ;
-            public float ScaleX, ScaleY, ScaleZ;
+            internal float ScaleX, ScaleY, ScaleZ;
-            public double SentTime;
+            internal double SentTime;
 
-            public Vector3 Position
+            internal Vector3 Position
             {
                 get { return new Vector3(PositionX, PositionY, PositionZ); }
                 set
@@ -167,7 +168,7 @@ namespace Unity.Netcode.Components
                 }
             }
 
-            public Vector3 Rotation
+            internal Vector3 Rotation
             {
                 get { return new Vector3(RotAngleX, RotAngleY, RotAngleZ); }
                 set
@@ -178,7 +179,7 @@ namespace Unity.Netcode.Components
                 }
             }
 
-            public Vector3 Scale
+            internal Vector3 Scale
             {
                 get { return new Vector3(ScaleX, ScaleY, ScaleZ); }
                 set
@@ -249,7 +250,10 @@ namespace Unity.Netcode.Components
         public bool SyncScaleX = true, SyncScaleY = true, SyncScaleZ = true;
 
         public float PositionThreshold = PositionThresholdDefault;
+
+        [Range(0.001f, 360.0f)]
         public float RotAngleThreshold = RotAngleThresholdDefault;
+
         public float ScaleThreshold = ScaleThresholdDefault;
 
         /// <summary>
@@ -260,8 +264,10 @@ namespace Unity.Netcode.Components
         /// </summary>
         [Tooltip("Sets whether this transform should sync in local space or in world space")]
         public bool InLocalSpace = false;
+        private bool m_LastInterpolateLocal = false; // was the last frame local
 
         public bool Interpolate = true;
+        private bool m_LastInterpolate = true; // was the last frame interpolated
 
         /// <summary>
         /// Used to determine who can write to this transform. Server only for this transform.
@@ -270,7 +276,7 @@ namespace Unity.Netcode.Components
         /// If using different values, please use RPCs to write to the server. Netcode doesn't support client side network variable writing
         /// </summary>
         // This is public to make sure that users don't depend on this IsClient && IsOwner check in their code. If this logic changes in the future, we can make it invisible here
-        public bool CanCommitToTransform;
+        public bool CanCommitToTransform { get; protected set; }
         protected bool m_CachedIsServer;
         protected NetworkManager m_CachedNetworkManager;
 
@@ -278,8 +284,6 @@ namespace Unity.Netcode.Components
 
         private NetworkTransformState m_LocalAuthoritativeNetworkState;
 
-        private NetworkTransformState m_PrevNetworkState;
-
         private const int k_DebugDrawLineTime = 10;
 
         private bool m_HasSentLastValue = false; // used to send one last value, so clients can make the difference between lost replication data (clients extrapolate) and no more data to send.
@@ -367,7 +371,11 @@ namespace Unity.Netcode.Components
         private void CommitLocallyAndReplicate(NetworkTransformState networkState)
         {
             m_ReplicatedNetworkState.Value = networkState;
-            AddInterpolatedState(networkState);
+
+            if (Interpolate)
+            {
+                AddInterpolatedState(networkState);
+            }
         }
 
         private void ResetInterpolatedStateToCurrentAuthoritativeState()
@@ -384,6 +392,16 @@ namespace Unity.Netcode.Components
             m_ScaleZInterpolator.ResetTo(m_LocalAuthoritativeNetworkState.ScaleZ, serverTime);
         }
 
+        /// <summary>
+        /// Will apply the transform to the LocalAuthoritativeNetworkState and get detailed isDirty information returned.
+        /// </summary>
+        /// <param name="transform">transform to apply</param>
+        /// <returns>bool isDirty, bool isPositionDirty, bool isRotationDirty, bool isScaleDirty</returns>
+        internal (bool isDirty, bool isPositionDirty, bool isRotationDirty, bool isScaleDirty) ApplyLocalNetworkState(Transform transform)
+        {
+            return ApplyTransformToNetworkStateWithInfo(ref m_LocalAuthoritativeNetworkState, m_CachedNetworkManager.LocalTime.Time, transform);
+        }
+
         // updates `NetworkState` properties if they need to and returns a `bool` indicating whether or not there was any changes made
         // returned boolean would be useful to change encapsulating `NetworkVariable<NetworkState>`'s dirty state, e.g. ReplNetworkState.SetDirty(isDirty);
         internal bool ApplyTransformToNetworkState(ref NetworkTransformState networkState, double dirtyTime, Transform transformToUse)
@@ -444,7 +462,7 @@ namespace Unity.Netcode.Components
             }
 
             if (SyncRotAngleX &&
-                Mathf.Abs(networkState.RotAngleX - rotAngles.x) > RotAngleThreshold)
+                Mathf.Abs(Mathf.DeltaAngle(networkState.RotAngleX, rotAngles.x)) > RotAngleThreshold)
             {
                 networkState.RotAngleX = rotAngles.x;
                 networkState.HasRotAngleX = true;
@@ -452,7 +470,7 @@ namespace Unity.Netcode.Components
             }
 
             if (SyncRotAngleY &&
-                Mathf.Abs(networkState.RotAngleY - rotAngles.y) > RotAngleThreshold)
+                Mathf.Abs(Mathf.DeltaAngle(networkState.RotAngleY, rotAngles.y)) > RotAngleThreshold)
             {
                 networkState.RotAngleY = rotAngles.y;
                 networkState.HasRotAngleY = true;
@@ -460,7 +478,7 @@ namespace Unity.Netcode.Components
             }
 
             if (SyncRotAngleZ &&
-                Mathf.Abs(networkState.RotAngleZ - rotAngles.z) > RotAngleThreshold)
+                Mathf.Abs(Mathf.DeltaAngle(networkState.RotAngleZ, rotAngles.z)) > RotAngleThreshold)
             {
                 networkState.RotAngleZ = rotAngles.z;
                 networkState.HasRotAngleZ = true;
@@ -503,8 +521,6 @@ namespace Unity.Netcode.Components
 
         private void ApplyInterpolatedNetworkStateToTransform(NetworkTransformState networkState, Transform transformToUpdate)
         {
-            m_PrevNetworkState = networkState;
-
             var interpolatedPosition = InLocalSpace ? transformToUpdate.localPosition : transformToUpdate.position;
 
             // todo: we should store network state w/ quats vs. euler angles
@@ -532,7 +548,12 @@ namespace Unity.Netcode.Components
             // again, we should be using quats here
             if (SyncRotAngleX || SyncRotAngleY || SyncRotAngleZ)
             {
-                var eulerAngles = m_RotationInterpolator.GetInterpolatedValue().eulerAngles;
+                var eulerAngles = new Vector3();
+                if (Interpolate)
+                {
+                    eulerAngles = m_RotationInterpolator.GetInterpolatedValue().eulerAngles;
+                }
+
                 if (SyncRotAngleX)
                 {
                     interpolatedRotAngles.x = networkState.IsTeleportingNextFrame || !Interpolate ? networkState.Rotation.x : eulerAngles.x;
@@ -576,8 +597,6 @@ namespace Unity.Netcode.Components
                 {
                     transformToUpdate.position = interpolatedPosition;
                 }
-
-                m_PrevNetworkState.Position = interpolatedPosition;
             }
 
             // RotAngles Apply
@@ -591,22 +610,55 @@ namespace Unity.Netcode.Components
                 {
                     transformToUpdate.rotation = Quaternion.Euler(interpolatedRotAngles);
                 }
-
-                m_PrevNetworkState.Rotation = interpolatedRotAngles;
             }
 
             // Scale Apply
             if (SyncScaleX || SyncScaleY || SyncScaleZ)
             {
                 transformToUpdate.localScale = interpolatedScale;
-                m_PrevNetworkState.Scale = interpolatedScale;
             }
         }
 
-        private void AddInterpolatedState(NetworkTransformState newState)
+        private void AddInterpolatedState(NetworkTransformState newState, bool reset = false)
         {
             var sentTime = newState.SentTime;
 
+            if (reset)
+            {
+                if (newState.HasPositionX)
+                {
+                    m_PositionXInterpolator.ResetTo(newState.PositionX, sentTime);
+                }
+
+                if (newState.HasPositionY)
+                {
+                    m_PositionYInterpolator.ResetTo(newState.PositionY, sentTime);
+                }
+
+                if (newState.HasPositionZ)
+                {
+                    m_PositionZInterpolator.ResetTo(newState.PositionZ, sentTime);
+                }
+
+                m_RotationInterpolator.ResetTo(Quaternion.Euler(newState.Rotation), sentTime);
+
+                if (newState.HasScaleX)
+                {
+                    m_ScaleXInterpolator.ResetTo(newState.ScaleX, sentTime);
+                }
+
+                if (newState.HasScaleY)
+                {
+                    m_ScaleYInterpolator.ResetTo(newState.ScaleY, sentTime);
+                }
+
+                if (newState.HasScaleZ)
+                {
+                    m_ScaleZInterpolator.ResetTo(newState.ScaleZ, sentTime);
+                }
+
+                return;
+            }
             if (newState.HasPositionX)
             {
                 m_PositionXInterpolator.AddMeasurement(newState.PositionX, sentTime);
@@ -644,7 +696,6 @@ namespace Unity.Netcode.Components
         {
             if (!NetworkObject.IsSpawned)
             {
-                // todo MTT-849 should never happen but yet it does! maybe revisit/dig after NetVar updates and snapshot system lands?
                 return;
             }
 
@@ -656,7 +707,11 @@ namespace Unity.Netcode.Components
 
             Debug.DrawLine(newState.Position, newState.Position + Vector3.up + Vector3.left, Color.green, 10, false);
 
-            AddInterpolatedState(newState);
+            if (Interpolate)
+            {
+                AddInterpolatedState(newState, (newState.InLocalSpace != m_LastInterpolateLocal));
+            }
+            m_LastInterpolateLocal = newState.InLocalSpace;
 
             if (m_CachedNetworkManager.LogLevel == LogLevel.Developer)
             {
@@ -734,14 +789,12 @@ namespace Unity.Netcode.Components
             {
                 m_ReplicatedNetworkState.SetDirty(true);
             }
-            else
+            else if (m_Transform != null)
             {
                 ApplyInterpolatedNetworkStateToTransform(m_ReplicatedNetworkState.Value, m_Transform);
             }
         }
 
-        #region state set
-
         /// <summary>
         /// Directly sets a state on the authoritative transform.
         /// This will override any changes made previously to the transform
@@ -801,25 +854,33 @@ namespace Unity.Netcode.Components
             m_Transform.localScale = scale;
             m_LocalAuthoritativeNetworkState.IsTeleportingNextFrame = shouldTeleport;
         }
-        #endregion
 
         // todo this is currently in update, to be able to catch any transform changes. A FixedUpdate mode could be added to be less intense, but it'd be
         // conditional to users only making transform update changes in FixedUpdate.
         protected virtual void Update()
         {
-            if (!NetworkObject.IsSpawned)
+            if (!IsSpawned)
             {
                 return;
             }
 
+            if (!Interpolate && m_LastInterpolate)
+            {
+                // if we just stopped interpolating, let's clear the interpolators
+                foreach (var interpolator in m_AllFloatInterpolators)
+                {
+                    interpolator.Clear();
+                }
+            }
+
+            m_LastInterpolate = Interpolate;
+
             if (CanCommitToTransform)
             {
                 if (m_CachedIsServer)
                 {
                     TryCommitTransformToServer(m_Transform, m_CachedNetworkManager.LocalTime.Time);
                 }
-
-                m_PrevNetworkState = m_LocalAuthoritativeNetworkState;
             }
 
             // apply interpolated value
@@ -831,45 +892,22 @@ namespace Unity.Netcode.Components
                 var cachedServerTime = serverTime.Time;
                 var cachedRenderTime = serverTime.TimeTicksAgo(1).Time;
 
-                foreach (var interpolator in m_AllFloatInterpolators)
+                if (Interpolate)
                 {
-                    interpolator.Update(cachedDeltaTime, cachedRenderTime, cachedServerTime);
+                    foreach (var interpolator in m_AllFloatInterpolators)
-                }
+                    {
+                        interpolator.Update(cachedDeltaTime, cachedRenderTime, cachedServerTime);
+                    }
 
-                m_RotationInterpolator.Update(cachedDeltaTime, cachedRenderTime, cachedServerTime);
+                    m_RotationInterpolator.Update(cachedDeltaTime, cachedRenderTime, cachedServerTime);
+                }
 
                 if (!CanCommitToTransform)
                 {
-#if NGO_TRANSFORM_DEBUG
-                    if (m_CachedNetworkManager.LogLevel == LogLevel.Developer)
-                    {
-                        // TODO: This should be a component gizmo - not some debug draw based on log level
-                        var interpolatedPosition = new Vector3(m_PositionXInterpolator.GetInterpolatedValue(), m_PositionYInterpolator.GetInterpolatedValue(), m_PositionZInterpolator.GetInterpolatedValue());
-                        Debug.DrawLine(interpolatedPosition, interpolatedPosition + Vector3.up, Color.magenta, k_DebugDrawLineTime, false);
-
-                        // try to update previously consumed NetworkState
-                        // if we have any changes, that means made some updates locally
-                        // we apply the latest ReplNetworkState again to revert our changes
-                        var oldStateDirtyInfo = ApplyTransformToNetworkStateWithInfo(ref m_PrevNetworkState, 0, m_Transform);
-
-                        // there are several bugs in this code, as we the message is dumped out under odd circumstances
-                        //  For Matt, it would trigger when an object's rotation was perturbed by colliding with another
-                        //  object vs. explicitly rotating it
-                        if (oldStateDirtyInfo.isPositionDirty || oldStateDirtyInfo.isScaleDirty || (oldStateDirtyInfo.isRotationDirty && SyncRotAngleX && SyncRotAngleY && SyncRotAngleZ))
-                        {
-                            // ignoring rotation dirty since quaternions will mess with euler angles, making this impossible to determine if the change to a single axis comes
-                            // from an unauthorized transform change or euler to quaternion conversion artifacts.
-                            var dirtyField = oldStateDirtyInfo.isPositionDirty ? "position" : oldStateDirtyInfo.isRotationDirty ? "rotation" : "scale";
-                            Debug.LogWarning($"A local change to {dirtyField} without authority detected, reverting back to latest interpolated network state!", this);
-                        }
-                    }
-#endif
-
                     // Apply updated interpolated value
                     ApplyInterpolatedNetworkStateToTransform(m_ReplicatedNetworkState.Value, m_Transform);
                 }
             }
-
             m_LocalAuthoritativeNetworkState.IsTeleportingNextFrame = false;
         }
 
@@ -896,5 +934,22 @@ namespace Unity.Netcode.Components
             TryCommitValuesToServer(newPosition, newRotationEuler, newScale, m_CachedNetworkManager.LocalTime.Time);
             m_LocalAuthoritativeNetworkState.IsTeleportingNextFrame = false;
         }
+
+        /// <summary>
+        /// Override this and return false to follow the owner authoritative
+        /// Otherwise, it defaults to server authoritative
+        /// </summary>
+        protected virtual bool OnIsServerAuthoritatitive()
+        {
+            return true;
+        }
+
+        /// <summary>
+        /// Used by <see cref="NetworkRigidbody"/> to determines if this is server or owner authoritative.
+        /// </summary>
+        internal bool IsServerAuthoritative()
+        {
+            return OnIsServerAuthoritatitive();
+        }
     }
 }

Components/com.unity.netcode.components.asmdef

@@ -5,13 +5,22 @@
         "Unity.Netcode.Runtime",
         "Unity.Collections"
     ],
-    "includePlatforms": [],
-    "excludePlatforms": [],
     "allowUnsafeCode": true,
-    "overrideReferences": false,
+    "versionDefines": [
-    "precompiledReferences": [],
+        {
-    "autoReferenced": true,
+            "name": "com.unity.modules.animation",
-    "defineConstraints": [],
+            "expression": "",
-    "versionDefines": [],
+            "define": "COM_UNITY_MODULES_ANIMATION"
-    "noEngineReferences": false
+        },
+        {
+            "name": "com.unity.modules.physics",
+            "expression": "",
+            "define": "COM_UNITY_MODULES_PHYSICS"
+        },
+        {
+            "name": "com.unity.modules.physics2d",
+            "expression": "",
+            "define": "COM_UNITY_MODULES_PHYSICS2D"
+        }
+    ]
 }

Documentation~/Index.md

@@ -1,31 +0,0 @@
-# About Netcode for GameObjects
-
-Unity Netcode for GameObjects is a high-level networking library built to abstract networking. This allows developers to focus on the game rather than low level protocols and networking frameworks. 
-
-## Guides
-
-See guides below to install Unity Netcode for GameObjects, set up your project, and get started with your first networked game:
-
-* [Documentation](https://docs-multiplayer.unity3d.com/docs/getting-started/about-mlapi)
-* [Installation](https://docs-multiplayer.unity3d.com/docs/migration/install)
-* [First Steps](https://docs-multiplayer.unity3d.com/docs/tutorials/helloworld/helloworldintro)
-* [API Reference](https://docs-multiplayer.unity3d.com/docs/mlapi-api/introduction)
-
-# Technical details
-
-## Requirements
-
-This version of Netcode for GameObjects is compatible with the following Unity versions and platforms:
-
-* 2020.3 and later
-* Windows, Mac, Linux platforms
-
-## Document revision history
-
-|Date|Reason|
-|---|---|
-|March 10, 2021|Document created. Matches package version 0.1.0|
-|June 1, 2021|Update and add links for additional content. Matches patch version 0.1.0 and hotfixes.|
-|June 3, 2021|Update document to acknowledge Unity min version change. Matches package version 0.2.0|
-|August 5, 2021|Update product/package name|
-|September 9,2021|Updated the links and name of the file.|

Documentation~/index.md

@@ -0,0 +1,35 @@
+# About Netcode for GameObjects
+
+Netcode for GameObjects is a Unity package that provides networking capabilities to GameObject & MonoBehaviour workflows.
+
+## Guides
+
+See guides below to install Unity Netcode for GameObjects, set up your project, and get started with your first networked game:
+
+- [Documentation](https://docs-multiplayer.unity3d.com/netcode/current/about)
+- [Installation](https://docs-multiplayer.unity3d.com/netcode/current/migration/install)
+- [First Steps](https://docs-multiplayer.unity3d.com/netcode/current/tutorials/helloworld/helloworldintro)
+- [API Reference](https://docs-multiplayer.unity3d.com/netcode/current/api/introduction)
+
+# Technical details
+
+## Requirements
+
+Netcode for GameObjects targets the following Unity versions:
+- Unity 2020.3, 2021.1, 2021.2 and 2021.3
+
+On the following runtime platforms:
+- Windows, MacOS, and Linux
+- iOS and Android
+- Most closed platforms, such as consoles. Contact us for more information about specific closed platforms.
+
+## Document revision history
+
+|Date|Reason|
+|---|---|
+|March 10, 2021|Document created. Matches package version 0.1.0|
+|June 1, 2021|Update and add links for additional content. Matches patch version 0.1.0 and hotfixes.|
+|June 3, 2021|Update document to acknowledge Unity min version change. Matches package version 0.2.0|
+|August 5, 2021|Update product/package name|
+|September 9,2021|Updated the links and name of the file.|
+|April 20, 2022|Updated links|

Editor/CodeGen/CodeGenHelpers.cs

@@ -22,7 +22,12 @@ namespace Unity.Netcode.Editor.CodeGen
         public static readonly string ClientRpcAttribute_FullName = typeof(ClientRpcAttribute).FullName;
         public static readonly string ServerRpcParams_FullName = typeof(ServerRpcParams).FullName;
         public static readonly string ClientRpcParams_FullName = typeof(ClientRpcParams).FullName;
+        public static readonly string ClientRpcSendParams_FullName = typeof(ClientRpcSendParams).FullName;
+        public static readonly string ClientRpcReceiveParams_FullName = typeof(ClientRpcReceiveParams).FullName;
+        public static readonly string ServerRpcSendParams_FullName = typeof(ServerRpcSendParams).FullName;
+        public static readonly string ServerRpcReceiveParams_FullName = typeof(ServerRpcReceiveParams).FullName;
         public static readonly string INetworkSerializable_FullName = typeof(INetworkSerializable).FullName;
+        public static readonly string INetworkSerializeByMemcpy_FullName = typeof(INetworkSerializeByMemcpy).FullName;
         public static readonly string UnityColor_FullName = typeof(Color).FullName;
         public static readonly string UnityColor32_FullName = typeof(Color32).FullName;
         public static readonly string UnityVector2_FullName = typeof(Vector2).FullName;
@@ -73,6 +78,35 @@ namespace Unity.Netcode.Editor.CodeGen
             return false;
         }
 
+        public static string FullNameWithGenericParameters(this TypeReference typeReference, GenericParameter[] contextGenericParameters, TypeReference[] contextGenericParameterTypes)
+        {
+            var name = typeReference.FullName;
+            if (typeReference.HasGenericParameters)
+            {
+                name += "<";
+                for (var i = 0; i < typeReference.Resolve().GenericParameters.Count; ++i)
+                {
+                    if (i != 0)
+                    {
+                        name += ", ";
+                    }
+
+                    for (var j = 0; j < contextGenericParameters.Length; ++j)
+                    {
+                        if (typeReference.GenericParameters[i].FullName == contextGenericParameters[i].FullName)
+                        {
+                            name += contextGenericParameterTypes[i].FullName;
+                            break;
+                        }
+                    }
+                }
+
+                name += ">";
+            }
+
+            return name;
+        }
+
         public static bool HasInterface(this TypeReference typeReference, string interfaceTypeFullName)
         {
             if (typeReference.IsArray)
@@ -264,6 +298,28 @@ namespace Unity.Netcode.Editor.CodeGen
             });
         }
 
+        public static void AddWarning(this List<DiagnosticMessage> diagnostics, string message)
+        {
+            diagnostics.AddWarning((SequencePoint)null, message);
+        }
+
+        public static void AddWarning(this List<DiagnosticMessage> diagnostics, MethodDefinition methodDefinition, string message)
+        {
+            diagnostics.AddWarning(methodDefinition.DebugInformation.SequencePoints.FirstOrDefault(), message);
+        }
+
+        public static void AddWarning(this List<DiagnosticMessage> diagnostics, SequencePoint sequencePoint, string message)
+        {
+            diagnostics.Add(new DiagnosticMessage
+            {
+                DiagnosticType = DiagnosticType.Warning,
+                File = sequencePoint?.Document.Url.Replace($"{Environment.CurrentDirectory}{Path.DirectorySeparatorChar}", ""),
+                Line = sequencePoint?.StartLine ?? 0,
+                Column = sequencePoint?.StartColumn ?? 0,
+                MessageData = $" - {message}"
+            });
+        }
+
         public static void RemoveRecursiveReferences(this ModuleDefinition moduleDefinition)
         {
             // Weird behavior from Cecil: When importing a reference to a specific implementation of a generic

Editor/CodeGen/INetworkMessageILPP.cs

@@ -13,7 +13,6 @@ using MethodAttributes = Mono.Cecil.MethodAttributes;
 
 namespace Unity.Netcode.Editor.CodeGen
 {
-
     internal sealed class INetworkMessageILPP : ILPPInterface
     {
         public override ILPPInterface GetInstance() => this;
@@ -31,7 +30,6 @@ namespace Unity.Netcode.Editor.CodeGen
                 return null;
             }
 
-
             m_Diagnostics.Clear();
 
             // read
@@ -95,27 +93,23 @@ namespace Unity.Netcode.Editor.CodeGen
         }
 
 
-        private TypeReference m_FastBufferReader_TypeRef;
+        private MethodReference m_MessagingSystem_ReceiveMessage_MethodRef;
-        private TypeReference m_NetworkContext_TypeRef;
         private TypeReference m_MessagingSystem_MessageWithHandler_TypeRef;
         private MethodReference m_MessagingSystem_MessageHandler_Constructor_TypeRef;
         private FieldReference m_ILPPMessageProvider___network_message_types_FieldRef;
         private FieldReference m_MessagingSystem_MessageWithHandler_MessageType_FieldRef;
         private FieldReference m_MessagingSystem_MessageWithHandler_Handler_FieldRef;
         private MethodReference m_Type_GetTypeFromHandle_MethodRef;
-
         private MethodReference m_List_Add_MethodRef;
 
+        private const string k_ReceiveMessageName = nameof(MessagingSystem.ReceiveMessage);
+
         private bool ImportReferences(ModuleDefinition moduleDefinition)
         {
-            m_FastBufferReader_TypeRef = moduleDefinition.ImportReference(typeof(FastBufferReader));
+            m_MessagingSystem_MessageHandler_Constructor_TypeRef = moduleDefinition.ImportReference(typeof(MessagingSystem.MessageHandler).GetConstructors()[0]);
-            m_NetworkContext_TypeRef = moduleDefinition.ImportReference(typeof(NetworkContext));
-            m_MessagingSystem_MessageHandler_Constructor_TypeRef =
-                moduleDefinition.ImportReference(typeof(MessagingSystem.MessageHandler).GetConstructors()[0]);
 
             var messageWithHandlerType = typeof(MessagingSystem.MessageWithHandler);
-            m_MessagingSystem_MessageWithHandler_TypeRef =
+            m_MessagingSystem_MessageWithHandler_TypeRef = moduleDefinition.ImportReference(messageWithHandlerType);
-                moduleDefinition.ImportReference(messageWithHandlerType);
             foreach (var fieldInfo in messageWithHandlerType.GetFields())
             {
                 switch (fieldInfo.Name)
@@ -162,38 +156,18 @@ namespace Unity.Netcode.Editor.CodeGen
                 }
             }
 
-
+            var messagingSystemType = typeof(MessagingSystem);
-            return true;
+            foreach (var methodInfo in messagingSystemType.GetMethods(BindingFlags.Static | BindingFlags.NonPublic | BindingFlags.Public))
-        }
-
-        private MethodReference GetNetworkMessageRecieveHandler(TypeDefinition typeDefinition)
-        {
-            SequencePoint typeSequence = null;
-            foreach (var method in typeDefinition.Methods)
             {
-                var resolved = method.Resolve();
+                switch (methodInfo.Name)
-                var methodSequence = resolved.DebugInformation.SequencePoints.FirstOrDefault();
-                if (typeSequence == null || methodSequence.StartLine < typeSequence.StartLine)
                 {
-                    typeSequence = methodSequence;
+                    case k_ReceiveMessageName:
-                }
+                        m_MessagingSystem_ReceiveMessage_MethodRef = moduleDefinition.ImportReference(methodInfo);
-
+                        break;
-                if (resolved.IsStatic && resolved.IsPublic && resolved.Name == "Receive" && resolved.Parameters.Count == 2
-                    && !resolved.Parameters[0].IsIn
-                    && !resolved.Parameters[0].ParameterType.IsByReference
-                    && resolved.Parameters[0].ParameterType.Resolve() ==
-                        m_FastBufferReader_TypeRef.Resolve()
-                    && resolved.Parameters[1].IsIn
-                    && resolved.Parameters[1].ParameterType.IsByReference
-                    && resolved.Parameters[1].ParameterType.GetElementType().Resolve() == m_NetworkContext_TypeRef.Resolve()
-                    && resolved.ReturnType == resolved.Module.TypeSystem.Void)
-                {
-                    return method;
                 }
             }
 
-            m_Diagnostics.AddError(typeSequence, $"Class {typeDefinition.FullName} does not implement required method: `public static void Receive(FastBufferReader, in NetworkContext)`");
+            return true;
-            return null;
         }
 
         private MethodDefinition GetOrCreateStaticConstructor(TypeDefinition typeDefinition)
@@ -264,11 +238,8 @@ namespace Unity.Netcode.Editor.CodeGen
 
                     foreach (var type in networkMessageTypes)
                     {
-                        var receiveMethod = GetNetworkMessageRecieveHandler(type);
+                        var receiveMethod = new GenericInstanceMethod(m_MessagingSystem_ReceiveMessage_MethodRef);
-                        if (receiveMethod == null)
+                        receiveMethod.GenericArguments.Add(type);
-                        {
-                            continue;
-                        }
                         CreateInstructionsToRegisterType(processor, instructions, type, receiveMethod);
                     }
 

Editor/CodeGen/INetworkSerializableILPP.cs

@@ -0,0 +1,329 @@
+using System;
+using System.IO;
+using System.Linq;
+using System.Collections.Generic;
+using System.Reflection;
+using Mono.Cecil;
+using Mono.Cecil.Cil;
+using Mono.Cecil.Rocks;
+using Unity.CompilationPipeline.Common.Diagnostics;
+using Unity.CompilationPipeline.Common.ILPostProcessing;
+using ILPPInterface = Unity.CompilationPipeline.Common.ILPostProcessing.ILPostProcessor;
+using MethodAttributes = Mono.Cecil.MethodAttributes;
+
+namespace Unity.Netcode.Editor.CodeGen
+{
+
+    internal sealed class INetworkSerializableILPP : ILPPInterface
+    {
+        public override ILPPInterface GetInstance() => this;
+
+        public override bool WillProcess(ICompiledAssembly compiledAssembly) =>
+            compiledAssembly.Name == CodeGenHelpers.RuntimeAssemblyName ||
+            compiledAssembly.References.Any(filePath => Path.GetFileNameWithoutExtension(filePath) == CodeGenHelpers.RuntimeAssemblyName);
+
+        private readonly List<DiagnosticMessage> m_Diagnostics = new List<DiagnosticMessage>();
+
+        private TypeReference ResolveGenericType(TypeReference type, List<TypeReference> typeStack)
+        {
+            var genericName = type.Name;
+            var lastType = (GenericInstanceType)typeStack[typeStack.Count - 1];
+            var resolvedType = lastType.Resolve();
+            typeStack.RemoveAt(typeStack.Count - 1);
+            for (var i = 0; i < resolvedType.GenericParameters.Count; ++i)
+            {
+                var parameter = resolvedType.GenericParameters[i];
+                if (parameter.Name == genericName)
+                {
+                    var underlyingType = lastType.GenericArguments[i];
+                    if (underlyingType.Resolve() == null)
+                    {
+                        return ResolveGenericType(underlyingType, typeStack);
+                    }
+
+                    return underlyingType;
+                }
+            }
+
+            return null;
+        }
+
+        public override ILPostProcessResult Process(ICompiledAssembly compiledAssembly)
+        {
+            if (!WillProcess(compiledAssembly))
+            {
+                return null;
+            }
+
+            m_Diagnostics.Clear();
+
+            // read
+            var assemblyDefinition = CodeGenHelpers.AssemblyDefinitionFor(compiledAssembly, out var resolver);
+            if (assemblyDefinition == null)
+            {
+                m_Diagnostics.AddError($"Cannot read assembly definition: {compiledAssembly.Name}");
+                return null;
+            }
+
+            // process
+            var mainModule = assemblyDefinition.MainModule;
+            if (mainModule != null)
+            {
+                try
+                {
+                    if (ImportReferences(mainModule))
+                    {
+                        // Initialize all the delegates for various NetworkVariable types to ensure they can be serailized
+
+                        // Find all types we know we're going to want to serialize.
+                        // The list of these types includes:
+                        // - Non-generic INetworkSerializable types
+                        // - Non-Generic INetworkSerializeByMemcpy types
+                        // - Enums that are not declared within generic types
+                        // We can't process generic types because, to initialize a generic, we need a value
+                        // for `T` to initialize it with.
+                        var networkSerializableTypes = mainModule.GetTypes()
+                            .Where(t => t.Resolve().HasInterface(CodeGenHelpers.INetworkSerializable_FullName) && !t.Resolve().IsAbstract && !t.Resolve().HasGenericParameters && t.Resolve().IsValueType)
+                            .ToList();
+                        var structTypes = mainModule.GetTypes()
+                            .Where(t => t.Resolve().HasInterface(CodeGenHelpers.INetworkSerializeByMemcpy_FullName) && !t.Resolve().IsAbstract && !t.Resolve().HasGenericParameters && t.Resolve().IsValueType)
+                            .ToList();
+                        var enumTypes = mainModule.GetTypes()
+                            .Where(t => t.Resolve().IsEnum && !t.Resolve().IsAbstract && !t.Resolve().HasGenericParameters && t.Resolve().IsValueType)
+                            .ToList();
+
+                        // Now, to support generics, we have to do an extra pass.
+                        // We look for any type that's a NetworkBehaviour type
+                        // Then we look through all the fields in that type, finding any field whose type is
+                        // descended from `NetworkVariableSerialization`. Then we check `NetworkVariableSerialization`'s
+                        // `T` value, and if it's a generic, then we know it was missed in the above sweep and needs
+                        // to be initialized. Now we have a full generic instance rather than a generic definition,
+                        // so we can validly generate an initializer for that particular instance of the generic type.
+                        var networkSerializableTypesSet = new HashSet<TypeReference>(networkSerializableTypes);
+                        var structTypesSet = new HashSet<TypeReference>(structTypes);
+                        var enumTypesSet = new HashSet<TypeReference>(enumTypes);
+                        var typeStack = new List<TypeReference>();
+                        foreach (var type in mainModule.GetTypes())
+                        {
+                            // Check if it's a NetworkBehaviour
+                            if (type.IsSubclassOf(CodeGenHelpers.NetworkBehaviour_FullName))
+                            {
+                                // Iterate fields looking for NetworkVariableSerialization fields
+                                foreach (var field in type.Fields)
+                                {
+                                    // Get the field type and its base type
+                                    var fieldType = field.FieldType;
+                                    var baseType = fieldType.Resolve().BaseType;
+                                    if (baseType == null)
+                                    {
+                                        continue;
+                                    }
+                                    // This type stack is used for resolving NetworkVariableSerialization's T value
+                                    // When looking at base types, we get the type definition rather than the
+                                    // type reference... which means that we get the generic definition with an
+                                    // undefined T rather than the instance with the type filled in.
+                                    // We then have to walk backward back down the type stack to resolve what T
+                                    // is.
+                                    typeStack.Clear();
+                                    typeStack.Add(fieldType);
+                                    // Iterate through the base types until we get to Object.
+                                    // Object is the base for everything so we'll stop when we hit that.
+                                    while (baseType.Name != mainModule.TypeSystem.Object.Name)
+                                    {
+                                        // If we've found a NetworkVariableSerialization type...
+                                        if (baseType.IsGenericInstance && baseType.Resolve() == m_NetworkVariableSerializationType)
+                                        {
+                                            // Then we need to figure out what T is
+                                            var genericType = (GenericInstanceType)baseType;
+                                            var underlyingType = genericType.GenericArguments[0];
+                                            if (underlyingType.Resolve() == null)
+                                            {
+                                                underlyingType = ResolveGenericType(underlyingType, typeStack);
+                                            }
+
+                                            // If T is generic...
+                                            if (underlyingType.IsGenericInstance)
+                                            {
+                                                // Then we pick the correct set to add it to and set it up
+                                                // for initialization.
+                                                if (underlyingType.HasInterface(CodeGenHelpers.INetworkSerializable_FullName))
+                                                {
+                                                    networkSerializableTypesSet.Add(underlyingType);
+                                                }
+
+                                                if (underlyingType.HasInterface(CodeGenHelpers.INetworkSerializeByMemcpy_FullName))
+                                                {
+                                                    structTypesSet.Add(underlyingType);
+                                                }
+
+                                                if (underlyingType.Resolve().IsEnum)
+                                                {
+                                                    enumTypesSet.Add(underlyingType);
+                                                }
+                                            }
+
+                                            break;
+                                        }
+
+                                        typeStack.Add(baseType);
+                                        baseType = baseType.Resolve().BaseType;
+                                    }
+                                }
+                            }
+                            // We'll also avoid some confusion by ensuring users only choose one of the two
+                            // serialization schemes - by method OR by memcpy, not both. We'll also do a cursory
+                            // check that INetworkSerializeByMemcpy types are unmanaged.
+                            else if (type.HasInterface(CodeGenHelpers.INetworkSerializeByMemcpy_FullName))
+                            {
+                                if (type.HasInterface(CodeGenHelpers.INetworkSerializable_FullName))
+                                {
+                                    m_Diagnostics.AddError($"{nameof(INetworkSerializeByMemcpy)} types may not implement {nameof(INetworkSerializable)} - choose one or the other.");
+                                }
+                                if (!type.IsValueType)
+                                {
+                                    m_Diagnostics.AddError($"{nameof(INetworkSerializeByMemcpy)} types must be unmanaged types.");
+                                }
+                            }
+                        }
+
+                        if (networkSerializableTypes.Count + structTypes.Count + enumTypes.Count == 0)
+                        {
+                            return null;
+                        }
+
+                        // Finally we add to the module initializer some code to initialize the delegates in
+                        // NetworkVariableSerialization<T> for all necessary values of T, by calling initialization
+                        // methods in NetworkVariableHelpers.
+                        CreateModuleInitializer(assemblyDefinition, networkSerializableTypesSet.ToList(), structTypesSet.ToList(), enumTypesSet.ToList());
+                    }
+                    else
+                    {
+                        m_Diagnostics.AddError($"Cannot import references into main module: {mainModule.Name}");
+                    }
+                }
+                catch (Exception e)
+                {
+                    m_Diagnostics.AddError((e.ToString() + e.StackTrace.ToString()).Replace("\n", "|").Replace("\r", "|"));
+                }
+            }
+            else
+            {
+                m_Diagnostics.AddError($"Cannot get main module from assembly definition: {compiledAssembly.Name}");
+            }
+
+            mainModule.RemoveRecursiveReferences();
+
+            // write
+            var pe = new MemoryStream();
+            var pdb = new MemoryStream();
+
+            var writerParameters = new WriterParameters
+            {
+                SymbolWriterProvider = new PortablePdbWriterProvider(),
+                SymbolStream = pdb,
+                WriteSymbols = true
+            };
+
+            assemblyDefinition.Write(pe, writerParameters);
+
+            return new ILPostProcessResult(new InMemoryAssembly(pe.ToArray(), pdb.ToArray()), m_Diagnostics);
+        }
+
+        private MethodReference m_InitializeDelegatesNetworkSerializable_MethodRef;
+        private MethodReference m_InitializeDelegatesStruct_MethodRef;
+        private MethodReference m_InitializeDelegatesEnum_MethodRef;
+
+        private TypeDefinition m_NetworkVariableSerializationType;
+
+        private const string k_InitializeNetworkSerializableMethodName = nameof(NetworkVariableHelper.InitializeDelegatesNetworkSerializable);
+        private const string k_InitializeStructMethodName = nameof(NetworkVariableHelper.InitializeDelegatesStruct);
+        private const string k_InitializeEnumMethodName = nameof(NetworkVariableHelper.InitializeDelegatesEnum);
+
+        private bool ImportReferences(ModuleDefinition moduleDefinition)
+        {
+
+            var helperType = typeof(NetworkVariableHelper);
+            foreach (var methodInfo in helperType.GetMethods(BindingFlags.Static | BindingFlags.NonPublic | BindingFlags.Public))
+            {
+                switch (methodInfo.Name)
+                {
+                    case k_InitializeNetworkSerializableMethodName:
+                        m_InitializeDelegatesNetworkSerializable_MethodRef = moduleDefinition.ImportReference(methodInfo);
+                        break;
+                    case k_InitializeStructMethodName:
+                        m_InitializeDelegatesStruct_MethodRef = moduleDefinition.ImportReference(methodInfo);
+                        break;
+                    case k_InitializeEnumMethodName:
+                        m_InitializeDelegatesEnum_MethodRef = moduleDefinition.ImportReference(methodInfo);
+                        break;
+                }
+            }
+            m_NetworkVariableSerializationType = moduleDefinition.ImportReference(typeof(NetworkVariableSerialization<>)).Resolve();
+            return true;
+        }
+
+        private MethodDefinition GetOrCreateStaticConstructor(TypeDefinition typeDefinition)
+        {
+            var staticCtorMethodDef = typeDefinition.GetStaticConstructor();
+            if (staticCtorMethodDef == null)
+            {
+                staticCtorMethodDef = new MethodDefinition(
+                    ".cctor", // Static Constructor (constant-constructor)
+                    MethodAttributes.HideBySig |
+                    MethodAttributes.SpecialName |
+                    MethodAttributes.RTSpecialName |
+                    MethodAttributes.Static,
+                    typeDefinition.Module.TypeSystem.Void);
+                staticCtorMethodDef.Body.Instructions.Add(Instruction.Create(OpCodes.Ret));
+                typeDefinition.Methods.Add(staticCtorMethodDef);
+            }
+
+            return staticCtorMethodDef;
+        }
+
+        // Creates a static module constructor (which is executed when the module is loaded) that registers all the
+        // message types in the assembly with MessagingSystem.
+        // This is the same behavior as annotating a static method with [ModuleInitializer] in standardized
+        // C# (that attribute doesn't exist in Unity, but the static module constructor still works)
+        // https://docs.microsoft.com/en-us/dotnet/api/system.runtime.compilerservices.moduleinitializerattribute?view=net-5.0
+        // https://web.archive.org/web/20100212140402/http://blogs.msdn.com/junfeng/archive/2005/11/19/494914.aspx
+        private void CreateModuleInitializer(AssemblyDefinition assembly, List<TypeReference> networkSerializableTypes, List<TypeReference> structTypes, List<TypeReference> enumTypes)
+        {
+            foreach (var typeDefinition in assembly.MainModule.Types)
+            {
+                if (typeDefinition.FullName == "<Module>")
+                {
+                    var staticCtorMethodDef = GetOrCreateStaticConstructor(typeDefinition);
+
+                    var processor = staticCtorMethodDef.Body.GetILProcessor();
+
+                    var instructions = new List<Instruction>();
+
+                    foreach (var type in structTypes)
+                    {
+                        var method = new GenericInstanceMethod(m_InitializeDelegatesStruct_MethodRef);
+                        method.GenericArguments.Add(type);
+                        instructions.Add(processor.Create(OpCodes.Call, method));
+                    }
+
+                    foreach (var type in networkSerializableTypes)
+                    {
+                        var method = new GenericInstanceMethod(m_InitializeDelegatesNetworkSerializable_MethodRef);
+                        method.GenericArguments.Add(type);
+                        instructions.Add(processor.Create(OpCodes.Call, method));
+                    }
+
+                    foreach (var type in enumTypes)
+                    {
+                        var method = new GenericInstanceMethod(m_InitializeDelegatesEnum_MethodRef);
+                        method.GenericArguments.Add(type);
+                        instructions.Add(processor.Create(OpCodes.Call, method));
+                    }
+
+                    instructions.ForEach(instruction => processor.Body.Instructions.Insert(processor.Body.Instructions.Count - 1, instruction));
+                    break;
+                }
+            }
+        }
+    }
+}

Editor/CodeGen/INetworkSerializableILPP.cs.meta

@@ -0,0 +1,3 @@
+fileFormatVersion: 2
+guid: 64a0c1e708fa46a389d64e7b4708e6c7
+timeCreated: 1635535237

Editor/CodeGen/NetworkBehaviourILPP.cs

@@ -7,7 +7,6 @@ using System.Runtime.CompilerServices;
 using Mono.Cecil;
 using Mono.Cecil.Cil;
 using Mono.Cecil.Rocks;
-using Unity.Collections;
 using Unity.CompilationPipeline.Common.Diagnostics;
 using Unity.CompilationPipeline.Common.ILPostProcessing;
 using UnityEngine;
@@ -17,7 +16,6 @@ using ILPPInterface = Unity.CompilationPipeline.Common.ILPostProcessing.ILPostPr
 
 namespace Unity.Netcode.Editor.CodeGen
 {
-
     internal sealed class NetworkBehaviourILPP : ILPPInterface
     {
         private const string k_ReadValueMethodName = nameof(FastBufferReader.ReadValueSafe);
@@ -25,7 +23,8 @@ namespace Unity.Netcode.Editor.CodeGen
 
         public override ILPPInterface GetInstance() => this;
 
-        public override bool WillProcess(ICompiledAssembly compiledAssembly) => compiledAssembly.References.Any(filePath => Path.GetFileNameWithoutExtension(filePath) == CodeGenHelpers.RuntimeAssemblyName);
+        public override bool WillProcess(ICompiledAssembly compiledAssembly) =>
+            compiledAssembly.References.Any(filePath => Path.GetFileNameWithoutExtension(filePath) == CodeGenHelpers.RuntimeAssemblyName);
 
         private readonly List<DiagnosticMessage> m_Diagnostics = new List<DiagnosticMessage>();
 
@@ -109,8 +108,10 @@ namespace Unity.Netcode.Editor.CodeGen
         private FieldReference m_NetworkManager_rpc_name_table_FieldRef;
         private MethodReference m_NetworkManager_rpc_name_table_Add_MethodRef;
         private TypeReference m_NetworkBehaviour_TypeRef;
-        private MethodReference m_NetworkBehaviour_SendServerRpc_MethodRef;
+        private MethodReference m_NetworkBehaviour_beginSendServerRpc_MethodRef;
-        private MethodReference m_NetworkBehaviour_SendClientRpc_MethodRef;
+        private MethodReference m_NetworkBehaviour_endSendServerRpc_MethodRef;
+        private MethodReference m_NetworkBehaviour_beginSendClientRpc_MethodRef;
+        private MethodReference m_NetworkBehaviour_endSendClientRpc_MethodRef;
         private FieldReference m_NetworkBehaviour_rpc_exec_stage_FieldRef;
         private MethodReference m_NetworkBehaviour_getNetworkManager_MethodRef;
         private MethodReference m_NetworkBehaviour_getOwnerClientId_MethodRef;
@@ -124,8 +125,6 @@ namespace Unity.Netcode.Editor.CodeGen
         private TypeReference m_ClientRpcParams_TypeRef;
 
         private TypeReference m_FastBufferWriter_TypeRef;
-        private MethodReference m_FastBufferWriter_Constructor;
-        private MethodReference m_FastBufferWriter_Dispose;
         private Dictionary<string, MethodReference> m_FastBufferWriter_WriteValue_MethodRefs = new Dictionary<string, MethodReference>();
         private List<MethodReference> m_FastBufferWriter_ExtensionMethodRefs = new List<MethodReference>();
 
@@ -144,8 +143,10 @@ namespace Unity.Netcode.Editor.CodeGen
         private const string k_NetworkManager_rpc_name_table = nameof(NetworkManager.__rpc_name_table);
 
         private const string k_NetworkBehaviour_rpc_exec_stage = nameof(NetworkBehaviour.__rpc_exec_stage);
-        private const string k_NetworkBehaviour_SendServerRpc = nameof(NetworkBehaviour.__sendServerRpc);
+        private const string k_NetworkBehaviour_beginSendServerRpc = nameof(NetworkBehaviour.__beginSendServerRpc);
-        private const string k_NetworkBehaviour_SendClientRpc = nameof(NetworkBehaviour.__sendClientRpc);
+        private const string k_NetworkBehaviour_endSendServerRpc = nameof(NetworkBehaviour.__endSendServerRpc);
+        private const string k_NetworkBehaviour_beginSendClientRpc = nameof(NetworkBehaviour.__beginSendClientRpc);
+        private const string k_NetworkBehaviour_endSendClientRpc = nameof(NetworkBehaviour.__endSendClientRpc);
         private const string k_NetworkBehaviour_NetworkManager = nameof(NetworkBehaviour.NetworkManager);
         private const string k_NetworkBehaviour_OwnerClientId = nameof(NetworkBehaviour.OwnerClientId);
 
@@ -234,11 +235,17 @@ namespace Unity.Netcode.Editor.CodeGen
             {
                 switch (methodInfo.Name)
                 {
-                    case k_NetworkBehaviour_SendServerRpc:
+                    case k_NetworkBehaviour_beginSendServerRpc:
-                        m_NetworkBehaviour_SendServerRpc_MethodRef = moduleDefinition.ImportReference(methodInfo);
+                        m_NetworkBehaviour_beginSendServerRpc_MethodRef = moduleDefinition.ImportReference(methodInfo);
                         break;
-                    case k_NetworkBehaviour_SendClientRpc:
+                    case k_NetworkBehaviour_endSendServerRpc:
-                        m_NetworkBehaviour_SendClientRpc_MethodRef = moduleDefinition.ImportReference(methodInfo);
+                        m_NetworkBehaviour_endSendServerRpc_MethodRef = moduleDefinition.ImportReference(methodInfo);
+                        break;
+                    case k_NetworkBehaviour_beginSendClientRpc:
+                        m_NetworkBehaviour_beginSendClientRpc_MethodRef = moduleDefinition.ImportReference(methodInfo);
+                        break;
+                    case k_NetworkBehaviour_endSendClientRpc:
+                        m_NetworkBehaviour_endSendClientRpc_MethodRef = moduleDefinition.ImportReference(methodInfo);
                         break;
                 }
             }
@@ -299,24 +306,22 @@ namespace Unity.Netcode.Editor.CodeGen
             var fastBufferWriterType = typeof(FastBufferWriter);
             m_FastBufferWriter_TypeRef = moduleDefinition.ImportReference(fastBufferWriterType);
 
-            m_FastBufferWriter_Constructor = moduleDefinition.ImportReference(
-                fastBufferWriterType.GetConstructor(new[] { typeof(int), typeof(Allocator), typeof(int) }));
-            m_FastBufferWriter_Dispose = moduleDefinition.ImportReference(fastBufferWriterType.GetMethod("Dispose"));
-
             var fastBufferReaderType = typeof(FastBufferReader);
             m_FastBufferReader_TypeRef = moduleDefinition.ImportReference(fastBufferReaderType);
 
             // Find all extension methods for FastBufferReader and FastBufferWriter to enable user-implemented
             // methods to be called.
-            var assemblies = new List<AssemblyDefinition>();
+            var assemblies = new List<AssemblyDefinition> { m_MainModule.Assembly };
-            assemblies.Add(m_MainModule.Assembly);
             foreach (var reference in m_MainModule.AssemblyReferences)
             {
-                assemblies.Add(m_AssemblyResolver.Resolve(reference));
+                var assembly = m_AssemblyResolver.Resolve(reference);
+                if (assembly != null)
+                {
+                    assemblies.Add(assembly);
+                }
             }
 
-            var extensionConstructor =
+            var extensionConstructor = moduleDefinition.ImportReference(typeof(ExtensionAttribute).GetConstructor(new Type[] { }));
-                moduleDefinition.ImportReference(typeof(ExtensionAttribute).GetConstructor(new Type[] { }));
             foreach (var assembly in assemblies)
             {
                 foreach (var module in assembly.Modules)
@@ -328,6 +333,7 @@ namespace Unity.Netcode.Editor.CodeGen
                         {
                             continue;
                         }
+
                         foreach (var method in type.Methods)
                         {
                             if (!method.IsStatic)
@@ -352,13 +358,11 @@ namespace Unity.Netcode.Editor.CodeGen
 
                             var parameters = method.Parameters;
 
-                            if (parameters.Count == 2
+                            if (parameters.Count == 2 && parameters[0].ParameterType.Resolve() == m_FastBufferWriter_TypeRef.MakeByReferenceType().Resolve())
-                                && parameters[0].ParameterType.Resolve() == m_FastBufferWriter_TypeRef.MakeByReferenceType().Resolve())
                             {
                                 m_FastBufferWriter_ExtensionMethodRefs.Add(m_MainModule.ImportReference(method));
                             }
-                            else if (parameters.Count == 2
+                            else if (parameters.Count == 2 && parameters[0].ParameterType.Resolve() == m_FastBufferReader_TypeRef.MakeByReferenceType().Resolve())
-                                && parameters[0].ParameterType.Resolve() == m_FastBufferReader_TypeRef.MakeByReferenceType().Resolve())
                             {
                                 m_FastBufferReader_ExtensionMethodRefs.Add(m_MainModule.ImportReference(method));
                             }
@@ -391,9 +395,20 @@ namespace Unity.Netcode.Editor.CodeGen
                     continue;
                 }
 
+                if (methodDefinition.HasCustomAttributes)
+                {
+                    foreach (var attribute in methodDefinition.CustomAttributes)
+                    {
+                        if (attribute.AttributeType.Name == nameof(AsyncStateMachineAttribute))
+                        {
+                            m_Diagnostics.AddError(methodDefinition, $"{methodDefinition.FullName}: RPCs cannot be 'async'");
+                        }
+                    }
+                }
+
                 InjectWriteAndCallBlocks(methodDefinition, rpcAttribute, rpcMethodId);
 
-                rpcHandlers.Add((rpcMethodId, GenerateStaticHandler(methodDefinition, rpcAttribute)));
+                rpcHandlers.Add((rpcMethodId, GenerateStaticHandler(methodDefinition, rpcAttribute, rpcMethodId)));
 
                 if (isEditorOrDevelopment)
                 {
@@ -473,7 +488,6 @@ namespace Unity.Netcode.Editor.CodeGen
         private CustomAttribute CheckAndGetRpcAttribute(MethodDefinition methodDefinition)
         {
             CustomAttribute rpcAttribute = null;
-            bool isServerRpc = false;
             foreach (var customAttribute in methodDefinition.CustomAttributes)
             {
                 var customAttributeType_FullName = customAttribute.AttributeType.FullName;
@@ -495,6 +509,12 @@ namespace Unity.Netcode.Editor.CodeGen
                         isValid = false;
                     }
 
+                    if (methodDefinition.HasGenericParameters)
+                    {
+                        m_Diagnostics.AddError(methodDefinition, "RPC method must not be generic!");
+                        isValid = false;
+                    }
+
                     if (methodDefinition.ReturnType != methodDefinition.Module.TypeSystem.Void)
                     {
                         m_Diagnostics.AddError(methodDefinition, "RPC method must return `void`!");
@@ -517,9 +537,12 @@ namespace Unity.Netcode.Editor.CodeGen
 
                     if (isValid)
                     {
-                        isServerRpc = customAttributeType_FullName == CodeGenHelpers.ServerRpcAttribute_FullName;
                         rpcAttribute = customAttribute;
                     }
+                    else
+                    {
+                        return null;
+                    }
                 }
             }
 
@@ -562,34 +585,57 @@ namespace Unity.Netcode.Editor.CodeGen
                     var checkType = paramType.Resolve();
                     if (paramType.IsArray)
                     {
-                        checkType = paramType.GetElementType().Resolve();
+                        checkType = ((ArrayType)paramType).ElementType.Resolve();
                     }
 
-                    if (
+                    if ((parameters[0].ParameterType.Resolve() == checkType ||
-                        (parameters[0].ParameterType.Resolve() == checkType
+                         (parameters[0].ParameterType.Resolve() == checkType.MakeByReferenceType().Resolve() && parameters[0].IsIn)))
-                        || (parameters[0].ParameterType.Resolve() == checkType.MakeByReferenceType().Resolve() && parameters[0].IsIn)))
                     {
                         return method;
                     }
+
+                    if (parameters[0].ParameterType == paramType ||
+                        (parameters[0].ParameterType == paramType.MakeByReferenceType() && parameters[0].IsIn))
+                    {
+                        return method;
+                    }
+
                     if (method.HasGenericParameters && method.GenericParameters.Count == 1)
                     {
                         if (method.GenericParameters[0].HasConstraints)
                         {
+                            var meetsConstraints = true;
                             foreach (var constraint in method.GenericParameters[0].Constraints)
                             {
+#if CECIL_CONSTRAINTS_ARE_TYPE_REFERENCES
                                 var resolvedConstraint = constraint.Resolve();
+#else
+                                var resolvedConstraint = constraint.ConstraintType.Resolve();
+#endif
 
-                                if (
+                                var resolvedConstraintName = resolvedConstraint.FullNameWithGenericParameters(new[] { method.GenericParameters[0] }, new[] { checkType });
-                                    (resolvedConstraint.IsInterface &&
+                                if ((resolvedConstraint.IsInterface && !checkType.HasInterface(resolvedConstraintName)) ||
-                                     checkType.HasInterface(resolvedConstraint.FullName))
+                                    (resolvedConstraint.IsClass && !checkType.Resolve().IsSubclassOf(resolvedConstraintName)) ||
-                                    || (resolvedConstraint.IsClass &&
+                                    (resolvedConstraint.Name == "ValueType" && !checkType.IsValueType))
-                                        checkType.Resolve().IsSubclassOf(resolvedConstraint.FullName)))
                                 {
-                                    var instanceMethod = new GenericInstanceMethod(method);
+                                    meetsConstraints = false;
-                                    instanceMethod.GenericArguments.Add(checkType);
+                                    break;
-                                    return instanceMethod;
                                 }
                             }
+
+                            if (meetsConstraints)
+                            {
+                                var instanceMethod = new GenericInstanceMethod(method);
+                                if (paramType.IsArray)
+                                {
+                                    instanceMethod.GenericArguments.Add(((ArrayType)paramType).ElementType);
+                                }
+                                else
+                                {
+                                    instanceMethod.GenericArguments.Add(paramType);
+                                }
+                                return instanceMethod;
+                            }
                         }
                     }
                 }
@@ -613,8 +659,8 @@ namespace Unity.Netcode.Editor.CodeGen
                     {
                         if (parameters[1].IsIn)
                         {
-                            if (parameters[1].ParameterType.Resolve() == paramType.MakeByReferenceType().Resolve()
+                            if (parameters[1].ParameterType.Resolve() == paramType.MakeByReferenceType().Resolve() &&
-                                && ((ByReferenceType)parameters[1].ParameterType).ElementType.IsArray == paramType.IsArray)
+                                ((ByReferenceType)parameters[1].ParameterType).ElementType.IsArray == paramType.IsArray)
                             {
                                 methodRef = method;
                                 m_FastBufferWriter_WriteValue_MethodRefs[assemblyQualifiedName] = methodRef;
@@ -624,8 +670,8 @@ namespace Unity.Netcode.Editor.CodeGen
                         else
                         {
 
-                            if (parameters[1].ParameterType.Resolve() == paramType.Resolve()
+                            if (parameters[1].ParameterType.Resolve() == paramType.Resolve() &&
-                                && parameters[1].ParameterType.IsArray == paramType.IsArray)
+                                parameters[1].ParameterType.IsArray == paramType.IsArray)
                             {
                                 methodRef = method;
                                 m_FastBufferWriter_WriteValue_MethodRefs[assemblyQualifiedName] = methodRef;
@@ -635,13 +681,7 @@ namespace Unity.Netcode.Editor.CodeGen
                     }
                 }
 
-                // Try NetworkSerializable first because INetworkSerializable may also be valid for WriteValueSafe
+                var typeMethod = GetFastBufferWriterWriteMethod(k_WriteValueMethodName, paramType);
-                // and that would cause boxing if so.
-                var typeMethod = GetFastBufferWriterWriteMethod("WriteNetworkSerializable", paramType);
-                if (typeMethod == null)
-                {
-                    typeMethod = GetFastBufferWriterWriteMethod(k_WriteValueMethodName, paramType);
-                }
                 if (typeMethod != null)
                 {
                     methodRef = m_MainModule.ImportReference(typeMethod);
@@ -681,32 +721,58 @@ namespace Unity.Netcode.Editor.CodeGen
                     var checkType = paramType.Resolve();
                     if (paramType.IsArray)
                     {
-                        checkType = paramType.GetElementType().Resolve();
+                        checkType = ((ArrayType)paramType).ElementType.Resolve();
                     }
 
                     if (methodParam.Resolve() == checkType.Resolve() || methodParam.Resolve() == checkType.MakeByReferenceType().Resolve())
                     {
                         return method;
                     }
+
+                    if (methodParam.Resolve() == paramType || methodParam.Resolve() == paramType.MakeByReferenceType().Resolve())
+                    {
+                        return method;
+                    }
+
                     if (method.HasGenericParameters && method.GenericParameters.Count == 1)
                     {
                         if (method.GenericParameters[0].HasConstraints)
                         {
+                            var meetsConstraints = true;
                             foreach (var constraint in method.GenericParameters[0].Constraints)
                             {
+#if CECIL_CONSTRAINTS_ARE_TYPE_REFERENCES
                                 var resolvedConstraint = constraint.Resolve();
+#else
+                                var resolvedConstraint = constraint.ConstraintType.Resolve();
+#endif
 
-                                if (
+
-                                    (resolvedConstraint.IsInterface &&
+                                var resolvedConstraintName = resolvedConstraint.FullNameWithGenericParameters(new[] { method.GenericParameters[0] }, new[] { checkType });
-                                     checkType.HasInterface(resolvedConstraint.FullName))
+
-                                    || (resolvedConstraint.IsClass &&
+                                if ((resolvedConstraint.IsInterface && !checkType.HasInterface(resolvedConstraintName)) ||
-                                        checkType.Resolve().IsSubclassOf(resolvedConstraint.FullName)))
+                                    (resolvedConstraint.IsClass && !checkType.Resolve().IsSubclassOf(resolvedConstraintName)) ||
+                                    (resolvedConstraint.Name == "ValueType" && !checkType.IsValueType))
                                 {
-                                    var instanceMethod = new GenericInstanceMethod(method);
+                                    meetsConstraints = false;
-                                    instanceMethod.GenericArguments.Add(checkType);
+                                    break;
-                                    return instanceMethod;
                                 }
                             }
+
+                            if (meetsConstraints)
+                            {
+                                var instanceMethod = new GenericInstanceMethod(method);
+                                if (paramType.IsArray)
+                                {
+                                    instanceMethod.GenericArguments.Add(((ArrayType)paramType).ElementType);
+                                }
+                                else
+                                {
+                                    instanceMethod.GenericArguments.Add(paramType);
+                                }
+
+                                return instanceMethod;
+                            }
                         }
                     }
                 }
@@ -725,11 +791,10 @@ namespace Unity.Netcode.Editor.CodeGen
                 foreach (var method in m_FastBufferReader_ExtensionMethodRefs)
                 {
                     var parameters = method.Resolve().Parameters;
-                    if (
+                    if (method.Name == k_ReadValueMethodName &&
-                        method.Name == k_ReadValueMethodName
+                        parameters[1].IsOut &&
-                        && parameters[1].IsOut
+                        parameters[1].ParameterType.Resolve() == paramType.MakeByReferenceType().Resolve() &&
-                        && parameters[1].ParameterType.Resolve() == paramType.MakeByReferenceType().Resolve()
+                        ((ByReferenceType)parameters[1].ParameterType).ElementType.IsArray == paramType.IsArray)
-                        && ((ByReferenceType)parameters[1].ParameterType).ElementType.IsArray == paramType.IsArray)
                     {
                         methodRef = method;
                         m_FastBufferReader_ReadValue_MethodRefs[assemblyQualifiedName] = methodRef;
@@ -737,13 +802,7 @@ namespace Unity.Netcode.Editor.CodeGen
                     }
                 }
 
-                // Try NetworkSerializable first because INetworkSerializable may also be valid for ReadValueSafe
+                var typeMethod = GetFastBufferReaderReadMethod(k_ReadValueMethodName, paramType);
-                // and that would cause boxing if so.
-                var typeMethod = GetFastBufferReaderReadMethod("ReadNetworkSerializable", paramType);
-                if (typeMethod == null)
-                {
-                    typeMethod = GetFastBufferReaderReadMethod(k_ReadValueMethodName, paramType);
-                }
                 if (typeMethod != null)
                 {
                     methodRef = m_MainModule.ImportReference(typeMethod);
@@ -761,8 +820,8 @@ namespace Unity.Netcode.Editor.CodeGen
             var instructions = new List<Instruction>();
             var processor = methodDefinition.Body.GetILProcessor();
             var isServerRpc = rpcAttribute.AttributeType.FullName == CodeGenHelpers.ServerRpcAttribute_FullName;
-            var requireOwnership = true; // default value MUST be = `ServerRpcAttribute.RequireOwnership`
+            var requireOwnership = true; // default value MUST be == `ServerRpcAttribute.RequireOwnership`
-            var rpcDelivery = RpcDelivery.Reliable; // default value MUST be = `RpcAttribute.Delivery`
+            var rpcDelivery = RpcDelivery.Reliable; // default value MUST be == `RpcAttribute.Delivery`
             foreach (var attrField in rpcAttribute.Fields)
             {
                 switch (attrField.Name)
@@ -786,9 +845,9 @@ namespace Unity.Netcode.Editor.CodeGen
             // NetworkManager networkManager;
             methodDefinition.Body.Variables.Add(new VariableDefinition(m_NetworkManager_TypeRef));
             int netManLocIdx = methodDefinition.Body.Variables.Count - 1;
-            // NetworkSerializer serializer;
+            // FastBufferWriter bufferWriter;
             methodDefinition.Body.Variables.Add(new VariableDefinition(m_FastBufferWriter_TypeRef));
-            int serializerLocIdx = methodDefinition.Body.Variables.Count - 1;
+            int bufWriterLocIdx = methodDefinition.Body.Variables.Count - 1;
 
             // XXXRpcParams
             if (!hasRpcParams)
@@ -843,6 +902,8 @@ namespace Unity.Netcode.Editor.CodeGen
 
                 instructions.Add(beginInstr);
 
+                // var bufferWriter = __beginSendServerRpc(rpcMethodId, serverRpcParams, rpcDelivery) -> ServerRpc
+                // var bufferWriter = __beginSendClientRpc(rpcMethodId, clientRpcParams, rpcDelivery) -> ClientRpc
                 if (isServerRpc)
                 {
                     // ServerRpc
@@ -856,8 +917,7 @@ namespace Unity.Netcode.Editor.CodeGen
                         instructions.Add(processor.Create(OpCodes.Ldarg_0));
                         instructions.Add(processor.Create(OpCodes.Call, m_NetworkBehaviour_getOwnerClientId_MethodRef));
                         instructions.Add(processor.Create(OpCodes.Ldloc, netManLocIdx));
-                        instructions.Add(
+                        instructions.Add(processor.Create(OpCodes.Callvirt, m_NetworkManager_getLocalClientId_MethodRef));
-                            processor.Create(OpCodes.Callvirt, m_NetworkManager_getLocalClientId_MethodRef));
                         instructions.Add(processor.Create(OpCodes.Ceq));
                         instructions.Add(processor.Create(OpCodes.Ldc_I4, 0));
                         instructions.Add(processor.Create(OpCodes.Ceq));
@@ -875,8 +935,7 @@ namespace Unity.Netcode.Editor.CodeGen
                         instructions.Add(processor.Create(OpCodes.Brfalse, logNextInstr));
 
                         // Debug.LogError(...);
-                        instructions.Add(processor.Create(OpCodes.Ldstr,
+                        instructions.Add(processor.Create(OpCodes.Ldstr, "Only the owner can invoke a ServerRpc that requires ownership!"));
-                            "Only the owner can invoke a ServerRpc that requires ownership!"));
                         instructions.Add(processor.Create(OpCodes.Call, m_Debug_LogError_MethodRef));
 
                         instructions.Add(logNextInstr);
@@ -884,31 +943,86 @@ namespace Unity.Netcode.Editor.CodeGen
                         instructions.Add(roReturnInstr);
                         instructions.Add(roLastInstr);
                     }
+
+                    // var bufferWriter = __beginSendServerRpc(rpcMethodId, serverRpcParams, rpcDelivery);
+                    instructions.Add(processor.Create(OpCodes.Ldarg_0));
+
+                    // rpcMethodId
+                    instructions.Add(processor.Create(OpCodes.Ldc_I4, unchecked((int)rpcMethodId)));
+
+                    // rpcParams
+                    instructions.Add(hasRpcParams ? processor.Create(OpCodes.Ldarg, paramCount) : processor.Create(OpCodes.Ldloc, rpcParamsIdx));
+
+                    // rpcDelivery
+                    instructions.Add(processor.Create(OpCodes.Ldc_I4, (int)rpcDelivery));
+
+                    // __beginSendServerRpc
+                    instructions.Add(processor.Create(OpCodes.Call, m_NetworkBehaviour_beginSendServerRpc_MethodRef));
+                    instructions.Add(processor.Create(OpCodes.Stloc, bufWriterLocIdx));
                 }
+                else
+                {
+                    // ClientRpc
 
-                // var writer = new FastBufferWriter(1285, Allocator.Temp, 63985);
+                    // var bufferWriter = __beginSendClientRpc(rpcMethodId, clientRpcParams, rpcDelivery);
-                instructions.Add(processor.Create(OpCodes.Ldloca, serializerLocIdx));
+                    instructions.Add(processor.Create(OpCodes.Ldarg_0));
-                instructions.Add(processor.Create(OpCodes.Ldc_I4, 1300 - sizeof(byte) - sizeof(ulong) - sizeof(uint) - sizeof(ushort)));
-                instructions.Add(processor.Create(OpCodes.Ldc_I4_2));
-                instructions.Add(processor.Create(OpCodes.Ldc_I4, 64000 - sizeof(byte) - sizeof(ulong) - sizeof(uint) - sizeof(ushort)));
-                instructions.Add(processor.Create(OpCodes.Call, m_FastBufferWriter_Constructor));
 
-                var firstInstruction = processor.Create(OpCodes.Nop);
+                    // rpcMethodId
-                instructions.Add(firstInstruction);
+                    instructions.Add(processor.Create(OpCodes.Ldc_I4, unchecked((int)rpcMethodId)));
+
+                    // rpcParams
+                    instructions.Add(hasRpcParams ? processor.Create(OpCodes.Ldarg, paramCount) : processor.Create(OpCodes.Ldloc, rpcParamsIdx));
+
+                    // rpcDelivery
+                    instructions.Add(processor.Create(OpCodes.Ldc_I4, (int)rpcDelivery));
+
+                    // __beginSendClientRpc
+                    instructions.Add(processor.Create(OpCodes.Call, m_NetworkBehaviour_beginSendClientRpc_MethodRef));
+                    instructions.Add(processor.Create(OpCodes.Stloc, bufWriterLocIdx));
+                }
 
                 // write method parameters into stream
                 for (int paramIndex = 0; paramIndex < paramCount; ++paramIndex)
                 {
                     var paramDef = methodDefinition.Parameters[paramIndex];
                     var paramType = paramDef.ParameterType;
-                    // ServerRpcParams
+                    if (paramType.FullName == CodeGenHelpers.ClientRpcSendParams_FullName ||
-                    if (paramType.FullName == CodeGenHelpers.ServerRpcParams_FullName && isServerRpc && paramIndex == paramCount - 1)
+                        paramType.FullName == CodeGenHelpers.ClientRpcReceiveParams_FullName)
                     {
+                        m_Diagnostics.AddError($"Rpcs may not accept {paramType.FullName} as a parameter. Use {nameof(ClientRpcParams)} instead.");
+                        continue;
+                    }
+
+                    if (paramType.FullName == CodeGenHelpers.ServerRpcSendParams_FullName ||
+                        paramType.FullName == CodeGenHelpers.ServerRpcReceiveParams_FullName)
+                    {
+                        m_Diagnostics.AddError($"Rpcs may not accept {paramType.FullName} as a parameter. Use {nameof(ServerRpcParams)} instead.");
+                        continue;
+                    }
+                    // ServerRpcParams
+                    if (paramType.FullName == CodeGenHelpers.ServerRpcParams_FullName)
+                    {
+                        if (paramIndex != paramCount - 1)
+                        {
+                            m_Diagnostics.AddError(methodDefinition, $"{nameof(ServerRpcParams)} must be the last parameter in a ServerRpc.");
+                        }
+                        if (!isServerRpc)
+                        {
+                            m_Diagnostics.AddError($"ClientRpcs may not accept {nameof(ServerRpcParams)} as a parameter.");
+                        }
                         continue;
                     }
                     // ClientRpcParams
-                    if (paramType.FullName == CodeGenHelpers.ClientRpcParams_FullName && !isServerRpc && paramIndex == paramCount - 1)
+                    if (paramType.FullName == CodeGenHelpers.ClientRpcParams_FullName)
                     {
+                        if (paramIndex != paramCount - 1)
+                        {
+                            m_Diagnostics.AddError(methodDefinition, $"{nameof(ClientRpcParams)} must be the last parameter in a ClientRpc.");
+                        }
+                        if (isServerRpc)
+                        {
+                            m_Diagnostics.AddError($"ServerRpcs may not accept {nameof(ClientRpcParams)} as a parameter.");
+                        }
                         continue;
                     }
 
@@ -931,9 +1045,20 @@ namespace Unity.Netcode.Editor.CodeGen
                         instructions.Add(processor.Create(OpCodes.Cgt_Un));
                         instructions.Add(processor.Create(OpCodes.Stloc, isSetLocalIndex));
 
-                        // writer.WriteValueSafe(isSet);
+                        // bufferWriter.WriteValueSafe(isSet);
-                        instructions.Add(processor.Create(OpCodes.Ldloca, serializerLocIdx));
+                        instructions.Add(processor.Create(OpCodes.Ldloca, bufWriterLocIdx));
                         instructions.Add(processor.Create(OpCodes.Ldloca, isSetLocalIndex));
+
+                        for (var i = 1; i < boolMethodRef.Parameters.Count; ++i)
+                        {
+                            var param = boolMethodRef.Parameters[i];
+                            methodDefinition.Body.Variables.Add(new VariableDefinition(param.ParameterType));
+                            int overloadParamLocalIdx = methodDefinition.Body.Variables.Count - 1;
+                            instructions.Add(processor.Create(OpCodes.Ldloca, overloadParamLocalIdx));
+                            instructions.Add(processor.Create(OpCodes.Initobj, param.ParameterType));
+                            instructions.Add(processor.Create(OpCodes.Ldloc, overloadParamLocalIdx));
+                        }
+
                         instructions.Add(processor.Create(OpCodes.Call, boolMethodRef));
 
                         // if(isSet) {
@@ -945,22 +1070,28 @@ namespace Unity.Netcode.Editor.CodeGen
                     var foundMethodRef = GetWriteMethodForParameter(paramType, out var methodRef);
                     if (foundMethodRef)
                     {
-                        // writer.WriteNetworkSerializable(param) for INetworkSerializable, OR
+                        // bufferWriter.WriteNetworkSerializable(param) for INetworkSerializable, OR
-                        // writer.WriteNetworkSerializable(param, -1, 0) for INetworkSerializable arrays, OR
+                        // bufferWriter.WriteNetworkSerializable(param, -1, 0) for INetworkSerializable arrays, OR
-                        // writer.WriteValueSafe(param) for value types, OR
+                        // bufferWriter.WriteValueSafe(param) for value types, OR
-                        // writer.WriteValueSafe(param, -1, 0) for arrays of value types, OR
+                        // bufferWriter.WriteValueSafe(param, -1, 0) for arrays of value types, OR
-                        // writer.WriteValueSafe(param, false) for strings
+                        // bufferWriter.WriteValueSafe(param, false) for strings
-                        instructions.Add(processor.Create(OpCodes.Ldloca, serializerLocIdx));
                         var method = methodRef.Resolve();
                         var checkParameter = method.Parameters[0];
                         var isExtensionMethod = false;
-                        if (checkParameter.ParameterType.Resolve() ==
+                        if (methodRef.Resolve().DeclaringType != m_FastBufferWriter_TypeRef.Resolve())
-                            m_FastBufferWriter_TypeRef.MakeByReferenceType().Resolve())
                         {
                             isExtensionMethod = true;
                             checkParameter = method.Parameters[1];
                         }
-                        if (checkParameter.IsIn)
+                        if (!isExtensionMethod || method.Parameters[0].ParameterType.IsByReference)
+                        {
+                            instructions.Add(processor.Create(OpCodes.Ldloca, bufWriterLocIdx));
+                        }
+                        else
+                        {
+                            instructions.Add(processor.Create(OpCodes.Ldloc, bufWriterLocIdx));
+                        }
+                        if (checkParameter.IsIn || checkParameter.IsOut || checkParameter.ParameterType.IsByReference)
                         {
                             instructions.Add(processor.Create(OpCodes.Ldarga, paramIndex + 1));
                         }
@@ -969,24 +1100,49 @@ namespace Unity.Netcode.Editor.CodeGen
                             instructions.Add(processor.Create(OpCodes.Ldarg, paramIndex + 1));
                         }
                         // Special handling for WriteValue() on arrays and strings since they have additional arguments.
-                        if (paramType.IsArray
+                        if (paramType.IsArray && ((!isExtensionMethod && methodRef.Parameters.Count == 3) ||
-                            && ((!isExtensionMethod && methodRef.Parameters.Count == 3)
+                            (isExtensionMethod && methodRef.Parameters.Count == 4)))
-                                || (isExtensionMethod && methodRef.Parameters.Count == 4)))
                         {
                             instructions.Add(processor.Create(OpCodes.Ldc_I4_M1));
                             instructions.Add(processor.Create(OpCodes.Ldc_I4_0));
                         }
-                        else if (paramType == typeSystem.String
+                        else if (paramType == typeSystem.String && ((!isExtensionMethod && methodRef.Parameters.Count == 2) ||
-                             && ((!isExtensionMethod && methodRef.Parameters.Count == 2)
+                            (isExtensionMethod && methodRef.Parameters.Count == 3)))
-                                 || (isExtensionMethod && methodRef.Parameters.Count == 3)))
                         {
                             instructions.Add(processor.Create(OpCodes.Ldc_I4_0));
                         }
+                        else
+                        {
+                            if (isExtensionMethod && methodRef.Parameters.Count > 2)
+                            {
+                                for (var i = 2; i < methodRef.Parameters.Count; ++i)
+                                {
+                                    var param = methodRef.Parameters[i];
+                                    methodDefinition.Body.Variables.Add(new VariableDefinition(param.ParameterType));
+                                    int overloadParamLocalIdx = methodDefinition.Body.Variables.Count - 1;
+                                    instructions.Add(processor.Create(OpCodes.Ldloca, overloadParamLocalIdx));
+                                    instructions.Add(processor.Create(OpCodes.Initobj, param.ParameterType));
+                                    instructions.Add(processor.Create(OpCodes.Ldloc, overloadParamLocalIdx));
+                                }
+                            }
+                            else if (!isExtensionMethod && methodRef.Parameters.Count > 1)
+                            {
+                                for (var i = 1; i < methodRef.Parameters.Count; ++i)
+                                {
+                                    var param = methodRef.Parameters[i];
+                                    methodDefinition.Body.Variables.Add(new VariableDefinition(param.ParameterType));
+                                    int overloadParamLocalIdx = methodDefinition.Body.Variables.Count - 1;
+                                    instructions.Add(processor.Create(OpCodes.Ldloca, overloadParamLocalIdx));
+                                    instructions.Add(processor.Create(OpCodes.Initobj, param.ParameterType));
+                                    instructions.Add(processor.Create(OpCodes.Ldloc, overloadParamLocalIdx));
+                                }
+                            }
+                        }
                         instructions.Add(processor.Create(OpCodes.Call, methodRef));
                     }
                     else
                     {
-                        m_Diagnostics.AddError(methodDefinition, $"Don't know how to serialize {paramType.Name} - implement {nameof(INetworkSerializable)} or add an extension method for {nameof(FastBufferWriter)}.{k_WriteValueMethodName} to define serialization.");
+                        m_Diagnostics.AddError(methodDefinition, $"Don't know how to serialize {paramType.Name} - implement {nameof(INetworkSerializable)}, tag memcpyable struct with {nameof(INetworkSerializeByMemcpy)}, or add an extension method for {nameof(FastBufferWriter)}.{k_WriteValueMethodName} to define serialization.");
                         continue;
                     }
 
@@ -998,20 +1154,20 @@ namespace Unity.Netcode.Editor.CodeGen
 
                 instructions.Add(endInstr);
 
-                // __sendServerRpc(ref serializer, rpcMethodId, serverRpcParams, rpcDelivery) -> ServerRpc
+                // __endSendServerRpc(ref bufferWriter, rpcMethodId, serverRpcParams, rpcDelivery) -> ServerRpc
-                // __sendClientRpc(ref serializer, rpcMethodId, clientRpcParams, rpcDelivery) -> ClientRpc
+                // __endSendClientRpc(ref bufferWriter, rpcMethodId, clientRpcParams, rpcDelivery) -> ClientRpc
                 if (isServerRpc)
                 {
                     // ServerRpc
-                    // __sendServerRpc(ref serializer, rpcMethodId, serverRpcParams, rpcDelivery);
+
+                    // __endSendServerRpc(ref bufferWriter, rpcMethodId, serverRpcParams, rpcDelivery);
                     instructions.Add(processor.Create(OpCodes.Ldarg_0));
 
-                    // serializer
+                    // bufferWriter
-                    instructions.Add(processor.Create(OpCodes.Ldloc, serializerLocIdx));
+                    instructions.Add(processor.Create(OpCodes.Ldloca, bufWriterLocIdx));
 
                     // rpcMethodId
                     instructions.Add(processor.Create(OpCodes.Ldc_I4, unchecked((int)rpcMethodId)));
-
                     if (hasRpcParams)
                     {
                         // rpcParams
@@ -1022,25 +1178,24 @@ namespace Unity.Netcode.Editor.CodeGen
                         // default
                         instructions.Add(processor.Create(OpCodes.Ldloc, rpcParamsIdx));
                     }
-
                     // rpcDelivery
                     instructions.Add(processor.Create(OpCodes.Ldc_I4, (int)rpcDelivery));
 
-                    // EndSendServerRpc
+                    // __endSendServerRpc
-                    instructions.Add(processor.Create(OpCodes.Call, m_NetworkBehaviour_SendServerRpc_MethodRef));
+                    instructions.Add(processor.Create(OpCodes.Call, m_NetworkBehaviour_endSendServerRpc_MethodRef));
                 }
                 else
                 {
                     // ClientRpc
-                    // __sendClientRpc(ref serializer, rpcMethodId, clientRpcParams, rpcDelivery);
+
+                    // __endSendClientRpc(ref bufferWriter, rpcMethodId, clientRpcParams, rpcDelivery);
                     instructions.Add(processor.Create(OpCodes.Ldarg_0));
 
-                    // serializer
+                    // bufferWriter
-                    instructions.Add(processor.Create(OpCodes.Ldloc, serializerLocIdx));
+                    instructions.Add(processor.Create(OpCodes.Ldloca, bufWriterLocIdx));
 
                     // rpcMethodId
                     instructions.Add(processor.Create(OpCodes.Ldc_I4, unchecked((int)rpcMethodId)));
-
                     if (hasRpcParams)
                     {
                         // rpcParams
@@ -1051,36 +1206,11 @@ namespace Unity.Netcode.Editor.CodeGen
                         // default
                         instructions.Add(processor.Create(OpCodes.Ldloc, rpcParamsIdx));
                     }
-
                     // rpcDelivery
                     instructions.Add(processor.Create(OpCodes.Ldc_I4, (int)rpcDelivery));
 
-                    // EndSendClientRpc
+                    // __endSendClientRpc
-                    instructions.Add(processor.Create(OpCodes.Call, m_NetworkBehaviour_SendClientRpc_MethodRef));
+                    instructions.Add(processor.Create(OpCodes.Call, m_NetworkBehaviour_endSendClientRpc_MethodRef));
-                }
-
-                {
-                    // TODO: Figure out why try/catch here cause the try block not to execute at all.
-                    // End try block
-                    //instructions.Add(processor.Create(OpCodes.Leave, lastInstr));
-
-                    // writer.Dispose();
-                    var handlerFirst = processor.Create(OpCodes.Ldloca, serializerLocIdx);
-                    instructions.Add(handlerFirst);
-                    instructions.Add(processor.Create(OpCodes.Call, m_FastBufferWriter_Dispose));
-
-                    // End finally block
-                    //instructions.Add(processor.Create(OpCodes.Endfinally));
-
-                    // try { ... serialization code ... } finally { writer.Dispose(); }
-                    /*var handler = new ExceptionHandler(ExceptionHandlerType.Finally)
-                    {
-                        TryStart = firstInstruction,
-                        TryEnd = handlerFirst,
-                        HandlerStart = handlerFirst,
-                        HandlerEnd = lastInstr
-                    };
-                    processor.Body.ExceptionHandlers.Add(handler);*/
                 }
 
                 instructions.Add(lastInstr);
@@ -1115,25 +1245,21 @@ namespace Unity.Netcode.Editor.CodeGen
             instructions.ForEach(instruction => processor.Body.Instructions.Insert(0, instruction));
         }
 
-        private MethodDefinition GenerateStaticHandler(MethodDefinition methodDefinition, CustomAttribute rpcAttribute)
+        private MethodDefinition GenerateStaticHandler(MethodDefinition methodDefinition, CustomAttribute rpcAttribute, uint rpcMethodId)
         {
             var typeSystem = methodDefinition.Module.TypeSystem;
-            var nhandler = new MethodDefinition(
+            var rpcHandler = new MethodDefinition(
-                $"{methodDefinition.Name}__nhandler",
+                $"__rpc_handler_{rpcMethodId}",
                 MethodAttributes.Private | MethodAttributes.Static | MethodAttributes.HideBySig,
                 methodDefinition.Module.TypeSystem.Void);
-            nhandler.Parameters.Add(new ParameterDefinition("target", ParameterAttributes.None, m_NetworkBehaviour_TypeRef));
+            rpcHandler.Parameters.Add(new ParameterDefinition("target", ParameterAttributes.None, m_NetworkBehaviour_TypeRef));
-            nhandler.Parameters.Add(new ParameterDefinition("reader", ParameterAttributes.None, m_FastBufferReader_TypeRef));
+            rpcHandler.Parameters.Add(new ParameterDefinition("reader", ParameterAttributes.None, m_FastBufferReader_TypeRef));
-            nhandler.Parameters.Add(new ParameterDefinition("rpcParams", ParameterAttributes.None, m_RpcParams_TypeRef));
+            rpcHandler.Parameters.Add(new ParameterDefinition("rpcParams", ParameterAttributes.None, m_RpcParams_TypeRef));
 
-            var processor = nhandler.Body.GetILProcessor();
+            var processor = rpcHandler.Body.GetILProcessor();
-
-            // begin Try/Catch
-            var tryStart = processor.Create(OpCodes.Nop);
-            processor.Append(tryStart);
 
             var isServerRpc = rpcAttribute.AttributeType.FullName == CodeGenHelpers.ServerRpcAttribute_FullName;
-            var requireOwnership = true; // default value MUST be = `ServerRpcAttribute.RequireOwnership`
+            var requireOwnership = true; // default value MUST be == `ServerRpcAttribute.RequireOwnership`
             foreach (var attrField in rpcAttribute.Fields)
             {
                 switch (attrField.Name)
@@ -1144,10 +1270,10 @@ namespace Unity.Netcode.Editor.CodeGen
                 }
             }
 
-            nhandler.Body.InitLocals = true;
+            rpcHandler.Body.InitLocals = true;
             // NetworkManager networkManager;
-            nhandler.Body.Variables.Add(new VariableDefinition(m_NetworkManager_TypeRef));
+            rpcHandler.Body.Variables.Add(new VariableDefinition(m_NetworkManager_TypeRef));
-            int netManLocIdx = nhandler.Body.Variables.Count - 1;
+            int netManLocIdx = rpcHandler.Body.Variables.Count - 1;
 
             {
                 var returnInstr = processor.Create(OpCodes.Ret);
@@ -1216,8 +1342,8 @@ namespace Unity.Netcode.Editor.CodeGen
                 var paramType = paramDef.ParameterType;
 
                 // local variable
-                nhandler.Body.Variables.Add(new VariableDefinition(paramType));
+                rpcHandler.Body.Variables.Add(new VariableDefinition(paramType));
-                int localIndex = nhandler.Body.Variables.Count - 1;
+                int localIndex = rpcHandler.Body.Variables.Count - 1;
                 paramLocalMap[paramIndex] = localIndex;
 
                 // ServerRpcParams, ClientRpcParams
@@ -1251,10 +1377,21 @@ namespace Unity.Netcode.Editor.CodeGen
                     }
 
                     // reader.ReadValueSafe(out bool isSet)
-                    nhandler.Body.Variables.Add(new VariableDefinition(typeSystem.Boolean));
+                    rpcHandler.Body.Variables.Add(new VariableDefinition(typeSystem.Boolean));
-                    int isSetLocalIndex = nhandler.Body.Variables.Count - 1;
+                    int isSetLocalIndex = rpcHandler.Body.Variables.Count - 1;
                     processor.Emit(OpCodes.Ldarga, 1);
                     processor.Emit(OpCodes.Ldloca, isSetLocalIndex);
+
+                    for (var i = 1; i < boolMethodRef.Parameters.Count; ++i)
+                    {
+                        var param = boolMethodRef.Parameters[i];
+                        rpcHandler.Body.Variables.Add(new VariableDefinition(param.ParameterType));
+                        int overloadParamLocalIdx = rpcHandler.Body.Variables.Count - 1;
+                        processor.Emit(OpCodes.Ldloca, overloadParamLocalIdx);
+                        processor.Emit(OpCodes.Initobj, param.ParameterType);
+                        processor.Emit(OpCodes.Ldloc, overloadParamLocalIdx);
+                    }
+
                     processor.Emit(OpCodes.Call, boolMethodRef);
 
                     // paramType param = null;
@@ -1271,17 +1408,55 @@ namespace Unity.Netcode.Editor.CodeGen
                 if (foundMethodRef)
                 {
                     // reader.ReadValueSafe(out localVar);
-                    processor.Emit(OpCodes.Ldarga, 1);
+
+                    var checkParameter = methodRef.Resolve().Parameters[0];
+
+                    var isExtensionMethod = methodRef.Resolve().DeclaringType != m_FastBufferReader_TypeRef.Resolve();
+                    if (!isExtensionMethod || checkParameter.ParameterType.IsByReference)
+                    {
+                        processor.Emit(OpCodes.Ldarga, 1);
+                    }
+                    else
+                    {
+                        processor.Emit(OpCodes.Ldarg, 1);
+                    }
                     processor.Emit(OpCodes.Ldloca, localIndex);
                     if (paramType == typeSystem.String)
                     {
                         processor.Emit(OpCodes.Ldc_I4_0);
                     }
+                    else
+                    {
+                        if (isExtensionMethod && methodRef.Parameters.Count > 2)
+                        {
+                            for (var i = 2; i < methodRef.Parameters.Count; ++i)
+                            {
+                                var param = methodRef.Parameters[i];
+                                rpcHandler.Body.Variables.Add(new VariableDefinition(param.ParameterType));
+                                int overloadParamLocalIdx = rpcHandler.Body.Variables.Count - 1;
+                                processor.Emit(OpCodes.Ldloca, overloadParamLocalIdx);
+                                processor.Emit(OpCodes.Initobj, param.ParameterType);
+                                processor.Emit(OpCodes.Ldloc, overloadParamLocalIdx);
+                            }
+                        }
+                        else if (!isExtensionMethod && methodRef.Parameters.Count > 1)
+                        {
+                            for (var i = 1; i < methodRef.Parameters.Count; ++i)
+                            {
+                                var param = methodRef.Parameters[i];
+                                rpcHandler.Body.Variables.Add(new VariableDefinition(param.ParameterType));
+                                int overloadParamLocalIdx = rpcHandler.Body.Variables.Count - 1;
+                                processor.Emit(OpCodes.Ldloca, overloadParamLocalIdx);
+                                processor.Emit(OpCodes.Initobj, param.ParameterType);
+                                processor.Emit(OpCodes.Ldloc, overloadParamLocalIdx);
+                            }
+                        }
+                    }
                     processor.Emit(OpCodes.Call, methodRef);
                 }
                 else
                 {
-                    m_Diagnostics.AddError(methodDefinition, $"Don't know how to deserialize {paramType.Name} - implement {nameof(INetworkSerializable)} or add an extension method for {nameof(FastBufferReader)}.{k_ReadValueMethodName} to define serialization.");
+                    m_Diagnostics.AddError(methodDefinition, $"Don't know how to serialize {paramType.Name} - implement {nameof(INetworkSerializable)}, tag memcpyable struct with {nameof(INetworkSerializeByMemcpy)}, or add an extension method for {nameof(FastBufferWriter)}.{k_WriteValueMethodName} to define serialization.");
                     continue;
                 }
 
@@ -1308,55 +1483,8 @@ namespace Unity.Netcode.Editor.CodeGen
             processor.Emit(OpCodes.Ldc_I4, (int)NetworkBehaviour.__RpcExecStage.None);
             processor.Emit(OpCodes.Stfld, m_NetworkBehaviour_rpc_exec_stage_FieldRef);
 
-            // pull in the Exception Module
-            var exception = m_MainModule.ImportReference(typeof(Exception));
-
-            // Get Exception.ToString()
-            var exp = m_MainModule.ImportReference(typeof(Exception).GetMethod("ToString", new Type[] { }));
-
-            // Get String.Format (This is equivalent to an interpolated string)
-            var stringFormat = m_MainModule.ImportReference(typeof(string).GetMethod("Format", new Type[] { typeof(string), typeof(object) }));
-
-            nhandler.Body.Variables.Add(new VariableDefinition(exception));
-            int exceptionVariableIndex = nhandler.Body.Variables.Count - 1;
-
-            //try ends/catch begins
-            var catchEnds = processor.Create(OpCodes.Nop);
-            processor.Emit(OpCodes.Leave, catchEnds);
-
-            // Load the Exception onto the stack
-            var catchStarts = processor.Create(OpCodes.Stloc, exceptionVariableIndex);
-            processor.Append(catchStarts);
-
-            // Load string for the error log that will be shown
-            processor.Emit(OpCodes.Ldstr, $"Unhandled RPC Exception:\n {{0}}");
-            processor.Emit(OpCodes.Ldloc, exceptionVariableIndex);
-            processor.Emit(OpCodes.Callvirt, exp);
-            processor.Emit(OpCodes.Call, stringFormat);
-
-            // Call Debug.LogError
-            processor.Emit(OpCodes.Call, m_Debug_LogError_MethodRef);
-
-            // reset NetworkBehaviour.__rpc_exec_stage = __RpcExecStage.None;
-            processor.Emit(OpCodes.Ldarg_0);
-            processor.Emit(OpCodes.Ldc_I4, (int)NetworkBehaviour.__RpcExecStage.None);
-            processor.Emit(OpCodes.Stfld, m_NetworkBehaviour_rpc_exec_stage_FieldRef);
-
-            // catch ends
-            processor.Append(catchEnds);
-
-            processor.Body.ExceptionHandlers.Add(new ExceptionHandler(ExceptionHandlerType.Catch)
-            {
-                CatchType = exception,
-                TryStart = tryStart,
-                TryEnd = catchStarts,
-                HandlerStart = catchStarts,
-                HandlerEnd = catchEnds
-            });
-
             processor.Emit(OpCodes.Ret);
-
+            return rpcHandler;
-            return nhandler;
         }
     }
 }

Editor/CodeGen/RuntimeAccessModifiersILPP.cs

@@ -52,6 +52,9 @@ namespace Unity.Netcode.Editor.CodeGen
                         case nameof(NetworkBehaviour):
                             ProcessNetworkBehaviour(typeDefinition);
                             break;
+                        case nameof(NetworkVariableHelper):
+                            ProcessNetworkVariableHelper(typeDefinition);
+                            break;
                         case nameof(__RpcParams):
                             typeDefinition.IsPublic = true;
                             break;
@@ -100,6 +103,25 @@ namespace Unity.Netcode.Editor.CodeGen
             }
         }
 
+        private void ProcessNetworkVariableHelper(TypeDefinition typeDefinition)
+        {
+            foreach (var methodDefinition in typeDefinition.Methods)
+            {
+                if (methodDefinition.Name == nameof(NetworkVariableHelper.InitializeDelegatesEnum))
+                {
+                    methodDefinition.IsPublic = true;
+                }
+                if (methodDefinition.Name == nameof(NetworkVariableHelper.InitializeDelegatesStruct))
+                {
+                    methodDefinition.IsPublic = true;
+                }
+                if (methodDefinition.Name == nameof(NetworkVariableHelper.InitializeDelegatesNetworkSerializable))
+                {
+                    methodDefinition.IsPublic = true;
+                }
+            }
+        }
+
         private void ProcessNetworkBehaviour(TypeDefinition typeDefinition)
         {
             foreach (var nestedType in typeDefinition.NestedTypes)
@@ -120,8 +142,10 @@ namespace Unity.Netcode.Editor.CodeGen
 
             foreach (var methodDefinition in typeDefinition.Methods)
             {
-                if (methodDefinition.Name == nameof(NetworkBehaviour.__sendServerRpc)
+                if (methodDefinition.Name == nameof(NetworkBehaviour.__beginSendServerRpc) ||
-                    || methodDefinition.Name == nameof(NetworkBehaviour.__sendClientRpc))
+                    methodDefinition.Name == nameof(NetworkBehaviour.__endSendServerRpc) ||
+                    methodDefinition.Name == nameof(NetworkBehaviour.__beginSendClientRpc) ||
+                    methodDefinition.Name == nameof(NetworkBehaviour.__endSendClientRpc))
                 {
                     methodDefinition.IsFamily = true;
                 }

Editor/CodeGen/com.unity.netcode.editor.codegen.asmdef

@@ -7,6 +7,7 @@
     "includePlatforms": [
         "Editor"
     ],
+    "excludePlatforms": [],
     "allowUnsafeCode": true,
     "overrideReferences": true,
     "precompiledReferences": [
@@ -15,5 +16,14 @@
         "Mono.Cecil.Pdb.dll",
         "Mono.Cecil.Rocks.dll"
     ],
-    "autoReferenced": false
+    "autoReferenced": false,
-}
+    "defineConstraints": [],
+    "versionDefines": [
+        {
+            "name": "com.unity.nuget.mono-cecil",
+            "expression": "(0,1.11.4)",
+            "define": "CECIL_CONSTRAINTS_ARE_TYPE_REFERENCES"
+        }
+    ],
+    "noEngineReferences": false
+}

Editor/DontShowInTransportDropdownAttribute.cs

@@ -1,8 +0,0 @@
-using System;
-
-namespace Unity.Netcode.Editor
-{
-    public class DontShowInTransportDropdownAttribute : Attribute
-    {
-    }
-}

Editor/DontShowInTransportDropdownAttribute.cs.meta

@@ -1,3 +0,0 @@
-fileFormatVersion: 2
-guid: 5f097067d4254dc7ad018d7ad90df7c3
-timeCreated: 1620386886

Editor/NetworkAnimatorEditor.cs

@@ -1,103 +0,0 @@
-using System;
-using Unity.Netcode.Components;
-using UnityEditor;
-using UnityEditor.Animations;
-using UnityEngine;
-
-namespace Unity.Netcode.Editor
-{
-    public static class TextUtility
-    {
-        public static GUIContent TextContent(string name, string tooltip)
-        {
-            var newContent = new GUIContent(name);
-            newContent.tooltip = tooltip;
-            return newContent;
-        }
-
-        public static GUIContent TextContent(string name)
-        {
-            return new GUIContent(name);
-        }
-    }
-
-    [CustomEditor(typeof(NetworkAnimator), true)]
-    [CanEditMultipleObjects]
-    public class NetworkAnimatorEditor : UnityEditor.Editor
-    {
-        private NetworkAnimator m_AnimSync;
-        [NonSerialized] private bool m_Initialized;
-        private SerializedProperty m_AnimatorProperty;
-        private GUIContent m_AnimatorLabel;
-
-        private void Init()
-        {
-            if (m_Initialized)
-            {
-                return;
-            }
-
-            m_Initialized = true;
-            m_AnimSync = target as NetworkAnimator;
-
-            m_AnimatorProperty = serializedObject.FindProperty("m_Animator");
-            m_AnimatorLabel = TextUtility.TextContent("Animator", "The Animator component to synchronize.");
-        }
-
-        public override void OnInspectorGUI()
-        {
-            Init();
-            serializedObject.Update();
-            DrawControls();
-            serializedObject.ApplyModifiedProperties();
-        }
-
-        private void DrawControls()
-        {
-            EditorGUI.BeginChangeCheck();
-            EditorGUILayout.PropertyField(m_AnimatorProperty, m_AnimatorLabel);
-            if (EditorGUI.EndChangeCheck())
-            {
-                m_AnimSync.ResetParameterOptions();
-            }
-
-            if (m_AnimSync.Animator == null)
-            {
-                return;
-            }
-
-            var controller = m_AnimSync.Animator.runtimeAnimatorController as AnimatorController;
-            if (controller != null)
-            {
-                var showWarning = false;
-                EditorGUI.indentLevel += 1;
-                int i = 0;
-
-                foreach (var p in controller.parameters)
-                {
-                    if (i >= NetworkAnimator.K_MaxAnimationParams)
-                    {
-                        showWarning = true;
-                        break;
-                    }
-
-                    bool oldSend = m_AnimSync.GetParameterAutoSend(i);
-                    bool send = EditorGUILayout.Toggle(p.name, oldSend);
-                    if (send != oldSend)
-                    {
-                        m_AnimSync.SetParameterAutoSend(i, send);
-                        EditorUtility.SetDirty(target);
-                    }
-                    i += 1;
-                }
-
-                if (showWarning)
-                {
-                    EditorGUILayout.HelpBox($"NetworkAnimator can only select between the first {NetworkAnimator.K_MaxAnimationParams} parameters in a mecanim controller", MessageType.Warning);
-                }
-
-                EditorGUI.indentLevel -= 1;
-            }
-        }
-    }
-}

Editor/NetworkBehaviourEditor.cs

@@ -211,5 +211,91 @@ namespace Unity.Netcode.Editor
             serializedObject.ApplyModifiedProperties();
             EditorGUI.EndChangeCheck();
         }
+
+        /// <summary>
+        /// Invoked once when a NetworkBehaviour component is
+        /// displayed in the inspector view.
+        /// </summary>
+        private void OnEnable()
+        {
+            // When we first add a NetworkBehaviour this editor will be enabled
+            // so we go ahead and check for an already existing NetworkObject here
+            CheckForNetworkObject((target as NetworkBehaviour).gameObject);
+        }
+
+        internal const string AutoAddNetworkObjectIfNoneExists = "AutoAdd-NetworkObject-When-None-Exist";
+
+        public static Transform GetRootParentTransform(Transform transform)
+        {
+            if (transform.parent == null || transform.parent == transform)
+            {
+                return transform;
+            }
+            return GetRootParentTransform(transform.parent);
+        }
+
+        /// <summary>
+        /// Used to determine if a GameObject has one or more NetworkBehaviours but
+        /// does not already have a NetworkObject component.  If not it will notify
+        /// the user that NetworkBehaviours require a NetworkObject.
+        /// </summary>
+        public static void CheckForNetworkObject(GameObject gameObject, bool networkObjectRemoved = false)
+        {
+            // If there are no NetworkBehaviours or no gameObject, then exit early
+            if (gameObject == null || (gameObject.GetComponent<NetworkBehaviour>() == null && gameObject.GetComponentInChildren<NetworkBehaviour>() == null))
+            {
+                return;
+            }
+
+            // Now get the root parent transform to the current GameObject (or itself)
+            var rootTransform = GetRootParentTransform(gameObject.transform);
+
+            // Otherwise, check to see if there is any NetworkObject from the root GameObject down to all children.
+            // If not, notify the user that NetworkBehaviours require that the relative GameObject has a NetworkObject component.
+            var networkObject = rootTransform.GetComponent<NetworkObject>();
+            if (networkObject == null)
+            {
+                networkObject = rootTransform.GetComponentInChildren<NetworkObject>();
+
+                if (networkObject == null)
+                {
+                    // If we are removing a NetworkObject but there is still one or more NetworkBehaviour components
+                    // and the user has already turned "Auto-Add NetworkObject" on when first notified about the requirement
+                    // then just send a reminder to the user why the NetworkObject they just deleted seemingly "re-appeared"
+                    // again.
+                    if (networkObjectRemoved && EditorPrefs.HasKey(AutoAddNetworkObjectIfNoneExists) && EditorPrefs.GetBool(AutoAddNetworkObjectIfNoneExists))
+                    {
+                        Debug.LogWarning($"{gameObject.name} still has {nameof(NetworkBehaviour)}s and Auto-Add NetworkObjects is enabled. A NetworkObject is being added back to {gameObject.name}.");
+                        Debug.Log($"To reset Auto-Add NetworkObjects: Select the Netcode->General->Reset Auto-Add NetworkObject menu item.");
+                    }
+
+                    // Notify and provide the option to add it one time, always add a NetworkObject, or do nothing and let the user manually add it
+                    if (EditorUtility.DisplayDialog($"{nameof(NetworkBehaviour)}s require a {nameof(NetworkObject)}",
+                    $"{gameObject.name} does not have a {nameof(NetworkObject)} component.  Would you like to add one now?", "Yes", "No (manually add it)",
+                    DialogOptOutDecisionType.ForThisMachine, AutoAddNetworkObjectIfNoneExists))
+                    {
+                        gameObject.AddComponent<NetworkObject>();
+                        var activeScene = UnityEngine.SceneManagement.SceneManager.GetActiveScene();
+                        UnityEditor.SceneManagement.EditorSceneManager.MarkSceneDirty(activeScene);
+                        UnityEditor.SceneManagement.EditorSceneManager.SaveScene(activeScene);
+                    }
+                }
+            }
+        }
+
+        /// <summary>
+        /// This allows users to reset the Auto-Add NetworkObject preference
+        /// so the next time they add a NetworkBehaviour to a GameObject without
+        /// a NetworkObject it will display the dialog box again and not
+        /// automatically add a NetworkObject.
+        /// </summary>
+        [MenuItem("Netcode/General/Reset Auto-Add NetworkObject", false, 1)]
+        private static void ResetMultiplayerToolsTipStatus()
+        {
+            if (EditorPrefs.HasKey(AutoAddNetworkObjectIfNoneExists))
+            {
+                EditorPrefs.SetBool(AutoAddNetworkObjectIfNoneExists, false);
+            }
+        }
     }
 }

Editor/NetworkManagerEditor.cs

@@ -15,7 +15,6 @@ namespace Unity.Netcode.Editor
         private static GUIStyle s_HelpBoxStyle;
 
         // Properties
-        private SerializedProperty m_DontDestroyOnLoadProperty;
         private SerializedProperty m_RunInBackgroundProperty;
         private SerializedProperty m_LogLevelProperty;
 
@@ -58,7 +57,7 @@ namespace Unity.Netcode.Editor
 
                 foreach (var type in types)
                 {
-                    if (type.IsSubclassOf(typeof(NetworkTransport)) && type.GetCustomAttributes(typeof(DontShowInTransportDropdownAttribute), true).Length == 0)
+                    if (type.IsSubclassOf(typeof(NetworkTransport)) && !type.IsSubclassOf(typeof(TestingNetworkTransport)) && type != typeof(TestingNetworkTransport))
                     {
                         m_TransportTypes.Add(type);
                     }
@@ -85,7 +84,6 @@ namespace Unity.Netcode.Editor
             m_NetworkManager = (NetworkManager)target;
 
             // Base properties
-            m_DontDestroyOnLoadProperty = serializedObject.FindProperty(nameof(NetworkManager.DontDestroy));
             m_RunInBackgroundProperty = serializedObject.FindProperty(nameof(NetworkManager.RunInBackground));
             m_LogLevelProperty = serializedObject.FindProperty(nameof(NetworkManager.LogLevel));
             m_NetworkConfigProperty = serializedObject.FindProperty(nameof(NetworkManager.NetworkConfig));
@@ -112,7 +110,6 @@ namespace Unity.Netcode.Editor
         private void CheckNullProperties()
         {
             // Base properties
-            m_DontDestroyOnLoadProperty = serializedObject.FindProperty(nameof(NetworkManager.DontDestroy));
             m_RunInBackgroundProperty = serializedObject.FindProperty(nameof(NetworkManager.RunInBackground));
             m_LogLevelProperty = serializedObject.FindProperty(nameof(NetworkManager.LogLevel));
             m_NetworkConfigProperty = serializedObject.FindProperty(nameof(NetworkManager.NetworkConfig));
@@ -138,9 +135,13 @@ namespace Unity.Netcode.Editor
             m_NetworkPrefabsList = new ReorderableList(serializedObject, serializedObject.FindProperty(nameof(NetworkManager.NetworkConfig)).FindPropertyRelative(nameof(NetworkConfig.NetworkPrefabs)), true, true, true, true);
             m_NetworkPrefabsList.elementHeightCallback = index =>
             {
-                var networkPrefab = m_NetworkPrefabsList.serializedProperty.GetArrayElementAtIndex(index);
+                var networkOverrideInt = 0;
-                var networkOverrideProp = networkPrefab.FindPropertyRelative(nameof(NetworkPrefab.Override));
+                if (m_NetworkPrefabsList.count > 0)
-                var networkOverrideInt = networkOverrideProp.enumValueIndex;
+                {
+                    var networkPrefab = m_NetworkPrefabsList.serializedProperty.GetArrayElementAtIndex(index);
+                    var networkOverrideProp = networkPrefab.FindPropertyRelative(nameof(NetworkPrefab.Override));
+                    networkOverrideInt = networkOverrideProp.enumValueIndex;
+                }
 
                 return 8 + (networkOverrideInt == 0 ? EditorGUIUtility.singleLineHeight : (EditorGUIUtility.singleLineHeight * 2) + 5);
             };
@@ -223,7 +224,6 @@ namespace Unity.Netcode.Editor
             if (!m_NetworkManager.IsServer && !m_NetworkManager.IsClient)
             {
                 serializedObject.Update();
-                EditorGUILayout.PropertyField(m_DontDestroyOnLoadProperty);
                 EditorGUILayout.PropertyField(m_RunInBackgroundProperty);
                 EditorGUILayout.PropertyField(m_LogLevelProperty);
                 EditorGUILayout.Space();
@@ -363,7 +363,7 @@ namespace Unity.Netcode.Editor
             const string getToolsText = "Access additional tools for multiplayer development by installing the Multiplayer Tools package in the Package Manager.";
             const string openDocsButtonText = "Open Docs";
             const string dismissButtonText = "Dismiss";
-            const string targetUrl = "https://docs-multiplayer.unity3d.com/docs/tutorials/goldenpath_series/goldenpath_foundation_module";
+            const string targetUrl = "https://docs-multiplayer.unity3d.com/netcode/current/tools/install-tools";
             const string infoIconName = "console.infoicon";
 
             if (PlayerPrefs.GetInt(InstallMultiplayerToolsTipDismissedPlayerPrefKey, 0) != 0)

Editor/NetworkManagerHelper.cs

@@ -0,0 +1,195 @@
+using System.Collections.Generic;
+using System.Linq;
+using UnityEngine;
+using UnityEngine.SceneManagement;
+using UnityEditor;
+
+namespace Unity.Netcode.Editor
+{
+#if UNITY_EDITOR
+    /// <summary>
+    /// Specialized editor specific NetworkManager code
+    /// </summary>
+    public class NetworkManagerHelper : NetworkManager.INetworkManagerHelper
+    {
+        internal static NetworkManagerHelper Singleton;
+
+        // This is primarily to handle IntegrationTest scenarios where more than 1 NetworkManager could exist
+        private static Dictionary<NetworkManager, Transform> s_LastKnownNetworkManagerParents = new Dictionary<NetworkManager, Transform>();
+
+        /// <summary>
+        /// Initializes the singleton instance and registers for:
+        /// Hierarchy changed notification: to notify the user when they nest a NetworkManager
+        /// Play mode state change notification: to capture when entering or exiting play mode (currently only exiting)
+        /// </summary>
+        [InitializeOnLoadMethod]
+        private static void InitializeOnload()
+        {
+            Singleton = new NetworkManagerHelper();
+            NetworkManager.NetworkManagerHelper = Singleton;
+            EditorApplication.playModeStateChanged -= EditorApplication_playModeStateChanged;
+            EditorApplication.hierarchyChanged -= EditorApplication_hierarchyChanged;
+
+            EditorApplication.playModeStateChanged += EditorApplication_playModeStateChanged;
+            EditorApplication.hierarchyChanged += EditorApplication_hierarchyChanged;
+        }
+
+        private static void EditorApplication_playModeStateChanged(PlayModeStateChange playModeStateChange)
+        {
+            switch (playModeStateChange)
+            {
+                case PlayModeStateChange.ExitingEditMode:
+                    {
+                        s_LastKnownNetworkManagerParents.Clear();
+                        ScenesInBuildActiveSceneCheck();
+                        break;
+                    }
+            }
+        }
+
+        /// <summary>
+        /// Detects if a user is trying to enter into play mode when both conditions are true:
+        /// - the currently active and open scene is not added to the scenes in build list
+        /// - an instance of a NetworkManager with scene management enabled can be found
+        /// If both conditions are met then the user is presented with a dialog box that
+        /// provides the user with the option to add the scene to the scenes in build list
+        /// before entering into play mode or the user can continue under those conditions.
+        ///
+        /// ** When scene management is enabled the user should treat all scenes that need to
+        /// be synchronized using network scene management as if they were preparing for a build.
+        /// Any scene that needs to be loaded at run time has to be included in the scenes in
+        /// build list. **
+        /// </summary>
+        private static void ScenesInBuildActiveSceneCheck()
+        {
+            var scenesList = EditorBuildSettings.scenes.ToList();
+            var activeScene = SceneManager.GetActiveScene();
+            var isSceneInBuildSettings = scenesList.Where((c) => c.path == activeScene.path).Count() == 1;
+            var networkManager = Object.FindObjectOfType<NetworkManager>();
+            if (!isSceneInBuildSettings && networkManager != null)
+            {
+                if (networkManager.NetworkConfig != null && networkManager.NetworkConfig.EnableSceneManagement)
+                {
+                    if (EditorUtility.DisplayDialog("Add Scene to Scenes in Build", $"The current scene was not found in the scenes" +
+                        $" in build and a {nameof(NetworkManager)} instance was found with scene management enabled! Clients will not be able " +
+                        $"to synchronize to this scene unless it is added to the scenes in build list.\n\nWould you like to add it now?",
+                        "Yes", "No - Continue"))
+                    {
+                        scenesList.Add(new EditorBuildSettingsScene(activeScene.path, true));
+                        EditorBuildSettings.scenes = scenesList.ToArray();
+                    }
+                }
+            }
+        }
+
+        /// <summary>
+        /// Invoked only when the hierarchy changes
+        /// </summary>
+        private static void EditorApplication_hierarchyChanged()
+        {
+            var allNetworkManagers = Resources.FindObjectsOfTypeAll<NetworkManager>();
+            foreach (var networkManager in allNetworkManagers)
+            {
+                if (!networkManager.NetworkManagerCheckForParent())
+                {
+                    Singleton.CheckAndNotifyUserNetworkObjectRemoved(networkManager);
+                }
+            }
+        }
+
+        /// <summary>
+        /// Handles notifying users that they cannot add a NetworkObject component
+        /// to a GameObject that also has a NetworkManager component. The NetworkObject
+        /// will always be removed.
+        /// GameObject + NetworkObject then NetworkManager = NetworkObject removed
+        /// GameObject + NetworkManager then NetworkObject = NetworkObject removed
+        /// Note: Since this is always invoked after <see cref="NetworkManagerCheckForParent"/>
+        /// we do not need to check for parent when searching for a NetworkObject component
+        /// </summary>
+        public void CheckAndNotifyUserNetworkObjectRemoved(NetworkManager networkManager, bool editorTest = false)
+        {
+            // Check for any NetworkObject at the same gameObject relative layer
+            var networkObject = networkManager.gameObject.GetComponent<NetworkObject>();
+
+            if (networkObject == null)
+            {
+                // if none is found, check to see if any children have a NetworkObject
+                networkObject = networkManager.gameObject.GetComponentInChildren<NetworkObject>();
+                if (networkObject == null)
+                {
+                    return;
+                }
+            }
+
+            if (!EditorApplication.isUpdating)
+            {
+                Object.DestroyImmediate(networkObject);
+
+                if (!EditorApplication.isPlaying && !editorTest)
+                {
+                    EditorUtility.DisplayDialog($"Removing {nameof(NetworkObject)}", NetworkManagerAndNetworkObjectNotAllowedMessage(), "OK");
+                }
+                else
+                {
+                    Debug.LogError(NetworkManagerAndNetworkObjectNotAllowedMessage());
+                }
+            }
+        }
+
+        public string NetworkManagerAndNetworkObjectNotAllowedMessage()
+        {
+            return $"A {nameof(GameObject)} cannot have both a {nameof(NetworkManager)} and {nameof(NetworkObject)} assigned to it or any children under it.";
+        }
+
+        /// <summary>
+        /// Handles notifying the user, via display dialog window, that they have nested a NetworkManager.
+        /// When in edit mode it provides the option to automatically fix the issue
+        /// When in play mode it just notifies the user when entering play mode as well as when the user
+        /// tries to start a network session while a NetworkManager is still nested.
+        /// </summary>
+        public bool NotifyUserOfNestedNetworkManager(NetworkManager networkManager, bool ignoreNetworkManagerCache = false, bool editorTest = false)
+        {
+            var gameObject = networkManager.gameObject;
+            var transform = networkManager.transform;
+            var isParented = transform.root != transform;
+
+            var message = NetworkManager.GenerateNestedNetworkManagerMessage(transform);
+            if (s_LastKnownNetworkManagerParents.ContainsKey(networkManager) && !ignoreNetworkManagerCache)
+            {
+                // If we have already notified the user, then don't notify them again
+                if (s_LastKnownNetworkManagerParents[networkManager] == transform.root)
+                {
+                    return isParented;
+                }
+                else // If we are no longer a child, then we can remove ourself from this list
+                if (transform.root == gameObject.transform)
+                {
+                    s_LastKnownNetworkManagerParents.Remove(networkManager);
+                }
+            }
+            if (!EditorApplication.isUpdating && isParented)
+            {
+                if (!EditorApplication.isPlaying && !editorTest)
+                {
+                    message += $"Click 'Auto-Fix' to automatically remove it from {transform.root.gameObject.name} or 'Manual-Fix' to fix it yourself in the hierarchy view.";
+                    if (EditorUtility.DisplayDialog("Invalid Nested NetworkManager", message, "Auto-Fix", "Manual-Fix"))
+                    {
+                        transform.parent = null;
+                        isParented = false;
+                    }
+                }
+                else
+                {
+                    Debug.LogError(message);
+                }
+
+                if (!s_LastKnownNetworkManagerParents.ContainsKey(networkManager) && isParented)
+                {
+                    s_LastKnownNetworkManagerParents.Add(networkManager, networkManager.transform.root);
+                }
+            }
+            return isParented;
+        }
+    }
+#endif
+}

Editor/NetworkManagerHelper.cs.meta

@@ -1,5 +1,5 @@
 fileFormatVersion: 2
-guid: a32aeecf69a2542469927066f5b88005
+guid: b26b53dc28ae1b5488bbbecc3e499bbc
 MonoImporter:
   externalObjects: {}
   serializedVersion: 2

Editor/NetworkObjectEditor.cs

@@ -100,5 +100,32 @@ namespace Unity.Netcode.Editor
                 GUI.enabled = guiEnabled;
             }
         }
+
+        // Saved for use in OnDestroy
+        private GameObject m_GameObject;
+
+        /// <summary>
+        /// Invoked once when a NetworkObject component is
+        /// displayed in the inspector view.
+        /// </summary>
+        private void OnEnable()
+        {
+            // We set the GameObject upon being enabled because when the
+            // NetworkObject component is removed (i.e. when OnDestroy is invoked)
+            // it is no longer valid/available.
+            m_GameObject = (target as NetworkObject).gameObject;
+        }
+
+        /// <summary>
+        /// Invoked once when a NetworkObject component is
+        /// no longer displayed in the inspector view.
+        /// </summary>
+        private void OnDestroy()
+        {
+            // Since this is also invoked when a NetworkObject component is removed
+            // from a GameObject, we go ahead and check for a NetworkObject when
+            // this custom editor is destroyed.
+            NetworkBehaviourEditor.CheckForNetworkObject(m_GameObject, true);
+        }
     }
 }

Editor/NetworkTransformEditor.cs

@@ -4,7 +4,7 @@ using Unity.Netcode.Components;
 
 namespace Unity.Netcode.Editor
 {
-    [CustomEditor(typeof(NetworkTransform))]
+    [CustomEditor(typeof(NetworkTransform), true)]
     public class NetworkTransformEditor : UnityEditor.Editor
     {
         private SerializedProperty m_SyncPositionXProperty;
@@ -112,6 +112,7 @@ namespace Unity.Netcode.Editor
             EditorGUILayout.PropertyField(m_InLocalSpaceProperty);
             EditorGUILayout.PropertyField(m_InterpolateProperty);
 
+#if COM_UNITY_MODULES_PHYSICS
             // if rigidbody is present but network rigidbody is not present
             var go = ((NetworkTransform)target).gameObject;
             if (go.TryGetComponent<Rigidbody>(out _) && go.TryGetComponent<NetworkRigidbody>(out _) == false)
@@ -119,12 +120,15 @@ namespace Unity.Netcode.Editor
                 EditorGUILayout.HelpBox("This GameObject contains a Rigidbody but no NetworkRigidbody.\n" +
                     "Add a NetworkRigidbody component to improve Rigidbody synchronization.", MessageType.Warning);
             }
+#endif // COM_UNITY_MODULES_PHYSICS
 
+#if COM_UNITY_MODULES_PHYSICS2D
             if (go.TryGetComponent<Rigidbody2D>(out _) && go.TryGetComponent<NetworkRigidbody2D>(out _) == false)
             {
                 EditorGUILayout.HelpBox("This GameObject contains a Rigidbody2D but no NetworkRigidbody2D.\n" +
                     "Add a NetworkRigidbody2D component to improve Rigidbody2D synchronization.", MessageType.Warning);
             }
+#endif // COM_UNITY_MODULES_PHYSICS2D
 
             serializedObject.ApplyModifiedProperties();
         }

Editor/PackageChecker.meta

@@ -1,5 +1,5 @@
 fileFormatVersion: 2
-guid: af81f9951b096ff4cb8e4f8a4106104a
+guid: a325130169714440ba1b4878082e8956
 folderAsset: yes
 DefaultImporter:
   externalObjects: {}

Editor/PackageChecker/UTPAdapterChecker.cs

@@ -0,0 +1,53 @@
+#if COM_UNITY_NETCODE_ADAPTER_UTP
+using System.Linq;
+using UnityEngine;
+using UnityEditor;
+using UnityEditor.PackageManager;
+using UnityEditor.PackageManager.Requests;
+
+namespace Unity.Netcode.Editor.PackageChecker
+{
+    [InitializeOnLoad]
+    internal class UTPAdapterChecker
+    {
+        private const string k_UTPAdapterPackageName = "com.unity.netcode.adapter.utp";
+
+        private static ListRequest s_ListRequest = null;
+
+        static UTPAdapterChecker()
+        {
+            if (s_ListRequest == null)
+            {
+                s_ListRequest = Client.List();
+                EditorApplication.update += EditorUpdate;
+            }
+        }
+
+        private static void EditorUpdate()
+        {
+            if (!s_ListRequest.IsCompleted)
+            {
+                return;
+            }
+
+            EditorApplication.update -= EditorUpdate;
+
+            if (s_ListRequest.Status == StatusCode.Success)
+            {
+                if (s_ListRequest.Result.Any(p => p.name == k_UTPAdapterPackageName))
+                {
+                    Debug.Log($"({nameof(UTPAdapterChecker)}) Found UTP Adapter package, it is no longer needed, `UnityTransport` is now directly integrated into the SDK therefore removing it from the project.");
+                    Client.Remove(k_UTPAdapterPackageName);
+                }
+            }
+            else
+            {
+                var error = s_ListRequest.Error;
+                Debug.LogError($"({nameof(UTPAdapterChecker)}) Cannot check the list of packages -> error #{error.errorCode}: {error.message}");
+            }
+
+            s_ListRequest = null;
+        }
+    }
+}
+#endif // COM_UNITY_NETCODE_ADAPTER_UTP

Editor/PackageChecker/UTPAdapterChecker.cs.meta

@@ -1,5 +1,5 @@
 fileFormatVersion: 2
-guid: 69c3c1c5a885d4aed99ee2e1fa40f763
+guid: df5ed97df956b4aad91a221ba59fa304
 MonoImporter:
   externalObjects: {}
   serializedVersion: 2

Editor/PackageChecker/com.unity.netcode.editor.packagechecker.asmdef

@@ -0,0 +1,14 @@
+{
+    "name": "Unity.Netcode.Editor.PackageChecker",
+    "rootNamespace": "Unity.Netcode.Editor.PackageChecker",
+    "includePlatforms": [
+        "Editor"
+    ],
+    "versionDefines": [
+        {
+            "name": "com.unity.netcode.adapter.utp",
+            "expression": "",
+            "define": "COM_UNITY_NETCODE_ADAPTER_UTP"
+        }
+    ]
+}

Editor/PackageChecker/com.unity.netcode.editor.packagechecker.asmdef.meta

@@ -1,5 +1,5 @@
 fileFormatVersion: 2
-guid: 78ac2a8d1365141f68da5d0a9e10dbc6
+guid: de64d7f9ca85d4bf59c8c24738bc1057
 AssemblyDefinitionImporter:
   externalObjects: {}
   userData: 

Editor/com.unity.netcode.editor.asmdef

@@ -8,18 +8,11 @@
     "includePlatforms": [
         "Editor"
     ],
-    "excludePlatforms": [],
-    "allowUnsafeCode": false,
-    "overrideReferences": false,
-    "precompiledReferences": [],
-    "autoReferenced": true,
-    "defineConstraints": [],
     "versionDefines": [
         {
             "name": "com.unity.multiplayer.tools",
             "expression": "",
             "define": "MULTIPLAYER_TOOLS"
         }
-    ],
+    ]
-    "noEngineReferences": false
 }

README.md

@@ -1,10 +1,16 @@
-[![Forums](https://img.shields.io/badge/unity--forums-multiplayer-blue)](https://forum.unity.com/forums/multiplayer.26/) [![Discord](https://img.shields.io/discord/449263083769036810.svg?label=discord&logo=discord&color=informational)](https://discord.gg/FM8SE9E)
+# Netcode for GameObjects
-[![Website](https://img.shields.io/badge/docs-website-informational.svg)](https://docs-multiplayer.unity3d.com/) [![Api](https://img.shields.io/badge/docs-api-informational.svg)](https://docs-multiplayer.unity3d.com/docs/mlapi-api/introduction)
 
-Netcode for GameObjects provides networking capabilities to GameObject & MonoBehaviour Unity workflows. The framework is interoperable with many low-level transports, including the official [Unity Transport Package](https://docs.unity3d.com/Packages/com.unity.transport@1.0/manual/index.html).
+[![Forums](https://img.shields.io/badge/unity--forums-multiplayer-blue)](https://forum.unity.com/forums/multiplayer.26/) [![Discord](https://img.shields.io/discord/449263083769036810.svg?label=discord&logo=discord&color=informational)](https://discord.gg/FM8SE9E)
+[![Manual](https://img.shields.io/badge/docs-manual-informational.svg)](https://docs-multiplayer.unity3d.com/netcode/current/about) [![API](https://img.shields.io/badge/docs-api-informational.svg)](https://docs-multiplayer.unity3d.com/netcode/current/api/introduction)
+
+Netcode for GameObjects is a Unity package that provides networking capabilities to GameObject & MonoBehaviour workflows. The framework is interoperable with many low-level transports, including the official [Unity Transport Package](https://docs-multiplayer.unity3d.com/transport/current/about).
 
 ### Getting Started
+
 Visit the [Multiplayer Docs Site](https://docs-multiplayer.unity3d.com/) for package & API documentation, as well as information about several samples which leverage the Netcode for GameObjects package.
 
+You can also jump right into our [Hello World](https://docs-multiplayer.unity3d.com/netcode/current/tutorials/helloworld/helloworldintro) guide for a taste of how to use the framework for basic networked tasks.
+
 ### Community and Feedback
+
 For general questions, networking advice or discussions about Netcode for GameObjects, please join our [Discord Community](https://discord.gg/FM8SE9E) or create a post in the [Unity Multiplayer Forum](https://forum.unity.com/forums/multiplayer.26/).

Runtime/AssemblyInfo.cs

@@ -5,8 +5,10 @@ using System.Runtime.CompilerServices;
 [assembly: InternalsVisibleTo("Unity.Netcode.Editor.CodeGen")]
 [assembly: InternalsVisibleTo("Unity.Netcode.Editor")]
 [assembly: InternalsVisibleTo("TestProject.EditorTests")]
-[assembly: InternalsVisibleTo("TestProject.RuntimeTests")]
+[assembly: InternalsVisibleTo("Unity.Netcode.Editor.CodeGen")]
-[assembly: InternalsVisibleTo("TestProject.ToolsIntegration.RuntimeTests")]
 #endif
+[assembly: InternalsVisibleTo("TestProject.ToolsIntegration.RuntimeTests")]
+[assembly: InternalsVisibleTo("TestProject.RuntimeTests")]
 [assembly: InternalsVisibleTo("Unity.Netcode.RuntimeTests")]
-
+[assembly: InternalsVisibleTo("Unity.Netcode.TestHelpers.Runtime")]
+[assembly: InternalsVisibleTo("Unity.Netcode.Adapter.UTP")]

Runtime/Collections/FixedQueue.cs

@@ -1,77 +0,0 @@
-using System;
-
-namespace Unity.Netcode
-{
-    /// <summary>
-    /// Queue with a fixed size
-    /// </summary>
-    /// <typeparam name="T">The type of the queue</typeparam>
-    public sealed class FixedQueue<T>
-    {
-        private readonly T[] m_Queue;
-        private int m_QueueCount = 0;
-        private int m_QueueStart;
-
-        /// <summary>
-        /// The amount of enqueued objects
-        /// </summary>
-        public int Count => m_QueueCount;
-
-        /// <summary>
-        /// Gets the element at a given virtual index
-        /// </summary>
-        /// <param name="index">The virtual index to get the item from</param>
-        /// <returns>The element at the virtual index</returns>
-        public T this[int index] => m_Queue[(m_QueueStart + index) % m_Queue.Length];
-
-        /// <summary>
-        /// Creates a new FixedQueue with a given size
-        /// </summary>
-        /// <param name="maxSize">The size of the queue</param>
-        public FixedQueue(int maxSize)
-        {
-            m_Queue = new T[maxSize];
-            m_QueueStart = 0;
-        }
-
-        /// <summary>
-        /// Enqueues an object
-        /// </summary>
-        /// <param name="t"></param>
-        /// <returns></returns>
-        public bool Enqueue(T t)
-        {
-            m_Queue[(m_QueueStart + m_QueueCount) % m_Queue.Length] = t;
-            if (++m_QueueCount > m_Queue.Length)
-            {
-                --m_QueueCount;
-                return true;
-            }
-
-            return false;
-        }
-
-        /// <summary>
-        /// Dequeues an object
-        /// </summary>
-        /// <returns></returns>
-        public T Dequeue()
-        {
-            if (--m_QueueCount == -1)
-            {
-                throw new IndexOutOfRangeException("Cannot dequeue empty queue!");
-            }
-
-            T res = m_Queue[m_QueueStart];
-            m_QueueStart = (m_QueueStart + 1) % m_Queue.Length;
-            return res;
-        }
-
-        /// <summary>
-        /// Gets the element at a given virtual index
-        /// </summary>
-        /// <param name="index">The virtual index to get the item from</param>
-        /// <returns>The element at the virtual index</returns>
-        public T ElementAt(int index) => m_Queue[(m_QueueStart + index) % m_Queue.Length];
-    }
-}

Runtime/Configuration/NetworkConfig.cs

@@ -53,9 +53,21 @@ namespace Unity.Netcode
         public uint TickRate = 30;
 
         /// <summary>
-        /// The amount of seconds to wait for handshake to complete before timing out a client
+        /// The amount of seconds for the server to wait for the connection approval handshake to complete before the client is disconnected.
+        ///
+        /// If the timeout is reached before approval is completed the client will be disconnected.
         /// </summary>
-        [Tooltip("The amount of seconds to wait for the handshake to complete before the client times out")]
+        /// <remarks>
+        /// The period begins after the <see cref="NetworkEvent.Connect"/> is received on the server.
+        /// The period ends once the server finishes processing a <see cref="ConnectionRequestMessage"/> from the client.
+        ///
+        /// This setting is independent of any Transport-level timeouts that may be in effect. It covers the time between
+        /// the connection being established on the Transport layer, the client sending a
+        /// <see cref="ConnectionRequestMessage"/>, and the server processing that message through <see cref="ConnectionApproval"/>.
+        ///
+        /// This setting is server-side only.
+        /// </remarks>
+        [Tooltip("The amount of seconds for the server to wait for the connection approval handshake to complete before the client is disconnected")]
         public int ClientConnectionBufferTimeout = 10;
 
         /// <summary>
@@ -128,29 +140,16 @@ namespace Unity.Netcode
         public int LoadSceneTimeOut = 120;
 
         /// <summary>
-        /// The amount of time a message should be buffered for without being consumed. If it is not consumed within this time, it will be dropped.
+        /// The amount of time a message should be buffered if the asset or object needed to process it doesn't exist yet. If the asset is not added/object is not spawned within this time, it will be dropped.
         /// </summary>
-        [Tooltip("The amount of time a message should be buffered for without being consumed. If it is not consumed within this time, it will be dropped")]
+        [Tooltip("The amount of time a message should be buffered if the asset or object needed to process it doesn't exist yet. If the asset is not added/object is not spawned within this time, it will be dropped")]
-        public float MessageBufferTimeout = 20f;
+        public float SpawnTimeout = 1f;
 
         /// <summary>
         /// Whether or not to enable network logs.
         /// </summary>
         public bool EnableNetworkLogs = true;
 
-        /// <summary>
-        /// Whether or not to enable Snapshot System for variable updates. Not supported in this version.
-        /// </summary>
-        public bool UseSnapshotDelta { get; } = false;
-        /// <summary>
-        /// Whether or not to enable Snapshot System for spawn and despawn commands. Not supported in this version.
-        /// </summary>
-        public bool UseSnapshotSpawn { get; } = false;
-        /// <summary>
-        /// When Snapshot System spawn is enabled: max size of Snapshot Messages. Meant to fit MTU.
-        /// </summary>
-        public int SnapshotMaxSpawnUsage { get; } = 1200;
-
         public const int RttAverageSamples = 5; // number of RTT to keep an average of (plus one)
         public const int RttWindowSize = 64; // number of slots to use for RTT computations (max number of in-flight packets)
         /// <summary>
@@ -224,7 +223,7 @@ namespace Unity.Netcode
                 return m_ConfigHash.Value;
             }
 
-            var writer = new FastBufferWriter(MessagingSystem.NON_FRAGMENTED_MESSAGE_MAX_SIZE, Allocator.Temp);
+            var writer = new FastBufferWriter(MessagingSystem.NON_FRAGMENTED_MESSAGE_MAX_SIZE, Allocator.Temp, int.MaxValue);
             using (writer)
             {
                 writer.WriteValueSafe(ProtocolVersion);
@@ -239,6 +238,8 @@ namespace Unity.Netcode
                         writer.WriteValueSafe(sortedEntry.Key);
                     }
                 }
+
+                writer.WriteValueSafe(TickRate);
                 writer.WriteValueSafe(ConnectionApproval);
                 writer.WriteValueSafe(ForceSamePrefabs);
                 writer.WriteValueSafe(EnableSceneManagement);

Runtime/Configuration/NetworkConstants.cs

@@ -5,6 +5,6 @@ namespace Unity.Netcode
     /// </summary>
     internal static class NetworkConstants
     {
-        internal const string PROTOCOL_VERSION = "14.0.0";
+        internal const string PROTOCOL_VERSION = "15.0.0";
     }
 }

Runtime/Connection/NetworkClient.cs

@@ -20,6 +20,17 @@ namespace Unity.Netcode
         /// <summary>
         /// The NetworkObject's owned by this Client
         /// </summary>
-        public readonly List<NetworkObject> OwnedObjects = new List<NetworkObject>();
+        public List<NetworkObject> OwnedObjects
+        {
+            get
+            {
+                if (PlayerObject != null && PlayerObject.NetworkManager != null && PlayerObject.NetworkManager.IsListening)
+                {
+                    return PlayerObject.NetworkManager.SpawnManager.GetClientOwnedObjects(ClientId);
+                }
+
+                return new List<NetworkObject>();
+            }
+        }
     }
 }

Runtime/Core/ComponentFactory.cs

@@ -0,0 +1,65 @@
+using System;
+using System.Collections.Generic;
+
+namespace Unity.Netcode
+{
+    /// <summary>
+    /// This class is used to support testable code by allowing any supported component used by NetworkManager to be replaced
+    /// with a mock component or a test version that overloads certain methods to change or record their behavior.
+    /// Components currently supported by ComponentFactory:
+    /// - IDeferredMessageManager
+    /// </summary>
+    internal static class ComponentFactory
+    {
+        internal delegate object CreateObjectDelegate(NetworkManager networkManager);
+
+        private static Dictionary<Type, CreateObjectDelegate> s_Delegates = new Dictionary<Type, CreateObjectDelegate>();
+
+        /// <summary>
+        /// Instantiates an instance of a given interface
+        /// </summary>
+        /// <param name="networkManager">The network manager</param>
+        /// <typeparam name="T">The interface to instantiate it with</typeparam>
+        /// <returns></returns>
+        public static T Create<T>(NetworkManager networkManager)
+        {
+            return (T)s_Delegates[typeof(T)](networkManager);
+        }
+
+        /// <summary>
+        /// Overrides the default creation logic for a given interface type
+        /// </summary>
+        /// <param name="creator">The factory delegate to create the instance</param>
+        /// <typeparam name="T">The interface type to override</typeparam>
+        public static void Register<T>(CreateObjectDelegate creator)
+        {
+            s_Delegates[typeof(T)] = creator;
+        }
+
+        /// <summary>
+        /// Reverts the creation logic for a given interface type to the default logic
+        /// </summary>
+        /// <typeparam name="T">The interface type to revert</typeparam>
+        public static void Deregister<T>()
+        {
+            s_Delegates.Remove(typeof(T));
+            SetDefaults();
+        }
+
+        /// <summary>
+        /// Initializes the default creation logic for all supported component types
+        /// </summary>
+        public static void SetDefaults()
+        {
+            SetDefault<IDeferredMessageManager>(networkManager => new DeferredMessageManager(networkManager));
+        }
+
+        private static void SetDefault<T>(CreateObjectDelegate creator)
+        {
+            if (!s_Delegates.ContainsKey(typeof(T)))
+            {
+                s_Delegates[typeof(T)] = creator;
+            }
+        }
+    }
+}

Runtime/Core/ComponentFactory.cs.meta

@@ -0,0 +1,3 @@
+fileFormatVersion: 2
+guid: fda4c0eb89644fcea5416bbf98ea0ba0
+timeCreated: 1649966562

Runtime/Core/IndexAllocator.cs

@@ -1,388 +0,0 @@
-using UnityEngine;
-
-namespace Unity.Netcode
-{
-    internal struct IndexAllocatorEntry
-    {
-        internal int Pos; // Position where the memory of this slot is
-        internal int Length; // Length of the memory allocated to this slot
-        internal int Next; // Next and Prev define the order of the slots in the buffer
-        internal int Prev;
-        internal bool Free;  // Whether this is a free slot
-    }
-
-    internal class IndexAllocator
-    {
-        private const int k_NotSet = -1;
-        private readonly int m_MaxSlot; // Maximum number of sections (free or not) in the buffer
-        private readonly int m_BufferSize; // Size of the buffer we allocated into
-        private int m_LastSlot = 0; // Last allocated slot
-        private IndexAllocatorEntry[] m_Slots; // Array of slots
-        private int[] m_IndexToSlot; // Mapping from the client's index to the slot index
-
-        internal IndexAllocator(int bufferSize, int maxSlot)
-        {
-            m_MaxSlot = maxSlot;
-            m_BufferSize = bufferSize;
-            m_Slots = new IndexAllocatorEntry[m_MaxSlot];
-            m_IndexToSlot = new int[m_MaxSlot];
-            Reset();
-        }
-
-        /// <summary>
-        /// Reset this IndexAllocator to an empty one, with the same sized buffer and slots
-        /// </summary>
-        internal void Reset()
-        {
-            // todo: could be made faster, for example by having a last index
-            // and not needing valid stuff past it
-            for (int i = 0; i < m_MaxSlot; i++)
-            {
-                m_Slots[i].Free = true;
-                m_Slots[i].Next = i + 1;
-                m_Slots[i].Prev = i - 1;
-                m_Slots[i].Pos = m_BufferSize;
-                m_Slots[i].Length = 0;
-
-                m_IndexToSlot[i] = k_NotSet;
-            }
-
-            m_Slots[0].Pos = 0;
-            m_Slots[0].Length = m_BufferSize;
-            m_Slots[0].Prev = k_NotSet;
-            m_Slots[m_MaxSlot - 1].Next = k_NotSet;
-        }
-
-        /// <summary>
-        /// Returns the amount of memory used
-        /// </summary>
-        /// <returns>
-        /// Returns the amount of memory used, starting at 0, ending after the last used slot
-        /// </returns>
-        internal int Range
-        {
-            get
-            {
-                // when the whole buffer is free, m_LastSlot points to an empty slot
-                if (m_Slots[m_LastSlot].Free)
-                {
-                    return 0;
-                }
-                // otherwise return the end of the last slot used
-                return m_Slots[m_LastSlot].Pos + m_Slots[m_LastSlot].Length;
-            }
-        }
-
-        /// <summary>
-        /// Allocate a slot with "size" position, for index "index"
-        /// </summary>
-        /// <param name="index">The client index to identify this. Used in Deallocate to identify which slot</param>
-        /// <param name="size">The size required. </param>
-        /// <param name="pos">Returns the position to use in the buffer </param>
-        /// <returns>
-        /// true if successful, false is there isn't enough memory available or no slots are large enough
-        /// </returns>
-        internal bool Allocate(int index, int size, out int pos)
-        {
-            pos = 0;
-            // size must be positive, index must be within range
-            if (size < 0 || index < 0 || index >= m_MaxSlot)
-            {
-                return false;
-            }
-
-            // refuse allocation if the index is already in use
-            if (m_IndexToSlot[index] != k_NotSet)
-            {
-                return false;
-            }
-
-            // todo: this is the slowest part
-            // improvement 1: list of free blocks (minor)
-            // improvement 2: heap of free blocks
-            for (int i = 0; i < m_MaxSlot; i++)
-            {
-                if (m_Slots[i].Free && m_Slots[i].Length >= size)
-                {
-                    m_IndexToSlot[index] = i;
-
-                    int leftOver = m_Slots[i].Length - size;
-                    int next = m_Slots[i].Next;
-                    if (m_Slots[next].Free)
-                    {
-                        m_Slots[next].Pos -= leftOver;
-                        m_Slots[next].Length += leftOver;
-                    }
-                    else
-                    {
-                        int add = MoveSlotAfter(i);
-
-                        m_Slots[add].Pos = m_Slots[i].Pos + size;
-                        m_Slots[add].Length = m_Slots[i].Length - size;
-                    }
-
-                    m_Slots[i].Free = false;
-                    m_Slots[i].Length = size;
-
-                    pos = m_Slots[i].Pos;
-
-                    // if we allocate past the current range, we are the last slot
-                    if (m_Slots[i].Pos + m_Slots[i].Length > Range)
-                    {
-                        m_LastSlot = i;
-                    }
-
-                    return true;
-                }
-            }
-
-            return false;
-        }
-
-        /// <summary>
-        /// Deallocate a slot
-        /// </summary>
-        /// <param name="index">The client index to identify this. Same index used in Allocate </param>
-        /// <returns>
-        /// true if successful, false is there isn't an allocated slot at this index
-        /// </returns>
-        internal bool Deallocate(int index)
-        {
-            // size must be positive, index must be within range
-            if (index < 0 || index >= m_MaxSlot)
-            {
-                return false;
-            }
-
-            int slot = m_IndexToSlot[index];
-
-            if (slot == k_NotSet)
-            {
-                return false;
-            }
-
-            if (m_Slots[slot].Free)
-            {
-                return false;
-            }
-
-            m_Slots[slot].Free = true;
-
-            int prev = m_Slots[slot].Prev;
-            int next = m_Slots[slot].Next;
-
-            // if previous slot was free, merge and grow
-            if (prev != k_NotSet && m_Slots[prev].Free)
-            {
-                m_Slots[prev].Length += m_Slots[slot].Length;
-                m_Slots[slot].Length = 0;
-
-                // if the slot we're merging was the last one, the last one is now the one we merged with
-                if (slot == m_LastSlot)
-                {
-                    m_LastSlot = prev;
-                }
-
-                // todo: verify what this does on full or nearly full cases
-                MoveSlotToEnd(slot);
-                slot = prev;
-            }
-
-            next = m_Slots[slot].Next;
-
-            // merge with next slot if it is free
-            if (next != k_NotSet && m_Slots[next].Free)
-            {
-                m_Slots[slot].Length += m_Slots[next].Length;
-                m_Slots[next].Length = 0;
-                MoveSlotToEnd(next);
-            }
-
-            // if we just deallocate the last one, we need to move last back
-            if (slot == m_LastSlot)
-            {
-                m_LastSlot = m_Slots[m_LastSlot].Prev;
-                // if there's nothing allocated anymore, use 0
-                if (m_LastSlot == k_NotSet)
-                {
-                    m_LastSlot = 0;
-                }
-            }
-
-            // mark the index as available
-            m_IndexToSlot[index] = k_NotSet;
-
-            return true;
-        }
-
-        // Take a slot at the end and link it to go just after "slot".
-        // Used when allocating part of a slot and we need an entry for the rest
-        // Returns the slot that was picked
-        private int MoveSlotAfter(int slot)
-        {
-            int ret = m_Slots[m_MaxSlot - 1].Prev;
-            int p0 = m_Slots[ret].Prev;
-
-            m_Slots[p0].Next = m_MaxSlot - 1;
-            m_Slots[m_MaxSlot - 1].Prev = p0;
-
-            int p1 = m_Slots[slot].Next;
-            m_Slots[slot].Next = ret;
-            m_Slots[p1].Prev = ret;
-
-            m_Slots[ret].Prev = slot;
-            m_Slots[ret].Next = p1;
-
-            return ret;
-        }
-
-        // Move the slot "slot" to the end of the list.
-        // Used when merging two slots, that gives us an extra entry at the end
-        private void MoveSlotToEnd(int slot)
-        {
-            // if we're already there
-            if (m_Slots[slot].Next == k_NotSet)
-            {
-                return;
-            }
-
-            int prev = m_Slots[slot].Prev;
-            int next = m_Slots[slot].Next;
-
-            m_Slots[prev].Next = next;
-            if (next != k_NotSet)
-            {
-                m_Slots[next].Prev = prev;
-            }
-
-            int p0 = m_Slots[m_MaxSlot - 1].Prev;
-
-            m_Slots[p0].Next = slot;
-            m_Slots[slot].Next = m_MaxSlot - 1;
-
-            m_Slots[m_MaxSlot - 1].Prev = slot;
-            m_Slots[slot].Prev = p0;
-
-            m_Slots[slot].Pos = m_BufferSize;
-        }
-
-        // runs a bunch of consistency check on the Allocator
-        internal bool Verify()
-        {
-            int pos = k_NotSet;
-            int count = 0;
-            int total = 0;
-            int endPos = 0;
-
-            do
-            {
-                int prev = pos;
-                if (pos != k_NotSet)
-                {
-                    pos = m_Slots[pos].Next;
-                    if (pos == k_NotSet)
-                    {
-                        break;
-                    }
-                }
-                else
-                {
-                    pos = 0;
-                }
-
-                if (m_Slots[pos].Prev != prev)
-                {
-                    // the previous is not correct
-                    return false;
-                }
-
-                if (m_Slots[pos].Length < 0)
-                {
-                    // Length should be positive
-                    return false;
-                }
-
-                if (prev != k_NotSet && m_Slots[prev].Free && m_Slots[pos].Free && m_Slots[pos].Length > 0)
-                {
-                    // should not have two consecutive free slots
-                    return false;
-                }
-
-                if (m_Slots[pos].Pos != total)
-                {
-                    // slots should all line up nicely
-                    return false;
-                }
-
-                if (!m_Slots[pos].Free)
-                {
-                    endPos = m_Slots[pos].Pos + m_Slots[pos].Length;
-                }
-
-                total += m_Slots[pos].Length;
-                count++;
-
-            } while (pos != k_NotSet);
-
-            if (count != m_MaxSlot)
-            {
-                // some slots were lost
-                return false;
-            }
-
-            if (total != m_BufferSize)
-            {
-                // total buffer should be accounted for
-                return false;
-            }
-
-            if (endPos != Range)
-            {
-                // end position should match reported end position
-                return false;
-            }
-
-            return true;
-        }
-
-        // Debug display the allocator structure
-        internal void DebugDisplay()
-        {
-            string logMessage = "IndexAllocator structure\n";
-
-            bool[] seen = new bool[m_MaxSlot];
-
-            int pos = 0;
-            int count = 0;
-            bool prevEmpty = false;
-            do
-            {
-                seen[pos] = true;
-                count++;
-                if (m_Slots[pos].Length == 0 && prevEmpty)
-                {
-                    // don't display repetitive empty slots
-                }
-                else
-                {
-                    logMessage += string.Format("{0}:{1}, {2} ({3}) \n", m_Slots[pos].Pos, m_Slots[pos].Length,
-                        m_Slots[pos].Free ? "Free" : "Used", pos);
-                    if (m_Slots[pos].Length == 0)
-                    {
-                        prevEmpty = true;
-                    }
-                    else
-                    {
-                        prevEmpty = false;
-                    }
-                }
-
-                pos = m_Slots[pos].Next;
-            } while (pos != k_NotSet && !seen[pos]);
-
-            logMessage += string.Format("{0} Total entries\n", count);
-
-            Debug.Log(logMessage);
-        }
-    }
-}

Runtime/Core/NetworkBehaviour.cs

@@ -15,41 +15,56 @@ namespace Unity.Netcode
 #pragma warning disable IDE1006 // disable naming rule violation check
         // RuntimeAccessModifiersILPP will make this `protected`
         internal enum __RpcExecStage
-#pragma warning restore IDE1006 // restore naming rule violation check
         {
             None = 0,
             Server = 1,
             Client = 2
         }
 
-#pragma warning disable IDE1006 // disable naming rule violation check
         // NetworkBehaviourILPP will override this in derived classes to return the name of the concrete type
         internal virtual string __getTypeName() => nameof(NetworkBehaviour);
-#pragma warning restore IDE1006 // restore naming rule violation check
 
-#pragma warning disable 414 // disable assigned but its value is never used
-#pragma warning disable IDE1006 // disable naming rule violation check
         [NonSerialized]
         // RuntimeAccessModifiersILPP will make this `protected`
         internal __RpcExecStage __rpc_exec_stage = __RpcExecStage.None;
-#pragma warning restore 414 // restore assigned but its value is never used
 #pragma warning restore IDE1006 // restore naming rule violation check
 
-#pragma warning disable 414 // disable assigned but its value is never used
+        private const int k_RpcMessageDefaultSize = 1024; // 1k
+        private const int k_RpcMessageMaximumSize = 1024 * 64; // 64k
+
 #pragma warning disable IDE1006 // disable naming rule violation check
         // RuntimeAccessModifiersILPP will make this `protected`
-        internal void __sendServerRpc(FastBufferWriter writer, uint rpcMethodId, ServerRpcParams rpcParams, RpcDelivery delivery)
+        internal FastBufferWriter __beginSendServerRpc(uint rpcMethodId, ServerRpcParams serverRpcParams, RpcDelivery rpcDelivery)
-#pragma warning restore 414 // restore assigned but its value is never used
 #pragma warning restore IDE1006 // restore naming rule violation check
         {
-            NetworkDelivery networkDelivery = NetworkDelivery.Reliable;
+            return new FastBufferWriter(k_RpcMessageDefaultSize, Allocator.Temp, k_RpcMessageMaximumSize);
-            switch (delivery)
+        }
+
+#pragma warning disable IDE1006 // disable naming rule violation check
+        // RuntimeAccessModifiersILPP will make this `protected`
+        internal void __endSendServerRpc(ref FastBufferWriter bufferWriter, uint rpcMethodId, ServerRpcParams serverRpcParams, RpcDelivery rpcDelivery)
+#pragma warning restore IDE1006 // restore naming rule violation check
+        {
+            var serverRpcMessage = new ServerRpcMessage
             {
+                Metadata = new RpcMetadata
+                {
+                    NetworkObjectId = NetworkObjectId,
+                    NetworkBehaviourId = NetworkBehaviourId,
+                    NetworkRpcMethodId = rpcMethodId,
+                },
+                WriteBuffer = bufferWriter
+            };
+
+            NetworkDelivery networkDelivery;
+            switch (rpcDelivery)
+            {
+                default:
                 case RpcDelivery.Reliable:
                     networkDelivery = NetworkDelivery.ReliableFragmentedSequenced;
                     break;
                 case RpcDelivery.Unreliable:
-                    if (writer.Length > MessagingSystem.NON_FRAGMENTED_MESSAGE_MAX_SIZE - sizeof(RpcMessage.RpcType) - sizeof(ulong) - sizeof(uint) - sizeof(ushort))
+                    if (bufferWriter.Length > MessagingSystem.NON_FRAGMENTED_MESSAGE_MAX_SIZE)
                     {
                         throw new OverflowException("RPC parameters are too large for unreliable delivery.");
                     }
@@ -57,41 +72,33 @@ namespace Unity.Netcode
                     break;
             }
 
-            var message = new RpcMessage
+            var rpcWriteSize = 0;
-            {
-                Header = new RpcMessage.HeaderData
-                {
-                    Type = RpcMessage.RpcType.Server,
-                    NetworkObjectId = NetworkObjectId,
-                    NetworkBehaviourId = NetworkBehaviourId,
-                    NetworkMethodId = rpcMethodId
-                },
-                RpcData = writer
-            };
-
-            var rpcMessageSize = 0;
 
             // If we are a server/host then we just no op and send to ourself
             if (IsHost || IsServer)
             {
-                using var tempBuffer = new FastBufferReader(writer, Allocator.Temp);
+                using var tempBuffer = new FastBufferReader(bufferWriter, Allocator.Temp);
                 var context = new NetworkContext
                 {
                     SenderId = NetworkManager.ServerClientId,
                     Timestamp = Time.realtimeSinceStartup,
                     SystemOwner = NetworkManager,
                     // header information isn't valid since it's not a real message.
-                    // Passing false to canDefer prevents it being accessed.
+                    // RpcMessage doesn't access this stuff so it's just left empty.
-                    Header = new MessageHeader()
+                    Header = new MessageHeader(),
+                    SerializedHeaderSize = 0,
+                    MessageSize = 0
                 };
-                message.Handle(tempBuffer, context, NetworkManager, NetworkManager.ServerClientId, false);
+                serverRpcMessage.ReadBuffer = tempBuffer;
-                rpcMessageSize = tempBuffer.Length;
+                serverRpcMessage.Handle(ref context);
+                rpcWriteSize = tempBuffer.Length;
             }
             else
             {
-                rpcMessageSize = NetworkManager.SendMessage(message, networkDelivery, NetworkManager.ServerClientId);
+                rpcWriteSize = NetworkManager.SendMessage(ref serverRpcMessage, networkDelivery, NetworkManager.ServerClientId);
             }
 
+            bufferWriter.Dispose();
 
 #if DEVELOPMENT_BUILD || UNITY_EDITOR
             if (NetworkManager.__rpc_name_table.TryGetValue(rpcMethodId, out var rpcMethodName))
@@ -101,26 +108,44 @@ namespace Unity.Netcode
                     NetworkObject,
                     rpcMethodName,
                     __getTypeName(),
-                    rpcMessageSize);
+                    rpcWriteSize);
             }
 #endif
         }
 
-#pragma warning disable 414 // disable assigned but its value is never used
 #pragma warning disable IDE1006 // disable naming rule violation check
         // RuntimeAccessModifiersILPP will make this `protected`
-        internal unsafe void __sendClientRpc(FastBufferWriter writer, uint rpcMethodId, ClientRpcParams rpcParams, RpcDelivery delivery)
+        internal FastBufferWriter __beginSendClientRpc(uint rpcMethodId, ClientRpcParams clientRpcParams, RpcDelivery rpcDelivery)
-#pragma warning disable 414 // disable assigned but its value is never used
+#pragma warning restore IDE1006 // restore naming rule violation check
-#pragma warning disable IDE1006 // disable naming rule violation check
         {
-            NetworkDelivery networkDelivery = NetworkDelivery.Reliable;
+            return new FastBufferWriter(k_RpcMessageDefaultSize, Allocator.Temp, k_RpcMessageMaximumSize);
-            switch (delivery)
+        }
+
+#pragma warning disable IDE1006 // disable naming rule violation check
+        // RuntimeAccessModifiersILPP will make this `protected`
+        internal void __endSendClientRpc(ref FastBufferWriter bufferWriter, uint rpcMethodId, ClientRpcParams clientRpcParams, RpcDelivery rpcDelivery)
+#pragma warning restore IDE1006 // restore naming rule violation check
+        {
+            var clientRpcMessage = new ClientRpcMessage
             {
+                Metadata = new RpcMetadata
+                {
+                    NetworkObjectId = NetworkObjectId,
+                    NetworkBehaviourId = NetworkBehaviourId,
+                    NetworkRpcMethodId = rpcMethodId,
+                },
+                WriteBuffer = bufferWriter
+            };
+
+            NetworkDelivery networkDelivery;
+            switch (rpcDelivery)
+            {
+                default:
                 case RpcDelivery.Reliable:
                     networkDelivery = NetworkDelivery.ReliableFragmentedSequenced;
                     break;
                 case RpcDelivery.Unreliable:
-                    if (writer.Length > MessagingSystem.NON_FRAGMENTED_MESSAGE_MAX_SIZE - sizeof(RpcMessage.RpcType) - sizeof(ulong) - sizeof(uint) - sizeof(ushort))
+                    if (bufferWriter.Length > MessagingSystem.NON_FRAGMENTED_MESSAGE_MAX_SIZE)
                     {
                         throw new OverflowException("RPC parameters are too large for unreliable delivery.");
                     }
@@ -128,72 +153,85 @@ namespace Unity.Netcode
                     break;
             }
 
-            var message = new RpcMessage
+            var rpcWriteSize = 0;
-            {
-                Header = new RpcMessage.HeaderData
-                {
-                    Type = RpcMessage.RpcType.Client,
-                    NetworkObjectId = NetworkObjectId,
-                    NetworkBehaviourId = NetworkBehaviourId,
-                    NetworkMethodId = rpcMethodId
-                },
-                RpcData = writer
-            };
-            int messageSize;
 
             // We check to see if we need to shortcut for the case where we are the host/server and we can send a clientRPC
             // to ourself. Sadly we have to figure that out from the list of clientIds :(
             bool shouldSendToHost = false;
-
+            if (clientRpcParams.Send.TargetClientIds != null)
-            if (rpcParams.Send.TargetClientIds != null)
             {
-                foreach (var clientId in rpcParams.Send.TargetClientIds)
+                foreach (var targetClientId in clientRpcParams.Send.TargetClientIds)
                 {
-                    if (clientId == NetworkManager.ServerClientId)
+                    if (targetClientId == NetworkManager.ServerClientId)
                     {
                         shouldSendToHost = true;
                         break;
                     }
+
+                    // Check to make sure we are sending to only observers, if not log an error.
+                    if (NetworkManager.LogLevel >= LogLevel.Error && !NetworkObject.Observers.Contains(targetClientId))
+                    {
+                        NetworkLog.LogError(GenerateObserverErrorMessage(clientRpcParams, targetClientId));
+                    }
                 }
 
-                messageSize = NetworkManager.SendMessage(message, networkDelivery, in rpcParams.Send.TargetClientIds);
+                rpcWriteSize = NetworkManager.SendMessage(ref clientRpcMessage, networkDelivery, in clientRpcParams.Send.TargetClientIds);
             }
-            else if (rpcParams.Send.TargetClientIdsNativeArray != null)
+            else if (clientRpcParams.Send.TargetClientIdsNativeArray != null)
             {
-                foreach (var clientId in rpcParams.Send.TargetClientIdsNativeArray)
+                foreach (var targetClientId in clientRpcParams.Send.TargetClientIdsNativeArray)
                 {
-                    if (clientId == NetworkManager.ServerClientId)
+                    if (targetClientId == NetworkManager.ServerClientId)
                     {
                         shouldSendToHost = true;
                         break;
                     }
+
+                    // Check to make sure we are sending to only observers, if not log an error.
+                    if (NetworkManager.LogLevel >= LogLevel.Error && !NetworkObject.Observers.Contains(targetClientId))
+                    {
+                        NetworkLog.LogError(GenerateObserverErrorMessage(clientRpcParams, targetClientId));
+                    }
                 }
 
-                messageSize = NetworkManager.SendMessage(message, networkDelivery, rpcParams.Send.TargetClientIdsNativeArray.Value);
+                rpcWriteSize = NetworkManager.SendMessage(ref clientRpcMessage, networkDelivery, clientRpcParams.Send.TargetClientIdsNativeArray.Value);
             }
             else
             {
-                shouldSendToHost = IsHost;
+                var observerEnumerator = NetworkObject.Observers.GetEnumerator();
-                messageSize = NetworkManager.SendMessage(message, networkDelivery, NetworkManager.ConnectedClientsIds);
+                while (observerEnumerator.MoveNext())
+                {
+                    // Skip over the host
+                    if (IsHost && observerEnumerator.Current == NetworkManager.LocalClientId)
+                    {
+                        shouldSendToHost = true;
+                        continue;
+                    }
+                    rpcWriteSize = NetworkManager.MessagingSystem.SendMessage(ref clientRpcMessage, networkDelivery, observerEnumerator.Current);
+                }
             }
 
             // If we are a server/host then we just no op and send to ourself
             if (shouldSendToHost)
             {
-                using var tempBuffer = new FastBufferReader(writer, Allocator.Temp);
+                using var tempBuffer = new FastBufferReader(bufferWriter, Allocator.Temp);
                 var context = new NetworkContext
                 {
                     SenderId = NetworkManager.ServerClientId,
                     Timestamp = Time.realtimeSinceStartup,
                     SystemOwner = NetworkManager,
                     // header information isn't valid since it's not a real message.
-                    // Passing false to canDefer prevents it being accessed.
+                    // RpcMessage doesn't access this stuff so it's just left empty.
-                    Header = new MessageHeader()
+                    Header = new MessageHeader(),
+                    SerializedHeaderSize = 0,
+                    MessageSize = 0
                 };
-                message.Handle(tempBuffer, context, NetworkManager, NetworkManager.ServerClientId, false);
+                clientRpcMessage.ReadBuffer = tempBuffer;
-                messageSize = tempBuffer.Length;
+                clientRpcMessage.Handle(ref context);
             }
 
+            bufferWriter.Dispose();
+
 #if DEVELOPMENT_BUILD || UNITY_EDITOR
             if (NetworkManager.__rpc_name_table.TryGetValue(rpcMethodId, out var rpcMethodName))
             {
@@ -204,12 +242,18 @@ namespace Unity.Netcode
                         NetworkObject,
                         rpcMethodName,
                         __getTypeName(),
-                        messageSize);
+                        rpcWriteSize);
                 }
             }
 #endif
         }
 
+        internal string GenerateObserverErrorMessage(ClientRpcParams clientRpcParams, ulong targetClientId)
+        {
+            var containerNameHoldingId = clientRpcParams.Send.TargetClientIds != null ? nameof(ClientRpcParams.Send.TargetClientIds) : nameof(ClientRpcParams.Send.TargetClientIdsNativeArray);
+            return $"Sending ClientRpc to non-observer! {containerNameHoldingId} contains clientId {targetClientId} that is not an observer!";
+        }
+
         /// <summary>
         /// Gets the NetworkManager that owns this NetworkBehaviour instance
         ///   See note around `NetworkObject` for how there is a chicken / egg problem when we are not initialized
@@ -217,50 +261,50 @@ namespace Unity.Netcode
         public NetworkManager NetworkManager => NetworkObject.NetworkManager;
 
         /// <summary>
-        /// Gets if the object is the the personal clients player object
+        /// If a NetworkObject is assigned, it will return whether or not this NetworkObject
+        /// is the local player object.  If no NetworkObject is assigned it will always return false.
         /// </summary>
-        public bool IsLocalPlayer => NetworkObject.IsLocalPlayer;
+        public bool IsLocalPlayer { get; private set; }
 
         /// <summary>
         /// Gets if the object is owned by the local player or if the object is the local player object
         /// </summary>
-        public bool IsOwner => NetworkObject.IsOwner;
+        public bool IsOwner { get; internal set; }
 
         /// <summary>
         /// Gets if we are executing as server
         /// </summary>
-        protected bool IsServer => IsRunning && NetworkManager.IsServer;
+        protected bool IsServer { get; private set; }
 
         /// <summary>
         /// Gets if we are executing as client
         /// </summary>
-        protected bool IsClient => IsRunning && NetworkManager.IsClient;
+        protected bool IsClient { get; private set; }
+
 
         /// <summary>
         /// Gets if we are executing as Host, I.E Server and Client
         /// </summary>
-        protected bool IsHost => IsRunning && NetworkManager.IsHost;
+        protected bool IsHost { get; private set; }
-
-        private bool IsRunning => NetworkManager && NetworkManager.IsListening;
 
         /// <summary>
         /// Gets Whether or not the object has a owner
         /// </summary>
-        public bool IsOwnedByServer => NetworkObject.IsOwnedByServer;
+        public bool IsOwnedByServer { get; internal set; }
 
         /// <summary>
         /// Used to determine if it is safe to access NetworkObject and NetworkManager from within a NetworkBehaviour component
         /// Primarily useful when checking NetworkObject/NetworkManager properties within FixedUpate
         /// </summary>
-        public bool IsSpawned => HasNetworkObject ? NetworkObject.IsSpawned : false;
+        public bool IsSpawned { get; internal set; }
 
         internal bool IsBehaviourEditable()
         {
             // Only server can MODIFY. So allow modification if network is either not running or we are server
             return !m_NetworkObject ||
-                   (m_NetworkObject.NetworkManager == null ||
+                m_NetworkObject.NetworkManager == null ||
-                    !m_NetworkObject.NetworkManager.IsListening ||
+                m_NetworkObject.NetworkManager.IsListening == false ||
-                    m_NetworkObject.NetworkManager.IsServer);
+                m_NetworkObject.NetworkManager.IsServer;
         }
 
         /// <summary>
@@ -282,9 +326,17 @@ namespace Unity.Netcode
                     m_NetworkObject = GetComponentInParent<NetworkObject>();
                 }
 
-                if (m_NetworkObject == null && NetworkLog.CurrentLogLevel <= LogLevel.Normal)
+                // ShutdownInProgress check:
+                // This prevents an edge case scenario where the NetworkManager is shutting down but user code
+                // in Update and/or in FixedUpdate could still be checking NetworkBehaviour.NetworkObject directly (i.e. does it exist?)
+                // or NetworkBehaviour.IsSpawned (i.e. to early exit if not spawned) which, in turn, could generate several Warning messages
+                // per spawned NetworkObject.  Checking for ShutdownInProgress prevents these unnecessary LogWarning messages.
+                if (m_NetworkObject == null && (NetworkManager.Singleton == null || !NetworkManager.Singleton.ShutdownInProgress))
                 {
-                    NetworkLog.LogWarning($"Could not get {nameof(NetworkObject)} for the {nameof(NetworkBehaviour)}. Are you missing a {nameof(NetworkObject)} component?");
+                    if (NetworkLog.CurrentLogLevel <= LogLevel.Normal)
+                    {
+                        NetworkLog.LogWarning($"Could not get {nameof(NetworkObject)} for the {nameof(NetworkBehaviour)}. Are you missing a {nameof(NetworkObject)} component?");
+                    }
                 }
 
                 return m_NetworkObject;
@@ -301,12 +353,12 @@ namespace Unity.Netcode
         /// <summary>
         /// Gets the NetworkId of the NetworkObject that owns this NetworkBehaviour
         /// </summary>
-        public ulong NetworkObjectId => NetworkObject.NetworkObjectId;
+        public ulong NetworkObjectId { get; internal set; }
 
         /// <summary>
         /// Gets NetworkId for this NetworkBehaviour from the owner NetworkObject
         /// </summary>
-        public ushort NetworkBehaviourId => NetworkObject.GetNetworkBehaviourOrderIndex(this);
+        public ushort NetworkBehaviourId { get; internal set; }
 
         /// <summary>
         /// Internally caches the Id of this behaviour in a NetworkObject. Makes look-up faster
@@ -326,7 +378,47 @@ namespace Unity.Netcode
         /// <summary>
         /// Gets the ClientId that owns the NetworkObject
         /// </summary>
-        public ulong OwnerClientId => NetworkObject.OwnerClientId;
+        public ulong OwnerClientId { get; internal set; }
+
+        /// <summary>
+        /// Updates properties with network session related
+        /// dependencies such as a NetworkObject's spawned
+        /// state or NetworkManager's session state.
+        /// </summary>
+        internal void UpdateNetworkProperties()
+        {
+            // Set NetworkObject dependent properties
+            if (NetworkObject != null)
+            {
+                // Set identification related properties
+                NetworkObjectId = NetworkObject.NetworkObjectId;
+                IsLocalPlayer = NetworkObject.IsLocalPlayer;
+
+                // This is "OK" because GetNetworkBehaviourOrderIndex uses the order of
+                // NetworkObject.ChildNetworkBehaviours which is set once when first
+                // accessed.
+                NetworkBehaviourId = NetworkObject.GetNetworkBehaviourOrderIndex(this);
+
+                // Set ownership related properties
+                IsOwnedByServer = NetworkObject.IsOwnedByServer;
+                IsOwner = NetworkObject.IsOwner;
+                OwnerClientId = NetworkObject.OwnerClientId;
+
+                // Set NetworkManager dependent properties
+                if (NetworkManager != null)
+                {
+                    IsHost = NetworkManager.IsListening && NetworkManager.IsHost;
+                    IsClient = NetworkManager.IsListening && NetworkManager.IsClient;
+                    IsServer = NetworkManager.IsListening && NetworkManager.IsServer;
+                }
+            }
+            else // Shouldn't happen, but if so then set the properties to their default value;
+            {
+                OwnerClientId = NetworkObjectId = default;
+                IsOwnedByServer = IsOwner = IsHost = IsClient = IsServer = default;
+                NetworkBehaviourId = default;
+            }
+        }
 
         /// <summary>
         /// Gets called when the <see cref="NetworkObject"/> gets spawned, message handlers are ready to be registered and the network is setup.
@@ -340,12 +432,17 @@ namespace Unity.Netcode
 
         internal void InternalOnNetworkSpawn()
         {
+            IsSpawned = true;
             InitializeVariables();
+            UpdateNetworkProperties();
+            OnNetworkSpawn();
         }
 
         internal void InternalOnNetworkDespawn()
         {
-
+            IsSpawned = false;
+            UpdateNetworkProperties();
+            OnNetworkDespawn();
         }
 
         /// <summary>
@@ -353,11 +450,23 @@ namespace Unity.Netcode
         /// </summary>
         public virtual void OnGainedOwnership() { }
 
+        internal void InternalOnGainedOwnership()
+        {
+            UpdateNetworkProperties();
+            OnGainedOwnership();
+        }
+
         /// <summary>
         /// Gets called when we loose ownership of this object
         /// </summary>
         public virtual void OnLostOwnership() { }
 
+        internal void InternalOnLostOwnership()
+        {
+            UpdateNetworkProperties();
+            OnLostOwnership();
+        }
+
         /// <summary>
         /// Gets called when the parent NetworkObject of this NetworkBehaviour's NetworkObject has changed
         /// </summary>
@@ -410,20 +519,17 @@ namespace Unity.Netcode
 
             m_VarInit = true;
 
-            FieldInfo[] sortedFields = GetFieldInfoForType(GetType());
+            var sortedFields = GetFieldInfoForType(GetType());
-
             for (int i = 0; i < sortedFields.Length; i++)
             {
-                Type fieldType = sortedFields[i].FieldType;
+                var fieldType = sortedFields[i].FieldType;
-
                 if (fieldType.IsSubclassOf(typeof(NetworkVariableBase)))
                 {
                     var instance = (NetworkVariableBase)sortedFields[i].GetValue(this);
 
                     if (instance == null)
                     {
-                        instance = (NetworkVariableBase)Activator.CreateInstance(fieldType, true);
+                        throw new Exception($"{GetType().FullName}.{sortedFields[i].Name} cannot be null. All {nameof(NetworkVariableBase)} instances must be initialized.");
-                        sortedFields[i].SetValue(this, instance);
                     }
 
                     instance.Initialize(this);
@@ -477,7 +583,7 @@ namespace Unity.Netcode
             }
         }
 
-        internal void VariableUpdate(ulong clientId)
+        internal void VariableUpdate(ulong targetClientId)
         {
             if (!m_VarInit)
             {
@@ -485,67 +591,58 @@ namespace Unity.Netcode
             }
 
             PreNetworkVariableWrite();
-            NetworkVariableUpdate(clientId, NetworkBehaviourId);
+            NetworkVariableUpdate(targetClientId, NetworkBehaviourId);
         }
 
         internal readonly List<int> NetworkVariableIndexesToReset = new List<int>();
         internal readonly HashSet<int> NetworkVariableIndexesToResetSet = new HashSet<int>();
 
-        private void NetworkVariableUpdate(ulong clientId, int behaviourIndex)
+        private void NetworkVariableUpdate(ulong targetClientId, int behaviourIndex)
         {
             if (!CouldHaveDirtyNetworkVariables())
             {
                 return;
             }
 
-            if (NetworkManager.NetworkConfig.UseSnapshotDelta)
+            for (int j = 0; j < m_DeliveryMappedNetworkVariableIndices.Count; j++)
             {
+                var shouldSend = false;
                 for (int k = 0; k < NetworkVariableFields.Count; k++)
                 {
-                    NetworkManager.SnapshotSystem.Store(NetworkObjectId, behaviourIndex, k, NetworkVariableFields[k]);
+                    var networkVariable = NetworkVariableFields[k];
-                }
+                    if (networkVariable.IsDirty() && networkVariable.CanClientRead(targetClientId))
-            }
-
-            if (!NetworkManager.NetworkConfig.UseSnapshotDelta)
-            {
-                for (int j = 0; j < m_DeliveryMappedNetworkVariableIndices.Count; j++)
-                {
-                    var shouldSend = false;
-                    for (int k = 0; k < NetworkVariableFields.Count; k++)
                     {
-                        if (NetworkVariableFields[k].ShouldWrite(clientId, IsServer))
+                        shouldSend = true;
+                        break;
+                    }
+                }
+
+                if (shouldSend)
+                {
+                    var message = new NetworkVariableDeltaMessage
+                    {
+                        NetworkObjectId = NetworkObjectId,
+                        NetworkBehaviourIndex = NetworkObject.GetNetworkBehaviourOrderIndex(this),
+                        NetworkBehaviour = this,
+                        TargetClientId = targetClientId,
+                        DeliveryMappedNetworkVariableIndex = m_DeliveryMappedNetworkVariableIndices[j]
+                    };
+                    // TODO: Serialization is where the IsDirty flag gets changed.
+                    // Messages don't get sent from the server to itself, so if we're host and sending to ourselves,
+                    // we still have to actually serialize the message even though we're not sending it, otherwise
+                    // the dirty flag doesn't change properly. These two pieces should be decoupled at some point
+                    // so we don't have to do this serialization work if we're not going to use the result.
+                    if (IsServer && targetClientId == NetworkManager.ServerClientId)
+                    {
+                        var tmpWriter = new FastBufferWriter(MessagingSystem.NON_FRAGMENTED_MESSAGE_MAX_SIZE, Allocator.Temp, MessagingSystem.FRAGMENTED_MESSAGE_MAX_SIZE);
+                        using (tmpWriter)
                         {
-                            shouldSend = true;
+                            message.Serialize(tmpWriter);
                         }
                     }
-
+                    else
-                    if (shouldSend)
                     {
-                        var message = new NetworkVariableDeltaMessage
+                        NetworkManager.SendMessage(ref message, m_DeliveryTypesForNetworkVariableGroups[j], targetClientId);
-                        {
-                            NetworkObjectId = NetworkObjectId,
-                            NetworkBehaviourIndex = NetworkObject.GetNetworkBehaviourOrderIndex(this),
-                            NetworkBehaviour = this,
-                            ClientId = clientId,
-                            DeliveryMappedNetworkVariableIndex = m_DeliveryMappedNetworkVariableIndices[j]
-                        };
-                        // TODO: Serialization is where the IsDirty flag gets changed.
-                        // Messages don't get sent from the server to itself, so if we're host and sending to ourselves,
-                        // we still have to actually serialize the message even though we're not sending it, otherwise
-                        // the dirty flag doesn't change properly. These two pieces should be decoupled at some point
-                        // so we don't have to do this serialization work if we're not going to use the result.
-                        if (IsServer && clientId == NetworkManager.ServerClientId)
-                        {
-                            var tmpWriter = new FastBufferWriter(MessagingSystem.NON_FRAGMENTED_MESSAGE_MAX_SIZE, Allocator.Temp);
-                            using (tmpWriter)
-                            {
-                                message.Serialize(tmpWriter);
-                            }
-                        }
-                        else
-                        {
-                            NetworkManager.SendMessage(message, m_DeliveryTypesForNetworkVariableGroups[j], clientId);
-                        }
                     }
                 }
             }
@@ -573,7 +670,7 @@ namespace Unity.Netcode
             }
         }
 
-        internal void WriteNetworkVariableData(FastBufferWriter writer, ulong clientId)
+        internal void WriteNetworkVariableData(FastBufferWriter writer, ulong targetClientId)
         {
             if (NetworkVariableFields.Count == 0)
             {
@@ -582,7 +679,7 @@ namespace Unity.Netcode
 
             for (int j = 0; j < NetworkVariableFields.Count; j++)
             {
-                bool canClientRead = NetworkVariableFields[j].CanClientRead(clientId);
+                bool canClientRead = NetworkVariableFields[j].CanClientRead(targetClientId);
 
                 if (canClientRead)
                 {

Runtime/Core/NetworkBehaviourUpdater.cs

@@ -57,7 +57,7 @@ namespace Unity.Netcode
                         {
                             for (int k = 0; k < sobj.ChildNetworkBehaviours.Count; k++)
                             {
-                                sobj.ChildNetworkBehaviours[k].VariableUpdate(networkManager.ServerClientId);
+                                sobj.ChildNetworkBehaviours[k].VariableUpdate(NetworkManager.ServerClientId);
                             }
                         }
                     }

Runtime/Core/NetworkObject.cs

@@ -39,7 +39,7 @@ namespace Unity.Netcode
             var globalObjectIdString = UnityEditor.GlobalObjectId.GetGlobalObjectIdSlow(this).ToString();
             GlobalObjectIdHash = XXHash.Hash32(globalObjectIdString);
         }
-#endif
+#endif // UNITY_EDITOR
 
         /// <summary>
         /// Gets the NetworkManager that owns this NetworkObject instance
@@ -54,8 +54,6 @@ namespace Unity.Netcode
         /// </summary>
         internal NetworkManager NetworkManagerOwner;
 
-        private ulong m_NetworkObjectId;
-
         /// <summary>
         /// Gets the unique Id of this object that is synced across the network
         /// </summary>
@@ -64,33 +62,7 @@ namespace Unity.Netcode
         /// <summary>
         /// Gets the ClientId of the owner of this NetworkObject
         /// </summary>
-        public ulong OwnerClientId
+        public ulong OwnerClientId { get; internal set; }
-        {
-            get
-            {
-                if (OwnerClientIdInternal == null)
-                {
-                    return NetworkManager != null ? NetworkManager.ServerClientId : 0;
-                }
-                else
-                {
-                    return OwnerClientIdInternal.Value;
-                }
-            }
-            internal set
-            {
-                if (NetworkManager != null && value == NetworkManager.ServerClientId)
-                {
-                    OwnerClientIdInternal = null;
-                }
-                else
-                {
-                    OwnerClientIdInternal = value;
-                }
-            }
-        }
-
-        internal ulong? OwnerClientIdInternal = null;
 
         /// <summary>
         /// If true, the object will always be replicated as root on clients and the parent will be ignored.
@@ -234,11 +206,6 @@ namespace Unity.Netcode
                 throw new VisibilityChangeException("The object is already visible");
             }
 
-            if (NetworkManager.NetworkConfig.UseSnapshotSpawn)
-            {
-                SnapshotSpawn(clientId);
-            }
-
             Observers.Add(clientId);
 
             NetworkManager.SpawnManager.SendSpawnCallForObject(clientId, this);
@@ -314,23 +281,15 @@ namespace Unity.Netcode
                 throw new VisibilityChangeException("Cannot hide an object from the server");
             }
 
-
             Observers.Remove(clientId);
 
-            if (NetworkManager.NetworkConfig.UseSnapshotSpawn)
+            var message = new DestroyObjectMessage
             {
-                SnapshotDespawn(clientId);
+                NetworkObjectId = NetworkObjectId
-            }
+            };
-            else
+            // Send destroy call
-            {
+            var size = NetworkManager.SendMessage(ref message, NetworkDelivery.ReliableSequenced, clientId);
-                var message = new DestroyObjectMessage
+            NetworkManager.NetworkMetrics.TrackObjectDestroySent(clientId, this, size);
-                {
-                    NetworkObjectId = NetworkObjectId
-                };
-                // Send destroy call
-                var size = NetworkManager.SendMessage(message, NetworkDelivery.ReliableSequenced, clientId);
-                NetworkManager.NetworkMetrics.TrackObjectDestroySent(clientId, this, size);
-            }
         }
 
         /// <summary>
@@ -345,14 +304,14 @@ namespace Unity.Netcode
                 throw new ArgumentNullException("At least one " + nameof(NetworkObject) + " has to be provided");
             }
 
-            NetworkManager networkManager = networkObjects[0].NetworkManager;
+            var networkManager = networkObjects[0].NetworkManager;
 
             if (!networkManager.IsServer)
             {
                 throw new NotServerException("Only server can change visibility");
             }
 
-            if (clientId == networkManager.ServerClientId)
+            if (clientId == NetworkManager.ServerClientId)
             {
                 throw new VisibilityChangeException("Cannot hide an object from the server");
             }
@@ -384,84 +343,24 @@ namespace Unity.Netcode
 
         private void OnDestroy()
         {
-            if (NetworkManager != null && NetworkManager.IsListening && NetworkManager.IsServer == false && IsSpawned
+            if (NetworkManager != null && NetworkManager.IsListening && NetworkManager.IsServer == false && IsSpawned &&
-                && (IsSceneObject == null || (IsSceneObject != null && IsSceneObject.Value != true)))
+                (IsSceneObject == null || (IsSceneObject != null && IsSceneObject.Value != true)))
             {
                 throw new NotServerException($"Destroy a spawned {nameof(NetworkObject)} on a non-host client is not valid. Call {nameof(Destroy)} or {nameof(Despawn)} on the server/host instead.");
             }
 
-            if (NetworkManager != null && NetworkManager.SpawnManager != null && NetworkManager.SpawnManager.SpawnedObjects.TryGetValue(NetworkObjectId, out var networkObject))
+            if (NetworkManager != null && NetworkManager.SpawnManager != null &&
+                NetworkManager.SpawnManager.SpawnedObjects.TryGetValue(NetworkObjectId, out var networkObject))
             {
-                NetworkManager.SpawnManager.OnDespawnObject(networkObject, false);
+                if (this == networkObject)
+                {
+                    NetworkManager.SpawnManager.OnDespawnObject(networkObject, false);
+                }
             }
         }
 
-        private SnapshotDespawnCommand GetDespawnCommand()
-        {
-            var command = new SnapshotDespawnCommand();
-            command.NetworkObjectId = NetworkObjectId;
-
-            return command;
-        }
-
-        private SnapshotSpawnCommand GetSpawnCommand()
-        {
-            var command = new SnapshotSpawnCommand();
-            command.NetworkObjectId = NetworkObjectId;
-            command.OwnerClientId = OwnerClientId;
-            command.IsPlayerObject = IsPlayerObject;
-            command.IsSceneObject = (IsSceneObject == null) || IsSceneObject.Value;
-
-            ulong? parent = NetworkManager.SpawnManager.GetSpawnParentId(this);
-            if (parent != null)
-            {
-                command.ParentNetworkId = parent.Value;
-            }
-            else
-            {
-                // write own network id, when no parents. todo: optimize this.
-                command.ParentNetworkId = command.NetworkObjectId;
-            }
-
-            command.GlobalObjectIdHash = HostCheckForGlobalObjectIdHashOverride();
-            // todo: check if (IncludeTransformWhenSpawning == null || IncludeTransformWhenSpawning(clientId)) for any clientId
-            command.ObjectPosition = transform.position;
-            command.ObjectRotation = transform.rotation;
-            command.ObjectScale = transform.localScale;
-
-            return command;
-        }
-
-        private void SnapshotSpawn()
-        {
-            var command = GetSpawnCommand();
-            NetworkManager.SnapshotSystem.Spawn(command);
-        }
-
-        private void SnapshotSpawn(ulong clientId)
-        {
-            var command = GetSpawnCommand();
-            command.TargetClientIds = new List<ulong>();
-            command.TargetClientIds.Add(clientId);
-            NetworkManager.SnapshotSystem.Spawn(command);
-        }
-
-        internal void SnapshotDespawn()
-        {
-            var command = GetDespawnCommand();
-            NetworkManager.SnapshotSystem.Despawn(command);
-        }
-
-        internal void SnapshotDespawn(ulong clientId)
-        {
-            var command = GetDespawnCommand();
-            command.TargetClientIds = new List<ulong>();
-            command.TargetClientIds.Add(clientId);
-            NetworkManager.SnapshotSystem.Despawn(command);
-        }
-
         [MethodImpl(MethodImplOptions.AggressiveInlining)]
-        private void SpawnInternal(bool destroyWithScene, ulong? ownerClientId, bool playerObject)
+        private void SpawnInternal(bool destroyWithScene, ulong ownerClientId, bool playerObject)
         {
             if (!NetworkManager.IsListening)
             {
@@ -475,12 +374,6 @@ namespace Unity.Netcode
 
             NetworkManager.SpawnManager.SpawnNetworkObjectLocally(this, NetworkManager.SpawnManager.GetNetworkObjectId(), false, playerObject, ownerClientId, destroyWithScene);
 
-            if (NetworkManager.NetworkConfig.UseSnapshotSpawn)
-            {
-                SnapshotSpawn();
-            }
-
-            ulong ownerId = ownerClientId != null ? ownerClientId.Value : NetworkManager.ServerClientId;
             for (int i = 0; i < NetworkManager.ConnectedClientsList.Count; i++)
             {
                 if (Observers.Contains(NetworkManager.ConnectedClientsList[i].ClientId))
@@ -496,7 +389,7 @@ namespace Unity.Netcode
         /// <param name="destroyWithScene">Should the object be destroyed when the scene is changed</param>
         public void Spawn(bool destroyWithScene = false)
         {
-            SpawnInternal(destroyWithScene, null, false);
+            SpawnInternal(destroyWithScene, NetworkManager.ServerClientId, false);
         }
 
         /// <summary>
@@ -547,17 +440,29 @@ namespace Unity.Netcode
 
         internal void InvokeBehaviourOnLostOwnership()
         {
+            // Server already handles this earlier, hosts should ignore, all clients should update
+            if (!NetworkManager.IsServer)
+            {
+                NetworkManager.SpawnManager.UpdateOwnershipTable(this, OwnerClientId, true);
+            }
+
             for (int i = 0; i < ChildNetworkBehaviours.Count; i++)
             {
-                ChildNetworkBehaviours[i].OnLostOwnership();
+                ChildNetworkBehaviours[i].InternalOnLostOwnership();
             }
         }
 
         internal void InvokeBehaviourOnGainedOwnership()
         {
+            // Server already handles this earlier, hosts should ignore and only client owners should update
+            if (!NetworkManager.IsServer && NetworkManager.LocalClientId == OwnerClientId)
+            {
+                NetworkManager.SpawnManager.UpdateOwnershipTable(this, OwnerClientId);
+            }
+
             for (int i = 0; i < ChildNetworkBehaviours.Count; i++)
             {
-                ChildNetworkBehaviours[i].OnGainedOwnership();
+                ChildNetworkBehaviours[i].InternalOnGainedOwnership();
             }
         }
 
@@ -714,7 +619,7 @@ namespace Unity.Netcode
                     }
                 }
 
-                NetworkManager.SendMessage(message, NetworkDelivery.ReliableSequenced, clientIds, idx);
+                NetworkManager.SendMessage(ref message, NetworkDelivery.ReliableSequenced, clientIds, idx);
             }
         }
 
@@ -756,13 +661,7 @@ namespace Unity.Netcode
 
             if (!NetworkManager.SpawnManager.SpawnedObjects.ContainsKey(m_LatestParent.Value))
             {
-                if (OrphanChildren.Add(this))
+                OrphanChildren.Add(this);
-                {
-                    if (NetworkLog.CurrentLogLevel <= LogLevel.Normal)
-                    {
-                        NetworkLog.LogWarning($"{nameof(NetworkObject)} ({name}) cannot find its parent, added to {nameof(OrphanChildren)} set");
-                    }
-                }
                 return false;
             }
 
@@ -793,19 +692,21 @@ namespace Unity.Netcode
 
         internal void InvokeBehaviourNetworkSpawn()
         {
+            NetworkManager.SpawnManager.UpdateOwnershipTable(this, OwnerClientId);
+
             for (int i = 0; i < ChildNetworkBehaviours.Count; i++)
             {
                 ChildNetworkBehaviours[i].InternalOnNetworkSpawn();
-                ChildNetworkBehaviours[i].OnNetworkSpawn();
             }
         }
 
         internal void InvokeBehaviourNetworkDespawn()
         {
+            NetworkManager.SpawnManager.UpdateOwnershipTable(this, OwnerClientId, true);
+
             for (int i = 0; i < ChildNetworkBehaviours.Count; i++)
             {
                 ChildNetworkBehaviours[i].InternalOnNetworkDespawn();
-                ChildNetworkBehaviours[i].OnNetworkDespawn();
             }
         }
 
@@ -834,13 +735,13 @@ namespace Unity.Netcode
             }
         }
 
-        internal void WriteNetworkVariableData(FastBufferWriter writer, ulong clientId)
+        internal void WriteNetworkVariableData(FastBufferWriter writer, ulong targetClientId)
         {
             for (int i = 0; i < ChildNetworkBehaviours.Count; i++)
             {
                 var behavior = ChildNetworkBehaviours[i];
                 behavior.InitializeVariables();
-                behavior.WriteNetworkVariableData(writer, clientId);
+                behavior.WriteNetworkVariableData(writer, targetClientId);
             }
         }
 
@@ -853,6 +754,27 @@ namespace Unity.Netcode
             }
         }
 
+        // NGO currently guarantees that the client will receive spawn data for all objects in one network tick.
+        //  Children may arrive before their parents; when they do they are stored in OrphanedChildren and then
+        //  resolved when their parents arrived.  Because we don't send a partial list of spawns (yet), something
+        //  has gone wrong if by the end of an update we still have unresolved orphans
+        //
+
+        // if and when we have different systems for where it is expected that orphans survive across ticks,
+        //   then this warning will remind us that we need to revamp the system because then we can no longer simply
+        //   spawn the orphan without its parent (at least, not when its transform is set to local coords mode)
+        //   - because then you’ll have children popping at the wrong location not having their parent’s global position to root them
+        //   - and then they’ll pop to the correct location after they get the parent, and that would be not good
+        internal static void VerifyParentingStatus()
+        {
+            if (NetworkLog.CurrentLogLevel <= LogLevel.Normal)
+            {
+                if (OrphanChildren.Count > 0)
+                {
+                    NetworkLog.LogWarning($"{nameof(NetworkObject)} ({OrphanChildren.Count}) children not resolved to parents by the end of frame");
+                }
+            }
+        }
         internal void SetNetworkVariableData(FastBufferReader reader)
         {
             for (int i = 0; i < ChildNetworkBehaviours.Count; i++)
@@ -907,7 +829,7 @@ namespace Unity.Netcode
 
         internal struct SceneObject
         {
-            public struct HeaderData
+            public struct HeaderData : INetworkSerializeByMemcpy
             {
                 public ulong NetworkObjectId;
                 public ulong OwnerClientId;
@@ -918,7 +840,6 @@ namespace Unity.Netcode
                 public bool IsSceneObject;
                 public bool HasTransform;
                 public bool IsReparented;
-                public bool HasNetworkVariables;
             }
 
             public HeaderData Header;
@@ -927,7 +848,7 @@ namespace Unity.Netcode
             public ulong ParentObjectId;
 
             //If(Metadata.HasTransform)
-            public struct TransformData
+            public struct TransformData : INetworkSerializeByMemcpy
             {
                 public Vector3 Position;
                 public Quaternion Rotation;
@@ -979,10 +900,7 @@ namespace Unity.Netcode
                     }
                 }
 
-                if (Header.HasNetworkVariables)
+                OwnerObject.WriteNetworkVariableData(writer, TargetClientId);
-                {
-                    OwnerObject.WriteNetworkVariableData(writer, TargetClientId);
-                }
             }
 
             public unsafe void Deserialize(FastBufferReader reader)
@@ -1022,7 +940,7 @@ namespace Unity.Netcode
             }
         }
 
-        internal SceneObject GetMessageSceneObject(ulong targetClientId, bool includeNetworkVariableData = true)
+        internal SceneObject GetMessageSceneObject(ulong targetClientId)
         {
             var obj = new SceneObject
             {
@@ -1033,7 +951,6 @@ namespace Unity.Netcode
                     OwnerClientId = OwnerClientId,
                     IsSceneObject = IsSceneObject ?? true,
                     Hash = HostCheckForGlobalObjectIdHashOverride(),
-                    HasNetworkVariables = includeNetworkVariableData
                 },
                 OwnerObject = this,
                 TargetClientId = targetClientId
@@ -1142,8 +1059,7 @@ namespace Unity.Netcode
                     var globalObjectIdHash = NetworkManager.PrefabHandler.GetSourceGlobalObjectIdHash(GlobalObjectIdHash);
                     return globalObjectIdHash == 0 ? GlobalObjectIdHash : globalObjectIdHash;
                 }
-                else
+                else if (NetworkManager.NetworkConfig.OverrideToNetworkPrefab.ContainsKey(GlobalObjectIdHash))
-                if (NetworkManager.NetworkConfig.OverrideToNetworkPrefab.ContainsKey(GlobalObjectIdHash))
                 {
                     return NetworkManager.NetworkConfig.OverrideToNetworkPrefab[GlobalObjectIdHash];
                 }

Runtime/Core/SnapshotRTT.cs

@@ -1,93 +0,0 @@
-using System;
-
-namespace Unity.Netcode
-{
-    internal class ConnectionRtt
-    {
-        private double[] m_RttSendTimes; // times at which packet were sent for RTT computations
-        private int[] m_SendSequence; // tick, or other key, at which packets were sent (to allow matching)
-        private double[] m_MeasuredLatencies; // measured latencies (ring buffer)
-        private int m_LatenciesBegin = 0; // ring buffer begin
-        private int m_LatenciesEnd = 0; // ring buffer end
-
-        /// <summary>
-        /// Round-trip-time data
-        /// </summary>
-        public struct Rtt
-        {
-            public double BestSec; // best RTT
-            public double AverageSec; // average RTT
-            public double WorstSec; // worst RTT
-            public double LastSec; // latest ack'ed RTT
-            public int SampleCount; // number of contributing samples
-        }
-
-        public ConnectionRtt()
-        {
-            m_RttSendTimes = new double[NetworkConfig.RttWindowSize];
-            m_SendSequence = new int[NetworkConfig.RttWindowSize];
-            m_MeasuredLatencies = new double[NetworkConfig.RttWindowSize];
-        }
-
-        /// <summary>
-        /// Returns the Round-trip-time computation for this client
-        /// </summary>
-        public Rtt GetRtt()
-        {
-            var ret = new Rtt();
-            var index = m_LatenciesBegin;
-            double total = 0.0;
-            ret.BestSec = m_MeasuredLatencies[m_LatenciesBegin];
-            ret.WorstSec = m_MeasuredLatencies[m_LatenciesBegin];
-
-            while (index != m_LatenciesEnd)
-            {
-                total += m_MeasuredLatencies[index];
-                ret.SampleCount++;
-                ret.BestSec = Math.Min(ret.BestSec, m_MeasuredLatencies[index]);
-                ret.WorstSec = Math.Max(ret.WorstSec, m_MeasuredLatencies[index]);
-                index = (index + 1) % NetworkConfig.RttAverageSamples;
-            }
-
-            if (ret.SampleCount != 0)
-            {
-                ret.AverageSec = total / ret.SampleCount;
-                // the latest RTT is one before m_LatenciesEnd
-                ret.LastSec = m_MeasuredLatencies[(m_LatenciesEnd + (NetworkConfig.RttWindowSize - 1)) % NetworkConfig.RttWindowSize];
-            }
-            else
-            {
-                ret.AverageSec = 0;
-                ret.BestSec = 0;
-                ret.WorstSec = 0;
-                ret.SampleCount = 0;
-                ret.LastSec = 0;
-            }
-
-            return ret;
-        }
-
-        internal void NotifySend(int sequence, double timeSec)
-        {
-            m_RttSendTimes[sequence % NetworkConfig.RttWindowSize] = timeSec;
-            m_SendSequence[sequence % NetworkConfig.RttWindowSize] = sequence;
-        }
-
-        internal void NotifyAck(int sequence, double timeSec)
-        {
-            // if the same slot was not used by a later send
-            if (m_SendSequence[sequence % NetworkConfig.RttWindowSize] == sequence)
-            {
-                double latency = timeSec - m_RttSendTimes[sequence % NetworkConfig.RttWindowSize];
-
-                m_MeasuredLatencies[m_LatenciesEnd] = latency;
-                m_LatenciesEnd = (m_LatenciesEnd + 1) % NetworkConfig.RttAverageSamples;
-
-                if (m_LatenciesEnd == m_LatenciesBegin)
-                {
-                    m_LatenciesBegin = (m_LatenciesBegin + 1) % NetworkConfig.RttAverageSamples;
-                }
-            }
-        }
-    }
-}

Runtime/Core/SnapshotSystem.cs.meta

@@ -1,11 +0,0 @@
-fileFormatVersion: 2
-guid: c275febadb27c4d18b41218e3353b84b
-MonoImporter:
-  externalObjects: {}
-  serializedVersion: 2
-  defaultReferences: []
-  executionOrder: 0
-  icon: {instanceID: 0}
-  userData: 
-  assetBundleName: 
-  assetBundleVariant: 

Runtime/Logging/NetworkLog.cs

@@ -14,9 +14,9 @@ namespace Unity.Netcode
         public static LogLevel CurrentLogLevel => NetworkManager.Singleton == null ? LogLevel.Normal : NetworkManager.Singleton.LogLevel;
 
         // internal logging
-        internal static void LogInfo(string message) => Debug.Log($"[Netcode] {message}");
+        public static void LogInfo(string message) => Debug.Log($"[Netcode] {message}");
-        internal static void LogWarning(string message) => Debug.LogWarning($"[Netcode] {message}");
+        public static void LogWarning(string message) => Debug.LogWarning($"[Netcode] {message}");
-        internal static void LogError(string message) => Debug.LogError($"[Netcode] {message}");
+        public static void LogError(string message) => Debug.LogError($"[Netcode] {message}");
 
         /// <summary>
         /// Logs an info log locally and on the server if possible.
@@ -62,10 +62,9 @@ namespace Unity.Netcode
                     LogType = logType,
                     Message = message
                 };
-                var size = NetworkManager.Singleton.SendMessage(networkMessage, NetworkDelivery.ReliableFragmentedSequenced,
+                var size = NetworkManager.Singleton.SendMessage(ref networkMessage, NetworkDelivery.ReliableFragmentedSequenced, NetworkManager.ServerClientId);
-                    NetworkManager.Singleton.ServerClientId);
 
-                NetworkManager.Singleton.NetworkMetrics.TrackServerLogSent(NetworkManager.Singleton.ServerClientId, (uint)logType, size);
+                NetworkManager.Singleton.NetworkMetrics.TrackServerLogSent(NetworkManager.ServerClientId, (uint)logType, size);
             }
         }
 

Runtime/Messaging/BatchHeader.cs

@@ -3,7 +3,7 @@ namespace Unity.Netcode
     /// <summary>
     /// Header placed at the start of each message batch
     /// </summary>
-    internal struct BatchHeader
+    internal struct BatchHeader : INetworkSerializeByMemcpy
     {
         /// <summary>
         /// Total number of messages in the batch.

Runtime/Messaging/CustomMessageManager.cs

@@ -28,7 +28,7 @@ namespace Unity.Netcode
         /// </summary>
         public event UnnamedMessageDelegate OnUnnamedMessage;
 
-        internal void InvokeUnnamedMessage(ulong clientId, FastBufferReader reader)
+        internal void InvokeUnnamedMessage(ulong clientId, FastBufferReader reader, int serializedHeaderSize)
         {
             if (OnUnnamedMessage != null)
             {
@@ -40,7 +40,7 @@ namespace Unity.Netcode
                     ((UnnamedMessageDelegate)handler).Invoke(clientId, reader);
                 }
             }
-            m_NetworkManager.NetworkMetrics.TrackUnnamedMessageReceived(clientId, reader.Length + FastBufferWriter.GetWriteSize<MessageHeader>());
+            m_NetworkManager.NetworkMetrics.TrackUnnamedMessageReceived(clientId, reader.Length + serializedHeaderSize);
         }
 
         /// <summary>
@@ -73,9 +73,9 @@ namespace Unity.Netcode
 
             var message = new UnnamedMessage
             {
-                Data = messageBuffer
+                SendData = messageBuffer
             };
-            var size = m_NetworkManager.SendMessage(message, networkDelivery, clientIds);
+            var size = m_NetworkManager.SendMessage(ref message, networkDelivery, clientIds);
 
             // Size is zero if we were only sending the message to ourself in which case it isn't sent.
             if (size != 0)
@@ -94,9 +94,9 @@ namespace Unity.Netcode
         {
             var message = new UnnamedMessage
             {
-                Data = messageBuffer
+                SendData = messageBuffer
             };
-            var size = m_NetworkManager.SendMessage(message, networkDelivery, clientId);
+            var size = m_NetworkManager.SendMessage(ref message, networkDelivery, clientId);
             // Size is zero if we were only sending the message to ourself in which case it isn't sent.
             if (size != 0)
             {
@@ -115,9 +115,9 @@ namespace Unity.Netcode
         private Dictionary<ulong, string> m_MessageHandlerNameLookup32 = new Dictionary<ulong, string>();
         private Dictionary<ulong, string> m_MessageHandlerNameLookup64 = new Dictionary<ulong, string>();
 
-        internal void InvokeNamedMessage(ulong hash, ulong sender, FastBufferReader reader)
+        internal void InvokeNamedMessage(ulong hash, ulong sender, FastBufferReader reader, int serializedHeaderSize)
         {
-            var bytesCount = reader.Length + FastBufferWriter.GetWriteSize<MessageHeader>();
+            var bytesCount = reader.Length + serializedHeaderSize;
 
             if (m_NetworkManager == null)
             {
@@ -223,9 +223,9 @@ namespace Unity.Netcode
             var message = new NamedMessage
             {
                 Hash = hash,
-                Data = messageStream
+                SendData = messageStream,
             };
-            var size = m_NetworkManager.SendMessage(message, networkDelivery, clientId);
+            var size = m_NetworkManager.SendMessage(ref message, networkDelivery, clientId);
 
             // Size is zero if we were only sending the message to ourself in which case it isn't sent.
             if (size != 0)
@@ -266,9 +266,9 @@ namespace Unity.Netcode
             var message = new NamedMessage
             {
                 Hash = hash,
-                Data = messageStream
+                SendData = messageStream
             };
-            var size = m_NetworkManager.SendMessage(message, networkDelivery, clientIds);
+            var size = m_NetworkManager.SendMessage(ref message, networkDelivery, clientIds);
 
             // Size is zero if we were only sending the message to ourself in which case it isn't sent.
             if (size != 0)

Runtime/Messaging/DeferredMessageManager.cs

@@ -0,0 +1,149 @@
+using System.Collections.Generic;
+using Unity.Collections;
+using Time = UnityEngine.Time;
+
+namespace Unity.Netcode
+{
+    internal class DeferredMessageManager : IDeferredMessageManager
+    {
+        protected struct TriggerData
+        {
+            public FastBufferReader Reader;
+            public MessageHeader Header;
+            public ulong SenderId;
+            public float Timestamp;
+            public int SerializedHeaderSize;
+        }
+        protected struct TriggerInfo
+        {
+            public float Expiry;
+            public NativeList<TriggerData> TriggerData;
+        }
+
+        protected readonly Dictionary<IDeferredMessageManager.TriggerType, Dictionary<ulong, TriggerInfo>> m_Triggers = new Dictionary<IDeferredMessageManager.TriggerType, Dictionary<ulong, TriggerInfo>>();
+
+        private readonly NetworkManager m_NetworkManager;
+
+        internal DeferredMessageManager(NetworkManager networkManager)
+        {
+            m_NetworkManager = networkManager;
+        }
+
+        /// <summary>
+        /// Defers processing of a message until the moment a specific networkObjectId is spawned.
+        /// This is to handle situations where an RPC or other object-specific message arrives before the spawn does,
+        /// either due to it being requested in OnNetworkSpawn before the spawn call has been executed
+        ///
+        /// There is a one second maximum lifetime of triggers to avoid memory leaks. After one second has passed
+        /// without the requested object ID being spawned, the triggers for it are automatically deleted.
+        /// </summary>
+        public virtual unsafe void DeferMessage(IDeferredMessageManager.TriggerType trigger, ulong key, FastBufferReader reader, ref NetworkContext context)
+        {
+            if (!m_Triggers.TryGetValue(trigger, out var triggers))
+            {
+                triggers = new Dictionary<ulong, TriggerInfo>();
+                m_Triggers[trigger] = triggers;
+            }
+
+            if (!triggers.TryGetValue(key, out var triggerInfo))
+            {
+                triggerInfo = new TriggerInfo
+                {
+                    Expiry = Time.realtimeSinceStartup + m_NetworkManager.NetworkConfig.SpawnTimeout,
+                    TriggerData = new NativeList<TriggerData>(Allocator.Persistent)
+                };
+                triggers[key] = triggerInfo;
+            }
+
+            triggerInfo.TriggerData.Add(new TriggerData
+            {
+                Reader = new FastBufferReader(reader.GetUnsafePtr(), Allocator.Persistent, reader.Length),
+                Header = context.Header,
+                Timestamp = context.Timestamp,
+                SenderId = context.SenderId,
+                SerializedHeaderSize = context.SerializedHeaderSize
+            });
+        }
+
+        /// <summary>
+        /// Cleans up any trigger that's existed for more than a second.
+        /// These triggers were probably for situations where a request was received after a despawn rather than before a spawn.
+        /// </summary>
+        public virtual unsafe void CleanupStaleTriggers()
+        {
+            foreach (var kvp in m_Triggers)
+            {
+                ulong* staleKeys = stackalloc ulong[kvp.Value.Count];
+                int index = 0;
+                foreach (var kvp2 in kvp.Value)
+                {
+                    if (kvp2.Value.Expiry < Time.realtimeSinceStartup)
+                    {
+                        staleKeys[index++] = kvp2.Key;
+                        PurgeTrigger(kvp.Key, kvp2.Key, kvp2.Value);
+                    }
+                }
+
+                for (var i = 0; i < index; ++i)
+                {
+                    kvp.Value.Remove(staleKeys[i]);
+                }
+            }
+        }
+
+        protected virtual void PurgeTrigger(IDeferredMessageManager.TriggerType triggerType, ulong key, TriggerInfo triggerInfo)
+        {
+            if (NetworkLog.CurrentLogLevel <= LogLevel.Normal)
+            {
+                NetworkLog.LogWarning($"Deferred messages were received for a trigger of type {triggerType} with key {key}, but that trigger was not received within within {m_NetworkManager.NetworkConfig.SpawnTimeout} second(s).");
+            }
+
+            foreach (var data in triggerInfo.TriggerData)
+            {
+                data.Reader.Dispose();
+            }
+
+            triggerInfo.TriggerData.Dispose();
+        }
+
+        public virtual void ProcessTriggers(IDeferredMessageManager.TriggerType trigger, ulong key)
+        {
+            if (m_Triggers.TryGetValue(trigger, out var triggers))
+            {
+                // This must happen after InvokeBehaviourNetworkSpawn, otherwise ClientRPCs and other messages can be
+                // processed before the object is fully spawned. This must be the last thing done in the spawn process.
+                if (triggers.TryGetValue(key, out var triggerInfo))
+                {
+                    foreach (var deferredMessage in triggerInfo.TriggerData)
+                    {
+                        // Reader will be disposed within HandleMessage
+                        m_NetworkManager.MessagingSystem.HandleMessage(deferredMessage.Header, deferredMessage.Reader, deferredMessage.SenderId, deferredMessage.Timestamp, deferredMessage.SerializedHeaderSize);
+                    }
+
+                    triggerInfo.TriggerData.Dispose();
+                    triggers.Remove(key);
+                }
+            }
+        }
+
+        /// <summary>
+        /// Cleans up any trigger that's existed for more than a second.
+        /// These triggers were probably for situations where a request was received after a despawn rather than before a spawn.
+        /// </summary>
+        public virtual void CleanupAllTriggers()
+        {
+            foreach (var kvp in m_Triggers)
+            {
+                foreach (var kvp2 in kvp.Value)
+                {
+                    foreach (var data in kvp2.Value.TriggerData)
+                    {
+                        data.Reader.Dispose();
+                    }
+                    kvp2.Value.TriggerData.Dispose();
+                }
+            }
+            m_Triggers.Clear();
+        }
+    }
+}

Runtime/Messaging/DeferredMessageManager.cs.meta

@@ -0,0 +1,3 @@
+fileFormatVersion: 2
+guid: ac7f57f7d16a46e2aba65558e873727f
+timeCreated: 1649799187

Runtime/Messaging/IDeferredMessageManager.cs

@@ -0,0 +1,35 @@
+namespace Unity.Netcode
+{
+    internal interface IDeferredMessageManager
+    {
+        internal enum TriggerType
+        {
+            OnSpawn,
+            OnAddPrefab,
+        }
+
+        /// <summary>
+        /// Defers processing of a message until the moment a specific networkObjectId is spawned.
+        /// This is to handle situations where an RPC or other object-specific message arrives before the spawn does,
+        /// either due to it being requested in OnNetworkSpawn before the spawn call has been executed
+        ///
+        /// There is a one second maximum lifetime of triggers to avoid memory leaks. After one second has passed
+        /// without the requested object ID being spawned, the triggers for it are automatically deleted.
+        /// </summary>
+        void DeferMessage(TriggerType trigger, ulong key, FastBufferReader reader, ref NetworkContext context);
+
+        /// <summary>
+        /// Cleans up any trigger that's existed for more than a second.
+        /// These triggers were probably for situations where a request was received after a despawn rather than before a spawn.
+        /// </summary>
+        void CleanupStaleTriggers();
+
+        void ProcessTriggers(TriggerType trigger, ulong key);
+
+        /// <summary>
+        /// Cleans up any trigger that's existed for more than a second.
+        /// These triggers were probably for situations where a request was received after a despawn rather than before a spawn.
+        /// </summary>
+        void CleanupAllTriggers();
+    }
+}

Runtime/Messaging/IDeferredMessageManager.cs.meta

@@ -0,0 +1,3 @@
+fileFormatVersion: 2
+guid: 7fb73a029c314763a04ebb015a07664d
+timeCreated: 1649966331

Runtime/Messaging/INetworkHooks.cs

@@ -13,18 +13,18 @@ namespace Unity.Netcode
         /// Called before an individual message is sent.
         /// </summary>
         /// <param name="clientId">The destination clientId</param>
-        /// <param name="messageType">The type of the message being sent</param>
+        /// <param name="message">The message being sent</param>
         /// <param name="delivery"></param>
-        void OnBeforeSendMessage(ulong clientId, Type messageType, NetworkDelivery delivery);
+        void OnBeforeSendMessage<T>(ulong clientId, ref T message, NetworkDelivery delivery) where T : INetworkMessage;
 
         /// <summary>
         /// Called after an individual message is sent.
         /// </summary>
         /// <param name="clientId">The destination clientId</param>
-        /// <param name="messageType">The type of the message being sent</param>
+        /// <param name="message">The message being sent</param>
         /// <param name="delivery"></param>
         /// <param name="messageSizeBytes">Number of bytes in the message, not including the message header</param>
-        void OnAfterSendMessage(ulong clientId, Type messageType, NetworkDelivery delivery, int messageSizeBytes);
+        void OnAfterSendMessage<T>(ulong clientId, ref T message, NetworkDelivery delivery, int messageSizeBytes) where T : INetworkMessage;
 
         /// <summary>
         /// Called before an individual message is received.
@@ -91,7 +91,27 @@ namespace Unity.Netcode
         /// </summary>
         /// <param name="senderId">The source clientId</param>
         /// <param name="messageType">The type of the message</param>
+        /// <param name="messageContent">The FastBufferReader containing the message</param>
+        /// <param name="context">The NetworkContext the message is being processed in</param>
         /// <returns></returns>
-        bool OnVerifyCanReceive(ulong senderId, Type messageType);
+        bool OnVerifyCanReceive(ulong senderId, Type messageType, FastBufferReader messageContent, ref NetworkContext context);
+
+        /// <summary>
+        /// Called after a message is serialized, but before it's handled.
+        /// Differs from OnBeforeReceiveMessage in that the actual message object is passed and can be inspected.
+        /// </summary>
+        /// <param name="message">The message object</param>
+        /// <param name="context">The network context the message is being ahandled in</param>
+        /// <typeparam name="T"></typeparam>
+        void OnBeforeHandleMessage<T>(ref T message, ref NetworkContext context) where T : INetworkMessage;
+
+        /// <summary>
+        /// Called after a message is serialized and handled.
+        /// Differs from OnAfterReceiveMessage in that the actual message object is passed and can be inspected.
+        /// </summary>
+        /// <param name="message">The message object</param>
+        /// <param name="context">The network context the message is being ahandled in</param>
+        /// <typeparam name="T"></typeparam>
+        void OnAfterHandleMessage<T>(ref T message, ref NetworkContext context) where T : INetworkMessage;
     }
 }

Runtime/Messaging/INetworkMessage.cs

@@ -15,7 +15,7 @@ namespace Unity.Netcode
     /// static message handler for receiving messages of the following name and signature:
     ///
     /// <code>
-    /// public static void Receive(FastBufferReader reader, in NetworkContext context)
+    /// public static void Receive(FastBufferReader reader, ref NetworkContext context)
     /// </code>
     ///
     /// It is the responsibility of the Serialize and Receive methods to ensure there is enough buffer space
@@ -40,10 +40,8 @@ namespace Unity.Netcode
     /// </summary>
     internal interface INetworkMessage
     {
-        /// <summary>
-        /// Used to serialize the message.
-        /// </summary>
-        /// <param name="writer"></param>
         void Serialize(FastBufferWriter writer);
+        bool Deserialize(FastBufferReader reader, ref NetworkContext context);
+        void Handle(ref NetworkContext context);
     }
 }

Runtime/Messaging/MessageHeader.cs

@@ -3,7 +3,7 @@ namespace Unity.Netcode
     /// <summary>
     /// This is the header data that's serialized to the network when sending an <see cref="INetworkMessage"/>
     /// </summary>
-    internal struct MessageHeader
+    internal struct MessageHeader : INetworkSerializeByMemcpy
     {
         /// <summary>
         /// The byte representation of the message type. This is automatically assigned to each message
@@ -11,11 +11,12 @@ namespace Unity.Netcode
         /// unchanged - if new messages are added or messages are removed, MessageType assignments may be
         /// calculated differently.
         /// </summary>
-        public byte MessageType;
+        public uint MessageType;
 
         /// <summary>
         /// The total size of the message, NOT including the header.
+        /// Stored as a uint to avoid zig-zag encoding, but capped at int.MaxValue.
         /// </summary>
-        public ushort MessageSize;
+        public uint MessageSize;
     }
 }

Runtime/Messaging/Messages/ChangeOwnershipMessage.cs

@@ -1,6 +1,6 @@
 namespace Unity.Netcode
 {
-    internal struct ChangeOwnershipMessage : INetworkMessage
+    internal struct ChangeOwnershipMessage : INetworkMessage, INetworkSerializeByMemcpy
     {
         public ulong NetworkObjectId;
         public ulong OwnerClientId;
@@ -10,40 +10,53 @@ namespace Unity.Netcode
             writer.WriteValueSafe(this);
         }
 
-        public static void Receive(FastBufferReader reader, in NetworkContext context)
+        public bool Deserialize(FastBufferReader reader, ref NetworkContext context)
         {
             var networkManager = (NetworkManager)context.SystemOwner;
             if (!networkManager.IsClient)
             {
-                return;
+                return false;
             }
-            reader.ReadValueSafe(out ChangeOwnershipMessage message);
+            reader.ReadValueSafe(out this);
-            message.Handle(reader, context, context.SenderId, networkManager, reader.Length);
+            if (!networkManager.SpawnManager.SpawnedObjects.ContainsKey(NetworkObjectId))
+            {
+                networkManager.DeferredMessageManager.DeferMessage(IDeferredMessageManager.TriggerType.OnSpawn, NetworkObjectId, reader, ref context);
+                return false;
+            }
+
+            return true;
         }
 
-        public void Handle(FastBufferReader reader, in NetworkContext context, ulong senderId, NetworkManager networkManager, int messageSize)
+        public void Handle(ref NetworkContext context)
         {
-            if (!networkManager.SpawnManager.SpawnedObjects.TryGetValue(NetworkObjectId, out var networkObject))
+            var networkManager = (NetworkManager)context.SystemOwner;
-            {
+            var networkObject = networkManager.SpawnManager.SpawnedObjects[NetworkObjectId];
-                networkManager.SpawnManager.TriggerOnSpawn(NetworkObjectId, reader, context);
+            var originalOwner = networkObject.OwnerClientId;
-                return;
-            }
-
-            if (networkObject.OwnerClientId == networkManager.LocalClientId)
-            {
-                //We are current owner.
-                networkObject.InvokeBehaviourOnLostOwnership();
-            }
 
             networkObject.OwnerClientId = OwnerClientId;
 
+            // We are current owner.
+            if (originalOwner == networkManager.LocalClientId)
+            {
+                networkObject.InvokeBehaviourOnLostOwnership();
+            }
+
+            // We are new owner.
             if (OwnerClientId == networkManager.LocalClientId)
             {
-                //We are new owner.
                 networkObject.InvokeBehaviourOnGainedOwnership();
             }
 
-            networkManager.NetworkMetrics.TrackOwnershipChangeReceived(senderId, networkObject, messageSize);
+            // For all other clients that are neither the former or current owner, update the behaviours' properties
+            if (OwnerClientId != networkManager.LocalClientId && originalOwner != networkManager.LocalClientId)
+            {
+                for (int i = 0; i < networkObject.ChildNetworkBehaviours.Count; i++)
+                {
+                    networkObject.ChildNetworkBehaviours[i].UpdateNetworkProperties();
+                }
+            }
+
+            networkManager.NetworkMetrics.TrackOwnershipChangeReceived(context.SenderId, networkObject, context.MessageSize);
         }
     }
 }

Runtime/Messaging/Messages/ConnectionApprovedMessage.cs

@@ -7,24 +7,27 @@ namespace Unity.Netcode
     {
         public ulong OwnerClientId;
         public int NetworkTick;
-        public int SceneObjectCount;
 
         // Not serialized, held as references to serialize NetworkVariable data
         public HashSet<NetworkObject> SpawnedObjectsList;
 
+        private FastBufferReader m_ReceivedSceneObjectData;
+
         public void Serialize(FastBufferWriter writer)
         {
             if (!writer.TryBeginWrite(sizeof(ulong) + sizeof(int) + sizeof(int)))
             {
-                throw new OverflowException(
+                throw new OverflowException($"Not enough space in the write buffer to serialize {nameof(ConnectionApprovedMessage)}");
-                    $"Not enough space in the write buffer to serialize {nameof(ConnectionApprovedMessage)}");
             }
             writer.WriteValue(OwnerClientId);
             writer.WriteValue(NetworkTick);
-            writer.WriteValue(SceneObjectCount);
 
-            if (SceneObjectCount != 0)
+            uint sceneObjectCount = 0;
+            if (SpawnedObjectsList != null)
             {
+                var pos = writer.Position;
+                writer.Seek(writer.Position + FastBufferWriter.GetWriteSize(sceneObjectCount));
+
                 // Serialize NetworkVariable data
                 foreach (var sobj in SpawnedObjectsList)
                 {
@@ -33,34 +36,41 @@ namespace Unity.Netcode
                         sobj.Observers.Add(OwnerClientId);
                         var sceneObject = sobj.GetMessageSceneObject(OwnerClientId);
                         sceneObject.Serialize(writer);
+                        ++sceneObjectCount;
                     }
                 }
+                writer.Seek(pos);
+                writer.WriteValue(sceneObjectCount);
+                writer.Seek(writer.Length);
+            }
+            else
+            {
+                writer.WriteValue(sceneObjectCount);
             }
         }
 
-        public static void Receive(FastBufferReader reader, in NetworkContext context)
+        public bool Deserialize(FastBufferReader reader, ref NetworkContext context)
         {
             var networkManager = (NetworkManager)context.SystemOwner;
             if (!networkManager.IsClient)
             {
-                return;
+                return false;
             }
 
             if (!reader.TryBeginRead(sizeof(ulong) + sizeof(int) + sizeof(int)))
             {
-                throw new OverflowException(
+                throw new OverflowException($"Not enough space in the buffer to read {nameof(ConnectionApprovedMessage)}");
-                    $"Not enough space in the buffer to read {nameof(ConnectionApprovedMessage)}");
             }
 
-            var message = new ConnectionApprovedMessage();
+            reader.ReadValue(out OwnerClientId);
-            reader.ReadValue(out message.OwnerClientId);
+            reader.ReadValue(out NetworkTick);
-            reader.ReadValue(out message.NetworkTick);
+            m_ReceivedSceneObjectData = reader;
-            reader.ReadValue(out message.SceneObjectCount);
+            return true;
-            message.Handle(reader, context.SenderId, networkManager);
         }
 
-        public void Handle(FastBufferReader reader, ulong clientId, NetworkManager networkManager)
+        public void Handle(ref NetworkContext context)
         {
+            var networkManager = (NetworkManager)context.SystemOwner;
             networkManager.LocalClientId = OwnerClientId;
             networkManager.NetworkMetrics.SetConnectionId(networkManager.LocalClientId);
 
@@ -74,20 +84,21 @@ namespace Unity.Netcode
             if (!networkManager.NetworkConfig.EnableSceneManagement)
             {
                 networkManager.SpawnManager.DestroySceneObjects();
+                m_ReceivedSceneObjectData.ReadValue(out uint sceneObjectCount);
 
                 // Deserializing NetworkVariable data is deferred from Receive() to Handle to avoid needing
                 // to create a list to hold the data. This is a breach of convention for performance reasons.
-                for (ushort i = 0; i < SceneObjectCount; i++)
+                for (ushort i = 0; i < sceneObjectCount; i++)
                 {
                     var sceneObject = new NetworkObject.SceneObject();
-                    sceneObject.Deserialize(reader);
+                    sceneObject.Deserialize(m_ReceivedSceneObjectData);
-                    NetworkObject.AddSceneObject(sceneObject, reader, networkManager);
+                    NetworkObject.AddSceneObject(sceneObject, m_ReceivedSceneObjectData, networkManager);
                 }
 
                 // Mark the client being connected
                 networkManager.IsConnectedClient = true;
                 // When scene management is disabled we notify after everything is synchronized
-                networkManager.InvokeOnClientConnectedCallback(clientId);
+                networkManager.InvokeOnClientConnectedCallback(context.SenderId);
             }
         }
     }

Runtime/Messaging/Messages/ConnectionRequestMessage.cs

@@ -21,19 +21,17 @@ namespace Unity.Netcode
             }
         }
 
-        public static void Receive(FastBufferReader reader, in NetworkContext context)
+        public bool Deserialize(FastBufferReader reader, ref NetworkContext context)
         {
             var networkManager = (NetworkManager)context.SystemOwner;
             if (!networkManager.IsServer)
             {
-                return;
+                return false;
             }
 
-            var message = new ConnectionRequestMessage();
             if (networkManager.NetworkConfig.ConnectionApproval)
             {
-                if (!reader.TryBeginRead(FastBufferWriter.GetWriteSize(message.ConfigHash) +
+                if (!reader.TryBeginRead(FastBufferWriter.GetWriteSize(ConfigHash) + FastBufferWriter.GetWriteSize<int>()))
-                                         FastBufferWriter.GetWriteSize<int>()))
                 {
                     if (NetworkLog.CurrentLogLevel <= LogLevel.Normal)
                     {
@@ -41,11 +39,12 @@ namespace Unity.Netcode
                     }
 
                     networkManager.DisconnectClient(context.SenderId);
-                    return;
+                    return false;
                 }
-                reader.ReadValue(out message.ConfigHash);
 
-                if (!networkManager.NetworkConfig.CompareConfig(message.ConfigHash))
+                reader.ReadValue(out ConfigHash);
+
+                if (!networkManager.NetworkConfig.CompareConfig(ConfigHash))
                 {
                     if (NetworkLog.CurrentLogLevel <= LogLevel.Normal)
                     {
@@ -53,14 +52,14 @@ namespace Unity.Netcode
                     }
 
                     networkManager.DisconnectClient(context.SenderId);
-                    return;
+                    return false;
                 }
 
-                reader.ReadValueSafe(out message.ConnectionData);
+                reader.ReadValueSafe(out ConnectionData);
             }
             else
             {
-                if (!reader.TryBeginRead(FastBufferWriter.GetWriteSize(message.ConfigHash)))
+                if (!reader.TryBeginRead(FastBufferWriter.GetWriteSize(ConfigHash)))
                 {
                     if (NetworkLog.CurrentLogLevel <= LogLevel.Normal)
                     {
@@ -68,11 +67,11 @@ namespace Unity.Netcode
                     }
 
                     networkManager.DisconnectClient(context.SenderId);
-                    return;
+                    return false;
                 }
-                reader.ReadValue(out message.ConfigHash);
+                reader.ReadValue(out ConfigHash);
 
-                if (!networkManager.NetworkConfig.CompareConfig(message.ConfigHash))
+                if (!networkManager.NetworkConfig.CompareConfig(ConfigHash))
                 {
                     if (NetworkLog.CurrentLogLevel <= LogLevel.Normal)
                     {
@@ -80,14 +79,18 @@ namespace Unity.Netcode
                     }
 
                     networkManager.DisconnectClient(context.SenderId);
-                    return;
+                    return false;
                 }
             }
-            message.Handle(networkManager, context.SenderId);
+
+            return true;
         }
 
-        public void Handle(NetworkManager networkManager, ulong senderId)
+        public void Handle(ref NetworkContext context)
         {
+            var networkManager = (NetworkManager)context.SystemOwner;
+            var senderId = context.SenderId;
+
             if (networkManager.PendingClients.TryGetValue(senderId, out PendingClient client))
             {
                 // Set to pending approval to prevent future connection requests from being approved
@@ -102,8 +105,7 @@ namespace Unity.Netcode
                     (createPlayerObject, playerPrefabHash, approved, position, rotation) =>
                     {
                         var localCreatePlayerObject = createPlayerObject;
-                        networkManager.HandleApproval(senderId, localCreatePlayerObject, playerPrefabHash, approved,
+                        networkManager.HandleApproval(senderId, localCreatePlayerObject, playerPrefabHash, approved, position, rotation);
-                            position, rotation);
                     });
             }
             else

Runtime/Messaging/Messages/CreateObjectMessage.cs

@@ -3,28 +3,38 @@ namespace Unity.Netcode
     internal struct CreateObjectMessage : INetworkMessage
     {
         public NetworkObject.SceneObject ObjectInfo;
+        private FastBufferReader m_ReceivedNetworkVariableData;
 
         public void Serialize(FastBufferWriter writer)
         {
             ObjectInfo.Serialize(writer);
         }
 
-        public static void Receive(FastBufferReader reader, in NetworkContext context)
+        public bool Deserialize(FastBufferReader reader, ref NetworkContext context)
         {
             var networkManager = (NetworkManager)context.SystemOwner;
             if (!networkManager.IsClient)
             {
-                return;
+                return false;
             }
-            var message = new CreateObjectMessage();
+
-            message.ObjectInfo.Deserialize(reader);
+            ObjectInfo.Deserialize(reader);
-            message.Handle(context.SenderId, reader, networkManager);
+            if (!networkManager.NetworkConfig.ForceSamePrefabs && !networkManager.SpawnManager.HasPrefab(ObjectInfo.Header.IsSceneObject, ObjectInfo.Header.Hash))
+            {
+                networkManager.DeferredMessageManager.DeferMessage(IDeferredMessageManager.TriggerType.OnAddPrefab, ObjectInfo.Header.Hash, reader, ref context);
+                return false;
+            }
+            m_ReceivedNetworkVariableData = reader;
+
+            return true;
         }
 
-        public void Handle(ulong senderId, FastBufferReader reader, NetworkManager networkManager)
+        public void Handle(ref NetworkContext context)
         {
-            var networkObject = NetworkObject.AddSceneObject(ObjectInfo, reader, networkManager);
+            var networkManager = (NetworkManager)context.SystemOwner;
-            networkManager.NetworkMetrics.TrackObjectSpawnReceived(senderId, networkObject, reader.Length);
+            var networkObject = NetworkObject.AddSceneObject(ObjectInfo, m_ReceivedNetworkVariableData, networkManager);
+
+            networkManager.NetworkMetrics.TrackObjectSpawnReceived(context.SenderId, networkObject, context.MessageSize);
         }
     }
 }

Runtime/Messaging/Messages/DestroyObjectMessage.cs

@@ -1,6 +1,6 @@
 namespace Unity.Netcode
 {
-    internal struct DestroyObjectMessage : INetworkMessage
+    internal struct DestroyObjectMessage : INetworkMessage, INetworkSerializeByMemcpy
     {
         public ulong NetworkObjectId;
 
@@ -9,32 +9,34 @@ namespace Unity.Netcode
             writer.WriteValueSafe(this);
         }
 
-        public static void Receive(FastBufferReader reader, in NetworkContext context)
+        public bool Deserialize(FastBufferReader reader, ref NetworkContext context)
         {
             var networkManager = (NetworkManager)context.SystemOwner;
             if (!networkManager.IsClient)
             {
-                return;
+                return false;
             }
-            reader.ReadValueSafe(out DestroyObjectMessage message);
+
-            message.Handle(context.SenderId, networkManager, reader.Length);
+            reader.ReadValueSafe(out this);
+
+            if (!networkManager.SpawnManager.SpawnedObjects.TryGetValue(NetworkObjectId, out var networkObject))
+            {
+                networkManager.DeferredMessageManager.DeferMessage(IDeferredMessageManager.TriggerType.OnSpawn, NetworkObjectId, reader, ref context);
+                return false;
+            }
+            return true;
         }
 
-        public void Handle(ulong senderId, NetworkManager networkManager, int messageSize)
+        public void Handle(ref NetworkContext context)
         {
+            var networkManager = (NetworkManager)context.SystemOwner;
             if (!networkManager.SpawnManager.SpawnedObjects.TryGetValue(NetworkObjectId, out var networkObject))
             {
                 // This is the same check and log message that happens inside OnDespawnObject, but we have to do it here
-                // while we still have access to the network ID, otherwise the log message will be less useful.
-                if (NetworkLog.CurrentLogLevel <= LogLevel.Normal)
-                {
-                    NetworkLog.LogWarning($"Trying to destroy {nameof(NetworkObject)} #{NetworkObjectId} but it does not exist in {nameof(NetworkSpawnManager.SpawnedObjects)} anymore!");
-                }
-
                 return;
             }
 
-            networkManager.NetworkMetrics.TrackObjectDestroyReceived(senderId, networkObject, messageSize);
+            networkManager.NetworkMetrics.TrackObjectDestroyReceived(context.SenderId, networkObject, context.MessageSize);
             networkManager.SpawnManager.OnDespawnObject(networkObject, true);
         }
     }

Runtime/Messaging/Messages/NamedMessage.cs

@@ -3,20 +3,26 @@ namespace Unity.Netcode
     internal struct NamedMessage : INetworkMessage
     {
         public ulong Hash;
-        public FastBufferWriter Data;
+        public FastBufferWriter SendData;
+
+        private FastBufferReader m_ReceiveData;
 
         public unsafe void Serialize(FastBufferWriter writer)
         {
             writer.WriteValueSafe(Hash);
-            writer.WriteBytesSafe(Data.GetUnsafePtr(), Data.Length);
+            writer.WriteBytesSafe(SendData.GetUnsafePtr(), SendData.Length);
         }
 
-        public static void Receive(FastBufferReader reader, in NetworkContext context)
+        public bool Deserialize(FastBufferReader reader, ref NetworkContext context)
         {
-            var message = new NamedMessage();
+            reader.ReadValueSafe(out Hash);
-            reader.ReadValueSafe(out message.Hash);
+            m_ReceiveData = reader;
+            return true;
+        }
 
-            ((NetworkManager)context.SystemOwner).CustomMessagingManager.InvokeNamedMessage(message.Hash, context.SenderId, reader);
+        public void Handle(ref NetworkContext context)
+        {
+            ((NetworkManager)context.SystemOwner).CustomMessagingManager.InvokeNamedMessage(Hash, context.SenderId, m_ReceiveData, context.SerializedHeaderSize);
         }
     }
 }

Runtime/Messaging/Messages/NetworkVariableDeltaMessage.cs

@@ -16,27 +16,29 @@ namespace Unity.Netcode
         public ushort NetworkBehaviourIndex;
 
         public HashSet<int> DeliveryMappedNetworkVariableIndex;
-        public ulong ClientId;
+        public ulong TargetClientId;
         public NetworkBehaviour NetworkBehaviour;
 
+        private FastBufferReader m_ReceivedNetworkVariableData;
+
         public void Serialize(FastBufferWriter writer)
         {
-            if (!writer.TryBeginWrite(FastBufferWriter.GetWriteSize(NetworkObjectId) +
+            if (!writer.TryBeginWrite(FastBufferWriter.GetWriteSize(NetworkObjectId) + FastBufferWriter.GetWriteSize(NetworkBehaviourIndex)))
-                                      FastBufferWriter.GetWriteSize(NetworkBehaviourIndex)))
             {
-                throw new OverflowException(
+                throw new OverflowException($"Not enough space in the buffer to write {nameof(NetworkVariableDeltaMessage)}");
-                    $"Not enough space in the buffer to write {nameof(NetworkVariableDeltaMessage)}");
             }
+
             writer.WriteValue(NetworkObjectId);
             writer.WriteValue(NetworkBehaviourIndex);
-            for (int k = 0; k < NetworkBehaviour.NetworkVariableFields.Count; k++)
+
+            for (int i = 0; i < NetworkBehaviour.NetworkVariableFields.Count; i++)
             {
-                if (!DeliveryMappedNetworkVariableIndex.Contains(k))
+                if (!DeliveryMappedNetworkVariableIndex.Contains(i))
                 {
                     // This var does not belong to the currently iterating delivery group.
                     if (NetworkBehaviour.NetworkManager.NetworkConfig.EnsureNetworkVariableLengthSafety)
                     {
-                        writer.WriteValueSafe((short)0);
+                        writer.WriteValueSafe((ushort)0);
                     }
                     else
                     {
@@ -46,15 +48,25 @@ namespace Unity.Netcode
                     continue;
                 }
 
-                //   if I'm dirty AND a client, write (server always has all permissions)
+                var startingSize = writer.Length;
-                //   if I'm dirty AND the server AND the client can read me, send.
+                var networkVariable = NetworkBehaviour.NetworkVariableFields[i];
-                bool shouldWrite = NetworkBehaviour.NetworkVariableFields[k].ShouldWrite(ClientId, NetworkBehaviour.NetworkManager.IsServer);
+                var shouldWrite = networkVariable.IsDirty() &&
+                    networkVariable.CanClientRead(TargetClientId) &&
+                    (NetworkBehaviour.NetworkManager.IsServer || networkVariable.CanClientWrite(NetworkBehaviour.NetworkManager.LocalClientId));
+
+                // Prevent the server from writing to the client that owns a given NetworkVariable
+                // Allowing the write would send an old value to the client and cause jitter
+                if (networkVariable.WritePerm == NetworkVariableWritePermission.Owner &&
+                    networkVariable.OwnerClientId() == TargetClientId)
+                {
+                    shouldWrite = false;
+                }
 
                 if (NetworkBehaviour.NetworkManager.NetworkConfig.EnsureNetworkVariableLengthSafety)
                 {
                     if (!shouldWrite)
                     {
-                        writer.WriteValueSafe((ushort)0);
+                        BytePacker.WriteValueBitPacked(writer, 0);
                     }
                 }
                 else
@@ -66,56 +78,62 @@ namespace Unity.Netcode
                 {
                     if (NetworkBehaviour.NetworkManager.NetworkConfig.EnsureNetworkVariableLengthSafety)
                     {
-                        var tmpWriter = new FastBufferWriter(MessagingSystem.NON_FRAGMENTED_MESSAGE_MAX_SIZE, Allocator.Temp, short.MaxValue);
+                        var tempWriter = new FastBufferWriter(MessagingSystem.NON_FRAGMENTED_MESSAGE_MAX_SIZE, Allocator.Temp, MessagingSystem.FRAGMENTED_MESSAGE_MAX_SIZE);
-                        NetworkBehaviour.NetworkVariableFields[k].WriteDelta(tmpWriter);
+                        NetworkBehaviour.NetworkVariableFields[i].WriteDelta(tempWriter);
+                        BytePacker.WriteValueBitPacked(writer, tempWriter.Length);
 
-                        writer.WriteValueSafe((ushort)tmpWriter.Length);
+                        if (!writer.TryBeginWrite(tempWriter.Length))
-                        tmpWriter.CopyTo(writer);
+                        {
+                            throw new OverflowException($"Not enough space in the buffer to write {nameof(NetworkVariableDeltaMessage)}");
+                        }
+
+                        tempWriter.CopyTo(writer);
                     }
                     else
                     {
-                        NetworkBehaviour.NetworkVariableFields[k].WriteDelta(writer);
+                        networkVariable.WriteDelta(writer);
                     }
 
-                    if (!NetworkBehaviour.NetworkVariableIndexesToResetSet.Contains(k))
+                    if (!NetworkBehaviour.NetworkVariableIndexesToResetSet.Contains(i))
                     {
-                        NetworkBehaviour.NetworkVariableIndexesToResetSet.Add(k);
+                        NetworkBehaviour.NetworkVariableIndexesToResetSet.Add(i);
-                        NetworkBehaviour.NetworkVariableIndexesToReset.Add(k);
+                        NetworkBehaviour.NetworkVariableIndexesToReset.Add(i);
                     }
 
                     NetworkBehaviour.NetworkManager.NetworkMetrics.TrackNetworkVariableDeltaSent(
-                        ClientId,
+                        TargetClientId,
                         NetworkBehaviour.NetworkObject,
-                        NetworkBehaviour.NetworkVariableFields[k].Name,
+                        networkVariable.Name,
                         NetworkBehaviour.__getTypeName(),
-                        writer.Length);
+                        writer.Length - startingSize);
                 }
             }
         }
 
-        public static void Receive(FastBufferReader reader, in NetworkContext context)
+        public bool Deserialize(FastBufferReader reader, ref NetworkContext context)
+        {
+            if (!reader.TryBeginRead(FastBufferWriter.GetWriteSize(NetworkObjectId) + FastBufferWriter.GetWriteSize(NetworkBehaviourIndex)))
+            {
+                throw new OverflowException($"Not enough data in the buffer to read {nameof(NetworkVariableDeltaMessage)}");
+            }
+
+            reader.ReadValue(out NetworkObjectId);
+            reader.ReadValue(out NetworkBehaviourIndex);
+
+            m_ReceivedNetworkVariableData = reader;
+
+            return true;
+        }
+
+        public void Handle(ref NetworkContext context)
         {
             var networkManager = (NetworkManager)context.SystemOwner;
 
-            var message = new NetworkVariableDeltaMessage();
-            if (!reader.TryBeginRead(FastBufferWriter.GetWriteSize(message.NetworkObjectId) +
-                                      FastBufferWriter.GetWriteSize(message.NetworkBehaviourIndex)))
-            {
-                throw new OverflowException(
-                    $"Not enough data in the buffer to read {nameof(NetworkVariableDeltaMessage)}");
-            }
-            reader.ReadValue(out message.NetworkObjectId);
-            reader.ReadValue(out message.NetworkBehaviourIndex);
-            message.Handle(context.SenderId, reader, context, networkManager);
-        }
-
-        public void Handle(ulong senderId, FastBufferReader reader, in NetworkContext context, NetworkManager networkManager)
-        {
             if (networkManager.SpawnManager.SpawnedObjects.TryGetValue(NetworkObjectId, out NetworkObject networkObject))
             {
-                NetworkBehaviour behaviour = networkObject.GetNetworkBehaviourAtOrderIndex(NetworkBehaviourIndex);
+                var networkBehaviour = networkObject.GetNetworkBehaviourAtOrderIndex(NetworkBehaviourIndex);
 
-                if (behaviour == null)
+                if (networkBehaviour == null)
                 {
                     if (NetworkLog.CurrentLogLevel <= LogLevel.Normal)
                     {
@@ -124,13 +142,12 @@ namespace Unity.Netcode
                 }
                 else
                 {
-                    for (int i = 0; i < behaviour.NetworkVariableFields.Count; i++)
+                    for (int i = 0; i < networkBehaviour.NetworkVariableFields.Count; i++)
                     {
-                        ushort varSize = 0;
+                        int varSize = 0;
-
                         if (networkManager.NetworkConfig.EnsureNetworkVariableLengthSafety)
                         {
-                            reader.ReadValueSafe(out varSize);
+                            ByteUnpacker.ReadValueBitPacked(m_ReceivedNetworkVariableData, out varSize);
 
                             if (varSize == 0)
                             {
@@ -139,25 +156,27 @@ namespace Unity.Netcode
                         }
                         else
                         {
-                            reader.ReadValueSafe(out bool deltaExists);
+                            m_ReceivedNetworkVariableData.ReadValueSafe(out bool deltaExists);
                             if (!deltaExists)
                             {
                                 continue;
                             }
                         }
 
-                        if (networkManager.IsServer)
+                        var networkVariable = networkBehaviour.NetworkVariableFields[i];
+
+                        if (networkManager.IsServer && !networkVariable.CanClientWrite(context.SenderId))
                         {
                             // we are choosing not to fire an exception here, because otherwise a malicious client could use this to crash the server
                             if (networkManager.NetworkConfig.EnsureNetworkVariableLengthSafety)
                             {
-                                if (NetworkLog.CurrentLogLevel <= LogLevel.Normal)
+                                if (NetworkLog.CurrentLogLevel <= LogLevel.Developer)
                                 {
-                                    NetworkLog.LogWarning($"Client wrote to {typeof(NetworkVariable<>).Name} without permission. => {nameof(NetworkObjectId)}: {NetworkObjectId} - {nameof(NetworkObject.GetNetworkBehaviourOrderIndex)}(): {networkObject.GetNetworkBehaviourOrderIndex(behaviour)} - VariableIndex: {i}");
+                                    NetworkLog.LogWarning($"Client wrote to {typeof(NetworkVariable<>).Name} without permission. => {nameof(NetworkObjectId)}: {NetworkObjectId} - {nameof(NetworkObject.GetNetworkBehaviourOrderIndex)}(): {networkObject.GetNetworkBehaviourOrderIndex(networkBehaviour)} - VariableIndex: {i}");
-                                    NetworkLog.LogError($"[{behaviour.NetworkVariableFields[i].GetType().Name}]");
+                                    NetworkLog.LogError($"[{networkVariable.GetType().Name}]");
                                 }
 
-                                reader.Seek(reader.Position + varSize);
+                                m_ReceivedNetworkVariableData.Seek(m_ReceivedNetworkVariableData.Position + varSize);
                                 continue;
                             }
 
@@ -168,47 +187,45 @@ namespace Unity.Netcode
                             //A dummy read COULD be added to the interface for this situation, but it's just being too nice.
                             //This is after all a developer fault. A critical error should be fine.
                             // - TwoTen
-                            if (NetworkLog.CurrentLogLevel <= LogLevel.Error)
+                            if (NetworkLog.CurrentLogLevel <= LogLevel.Developer)
                             {
-                                NetworkLog.LogError($"Client wrote to {typeof(NetworkVariable<>).Name} without permission. No more variables can be read. This is critical. => {nameof(NetworkObjectId)}: {NetworkObjectId} - {nameof(NetworkObject.GetNetworkBehaviourOrderIndex)}(): {networkObject.GetNetworkBehaviourOrderIndex(behaviour)} - VariableIndex: {i}");
+                                NetworkLog.LogError($"Client wrote to {typeof(NetworkVariable<>).Name} without permission. No more variables can be read. This is critical. => {nameof(NetworkObjectId)}: {NetworkObjectId} - {nameof(NetworkObject.GetNetworkBehaviourOrderIndex)}(): {networkObject.GetNetworkBehaviourOrderIndex(networkBehaviour)} - VariableIndex: {i}");
-                                NetworkLog.LogError($"[{behaviour.NetworkVariableFields[i].GetType().Name}]");
+                                NetworkLog.LogError($"[{networkVariable.GetType().Name}]");
                             }
 
                             return;
                         }
-                        int readStartPos = reader.Position;
+                        int readStartPos = m_ReceivedNetworkVariableData.Position;
 
-                        behaviour.NetworkVariableFields[i].ReadDelta(reader, networkManager.IsServer);
+                        networkVariable.ReadDelta(m_ReceivedNetworkVariableData, networkManager.IsServer);
 
                         networkManager.NetworkMetrics.TrackNetworkVariableDeltaReceived(
-                            senderId,
+                            context.SenderId,
                             networkObject,
-                            behaviour.NetworkVariableFields[i].Name,
+                            networkVariable.Name,
-                            behaviour.__getTypeName(),
+                            networkBehaviour.__getTypeName(),
-                            reader.Length);
+                            context.MessageSize);
 
 
                         if (networkManager.NetworkConfig.EnsureNetworkVariableLengthSafety)
                         {
-                            if (reader.Position > (readStartPos + varSize))
+                            if (m_ReceivedNetworkVariableData.Position > (readStartPos + varSize))
                             {
                                 if (NetworkLog.CurrentLogLevel <= LogLevel.Normal)
                                 {
-                                    NetworkLog.LogWarning(
+                                    NetworkLog.LogWarning($"Var delta read too far. {m_ReceivedNetworkVariableData.Position - (readStartPos + varSize)} bytes. => {nameof(NetworkObjectId)}: {NetworkObjectId} - {nameof(NetworkObject.GetNetworkBehaviourOrderIndex)}(): {networkObject.GetNetworkBehaviourOrderIndex(networkBehaviour)} - VariableIndex: {i}");
-                                        $"Var delta read too far. {reader.Position - (readStartPos + varSize)} bytes. => {nameof(NetworkObjectId)}: {NetworkObjectId} - {nameof(NetworkObject.GetNetworkBehaviourOrderIndex)}(): {networkObject.GetNetworkBehaviourOrderIndex(behaviour)} - VariableIndex: {i}");
                                 }
 
-                                reader.Seek(readStartPos + varSize);
+                                m_ReceivedNetworkVariableData.Seek(readStartPos + varSize);
                             }
-                            else if (reader.Position < (readStartPos + varSize))
+                            else if (m_ReceivedNetworkVariableData.Position < (readStartPos + varSize))
                             {
                                 if (NetworkLog.CurrentLogLevel <= LogLevel.Normal)
                                 {
-                                    NetworkLog.LogWarning(
+                                    NetworkLog.LogWarning($"Var delta read too little. {readStartPos + varSize - m_ReceivedNetworkVariableData.Position} bytes. => {nameof(NetworkObjectId)}: {NetworkObjectId} - {nameof(NetworkObject.GetNetworkBehaviourOrderIndex)}(): {networkObject.GetNetworkBehaviourOrderIndex(networkBehaviour)} - VariableIndex: {i}");
-                                        $"Var delta read too little. {(readStartPos + varSize) - reader.Position} bytes. => {nameof(NetworkObjectId)}: {NetworkObjectId} - {nameof(NetworkObject.GetNetworkBehaviourOrderIndex)}(): {networkObject.GetNetworkBehaviourOrderIndex(behaviour)} - VariableIndex: {i}");
                                 }
 
-                                reader.Seek(readStartPos + varSize);
+                                m_ReceivedNetworkVariableData.Seek(readStartPos + varSize);
                             }
                         }
                     }
@@ -216,7 +233,7 @@ namespace Unity.Netcode
             }
             else
             {
-                networkManager.SpawnManager.TriggerOnSpawn(NetworkObjectId, reader, context);
+                networkManager.DeferredMessageManager.DeferMessage(IDeferredMessageManager.TriggerType.OnSpawn, NetworkObjectId, m_ReceivedNetworkVariableData, ref context);
             }
         }
     }

Runtime/Messaging/Messages/ParentSyncMessage.cs

@@ -26,42 +26,41 @@ namespace Unity.Netcode
             }
         }
 
-        public static void Receive(FastBufferReader reader, in NetworkContext context)
+        public bool Deserialize(FastBufferReader reader, ref NetworkContext context)
         {
             var networkManager = (NetworkManager)context.SystemOwner;
             if (!networkManager.IsClient)
             {
-                return;
+                return false;
             }
 
-            var message = new ParentSyncMessage();
+            reader.ReadValueSafe(out NetworkObjectId);
-            reader.ReadValueSafe(out message.NetworkObjectId);
+            reader.ReadValueSafe(out IsReparented);
-            reader.ReadValueSafe(out message.IsReparented);
+            if (IsReparented)
-            if (message.IsReparented)
             {
-                reader.ReadValueSafe(out message.IsLatestParentSet);
+                reader.ReadValueSafe(out IsLatestParentSet);
-                if (message.IsLatestParentSet)
+                if (IsLatestParentSet)
                 {
                     reader.ReadValueSafe(out ulong latestParent);
-                    message.LatestParent = latestParent;
+                    LatestParent = latestParent;
                 }
             }
 
-            message.Handle(reader, context, networkManager);
+            if (!networkManager.SpawnManager.SpawnedObjects.ContainsKey(NetworkObjectId))
+            {
+                networkManager.DeferredMessageManager.DeferMessage(IDeferredMessageManager.TriggerType.OnSpawn, NetworkObjectId, reader, ref context);
+                return false;
+            }
+
+            return true;
         }
 
-        public void Handle(FastBufferReader reader, in NetworkContext context, NetworkManager networkManager)
+        public void Handle(ref NetworkContext context)
         {
-            if (networkManager.SpawnManager.SpawnedObjects.ContainsKey(NetworkObjectId))
+            var networkManager = (NetworkManager)context.SystemOwner;
-            {
+            var networkObject = networkManager.SpawnManager.SpawnedObjects[NetworkObjectId];
-                var networkObject = networkManager.SpawnManager.SpawnedObjects[NetworkObjectId];
+            networkObject.SetNetworkParenting(IsReparented, LatestParent);
-                networkObject.SetNetworkParenting(IsReparented, LatestParent);
+            networkObject.ApplyNetworkParenting();
-                networkObject.ApplyNetworkParenting();
-            }
-            else
-            {
-                networkManager.SpawnManager.TriggerOnSpawn(NetworkObjectId, reader, context);
-            }
         }
     }
 }

Runtime/Messaging/Messages/RpcMessage.cs

@@ -1,109 +0,0 @@
-using System;
-
-namespace Unity.Netcode
-{
-    internal struct RpcMessage : INetworkMessage
-    {
-        public enum RpcType : byte
-        {
-            Server,
-            Client
-        }
-
-        public struct HeaderData
-        {
-            public RpcType Type;
-            public ulong NetworkObjectId;
-            public ushort NetworkBehaviourId;
-            public uint NetworkMethodId;
-        }
-
-        public HeaderData Header;
-        public FastBufferWriter RpcData;
-
-
-        public unsafe void Serialize(FastBufferWriter writer)
-        {
-            if (!writer.TryBeginWrite(FastBufferWriter.GetWriteSize(Header) + RpcData.Length))
-            {
-                throw new OverflowException("Not enough space in the buffer to store RPC data.");
-            }
-            writer.WriteValue(Header);
-            writer.WriteBytes(RpcData.GetUnsafePtr(), RpcData.Length);
-        }
-
-        public static void Receive(FastBufferReader reader, in NetworkContext context)
-        {
-            var message = new RpcMessage();
-            if (!reader.TryBeginRead(FastBufferWriter.GetWriteSize(message.Header)))
-            {
-                throw new OverflowException("Not enough space in the buffer to read RPC data.");
-            }
-            reader.ReadValue(out message.Header);
-            message.Handle(reader, context, (NetworkManager)context.SystemOwner, context.SenderId, true);
-        }
-
-        public void Handle(FastBufferReader reader, in NetworkContext context, NetworkManager networkManager, ulong senderId, bool canDefer)
-        {
-            if (NetworkManager.__rpc_func_table.ContainsKey(Header.NetworkMethodId))
-            {
-                if (!networkManager.SpawnManager.SpawnedObjects.ContainsKey(Header.NetworkObjectId))
-                {
-                    if (canDefer)
-                    {
-                        networkManager.SpawnManager.TriggerOnSpawn(Header.NetworkObjectId, reader, context);
-                    }
-                    else
-                    {
-                        NetworkLog.LogError($"Tried to invoke an RPC on a non-existent {nameof(NetworkObject)} with {nameof(canDefer)}=false");
-                    }
-                    return;
-                }
-
-                var networkObject = networkManager.SpawnManager.SpawnedObjects[Header.NetworkObjectId];
-
-                var networkBehaviour = networkObject.GetNetworkBehaviourAtOrderIndex(Header.NetworkBehaviourId);
-                if (networkBehaviour == null)
-                {
-                    return;
-                }
-
-                var rpcParams = new __RpcParams();
-                switch (Header.Type)
-                {
-                    case RpcType.Server:
-                        rpcParams.Server = new ServerRpcParams
-                        {
-                            Receive = new ServerRpcReceiveParams
-                            {
-                                SenderClientId = senderId
-                            }
-                        };
-                        break;
-                    case RpcType.Client:
-                        rpcParams.Client = new ClientRpcParams
-                        {
-                            Receive = new ClientRpcReceiveParams
-                            {
-                            }
-                        };
-                        break;
-                }
-
-                NetworkManager.__rpc_func_table[Header.NetworkMethodId](networkBehaviour, reader, rpcParams);
-
-#if DEVELOPMENT_BUILD || UNITY_EDITOR
-                if (NetworkManager.__rpc_name_table.TryGetValue(Header.NetworkMethodId, out var rpcMethodName))
-                {
-                    networkManager.NetworkMetrics.TrackRpcReceived(
-                        senderId,
-                        networkObject,
-                        rpcMethodName,
-                        networkBehaviour.__getTypeName(),
-                        reader.Length);
-                }
-#endif
-            }
-        }
-    }
-}

Runtime/Messaging/Messages/RpcMessages.cs

@@ -0,0 +1,157 @@
+using System;
+using UnityEngine;
+using Unity.Collections;
+
+namespace Unity.Netcode
+{
+    internal static class RpcMessageHelpers
+    {
+        public static unsafe void Serialize(ref FastBufferWriter writer, ref RpcMetadata metadata, ref FastBufferWriter payload)
+        {
+            if (!writer.TryBeginWrite(FastBufferWriter.GetWriteSize<RpcMetadata>() + payload.Length))
+            {
+                throw new OverflowException("Not enough space in the buffer to store RPC data.");
+            }
+
+            writer.WriteValue(metadata);
+            writer.WriteBytes(payload.GetUnsafePtr(), payload.Length);
+        }
+
+        public static unsafe bool Deserialize(ref FastBufferReader reader, ref NetworkContext context, ref RpcMetadata metadata, ref FastBufferReader payload)
+        {
+            int metadataSize = FastBufferWriter.GetWriteSize<RpcMetadata>();
+            if (!reader.TryBeginRead(metadataSize))
+            {
+                throw new InvalidOperationException("Not enough data in the buffer to read RPC meta.");
+            }
+
+            reader.ReadValue(out metadata);
+
+            var networkManager = (NetworkManager)context.SystemOwner;
+            if (!networkManager.SpawnManager.SpawnedObjects.ContainsKey(metadata.NetworkObjectId))
+            {
+                networkManager.DeferredMessageManager.DeferMessage(IDeferredMessageManager.TriggerType.OnSpawn, metadata.NetworkObjectId, reader, ref context);
+                return false;
+            }
+
+            var networkObject = networkManager.SpawnManager.SpawnedObjects[metadata.NetworkObjectId];
+            var networkBehaviour = networkManager.SpawnManager.SpawnedObjects[metadata.NetworkObjectId].GetNetworkBehaviourAtOrderIndex(metadata.NetworkBehaviourId);
+            if (networkBehaviour == null)
+            {
+                return false;
+            }
+
+            if (!NetworkManager.__rpc_func_table.ContainsKey(metadata.NetworkRpcMethodId))
+            {
+                return false;
+            }
+
+            payload = new FastBufferReader(reader.GetUnsafePtr() + metadataSize, Allocator.None, reader.Length - metadataSize);
+
+#if DEVELOPMENT_BUILD || UNITY_EDITOR
+            if (NetworkManager.__rpc_name_table.TryGetValue(metadata.NetworkRpcMethodId, out var rpcMethodName))
+            {
+                networkManager.NetworkMetrics.TrackRpcReceived(
+                    context.SenderId,
+                    networkObject,
+                    rpcMethodName,
+                    networkBehaviour.__getTypeName(),
+                    reader.Length);
+            }
+#endif
+
+            return true;
+        }
+
+        public static void Handle(ref NetworkContext context, ref RpcMetadata metadata, ref FastBufferReader payload, ref __RpcParams rpcParams)
+        {
+            var networkManager = (NetworkManager)context.SystemOwner;
+            if (!networkManager.SpawnManager.SpawnedObjects.TryGetValue(metadata.NetworkObjectId, out var networkObject))
+            {
+                throw new InvalidOperationException($"An RPC called on a {nameof(NetworkObject)} that is not in the spawned objects list. Please make sure the {nameof(NetworkObject)} is spawned before calling RPCs.");
+            }
+            var networkBehaviour = networkObject.GetNetworkBehaviourAtOrderIndex(metadata.NetworkBehaviourId);
+
+            try
+            {
+                NetworkManager.__rpc_func_table[metadata.NetworkRpcMethodId](networkBehaviour, payload, rpcParams);
+            }
+            catch (Exception ex)
+            {
+                Debug.LogException(new Exception("Unhandled RPC exception!", ex));
+            }
+        }
+    }
+
+    internal struct RpcMetadata : INetworkSerializeByMemcpy
+    {
+        public ulong NetworkObjectId;
+        public ushort NetworkBehaviourId;
+        public uint NetworkRpcMethodId;
+    }
+
+    internal struct ServerRpcMessage : INetworkMessage
+    {
+        public RpcMetadata Metadata;
+
+        public FastBufferWriter WriteBuffer;
+        public FastBufferReader ReadBuffer;
+
+        public unsafe void Serialize(FastBufferWriter writer)
+        {
+            RpcMessageHelpers.Serialize(ref writer, ref Metadata, ref WriteBuffer);
+        }
+
+        public unsafe bool Deserialize(FastBufferReader reader, ref NetworkContext context)
+        {
+            return RpcMessageHelpers.Deserialize(ref reader, ref context, ref Metadata, ref ReadBuffer);
+        }
+
+        public void Handle(ref NetworkContext context)
+        {
+            var rpcParams = new __RpcParams
+            {
+                Server = new ServerRpcParams
+                {
+                    Receive = new ServerRpcReceiveParams
+                    {
+                        SenderClientId = context.SenderId
+                    }
+                }
+            };
+            RpcMessageHelpers.Handle(ref context, ref Metadata, ref ReadBuffer, ref rpcParams);
+        }
+    }
+
+    internal struct ClientRpcMessage : INetworkMessage
+    {
+        public RpcMetadata Metadata;
+
+        public FastBufferWriter WriteBuffer;
+        public FastBufferReader ReadBuffer;
+
+        public void Serialize(FastBufferWriter writer)
+        {
+            RpcMessageHelpers.Serialize(ref writer, ref Metadata, ref WriteBuffer);
+        }
+
+        public bool Deserialize(FastBufferReader reader, ref NetworkContext context)
+        {
+            return RpcMessageHelpers.Deserialize(ref reader, ref context, ref Metadata, ref ReadBuffer);
+        }
+
+        public void Handle(ref NetworkContext context)
+        {
+            var rpcParams = new __RpcParams
+            {
+                Client = new ClientRpcParams
+                {
+                    Receive = new ClientRpcReceiveParams
+                    {
+                    }
+                }
+            };
+            RpcMessageHelpers.Handle(ref context, ref Metadata, ref ReadBuffer, ref rpcParams);
+        }
+    }
+}

Runtime/Messaging/Messages/SceneEventMessage.cs

@@ -6,14 +6,22 @@ namespace Unity.Netcode
     {
         public SceneEventData EventData;
 
+        private FastBufferReader m_ReceivedData;
+
         public void Serialize(FastBufferWriter writer)
         {
             EventData.Serialize(writer);
         }
 
-        public static void Receive(FastBufferReader reader, in NetworkContext context)
+        public bool Deserialize(FastBufferReader reader, ref NetworkContext context)
         {
-            ((NetworkManager)context.SystemOwner).SceneManager.HandleSceneEvent(context.SenderId, reader);
+            m_ReceivedData = reader;
+            return true;
+        }
+
+        public void Handle(ref NetworkContext context)
+        {
+            ((NetworkManager)context.SystemOwner).SceneManager.HandleSceneEvent(context.SenderId, m_ReceivedData);
         }
     }
 }

Runtime/Messaging/Messages/ServerLogMessage.cs

@@ -17,21 +17,25 @@ namespace Unity.Netcode
             BytePacker.WriteValuePacked(writer, Message);
         }
 
-        public static void Receive(FastBufferReader reader, in NetworkContext context)
+        public bool Deserialize(FastBufferReader reader, ref NetworkContext context)
         {
             var networkManager = (NetworkManager)context.SystemOwner;
             if (networkManager.IsServer && networkManager.NetworkConfig.EnableNetworkLogs)
             {
-                var message = new ServerLogMessage();
+                reader.ReadValueSafe(out LogType);
-                reader.ReadValueSafe(out message.LogType);
+                ByteUnpacker.ReadValuePacked(reader, out Message);
-                ByteUnpacker.ReadValuePacked(reader, out message.Message);
+                return true;
-                message.Handle(context.SenderId, networkManager, reader.Length);
             }
+
+            return false;
         }
 
-        public void Handle(ulong senderId, NetworkManager networkManager, int messageSize)
+        public void Handle(ref NetworkContext context)
         {
-            networkManager.NetworkMetrics.TrackServerLogReceived(senderId, (uint)LogType, messageSize);
+            var networkManager = (NetworkManager)context.SystemOwner;
+            var senderId = context.SenderId;
+
+            networkManager.NetworkMetrics.TrackServerLogReceived(senderId, (uint)LogType, context.MessageSize);
 
             switch (LogType)
             {

Runtime/Messaging/Messages/SnapshotDataMessage.cs

@@ -1,161 +0,0 @@
-using System;
-using Unity.Collections;
-using Unity.Collections.LowLevel.Unsafe;
-using UnityEngine;
-
-namespace Unity.Netcode
-{
-    internal struct SnapshotDataMessage : INetworkMessage
-    {
-        public int CurrentTick;
-        public ushort Sequence;
-
-        public ushort Range;
-
-        public byte[] SendMainBuffer;
-        public NativeArray<byte> ReceiveMainBuffer;
-
-        public struct AckData
-        {
-            public ushort LastReceivedSequence;
-            public ushort ReceivedSequenceMask;
-        }
-
-        public AckData Ack;
-
-        public struct EntryData
-        {
-            public ulong NetworkObjectId;
-            public ushort BehaviourIndex;
-            public ushort VariableIndex;
-            public int TickWritten;
-            public ushort Position;
-            public ushort Length;
-        }
-
-        public NativeList<EntryData> Entries;
-
-        public struct SpawnData
-        {
-            public ulong NetworkObjectId;
-            public uint Hash;
-            public bool IsSceneObject;
-
-            public bool IsPlayerObject;
-            public ulong OwnerClientId;
-            public ulong ParentNetworkId;
-            public Vector3 Position;
-            public Quaternion Rotation;
-            public Vector3 Scale;
-
-            public int TickWritten;
-        }
-
-        public NativeList<SpawnData> Spawns;
-
-        public struct DespawnData
-        {
-            public ulong NetworkObjectId;
-            public int TickWritten;
-        }
-
-        public NativeList<DespawnData> Despawns;
-
-        public unsafe void Serialize(FastBufferWriter writer)
-        {
-            if (!writer.TryBeginWrite(
-                FastBufferWriter.GetWriteSize(CurrentTick) +
-                FastBufferWriter.GetWriteSize(Sequence) +
-                FastBufferWriter.GetWriteSize(Range) + Range +
-                FastBufferWriter.GetWriteSize(Ack) +
-                FastBufferWriter.GetWriteSize<ushort>() +
-                Entries.Length * sizeof(EntryData) +
-                FastBufferWriter.GetWriteSize<ushort>() +
-                Spawns.Length * sizeof(SpawnData) +
-                FastBufferWriter.GetWriteSize<ushort>() +
-                Despawns.Length * sizeof(DespawnData)
-            ))
-            {
-                Entries.Dispose();
-                Spawns.Dispose();
-                Despawns.Dispose();
-                throw new OverflowException($"Not enough space to serialize {nameof(SnapshotDataMessage)}");
-            }
-            writer.WriteValue(CurrentTick);
-            writer.WriteValue(Sequence);
-
-            writer.WriteValue(Range);
-            writer.WriteBytes(SendMainBuffer, Range);
-            writer.WriteValue(Ack);
-
-            writer.WriteValue((ushort)Entries.Length);
-            writer.WriteBytes((byte*)Entries.GetUnsafePtr(), Entries.Length * sizeof(EntryData));
-
-            writer.WriteValue((ushort)Spawns.Length);
-            writer.WriteBytes((byte*)Spawns.GetUnsafePtr(), Spawns.Length * sizeof(SpawnData));
-
-            writer.WriteValue((ushort)Despawns.Length);
-            writer.WriteBytes((byte*)Despawns.GetUnsafePtr(), Despawns.Length * sizeof(DespawnData));
-
-            Entries.Dispose();
-            Spawns.Dispose();
-            Despawns.Dispose();
-        }
-
-        public static unsafe void Receive(FastBufferReader reader, in NetworkContext context)
-        {
-            var networkManager = (NetworkManager)context.SystemOwner;
-            var message = new SnapshotDataMessage();
-            if (!reader.TryBeginRead(
-                FastBufferWriter.GetWriteSize(message.CurrentTick) +
-                FastBufferWriter.GetWriteSize(message.Sequence) +
-                FastBufferWriter.GetWriteSize(message.Range)
-            ))
-            {
-                throw new OverflowException($"Not enough space to deserialize {nameof(SnapshotDataMessage)}");
-            }
-            reader.ReadValue(out message.CurrentTick);
-            reader.ReadValue(out message.Sequence);
-
-            reader.ReadValue(out message.Range);
-            message.ReceiveMainBuffer = new NativeArray<byte>(message.Range, Allocator.Temp);
-            reader.ReadBytesSafe((byte*)message.ReceiveMainBuffer.GetUnsafePtr(), message.Range);
-            reader.ReadValueSafe(out message.Ack);
-
-            reader.ReadValueSafe(out ushort length);
-            message.Entries = new NativeList<EntryData>(length, Allocator.Temp);
-            message.Entries.Length = length;
-            reader.ReadBytesSafe((byte*)message.Entries.GetUnsafePtr(), message.Entries.Length * sizeof(EntryData));
-
-            reader.ReadValueSafe(out length);
-            message.Spawns = new NativeList<SpawnData>(length, Allocator.Temp);
-            message.Spawns.Length = length;
-            reader.ReadBytesSafe((byte*)message.Spawns.GetUnsafePtr(), message.Spawns.Length * sizeof(SpawnData));
-
-            reader.ReadValueSafe(out length);
-            message.Despawns = new NativeList<DespawnData>(length, Allocator.Temp);
-            message.Despawns.Length = length;
-            reader.ReadBytesSafe((byte*)message.Despawns.GetUnsafePtr(), message.Despawns.Length * sizeof(DespawnData));
-
-            using (message.ReceiveMainBuffer)
-            using (message.Entries)
-            using (message.Spawns)
-            using (message.Despawns)
-            {
-                message.Handle(context.SenderId, networkManager);
-            }
-        }
-
-        public void Handle(ulong senderId, NetworkManager networkManager)
-        {
-            // todo: temporary hack around bug
-            if (!networkManager.IsServer)
-            {
-                senderId = networkManager.ServerClientId;
-            }
-
-            var snapshotSystem = networkManager.SnapshotSystem;
-            snapshotSystem.HandleSnapshot(senderId, this);
-        }
-    }
-}

Runtime/Messaging/Messages/SnapshotDataMessage.cs.meta

@@ -1,11 +0,0 @@
-fileFormatVersion: 2
-guid: 5cf75026c2ab86646aac16b39d7259ad
-MonoImporter:
-  externalObjects: {}
-  serializedVersion: 2
-  defaultReferences: []
-  executionOrder: 0
-  icon: {instanceID: 0}
-  userData: 
-  assetBundleName: 
-  assetBundleVariant: 

Runtime/Messaging/Messages/TimeSyncMessage.cs

@@ -1,6 +1,6 @@
 namespace Unity.Netcode
 {
-    internal struct TimeSyncMessage : INetworkMessage
+    internal struct TimeSyncMessage : INetworkMessage, INetworkSerializeByMemcpy
     {
         public int Tick;
 
@@ -9,21 +9,22 @@ namespace Unity.Netcode
             writer.WriteValueSafe(this);
         }
 
-        public static void Receive(FastBufferReader reader, in NetworkContext context)
+        public bool Deserialize(FastBufferReader reader, ref NetworkContext context)
         {
             var networkManager = (NetworkManager)context.SystemOwner;
             if (!networkManager.IsClient)
             {
-                return;
+                return false;
             }
-            reader.ReadValueSafe(out TimeSyncMessage message);
+            reader.ReadValueSafe(out this);
-            message.Handle(context.SenderId, networkManager);
+            return true;
         }
 
-        public void Handle(ulong senderId, NetworkManager networkManager)
+        public void Handle(ref NetworkContext context)
         {
+            var networkManager = (NetworkManager)context.SystemOwner;
             var time = new NetworkTime(networkManager.NetworkTickSystem.TickRate, Tick);
-            networkManager.NetworkTimeSystem.Sync(time.Time, networkManager.NetworkConfig.NetworkTransport.GetCurrentRtt(senderId) / 1000d);
+            networkManager.NetworkTimeSystem.Sync(time.Time, networkManager.NetworkConfig.NetworkTransport.GetCurrentRtt(context.SenderId) / 1000d);
         }
     }
 }

Runtime/Messaging/Messages/UnnamedMessage.cs

@@ -2,16 +2,23 @@ namespace Unity.Netcode
 {
     internal struct UnnamedMessage : INetworkMessage
     {
-        public FastBufferWriter Data;
+        public FastBufferWriter SendData;
+        private FastBufferReader m_ReceivedData;
 
         public unsafe void Serialize(FastBufferWriter writer)
         {
-            writer.WriteBytesSafe(Data.GetUnsafePtr(), Data.Length);
+            writer.WriteBytesSafe(SendData.GetUnsafePtr(), SendData.Length);
         }
 
-        public static void Receive(FastBufferReader reader, in NetworkContext context)
+        public bool Deserialize(FastBufferReader reader, ref NetworkContext context)
         {
-            ((NetworkManager)context.SystemOwner).CustomMessagingManager.InvokeUnnamedMessage(context.SenderId, reader);
+            m_ReceivedData = reader;
+            return true;
+        }
+
+        public void Handle(ref NetworkContext context)
+        {
+            ((NetworkManager)context.SystemOwner).CustomMessagingManager.InvokeUnnamedMessage(context.SenderId, m_ReceivedData, context.SerializedHeaderSize);
         }
     }
 }

Runtime/Messaging/MessagingSystem.cs

@@ -23,6 +23,7 @@ namespace Unity.Netcode
             public MessageHeader Header;
             public ulong SenderId;
             public float Timestamp;
+            public int MessageHeaderSerializedSize;
         }
 
         private struct SendQueueItem
@@ -39,34 +40,34 @@ namespace Unity.Netcode
             }
         }
 
-        internal delegate void MessageHandler(FastBufferReader reader, in NetworkContext context);
+        internal delegate void MessageHandler(FastBufferReader reader, ref NetworkContext context, MessagingSystem system);
 
         private NativeList<ReceiveQueueItem> m_IncomingMessageQueue = new NativeList<ReceiveQueueItem>(16, Allocator.Persistent);
 
         private MessageHandler[] m_MessageHandlers = new MessageHandler[255];
         private Type[] m_ReverseTypeMap = new Type[255];
 
-        private Dictionary<Type, byte> m_MessageTypes = new Dictionary<Type, byte>();
+        private Dictionary<Type, uint> m_MessageTypes = new Dictionary<Type, uint>();
         private Dictionary<ulong, NativeList<SendQueueItem>> m_SendQueues = new Dictionary<ulong, NativeList<SendQueueItem>>();
 
         private List<INetworkHooks> m_Hooks = new List<INetworkHooks>();
 
-        private byte m_HighMessageType;
+        private uint m_HighMessageType;
         private object m_Owner;
         private IMessageSender m_MessageSender;
         private bool m_Disposed;
 
         internal Type[] MessageTypes => m_ReverseTypeMap;
         internal MessageHandler[] MessageHandlers => m_MessageHandlers;
-        internal int MessageHandlerCount => m_HighMessageType;
+        internal uint MessageHandlerCount => m_HighMessageType;
 
-        internal byte GetMessageType(Type t)
+        internal uint GetMessageType(Type t)
         {
             return m_MessageTypes[t];
         }
 
         public const int NON_FRAGMENTED_MESSAGE_MAX_SIZE = 1300;
-        public const int FRAGMENTED_MESSAGE_MAX_SIZE = 64000;
+        public const int FRAGMENTED_MESSAGE_MAX_SIZE = BytePacker.BitPackedIntMax;
 
         internal struct MessageWithHandler
         {
@@ -100,7 +101,7 @@ namespace Unity.Netcode
             }
         }
 
-        public void Dispose()
+        public unsafe void Dispose()
         {
             if (m_Disposed)
             {
@@ -113,6 +114,14 @@ namespace Unity.Netcode
             {
                 CleanupDisconnectedClient(kvp.Key);
             }
+
+            for (var queueIndex = 0; queueIndex < m_IncomingMessageQueue.Length; ++queueIndex)
+            {
+                // Avoid copies...
+                ref var item = ref m_IncomingMessageQueue.ElementAt(queueIndex);
+                item.Reader.Dispose();
+            }
+
             m_IncomingMessageQueue.Dispose();
             m_Disposed = true;
         }
@@ -127,6 +136,11 @@ namespace Unity.Netcode
             m_Hooks.Add(hooks);
         }
 
+        public void Unhook(INetworkHooks hooks)
+        {
+            m_Hooks.Remove(hooks);
+        }
+
         private void RegisterMessageType(MessageWithHandler messageWithHandler)
         {
             m_MessageHandlers[m_HighMessageType] = messageWithHandler.Handler;
@@ -141,7 +155,7 @@ namespace Unity.Netcode
                 fixed (byte* nativeData = data.Array)
                 {
                     var batchReader =
-                        new FastBufferReader(nativeData, Allocator.None, data.Count, data.Offset);
+                        new FastBufferReader(nativeData + data.Offset, Allocator.None, data.Count);
                     if (!batchReader.TryBeginRead(sizeof(BatchHeader)))
                     {
                         NetworkLog.LogWarning("Received a packet too small to contain a BatchHeader. Ignoring it.");
@@ -157,14 +171,23 @@ namespace Unity.Netcode
 
                     for (var messageIdx = 0; messageIdx < batchHeader.BatchSize; ++messageIdx)
                     {
-                        if (!batchReader.TryBeginRead(sizeof(MessageHeader)))
+
+                        var messageHeader = new MessageHeader();
+                        var position = batchReader.Position;
+                        try
+                        {
+                            ByteUnpacker.ReadValueBitPacked(batchReader, out messageHeader.MessageType);
+                            ByteUnpacker.ReadValueBitPacked(batchReader, out messageHeader.MessageSize);
+                        }
+                        catch (OverflowException)
                         {
                             NetworkLog.LogWarning("Received a batch that didn't have enough data for all of its batches, ending early!");
-                            return;
+                            throw;
                         }
-                        batchReader.ReadValue(out MessageHeader messageHeader);
 
-                        if (!batchReader.TryBeginRead(messageHeader.MessageSize))
+                        var receivedHeaderSize = batchReader.Position - position;
+
+                        if (!batchReader.TryBeginRead((int)messageHeader.MessageSize))
                         {
                             NetworkLog.LogWarning("Received a message that claimed a size larger than the packet, ending early!");
                             return;
@@ -177,9 +200,10 @@ namespace Unity.Netcode
                             // Copy the data for this message into a new FastBufferReader that owns that memory.
                             // We can't guarantee the memory in the ArraySegment stays valid because we don't own it,
                             // so we must move it to memory we do own.
-                            Reader = new FastBufferReader(batchReader.GetUnsafePtrAtCurrentPosition(), Allocator.TempJob, messageHeader.MessageSize)
+                            Reader = new FastBufferReader(batchReader.GetUnsafePtrAtCurrentPosition(), Allocator.TempJob, (int)messageHeader.MessageSize),
+                            MessageHeaderSerializedSize = receivedHeaderSize,
                         });
-                        batchReader.Seek(batchReader.Position + messageHeader.MessageSize);
+                        batchReader.Seek(batchReader.Position + (int)messageHeader.MessageSize);
                     }
                     for (var hookIdx = 0; hookIdx < m_Hooks.Count; ++hookIdx)
                     {
@@ -189,11 +213,11 @@ namespace Unity.Netcode
             }
         }
 
-        private bool CanReceive(ulong clientId, Type messageType)
+        private bool CanReceive(ulong clientId, Type messageType, FastBufferReader messageContent, ref NetworkContext context)
         {
             for (var hookIdx = 0; hookIdx < m_Hooks.Count; ++hookIdx)
             {
-                if (!m_Hooks[hookIdx].OnVerifyCanReceive(clientId, messageType))
+                if (!m_Hooks[hookIdx].OnVerifyCanReceive(clientId, messageType, messageContent, ref context))
                 {
                     return false;
                 }
@@ -202,7 +226,7 @@ namespace Unity.Netcode
             return true;
         }
 
-        public void HandleMessage(in MessageHeader header, FastBufferReader reader, ulong senderId, float timestamp)
+        public void HandleMessage(in MessageHeader header, FastBufferReader reader, ulong senderId, float timestamp, int serializedHeaderSize)
         {
             if (header.MessageType >= m_HighMessageType)
             {
@@ -215,10 +239,13 @@ namespace Unity.Netcode
                 SystemOwner = m_Owner,
                 SenderId = senderId,
                 Timestamp = timestamp,
-                Header = header
+                Header = header,
+                SerializedHeaderSize = serializedHeaderSize,
+                MessageSize = header.MessageSize,
             };
+
             var type = m_ReverseTypeMap[header.MessageType];
-            if (!CanReceive(senderId, type))
+            if (!CanReceive(senderId, type, reader, ref context))
             {
                 reader.Dispose();
                 return;
@@ -228,6 +255,7 @@ namespace Unity.Netcode
             {
                 m_Hooks[hookIdx].OnBeforeReceiveMessage(senderId, type, reader.Length + FastBufferWriter.GetWriteSize<MessageHeader>());
             }
+
             var handler = m_MessageHandlers[header.MessageType];
             using (reader)
             {
@@ -238,7 +266,7 @@ namespace Unity.Netcode
                 // for some dynamic-length value.
                 try
                 {
-                    handler.Invoke(reader, context);
+                    handler.Invoke(reader, ref context, this);
                 }
                 catch (Exception e)
                 {
@@ -253,11 +281,15 @@ namespace Unity.Netcode
 
         internal unsafe void ProcessIncomingMessageQueue()
         {
-            for (var i = 0; i < m_IncomingMessageQueue.Length; ++i)
+            for (var index = 0; index < m_IncomingMessageQueue.Length; ++index)
             {
                 // Avoid copies...
-                ref var item = ref m_IncomingMessageQueue.GetUnsafeList()->ElementAt(i);
+                ref var item = ref m_IncomingMessageQueue.ElementAt(index);
-                HandleMessage(item.Header, item.Reader, item.SenderId, item.Timestamp);
+                HandleMessage(item.Header, item.Reader, item.SenderId, item.Timestamp, item.MessageHeaderSerializedSize);
+                if (m_Disposed)
+                {
+                    return;
+                }
             }
 
             m_IncomingMessageQueue.Clear();
@@ -287,12 +319,31 @@ namespace Unity.Netcode
             var queue = m_SendQueues[clientId];
             for (var i = 0; i < queue.Length; ++i)
             {
-                queue.GetUnsafeList()->ElementAt(i).Writer.Dispose();
+                queue.ElementAt(i).Writer.Dispose();
             }
 
             queue.Dispose();
         }
 
+        public static void ReceiveMessage<T>(FastBufferReader reader, ref NetworkContext context, MessagingSystem system) where T : INetworkMessage, new()
+        {
+            var message = new T();
+            if (message.Deserialize(reader, ref context))
+            {
+                for (var hookIdx = 0; hookIdx < system.m_Hooks.Count; ++hookIdx)
+                {
+                    system.m_Hooks[hookIdx].OnBeforeHandleMessage(ref message, ref context);
+                }
+
+                message.Handle(ref context);
+
+                for (var hookIdx = 0; hookIdx < system.m_Hooks.Count; ++hookIdx)
+                {
+                    system.m_Hooks[hookIdx].OnAfterHandleMessage(ref message, ref context);
+                }
+            }
+        }
+
         private bool CanSend(ulong clientId, Type messageType, NetworkDelivery delivery)
         {
             for (var hookIdx = 0; hookIdx < m_Hooks.Count; ++hookIdx)
@@ -306,7 +357,7 @@ namespace Unity.Netcode
             return true;
         }
 
-        internal unsafe int SendMessage<TMessageType, TClientIdListType>(in TMessageType message, NetworkDelivery delivery, in TClientIdListType clientIds)
+        internal int SendMessage<TMessageType, TClientIdListType>(ref TMessageType message, NetworkDelivery delivery, in TClientIdListType clientIds)
             where TMessageType : INetworkMessage
             where TClientIdListType : IReadOnlyList<ulong>
         {
@@ -316,64 +367,81 @@ namespace Unity.Netcode
             }
 
             var maxSize = delivery == NetworkDelivery.ReliableFragmentedSequenced ? FRAGMENTED_MESSAGE_MAX_SIZE : NON_FRAGMENTED_MESSAGE_MAX_SIZE;
-            var tmpSerializer = new FastBufferWriter(NON_FRAGMENTED_MESSAGE_MAX_SIZE - FastBufferWriter.GetWriteSize<MessageHeader>(), Allocator.Temp, maxSize - FastBufferWriter.GetWriteSize<MessageHeader>());
+
-            using (tmpSerializer)
+            using var tmpSerializer = new FastBufferWriter(NON_FRAGMENTED_MESSAGE_MAX_SIZE - FastBufferWriter.GetWriteSize<MessageHeader>(), Allocator.Temp, maxSize - FastBufferWriter.GetWriteSize<MessageHeader>());
+
+            message.Serialize(tmpSerializer);
+
+            return SendPreSerializedMessage(tmpSerializer, maxSize, ref message, delivery, clientIds);
+        }
+
+        internal unsafe int SendPreSerializedMessage<TMessageType>(in FastBufferWriter tmpSerializer, int maxSize, ref TMessageType message, NetworkDelivery delivery, in IReadOnlyList<ulong> clientIds)
+            where TMessageType : INetworkMessage
+        {
+            using var headerSerializer = new FastBufferWriter(FastBufferWriter.GetWriteSize<MessageHeader>(), Allocator.Temp);
+
+            var header = new MessageHeader
             {
-                message.Serialize(tmpSerializer);
+                MessageSize = (uint)tmpSerializer.Length,
+                MessageType = m_MessageTypes[typeof(TMessageType)],
+            };
+            BytePacker.WriteValueBitPacked(headerSerializer, header.MessageType);
+            BytePacker.WriteValueBitPacked(headerSerializer, header.MessageSize);
 
-                for (var i = 0; i < clientIds.Count; ++i)
+            for (var i = 0; i < clientIds.Count; ++i)
+            {
+                var clientId = clientIds[i];
+
+                if (!CanSend(clientId, typeof(TMessageType), delivery))
                 {
-                    var clientId = clientIds[i];
+                    continue;
+                }
 
-                    if (!CanSend(clientId, typeof(TMessageType), delivery))
+                for (var hookIdx = 0; hookIdx < m_Hooks.Count; ++hookIdx)
-                    {
+                {
-                        continue;
+                    m_Hooks[hookIdx].OnBeforeSendMessage(clientId, ref message, delivery);
-                    }
+                }
 
-                    for (var hookIdx = 0; hookIdx < m_Hooks.Count; ++hookIdx)
+                var sendQueueItem = m_SendQueues[clientId];
-                    {
+                if (sendQueueItem.Length == 0)
-                        m_Hooks[hookIdx].OnBeforeSendMessage(clientId, typeof(TMessageType), delivery);
+                {
-                    }
+                    sendQueueItem.Add(new SendQueueItem(delivery, NON_FRAGMENTED_MESSAGE_MAX_SIZE, Allocator.TempJob,
-
+                        maxSize));
-                    var sendQueueItem = m_SendQueues[clientId];
+                    sendQueueItem.ElementAt(0).Writer.Seek(sizeof(BatchHeader));
-                    if (sendQueueItem.Length == 0)
+                }
+                else
+                {
+                    ref var lastQueueItem = ref sendQueueItem.ElementAt(sendQueueItem.Length - 1);
+                    if (lastQueueItem.NetworkDelivery != delivery ||
+                        lastQueueItem.Writer.MaxCapacity - lastQueueItem.Writer.Position
+                        < tmpSerializer.Length + headerSerializer.Length)
                     {
                         sendQueueItem.Add(new SendQueueItem(delivery, NON_FRAGMENTED_MESSAGE_MAX_SIZE, Allocator.TempJob,
                             maxSize));
-                        sendQueueItem.GetUnsafeList()->ElementAt(0).Writer.Seek(sizeof(BatchHeader));
+                        sendQueueItem.ElementAt(sendQueueItem.Length - 1).Writer.Seek(sizeof(BatchHeader));
-                    }
-                    else
-                    {
-                        ref var lastQueueItem = ref sendQueueItem.GetUnsafeList()->ElementAt(sendQueueItem.Length - 1);
-                        if (lastQueueItem.NetworkDelivery != delivery ||
-                            lastQueueItem.Writer.MaxCapacity - lastQueueItem.Writer.Position
-                            < tmpSerializer.Length + FastBufferWriter.GetWriteSize<MessageHeader>())
-                        {
-                            sendQueueItem.Add(new SendQueueItem(delivery, NON_FRAGMENTED_MESSAGE_MAX_SIZE, Allocator.TempJob,
-                                maxSize));
-                            sendQueueItem.GetUnsafeList()->ElementAt(sendQueueItem.Length - 1).Writer.Seek(sizeof(BatchHeader));
-                        }
-                    }
-
-                    ref var writeQueueItem = ref sendQueueItem.GetUnsafeList()->ElementAt(sendQueueItem.Length - 1);
-                    writeQueueItem.Writer.TryBeginWrite(tmpSerializer.Length + FastBufferWriter.GetWriteSize<MessageHeader>());
-                    var header = new MessageHeader
-                    {
-                        MessageSize = (ushort)tmpSerializer.Length,
-                        MessageType = m_MessageTypes[typeof(TMessageType)],
-                    };
-
-                    writeQueueItem.Writer.WriteValue(header);
-                    writeQueueItem.Writer.WriteBytes(tmpSerializer.GetUnsafePtr(), tmpSerializer.Length);
-                    writeQueueItem.BatchHeader.BatchSize++;
-                    for (var hookIdx = 0; hookIdx < m_Hooks.Count; ++hookIdx)
-                    {
-                        m_Hooks[hookIdx].OnAfterSendMessage(clientId, typeof(TMessageType), delivery, tmpSerializer.Length + FastBufferWriter.GetWriteSize<MessageHeader>());
                     }
                 }
 
-                return tmpSerializer.Length + FastBufferWriter.GetWriteSize<MessageHeader>();
+                ref var writeQueueItem = ref sendQueueItem.ElementAt(sendQueueItem.Length - 1);
+                writeQueueItem.Writer.TryBeginWrite(tmpSerializer.Length + headerSerializer.Length);
+
+                writeQueueItem.Writer.WriteBytes(headerSerializer.GetUnsafePtr(), headerSerializer.Length);
+                writeQueueItem.Writer.WriteBytes(tmpSerializer.GetUnsafePtr(), tmpSerializer.Length);
+                writeQueueItem.BatchHeader.BatchSize++;
+                for (var hookIdx = 0; hookIdx < m_Hooks.Count; ++hookIdx)
+                {
+                    m_Hooks[hookIdx].OnAfterSendMessage(clientId, ref message, delivery, tmpSerializer.Length + headerSerializer.Length);
+                }
             }
+
+            return tmpSerializer.Length + headerSerializer.Length;
+        }
+
+        internal unsafe int SendPreSerializedMessage<TMessageType>(in FastBufferWriter tmpSerializer, int maxSize, ref TMessageType message, NetworkDelivery delivery, ulong clientId)
+            where TMessageType : INetworkMessage
+        {
+            ulong* clientIds = stackalloc ulong[] { clientId };
+            return SendPreSerializedMessage(tmpSerializer, maxSize, ref message, delivery, new PointerListWrapper<ulong>(clientIds, 1));
         }
 
         private struct PointerListWrapper<T> : IReadOnlyList<T>
@@ -411,24 +479,24 @@ namespace Unity.Netcode
             }
         }
 
-        internal unsafe int SendMessage<T>(in T message, NetworkDelivery delivery,
+        internal unsafe int SendMessage<T>(ref T message, NetworkDelivery delivery,
             ulong* clientIds, int numClientIds)
             where T : INetworkMessage
         {
-            return SendMessage(message, delivery, new PointerListWrapper<ulong>(clientIds, numClientIds));
+            return SendMessage(ref message, delivery, new PointerListWrapper<ulong>(clientIds, numClientIds));
         }
 
-        internal unsafe int SendMessage<T>(in T message, NetworkDelivery delivery, ulong clientId)
+        internal unsafe int SendMessage<T>(ref T message, NetworkDelivery delivery, ulong clientId)
             where T : INetworkMessage
         {
             ulong* clientIds = stackalloc ulong[] { clientId };
-            return SendMessage(message, delivery, new PointerListWrapper<ulong>(clientIds, 1));
+            return SendMessage(ref message, delivery, new PointerListWrapper<ulong>(clientIds, 1));
         }
 
-        internal unsafe int SendMessage<T>(in T message, NetworkDelivery delivery, in NativeArray<ulong> clientIds)
+        internal unsafe int SendMessage<T>(ref T message, NetworkDelivery delivery, in NativeArray<ulong> clientIds)
             where T : INetworkMessage
         {
-            return SendMessage(message, delivery, new PointerListWrapper<ulong>((ulong*)clientIds.GetUnsafePtr(), clientIds.Length));
+            return SendMessage(ref message, delivery, new PointerListWrapper<ulong>((ulong*)clientIds.GetUnsafePtr(), clientIds.Length));
         }
 
         internal unsafe void ProcessSendQueues()
@@ -439,7 +507,7 @@ namespace Unity.Netcode
                 var sendQueueItem = kvp.Value;
                 for (var i = 0; i < sendQueueItem.Length; ++i)
                 {
-                    ref var queueItem = ref sendQueueItem.GetUnsafeList()->ElementAt(i);
+                    ref var queueItem = ref sendQueueItem.ElementAt(i);
                     if (queueItem.BatchHeader.BatchSize == 0)
                     {
                         queueItem.Writer.Dispose();
@@ -461,16 +529,16 @@ namespace Unity.Netcode
                     try
                     {
                         m_MessageSender.Send(clientId, queueItem.NetworkDelivery, queueItem.Writer);
+
+                        for (var hookIdx = 0; hookIdx < m_Hooks.Count; ++hookIdx)
+                        {
+                            m_Hooks[hookIdx].OnAfterSendBatch(clientId, queueItem.BatchHeader.BatchSize, queueItem.Writer.Length, queueItem.NetworkDelivery);
+                        }
                     }
                     finally
                     {
                         queueItem.Writer.Dispose();
                     }
-
-                    for (var hookIdx = 0; hookIdx < m_Hooks.Count; ++hookIdx)
-                    {
-                        m_Hooks[hookIdx].OnAfterSendBatch(clientId, queueItem.BatchHeader.BatchSize, queueItem.Writer.Length, queueItem.NetworkDelivery);
-                    }
                 }
                 sendQueueItem.Clear();
             }

Runtime/Messaging/NetworkContext.cs

@@ -25,5 +25,15 @@ namespace Unity.Netcode
         /// The header data that was sent with the message
         /// </summary>
         public MessageHeader Header;
+
+        /// <summary>
+        /// The actual serialized size of the header when packed into the buffer
+        /// </summary>
+        public int SerializedHeaderSize;
+
+        /// <summary>
+        /// The size of the message in the buffer, header excluded
+        /// </summary>
+        public uint MessageSize;
     }
 }

Runtime/Metrics/INetworkMetrics.cs

@@ -83,6 +83,18 @@ namespace Unity.Netcode
 
         void TrackSceneEventReceived(ulong senderClientId, uint sceneEventType, string sceneName, long bytesCount);
 
+        void TrackPacketSent(uint packetCount);
+
+        void TrackPacketReceived(uint packetCount);
+
+        void UpdateRttToServer(int rtt);
+
+        void UpdateNetworkObjectsCount(int count);
+
+        void UpdateConnectionsCount(int count);
+
+        void UpdatePacketLoss(float packetLoss);
+
         void DispatchFrame();
     }
 }

Runtime/Metrics/MetricHooks.cs

@@ -11,14 +11,13 @@ namespace Unity.Netcode
             m_NetworkManager = networkManager;
         }
 
-
+        public void OnBeforeSendMessage<T>(ulong clientId, ref T message, NetworkDelivery delivery) where T : INetworkMessage
-        public void OnBeforeSendMessage(ulong clientId, Type messageType, NetworkDelivery delivery)
         {
         }
 
-        public void OnAfterSendMessage(ulong clientId, Type messageType, NetworkDelivery delivery, int messageSizeBytes)
+        public void OnAfterSendMessage<T>(ulong clientId, ref T message, NetworkDelivery delivery, int messageSizeBytes) where T : INetworkMessage
         {
-            m_NetworkManager.NetworkMetrics.TrackNetworkMessageSent(clientId, messageType.Name, messageSizeBytes);
+            m_NetworkManager.NetworkMetrics.TrackNetworkMessageSent(clientId, typeof(T).Name, messageSizeBytes);
         }
 
         public void OnBeforeReceiveMessage(ulong senderId, Type messageType, int messageSizeBytes)
@@ -53,9 +52,19 @@ namespace Unity.Netcode
             return true;
         }
 
-        public bool OnVerifyCanReceive(ulong senderId, Type messageType)
+        public bool OnVerifyCanReceive(ulong senderId, Type messageType, FastBufferReader messageContent, ref NetworkContext context)
         {
             return true;
         }
+
+        public void OnBeforeHandleMessage<T>(ref T message, ref NetworkContext context) where T : INetworkMessage
+        {
+            // TODO: Per-message metrics recording moved here
+        }
+
+        public void OnAfterHandleMessage<T>(ref T message, ref NetworkContext context) where T : INetworkMessage
+        {
+            // TODO: Per-message metrics recording moved here
+        }
     }
 }

Runtime/Metrics/NetworkMetrics.cs

@@ -4,6 +4,7 @@ using System.Collections.Generic;
 using Unity.Multiplayer.Tools;
 using Unity.Multiplayer.Tools.MetricTypes;
 using Unity.Multiplayer.Tools.NetStats;
+using Unity.Profiling;
 using UnityEngine;
 
 namespace Unity.Netcode
@@ -14,6 +15,8 @@ namespace Unity.Netcode
 
         static Dictionary<uint, string> s_SceneEventTypeNames;
 
+        static ProfilerMarker s_FrameDispatch = new ProfilerMarker($"{nameof(NetworkMetrics)}.DispatchFrame");
+
         static NetworkMetrics()
         {
             s_SceneEventTypeNames = new Dictionary<uint, string>();
@@ -63,6 +66,30 @@ namespace Unity.Netcode
         private readonly EventMetric<SceneEventMetric> m_SceneEventSentEvent = new EventMetric<SceneEventMetric>(NetworkMetricTypes.SceneEventSent.Id);
         private readonly EventMetric<SceneEventMetric> m_SceneEventReceivedEvent = new EventMetric<SceneEventMetric>(NetworkMetricTypes.SceneEventReceived.Id);
 
+#if MULTIPLAYER_TOOLS_1_0_0_PRE_7
+        private readonly Counter m_PacketSentCounter = new Counter(NetworkMetricTypes.PacketsSent.Id)
+        {
+            ShouldResetOnDispatch = true,
+        };
+        private readonly Counter m_PacketReceivedCounter = new Counter(NetworkMetricTypes.PacketsReceived.Id)
+        {
+            ShouldResetOnDispatch = true,
+        };
+        private readonly Gauge m_RttToServerGauge = new Gauge(NetworkMetricTypes.RttToServer.Id)
+        {
+            ShouldResetOnDispatch = true,
+        };
+        private readonly Gauge m_NetworkObjectsGauge = new Gauge(NetworkMetricTypes.NetworkObjects.Id)
+        {
+            ShouldResetOnDispatch = true,
+        };
+        private readonly Gauge m_ConnectionsGauge = new Gauge(NetworkMetricTypes.ConnectedClients.Id)
+        {
+            ShouldResetOnDispatch = true,
+        };
+        private readonly Gauge m_PacketLossGauge = new Gauge(NetworkMetricTypes.PacketLoss.Id);
+#endif
+
         private ulong m_NumberOfMetricsThisFrame;
 
         public NetworkMetrics()
@@ -79,6 +106,13 @@ namespace Unity.Netcode
                 .WithMetricEvents(m_RpcSentEvent, m_RpcReceivedEvent)
                 .WithMetricEvents(m_ServerLogSentEvent, m_ServerLogReceivedEvent)
                 .WithMetricEvents(m_SceneEventSentEvent, m_SceneEventReceivedEvent)
+#if MULTIPLAYER_TOOLS_1_0_0_PRE_7
+                .WithCounters(m_PacketSentCounter, m_PacketReceivedCounter)
+                .WithGauges(m_RttToServerGauge)
+                .WithGauges(m_NetworkObjectsGauge)
+                .WithGauges(m_ConnectionsGauge)
+                .WithGauges(m_PacketLossGauge)
+#endif
                 .Build();
 
             Dispatcher.RegisterObserver(NetcodeObserver.Observer);
@@ -404,9 +438,85 @@ namespace Unity.Netcode
             IncrementMetricCount();
         }
 
+        public void TrackPacketSent(uint packetCount)
+        {
+#if MULTIPLAYER_TOOLS_1_0_0_PRE_7
+            if (!CanSendMetrics)
+            {
+                return;
+            }
+
+            m_PacketSentCounter.Increment(packetCount);
+            IncrementMetricCount();
+#endif
+        }
+
+        public void TrackPacketReceived(uint packetCount)
+        {
+#if MULTIPLAYER_TOOLS_1_0_0_PRE_7
+            if (!CanSendMetrics)
+            {
+                return;
+            }
+
+            m_PacketReceivedCounter.Increment(packetCount);
+            IncrementMetricCount();
+#endif
+        }
+
+        public void UpdateRttToServer(int rttMilliseconds)
+        {
+#if MULTIPLAYER_TOOLS_1_0_0_PRE_7
+            if (!CanSendMetrics)
+            {
+                return;
+            }
+            var rttSeconds = rttMilliseconds * 1e-3;
+            m_RttToServerGauge.Set(rttSeconds);
+#endif
+        }
+
+        public void UpdateNetworkObjectsCount(int count)
+        {
+#if MULTIPLAYER_TOOLS_1_0_0_PRE_7
+            if (!CanSendMetrics)
+            {
+                return;
+            }
+
+            m_NetworkObjectsGauge.Set(count);
+#endif
+        }
+
+        public void UpdateConnectionsCount(int count)
+        {
+#if MULTIPLAYER_TOOLS_1_0_0_PRE_7
+            if (!CanSendMetrics)
+            {
+                return;
+            }
+
+            m_ConnectionsGauge.Set(count);
+#endif
+        }
+
+        public void UpdatePacketLoss(float packetLoss)
+        {
+#if MULTIPLAYER_TOOLS_1_0_0_PRE_7
+            if (!CanSendMetrics)
+            {
+                return;
+            }
+
+            m_PacketLossGauge.Set(packetLoss);
+#endif
+        }
+
         public void DispatchFrame()
         {
+            s_FrameDispatch.Begin();
             Dispatcher.Dispatch();
+            s_FrameDispatch.End();
             m_NumberOfMetricsThisFrame = 0;
         }
 
@@ -421,7 +531,7 @@ namespace Unity.Netcode
         }
     }
 
-    internal class NetcodeObserver
+        internal class NetcodeObserver
     {
         public static IMetricObserver Observer { get; } = MetricObserverFactory.Construct();
     }

Runtime/Metrics/NullNetworkMetrics.cs

@@ -137,6 +137,30 @@ namespace Unity.Netcode
         {
         }
 
+        public void TrackPacketSent(uint packetCount)
+        {
+        }
+
+        public void TrackPacketReceived(uint packetCount)
+        {
+        }
+
+        public void UpdateRttToServer(int rtt)
+        {
+        }
+
+        public void UpdateNetworkObjectsCount(int count)
+        {
+        }
+
+        public void UpdateConnectionsCount(int count)
+        {
+        }
+
+        public void UpdatePacketLoss(float packetLoss)
+        {
+        }
+
         public void DispatchFrame()
         {
         }

Runtime/Metrics/StreamExtensions.cs

@@ -1,12 +0,0 @@
-using System.IO;
-
-namespace Unity.Netcode
-{
-    public static class StreamExtensions
-    {
-        public static long SafeGetLengthOrDefault(this Stream stream)
-        {
-            return stream.CanSeek ? stream.Length : 0;
-        }
-    }
-}

Runtime/Metrics/StreamExtensions.cs.meta

@@ -1,11 +0,0 @@
-fileFormatVersion: 2
-guid: 61dd9b1558f6d7c46ad323b2c2c03c29
-MonoImporter:
-  externalObjects: {}
-  serializedVersion: 2
-  defaultReferences: []
-  executionOrder: 0
-  icon: {instanceID: 0}
-  userData: 
-  assetBundleName: 
-  assetBundleVariant: 

Runtime/NetworkVariable/Collections/NetworkList.cs

@@ -8,9 +8,10 @@ namespace Unity.Netcode
     /// Event based NetworkVariable container for syncing Lists
     /// </summary>
     /// <typeparam name="T">The type for the list</typeparam>
-    public class NetworkList<T> : NetworkVariableBase where T : unmanaged, IEquatable<T>
+    public class NetworkList<T> : NetworkVariableSerialization<T> where T : unmanaged, IEquatable<T>
     {
         private NativeList<T> m_List = new NativeList<T>(64, Allocator.Persistent);
+        private NativeList<T> m_ListAtLastReset = new NativeList<T>(64, Allocator.Persistent);
         private NativeList<NetworkListEvent<T>> m_DirtyEvents = new NativeList<NetworkListEvent<T>>(64, Allocator.Persistent);
 
         /// <summary>
@@ -24,17 +25,12 @@ namespace Unity.Netcode
         /// </summary>
         public event OnListChangedDelegate OnListChanged;
 
-        /// <summary>
-        /// Creates a NetworkList with the default value and settings
-        /// </summary>
         public NetworkList() { }
 
-        /// <summary>
+        public NetworkList(IEnumerable<T> values = default,
-        /// Creates a NetworkList with the default value and custom settings
+            NetworkVariableReadPermission readPerm = DefaultReadPerm,
-        /// </summary>
+            NetworkVariableWritePermission writePerm = DefaultWritePerm)
-        /// <param name="readPerm">The read permission to use for the NetworkList</param>
+            : base(readPerm, writePerm)
-        /// <param name="values">The initial value to use for the NetworkList</param>
-        public NetworkList(NetworkVariableReadPermission readPerm, IEnumerable<T> values) : base(readPerm)
         {
             foreach (var value in values)
             {
@@ -42,24 +38,15 @@ namespace Unity.Netcode
             }
         }
 
-        /// <summary>
-        /// Creates a NetworkList with a custom value and the default settings
-        /// </summary>
-        /// <param name="values">The initial value to use for the NetworkList</param>
-        public NetworkList(IEnumerable<T> values)
-        {
-            foreach (var value in values)
-            {
-                m_List.Add(value);
-
-            }
-        }
-
         /// <inheritdoc />
         public override void ResetDirty()
         {
             base.ResetDirty();
-            m_DirtyEvents.Clear();
+            if (m_DirtyEvents.Length > 0)
+            {
+                m_DirtyEvents.Clear();
+                m_ListAtLastReset.CopyFrom(m_List);
+            }
         }
 
         /// <inheritdoc />
@@ -90,18 +77,18 @@ namespace Unity.Netcode
                 {
                     case NetworkListEvent<T>.EventType.Add:
                         {
-                            writer.WriteValueSafe(m_DirtyEvents[i].Value);
+                            Write(writer, m_DirtyEvents[i].Value);
                         }
                         break;
                     case NetworkListEvent<T>.EventType.Insert:
                         {
                             writer.WriteValueSafe(m_DirtyEvents[i].Index);
-                            writer.WriteValueSafe(m_DirtyEvents[i].Value);
+                            Write(writer, m_DirtyEvents[i].Value);
                         }
                         break;
                     case NetworkListEvent<T>.EventType.Remove:
                         {
-                            writer.WriteValueSafe(m_DirtyEvents[i].Value);
+                            Write(writer, m_DirtyEvents[i].Value);
                         }
                         break;
                     case NetworkListEvent<T>.EventType.RemoveAt:
@@ -112,7 +99,7 @@ namespace Unity.Netcode
                     case NetworkListEvent<T>.EventType.Value:
                         {
                             writer.WriteValueSafe(m_DirtyEvents[i].Index);
-                            writer.WriteValueSafe(m_DirtyEvents[i].Value);
+                            Write(writer, m_DirtyEvents[i].Value);
                         }
                         break;
                     case NetworkListEvent<T>.EventType.Clear:
@@ -127,10 +114,10 @@ namespace Unity.Netcode
         /// <inheritdoc />
         public override void WriteField(FastBufferWriter writer)
         {
-            writer.WriteValueSafe((ushort)m_List.Length);
+            writer.WriteValueSafe((ushort)m_ListAtLastReset.Length);
-            for (int i = 0; i < m_List.Length; i++)
+            for (int i = 0; i < m_ListAtLastReset.Length; i++)
             {
-                writer.WriteValueSafe(m_List[i]);
+                Write(writer, m_ListAtLastReset[i]);
             }
         }
 
@@ -141,7 +128,7 @@ namespace Unity.Netcode
             reader.ReadValueSafe(out ushort count);
             for (int i = 0; i < count; i++)
             {
-                reader.ReadValueSafe(out T value);
+                Read(reader, out T value);
                 m_List.Add(value);
             }
         }
@@ -157,7 +144,7 @@ namespace Unity.Netcode
                 {
                     case NetworkListEvent<T>.EventType.Add:
                         {
-                            reader.ReadValueSafe(out T value);
+                            Read(reader, out T value);
                             m_List.Add(value);
 
                             if (OnListChanged != null)
@@ -184,7 +171,7 @@ namespace Unity.Netcode
                     case NetworkListEvent<T>.EventType.Insert:
                         {
                             reader.ReadValueSafe(out int index);
-                            reader.ReadValueSafe(out T value);
+                            Read(reader, out T value);
                             m_List.InsertRangeWithBeginEnd(index, index + 1);
                             m_List[index] = value;
 
@@ -211,7 +198,7 @@ namespace Unity.Netcode
                         break;
                     case NetworkListEvent<T>.EventType.Remove:
                         {
-                            reader.ReadValueSafe(out T value);
+                            Read(reader, out T value);
                             int index = m_List.IndexOf(value);
                             if (index == -1)
                             {
@@ -271,19 +258,23 @@ namespace Unity.Netcode
                     case NetworkListEvent<T>.EventType.Value:
                         {
                             reader.ReadValueSafe(out int index);
-                            reader.ReadValueSafe(out T value);
+                            Read(reader, out T value);
-                            if (index < m_List.Length)
+                            if (index >= m_List.Length)
                             {
-                                m_List[index] = value;
+                                throw new Exception("Shouldn't be here, index is higher than list length");
                             }
 
+                            var previousValue = m_List[index];
+                            m_List[index] = value;
+
                             if (OnListChanged != null)
                             {
                                 OnListChanged(new NetworkListEvent<T>
                                 {
                                     Type = eventType,
                                     Index = index,
-                                    Value = value
+                                    Value = value,
+                                    PreviousValue = previousValue
                                 });
                             }
 
@@ -293,7 +284,8 @@ namespace Unity.Netcode
                                 {
                                     Type = eventType,
                                     Index = index,
-                                    Value = value
+                                    Value = value,
+                                    PreviousValue = previousValue
                                 });
                             }
                         }
@@ -368,7 +360,7 @@ namespace Unity.Netcode
         public bool Contains(T item)
         {
             int index = NativeArrayExtensions.IndexOf(m_List, item);
-            return index == -1;
+            return index != -1;
         }
 
         /// <inheritdoc />
@@ -467,6 +459,7 @@ namespace Unity.Netcode
         public override void Dispose()
         {
             m_List.Dispose();
+            m_ListAtLastReset.Dispose();
             m_DirtyEvents.Dispose();
         }
     }
@@ -528,6 +521,11 @@ namespace Unity.Netcode
         /// </summary>
         public T Value;
 
+        /// <summary>
+        /// The previous value when "Value" has changed, if available.
+        /// </summary>
+        public T PreviousValue;
+
         /// <summary>
         /// the index changed, added or removed if available
         /// </summary>

Runtime/NetworkVariable/NetworkVariable.cs

@@ -1,5 +1,7 @@
 using UnityEngine;
 using System;
+using System.Runtime.CompilerServices;
+using Unity.Collections.LowLevel.Unsafe;
 
 namespace Unity.Netcode
 {
@@ -7,7 +9,7 @@ namespace Unity.Netcode
     /// A variable that can be synchronized over the network.
     /// </summary>
     [Serializable]
-    public class NetworkVariable<T> : NetworkVariableBase where T : unmanaged
+    public class NetworkVariable<T> : NetworkVariableSerialization<T> where T : unmanaged
     {
         /// <summary>
         /// Delegate type for value changed event
@@ -20,38 +22,11 @@ namespace Unity.Netcode
         /// </summary>
         public OnValueChangedDelegate OnValueChanged;
 
-        /// <summary>
-        /// Creates a NetworkVariable with the default value and custom read permission
-        /// </summary>
-        /// <param name="readPerm">The read permission for the NetworkVariable</param>
 
-        public NetworkVariable()
+        public NetworkVariable(T value = default,
-        {
+            NetworkVariableReadPermission readPerm = DefaultReadPerm,
-        }
+            NetworkVariableWritePermission writePerm = DefaultWritePerm)
-
+            : base(readPerm, writePerm)
-        /// <summary>
-        /// Creates a NetworkVariable with the default value and custom read permission
-        /// </summary>
-        /// <param name="readPerm">The read permission for the NetworkVariable</param>
-        public NetworkVariable(NetworkVariableReadPermission readPerm) : base(readPerm)
-        {
-        }
-
-        /// <summary>
-        /// Creates a NetworkVariable with a custom value and custom settings
-        /// </summary>
-        /// <param name="readPerm">The read permission for the NetworkVariable</param>
-        /// <param name="value">The initial value to use for the NetworkVariable</param>
-        public NetworkVariable(NetworkVariableReadPermission readPerm, T value) : base(readPerm)
-        {
-            m_InternalValue = value;
-        }
-
-        /// <summary>
-        /// Creates a NetworkVariable with a custom value and the default read permission
-        /// </summary>
-        /// <param name="value">The initial value to use for the NetworkVariable</param>
-        public NetworkVariable(T value)
         {
             m_InternalValue = value;
         }
@@ -67,19 +42,36 @@ namespace Unity.Netcode
             get => m_InternalValue;
             set
             {
-                // this could be improved. The Networking Manager is not always initialized here
+                // Compare bitwise
-                //  Good place to decouple network manager from the network variable
+                if (ValueEquals(ref m_InternalValue, ref value))
-
-                // Also, note this is not really very water-tight, if you are running as a host
-                //  we cannot tell if a NetworkVariable write is happening inside client-ish code
-                if (m_NetworkBehaviour && (m_NetworkBehaviour.NetworkManager.IsClient && !m_NetworkBehaviour.NetworkManager.IsHost))
                 {
-                    throw new InvalidOperationException("Client can't write to NetworkVariables");
+                    return;
                 }
+
+                if (m_NetworkBehaviour && !CanClientWrite(m_NetworkBehaviour.NetworkManager.LocalClientId))
+                {
+                    throw new InvalidOperationException("Client is not allowed to write to this NetworkVariable");
+                }
+
                 Set(value);
             }
         }
 
+        // Compares two values of the same unmanaged type by underlying memory
+        // Ignoring any overriden value checks
+        // Size is fixed
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        private static unsafe bool ValueEquals(ref T a, ref T b)
+        {
+            // get unmanaged pointers
+            var aptr = UnsafeUtility.AddressOf(ref a);
+            var bptr = UnsafeUtility.AddressOf(ref b);
+
+            // compare addresses
+            return UnsafeUtility.MemCmp(aptr, bptr, sizeof(T)) == 0;
+        }
+
+
         private protected void Set(T value)
         {
             m_IsDirty = true;
@@ -97,7 +89,6 @@ namespace Unity.Netcode
             WriteField(writer);
         }
 
-
         /// <summary>
         /// Reads value from the reader and applies it
         /// </summary>
@@ -105,8 +96,13 @@ namespace Unity.Netcode
         /// <param name="keepDirtyDelta">Whether or not the container should keep the dirty delta, or mark the delta as consumed</param>
         public override void ReadDelta(FastBufferReader reader, bool keepDirtyDelta)
         {
+            // todo:
+            // keepDirtyDelta marks a variable received as dirty and causes the server to send the value to clients
+            // In a prefect world, whether a variable was A) modified locally or B) received and needs retransmit
+            // would be stored in different fields
+
             T previousValue = m_InternalValue;
-            reader.ReadValueSafe(out m_InternalValue);
+            Read(reader, out m_InternalValue);
 
             if (keepDirtyDelta)
             {
@@ -119,13 +115,13 @@ namespace Unity.Netcode
         /// <inheritdoc />
         public override void ReadField(FastBufferReader reader)
         {
-            reader.ReadValueSafe(out m_InternalValue);
+            Read(reader, out m_InternalValue);
         }
 
         /// <inheritdoc />
         public override void WriteField(FastBufferWriter writer)
         {
-            writer.WriteValueSafe(m_InternalValue);
+            Write(writer, m_InternalValue);
         }
     }
 }

Runtime/NetworkVariable/NetworkVariableBase.cs

@@ -10,7 +10,7 @@ namespace Unity.Netcode
         /// <summary>
         /// The delivery type (QoS) to send data with
         /// </summary>
-        internal const NetworkDelivery Delivery = NetworkDelivery.ReliableSequenced;
+        internal const NetworkDelivery Delivery = NetworkDelivery.ReliableFragmentedSequenced;
 
         private protected NetworkBehaviour m_NetworkBehaviour;
 
@@ -19,9 +19,15 @@ namespace Unity.Netcode
             m_NetworkBehaviour = networkBehaviour;
         }
 
-        protected NetworkVariableBase(NetworkVariableReadPermission readPermIn = NetworkVariableReadPermission.Everyone)
+        public const NetworkVariableReadPermission DefaultReadPerm = NetworkVariableReadPermission.Everyone;
+        public const NetworkVariableWritePermission DefaultWritePerm = NetworkVariableWritePermission.Server;
+
+        protected NetworkVariableBase(
+            NetworkVariableReadPermission readPerm = DefaultReadPerm,
+            NetworkVariableWritePermission writePerm = DefaultWritePerm)
         {
-            ReadPerm = readPermIn;
+            ReadPerm = readPerm;
+            WritePerm = writePerm;
         }
 
         private protected bool m_IsDirty;
@@ -37,6 +43,8 @@ namespace Unity.Netcode
         /// </summary>
         public readonly NetworkVariableReadPermission ReadPerm;
 
+        public readonly NetworkVariableWritePermission WritePerm;
+
         /// <summary>
         /// Sets whether or not the variable needs to be delta synced
         /// </summary>
@@ -62,26 +70,36 @@ namespace Unity.Netcode
             return m_IsDirty;
         }
 
-        public virtual bool ShouldWrite(ulong clientId, bool isServer)
-        {
-            return IsDirty() && isServer && CanClientRead(clientId);
-        }
-
-        /// <summary>
-        /// Gets Whether or not a specific client can read to the varaible
-        /// </summary>
-        /// <param name="clientId">The clientId of the remote client</param>
-        /// <returns>Whether or not the client can read to the variable</returns>
         public bool CanClientRead(ulong clientId)
         {
             switch (ReadPerm)
             {
+                default:
                 case NetworkVariableReadPermission.Everyone:
                     return true;
-                case NetworkVariableReadPermission.OwnerOnly:
+                case NetworkVariableReadPermission.Owner:
-                    return m_NetworkBehaviour.OwnerClientId == clientId;
+                    return clientId == m_NetworkBehaviour.NetworkObject.OwnerClientId;
             }
-            return true;
+        }
+
+        public bool CanClientWrite(ulong clientId)
+        {
+            switch (WritePerm)
+            {
+                default:
+                case NetworkVariableWritePermission.Server:
+                    return clientId == NetworkManager.ServerClientId;
+                case NetworkVariableWritePermission.Owner:
+                    return clientId == m_NetworkBehaviour.NetworkObject.OwnerClientId;
+            }
+        }
+
+        /// <summary>
+        /// Returns the ClientId of the owning client
+        /// </summary>
+        internal ulong OwnerClientId()
+        {
+            return m_NetworkBehaviour.NetworkObject.OwnerClientId;
         }
 
         /// <summary>
@@ -107,7 +125,6 @@ namespace Unity.Netcode
         /// </summary>
         /// <param name="reader">The stream to read the delta from</param>
         /// <param name="keepDirtyDelta">Whether or not the delta should be kept as dirty or consumed</param>
-
         public abstract void ReadDelta(FastBufferReader reader, bool keepDirtyDelta);
 
         public virtual void Dispose()

Runtime/NetworkVariable/NetworkVariableHelper.cs

@@ -0,0 +1,77 @@
+using System;
+using UnityEngine;
+
+namespace Unity.Netcode
+{
+    public class NetworkVariableHelper
+    {
+        // This is called by ILPP during module initialization for all unmanaged INetworkSerializable types
+        // This sets up NetworkVariable so that it properly calls NetworkSerialize() when wrapping an INetworkSerializable value
+        //
+        // The reason this is done is to avoid runtime reflection and boxing in NetworkVariable - without this,
+        // NetworkVariable would need to do a `var is INetworkSerializable` check, and then cast to INetworkSerializable,
+        // *both* of which would cause a boxing allocation. Alternatively, NetworkVariable could have been split into
+        // NetworkVariable and NetworkSerializableVariable or something like that, which would have caused a poor
+        // user experience and an API that's easier to get wrong than right. This is a bit ugly on the implementation
+        // side, but it gets the best achievable user experience and performance.
+        //
+        // RuntimeAccessModifiersILPP will make this `public`
+        internal static void InitializeDelegatesNetworkSerializable<T>() where T : unmanaged, INetworkSerializable
+        {
+            NetworkVariableSerialization<T>.SetWriteDelegate(NetworkVariableSerialization<T>.WriteNetworkSerializable);
+            NetworkVariableSerialization<T>.SetReadDelegate(NetworkVariableSerialization<T>.ReadNetworkSerializable);
+        }
+        internal static void InitializeDelegatesStruct<T>() where T : unmanaged, INetworkSerializeByMemcpy
+        {
+            NetworkVariableSerialization<T>.SetWriteDelegate(NetworkVariableSerialization<T>.WriteStruct);
+            NetworkVariableSerialization<T>.SetReadDelegate(NetworkVariableSerialization<T>.ReadStruct);
+        }
+        internal static void InitializeDelegatesEnum<T>() where T : unmanaged, Enum
+        {
+            NetworkVariableSerialization<T>.SetWriteDelegate(NetworkVariableSerialization<T>.WriteEnum);
+            NetworkVariableSerialization<T>.SetReadDelegate(NetworkVariableSerialization<T>.ReadEnum);
+        }
+        internal static void InitializeDelegatesPrimitive<T>() where T : unmanaged, IComparable, IConvertible, IComparable<T>, IEquatable<T>
+        {
+            NetworkVariableSerialization<T>.SetWriteDelegate(NetworkVariableSerialization<T>.WritePrimitive);
+            NetworkVariableSerialization<T>.SetReadDelegate(NetworkVariableSerialization<T>.ReadPrimitive);
+        }
+
+        internal static void InitializeAllBaseDelegates()
+        {
+            // Built-in C# types, serialized through a generic method
+            InitializeDelegatesPrimitive<bool>();
+            InitializeDelegatesPrimitive<byte>();
+            InitializeDelegatesPrimitive<sbyte>();
+            InitializeDelegatesPrimitive<char>();
+            InitializeDelegatesPrimitive<decimal>();
+            InitializeDelegatesPrimitive<float>();
+            InitializeDelegatesPrimitive<double>();
+            InitializeDelegatesPrimitive<short>();
+            InitializeDelegatesPrimitive<ushort>();
+            InitializeDelegatesPrimitive<int>();
+            InitializeDelegatesPrimitive<uint>();
+            InitializeDelegatesPrimitive<long>();
+            InitializeDelegatesPrimitive<ulong>();
+
+            // Built-in Unity types, serialized with specific overloads because they're structs without ISerializeByMemcpy attached
+            NetworkVariableSerialization<Vector2>.SetWriteDelegate((FastBufferWriter writer, in Vector2 value) => { writer.WriteValueSafe(value); });
+            NetworkVariableSerialization<Vector3>.SetWriteDelegate((FastBufferWriter writer, in Vector3 value) => { writer.WriteValueSafe(value); });
+            NetworkVariableSerialization<Vector4>.SetWriteDelegate((FastBufferWriter writer, in Vector4 value) => { writer.WriteValueSafe(value); });
+            NetworkVariableSerialization<Quaternion>.SetWriteDelegate((FastBufferWriter writer, in Quaternion value) => { writer.WriteValueSafe(value); });
+            NetworkVariableSerialization<Color>.SetWriteDelegate((FastBufferWriter writer, in Color value) => { writer.WriteValueSafe(value); });
+            NetworkVariableSerialization<Color32>.SetWriteDelegate((FastBufferWriter writer, in Color32 value) => { writer.WriteValueSafe(value); });
+            NetworkVariableSerialization<Ray>.SetWriteDelegate((FastBufferWriter writer, in Ray value) => { writer.WriteValueSafe(value); });
+            NetworkVariableSerialization<Ray2D>.SetWriteDelegate((FastBufferWriter writer, in Ray2D value) => { writer.WriteValueSafe(value); });
+
+            NetworkVariableSerialization<Vector2>.SetReadDelegate((FastBufferReader reader, out Vector2 value) => { reader.ReadValueSafe(out value); });
+            NetworkVariableSerialization<Vector3>.SetReadDelegate((FastBufferReader reader, out Vector3 value) => { reader.ReadValueSafe(out value); });
+            NetworkVariableSerialization<Vector4>.SetReadDelegate((FastBufferReader reader, out Vector4 value) => { reader.ReadValueSafe(out value); });
+            NetworkVariableSerialization<Quaternion>.SetReadDelegate((FastBufferReader reader, out Quaternion value) => { reader.ReadValueSafe(out value); });
+            NetworkVariableSerialization<Color>.SetReadDelegate((FastBufferReader reader, out Color value) => { reader.ReadValueSafe(out value); });
+            NetworkVariableSerialization<Color32>.SetReadDelegate((FastBufferReader reader, out Color32 value) => { reader.ReadValueSafe(out value); });
+            NetworkVariableSerialization<Ray>.SetReadDelegate((FastBufferReader reader, out Ray value) => { reader.ReadValueSafe(out value); });
+            NetworkVariableSerialization<Ray2D>.SetReadDelegate((FastBufferReader reader, out Ray2D value) => { reader.ReadValueSafe(out value); });
+        }
+    }
+}

Runtime/NetworkVariable/NetworkVariableHelper.cs.meta

@@ -1,5 +1,5 @@
 fileFormatVersion: 2
-guid: a8514b4eca0c7044d9b92faf9407ec93
+guid: e54b65208bd3bbe4eaf62ca0384ae21f
 MonoImporter:
   externalObjects: {}
   serializedVersion: 2

Runtime/NetworkVariable/NetworkVariablePermission.cs

@@ -1,18 +1,14 @@
 namespace Unity.Netcode
 {
-    /// <summary>
-    /// Permission type
-    /// </summary>
     public enum NetworkVariableReadPermission
     {
-        /// <summary>
-        /// Everyone
-        /// </summary>
         Everyone,
+        Owner,
+    }
 
-        /// <summary>
+    public enum NetworkVariableWritePermission
-        /// Owner-ownly
+    {
-        /// </summary>
+        Server,
-        OwnerOnly,
+        Owner
     }
 }

Runtime/NetworkVariable/NetworkVariableSerialization.cs

@@ -0,0 +1,169 @@
+using System;
+
+namespace Unity.Netcode
+{
+    /// <summary>
+    /// Support methods for reading/writing NetworkVariables
+    /// Because there are multiple overloads of WriteValue/ReadValue based on different generic constraints,
+    /// but there's no way to achieve the same thing with a class, this includes various read/write delegates
+    /// based on which constraints are met by `T`. These constraints are set up by `NetworkVariableHelpers`,
+    /// which is invoked by code generated by ILPP during module load.
+    /// (As it turns out, IL has support for a module initializer that C# doesn't expose.)
+    /// This installs the correct delegate for each `T` to ensure that each type is serialized properly.
+    ///
+    /// Any type that inherits from `NetworkVariableSerialization<T>` will implicitly result in any `T`
+    /// passed to it being picked up and initialized by ILPP.
+    ///
+    /// The methods here, despite being static, are `protected` specifically to ensure that anything that
+    /// wants access to them has to inherit from this base class, thus enabling ILPP to find and initialize it.
+    /// </summary>
+    [Serializable]
+    public abstract class NetworkVariableSerialization<T> : NetworkVariableBase where T : unmanaged
+    {
+        // Functions that know how to serialize INetworkSerializable
+        internal static void WriteNetworkSerializable<TForMethod>(FastBufferWriter writer, in TForMethod value)
+            where TForMethod : unmanaged, INetworkSerializable
+        {
+            writer.WriteNetworkSerializable(value);
+        }
+
+        internal static void ReadNetworkSerializable<TForMethod>(FastBufferReader reader, out TForMethod value)
+            where TForMethod : unmanaged, INetworkSerializable
+        {
+            reader.ReadNetworkSerializable(out value);
+        }
+
+        // Functions that serialize structs
+        internal static void WriteStruct<TForMethod>(FastBufferWriter writer, in TForMethod value)
+            where TForMethod : unmanaged, INetworkSerializeByMemcpy
+        {
+            writer.WriteValueSafe(value);
+        }
+        internal static void ReadStruct<TForMethod>(FastBufferReader reader, out TForMethod value)
+            where TForMethod : unmanaged, INetworkSerializeByMemcpy
+        {
+            reader.ReadValueSafe(out value);
+        }
+
+        // Functions that serialize enums
+        internal static void WriteEnum<TForMethod>(FastBufferWriter writer, in TForMethod value)
+            where TForMethod : unmanaged, Enum
+        {
+            writer.WriteValueSafe(value);
+        }
+        internal static void ReadEnum<TForMethod>(FastBufferReader reader, out TForMethod value)
+            where TForMethod : unmanaged, Enum
+        {
+            reader.ReadValueSafe(out value);
+        }
+
+        // Functions that serialize other types
+        internal static void WritePrimitive<TForMethod>(FastBufferWriter writer, in TForMethod value)
+            where TForMethod : unmanaged, IComparable, IConvertible, IComparable<TForMethod>, IEquatable<TForMethod>
+        {
+            writer.WriteValueSafe(value);
+        }
+
+        internal static void ReadPrimitive<TForMethod>(FastBufferReader reader, out TForMethod value)
+            where TForMethod : unmanaged, IComparable, IConvertible, IComparable<TForMethod>, IEquatable<TForMethod>
+        {
+            reader.ReadValueSafe(out value);
+        }
+
+        // Should never be reachable at runtime. All calls to this should be replaced with the correct
+        // call above by ILPP.
+        private static void WriteValue<TForMethod>(FastBufferWriter writer, in TForMethod value)
+            where TForMethod : unmanaged
+        {
+            if (value is INetworkSerializable)
+            {
+                typeof(NetworkVariableHelper).GetMethod(nameof(NetworkVariableHelper.InitializeDelegatesNetworkSerializable)).MakeGenericMethod(typeof(TForMethod)).Invoke(null, null);
+            }
+            else if (value is INetworkSerializeByMemcpy)
+            {
+                typeof(NetworkVariableHelper).GetMethod(nameof(NetworkVariableHelper.InitializeDelegatesStruct)).MakeGenericMethod(typeof(TForMethod)).Invoke(null, null);
+            }
+            else if (value is Enum)
+            {
+                typeof(NetworkVariableHelper).GetMethod(nameof(NetworkVariableHelper.InitializeDelegatesEnum)).MakeGenericMethod(typeof(TForMethod)).Invoke(null, null);
+            }
+            else
+            {
+                throw new Exception($"Type {typeof(T).FullName} is not serializable - it must implement either INetworkSerializable or ISerializeByMemcpy");
+
+            }
+            NetworkVariableSerialization<TForMethod>.Write(writer, value);
+        }
+
+        private static void ReadValue<TForMethod>(FastBufferReader reader, out TForMethod value)
+            where TForMethod : unmanaged
+        {
+            if (typeof(INetworkSerializable).IsAssignableFrom(typeof(TForMethod)))
+            {
+                typeof(NetworkVariableHelper).GetMethod(nameof(NetworkVariableHelper.InitializeDelegatesNetworkSerializable)).MakeGenericMethod(typeof(TForMethod)).Invoke(null, null);
+            }
+            else if (typeof(INetworkSerializeByMemcpy).IsAssignableFrom(typeof(TForMethod)))
+            {
+                typeof(NetworkVariableHelper).GetMethod(nameof(NetworkVariableHelper.InitializeDelegatesStruct)).MakeGenericMethod(typeof(TForMethod)).Invoke(null, null);
+            }
+            else if (typeof(Enum).IsAssignableFrom(typeof(TForMethod)))
+            {
+                typeof(NetworkVariableHelper).GetMethod(nameof(NetworkVariableHelper.InitializeDelegatesEnum)).MakeGenericMethod(typeof(TForMethod)).Invoke(null, null);
+            }
+            else
+            {
+                throw new Exception($"Type {typeof(T).FullName} is not serializable - it must implement either INetworkSerializable or ISerializeByMemcpy");
+
+            }
+            NetworkVariableSerialization<TForMethod>.Read(reader, out value);
+        }
+
+        protected internal delegate void WriteDelegate<TForMethod>(FastBufferWriter writer, in TForMethod value);
+
+        protected internal delegate void ReadDelegate<TForMethod>(FastBufferReader reader, out TForMethod value);
+
+        // These static delegates provide the right implementation for writing and reading a particular network variable type.
+        // For most types, these default to WriteValue() and ReadValue(), which perform simple memcpy operations.
+        //
+        // INetworkSerializableILPP will generate startup code that will set it to WriteNetworkSerializable()
+        // and ReadNetworkSerializable() for INetworkSerializable types, which will call NetworkSerialize().
+        //
+        // In the future we may be able to use this to provide packing implementations for floats and integers to optimize bandwidth usage.
+        //
+        // The reason this is done is to avoid runtime reflection and boxing in NetworkVariable - without this,
+        // NetworkVariable would need to do a `var is INetworkSerializable` check, and then cast to INetworkSerializable,
+        // *both* of which would cause a boxing allocation. Alternatively, NetworkVariable could have been split into
+        // NetworkVariable and NetworkSerializableVariable or something like that, which would have caused a poor
+        // user experience and an API that's easier to get wrong than right. This is a bit ugly on the implementation
+        // side, but it gets the best achievable user experience and performance.
+        private static WriteDelegate<T> s_Write = WriteValue;
+        private static ReadDelegate<T> s_Read = ReadValue;
+
+        protected static void Write(FastBufferWriter writer, in T value)
+        {
+            s_Write(writer, value);
+        }
+
+        protected static void Read(FastBufferReader reader, out T value)
+        {
+            s_Read(reader, out value);
+        }
+
+        internal static void SetWriteDelegate(WriteDelegate<T> write)
+        {
+            s_Write = write;
+        }
+
+        internal static void SetReadDelegate(ReadDelegate<T> read)
+        {
+            s_Read = read;
+        }
+
+        protected NetworkVariableSerialization(
+            NetworkVariableReadPermission readPerm = DefaultReadPerm,
+            NetworkVariableWritePermission writePerm = DefaultWritePerm)
+            : base(readPerm, writePerm)
+        {
+        }
+    }
+}

Runtime/NetworkVariable/NetworkVariableSerialization.cs.meta

@@ -0,0 +1,3 @@
+fileFormatVersion: 2
+guid: 2c6ef5fdf2e94ec3b4ce8086d52700b3
+timeCreated: 1650985453

Runtime/Profiling/ProfilingHooks.cs

@@ -37,14 +37,14 @@ namespace Unity.Netcode
             return marker;
         }
 
-        public void OnBeforeSendMessage(ulong clientId, Type messageType, NetworkDelivery delivery)
+        public void OnBeforeSendMessage<T>(ulong clientId, ref T message, NetworkDelivery delivery) where T : INetworkMessage
         {
-            GetSenderProfilerMarker(messageType).Begin();
+            GetSenderProfilerMarker(typeof(T)).Begin();
         }
 
-        public void OnAfterSendMessage(ulong clientId, Type messageType, NetworkDelivery delivery, int messageSizeBytes)
+        public void OnAfterSendMessage<T>(ulong clientId, ref T message, NetworkDelivery delivery, int messageSizeBytes) where T : INetworkMessage
         {
-            GetSenderProfilerMarker(messageType).End();
+            GetSenderProfilerMarker(typeof(T)).End();
         }
 
         public void OnBeforeReceiveMessage(ulong senderId, Type messageType, int messageSizeBytes)
@@ -82,9 +82,19 @@ namespace Unity.Netcode
             return true;
         }
 
-        public bool OnVerifyCanReceive(ulong senderId, Type messageType)
+        public bool OnVerifyCanReceive(ulong senderId, Type messageType, FastBufferReader messageContent, ref NetworkContext context)
         {
             return true;
         }
+
+        public void OnBeforeHandleMessage<T>(ref T message, ref NetworkContext context) where T : INetworkMessage
+        {
+            // nop
+        }
+
+        public void OnAfterHandleMessage<T>(ref T message, ref NetworkContext context) where T : INetworkMessage
+        {
+            // nop
+        }
     }
 }

Runtime/Reflection/TypeExtensions.cs

@@ -1,31 +0,0 @@
-using System;
-
-namespace Unity.Netcode
-{
-    internal static class TypeExtensions
-    {
-        internal static bool HasInterface(this Type type, Type interfaceType)
-        {
-            var ifaces = type.GetInterfaces();
-            for (int i = 0; i < ifaces.Length; i++)
-            {
-                if (ifaces[i] == interfaceType)
-                {
-                    return true;
-                }
-            }
-
-            return false;
-        }
-
-        internal static bool IsNullable(this Type type)
-        {
-            if (!type.IsValueType)
-            {
-                return true; // ref-type
-            }
-
-            return Nullable.GetUnderlyingType(type) != null;
-        }
-    }
-}

Runtime/Reflection/TypeExtensions.cs.meta

@@ -1,11 +0,0 @@
-fileFormatVersion: 2
-guid: 3e168a2bc1a1e2642af0369780fb560c
-MonoImporter:
-  externalObjects: {}
-  serializedVersion: 2
-  defaultReferences: []
-  executionOrder: 0
-  icon: {instanceID: 0}
-  userData: 
-  assetBundleName: 
-  assetBundleVariant: 

Runtime/SceneManagement/ISceneManagerHandler.cs

@@ -0,0 +1,28 @@
+using System;
+using UnityEngine;
+using UnityEngine.SceneManagement;
+
+namespace Unity.Netcode
+{
+    /// <summary>
+    /// Used to override the LoadSceneAsync and UnloadSceneAsync methods called
+    /// within the NetworkSceneManager.
+    /// </summary>
+    internal interface ISceneManagerHandler
+    {
+        // Generic action to call when a scene is finished loading/unloading
+        struct SceneEventAction
+        {
+            internal uint SceneEventId;
+            internal Action<uint> EventAction;
+            internal void Invoke()
+            {
+                EventAction.Invoke(SceneEventId);
+            }
+        }
+
+        AsyncOperation LoadSceneAsync(string sceneName, LoadSceneMode loadSceneMode, SceneEventAction sceneEventAction);
+
+        AsyncOperation UnloadSceneAsync(Scene scene, SceneEventAction sceneEventAction);
+    }
+}

Runtime/SceneManagement/ISceneManagerHandler.cs.meta

@@ -1,5 +1,5 @@
 fileFormatVersion: 2
-guid: bd9e1475e8c8e4a6d935fe2409e3bd26
+guid: de907a9fb8151e240800dbcc97f8e745
 MonoImporter:
   externalObjects: {}
   serializedVersion: 2

Runtime/SceneManagement/NetworkSceneManager.cs

@@ -132,20 +132,14 @@ namespace Unity.Netcode
         private const NetworkDelivery k_DeliveryType = NetworkDelivery.ReliableFragmentedSequenced;
         internal const int InvalidSceneNameOrPath = -1;
 
-        // Used to be able to turn re-synchronization off for future snapshot development purposes.
+        // Used to be able to turn re-synchronization off
         internal static bool DisableReSynchronization;
 
         /// <summary>
         /// Used to detect if a scene event is underway
         /// Only 1 scene event can occur on the server at a time for now.
         /// </summary>
-        private static bool s_IsSceneEventActive = false;
+        private bool m_IsSceneEventActive = false;
-
-        // TODO: Remove `m_IsRunningUnitTest` entirely after we switch to multi-process testing
-        // In MultiInstance tests, we cannot allow clients to load additional scenes as they're sharing the same scene space / Unity instance.
-#if UNITY_INCLUDE_TESTS
-        private readonly bool m_IsRunningUnitTest = SceneManager.GetActiveScene().name.StartsWith("InitTestScene");
-#endif
 
         /// <summary>
         /// The delegate callback definition for scene event notifications.<br/>
@@ -324,6 +318,31 @@ namespace Unity.Netcode
         /// </summary>
         public VerifySceneBeforeLoadingDelegateHandler VerifySceneBeforeLoading;
 
+        /// <summary>
+        ///  Proof of concept: Interface version that allows for the decoupling from
+        ///  the SceneManager's Load and Unload methods for testing purposes (potentially other future usage)
+        /// </summary>
+        private class DefaultSceneManagerHandler : ISceneManagerHandler
+        {
+            public AsyncOperation LoadSceneAsync(string sceneName, LoadSceneMode loadSceneMode, ISceneManagerHandler.SceneEventAction sceneEventAction)
+            {
+                var operation = SceneManager.LoadSceneAsync(sceneName, loadSceneMode);
+                operation.completed += new Action<AsyncOperation>(asyncOp2 => { sceneEventAction.Invoke(); });
+                return operation;
+            }
+
+            public AsyncOperation UnloadSceneAsync(Scene scene, ISceneManagerHandler.SceneEventAction sceneEventAction)
+            {
+                var operation = SceneManager.UnloadSceneAsync(scene);
+                operation.completed += new Action<AsyncOperation>(asyncOp2 => { sceneEventAction.Invoke(); });
+                return operation;
+            }
+        }
+
+        internal ISceneManagerHandler SceneManagerHandler = new DefaultSceneManagerHandler();
+        /// End of Proof of Concept
+
+
         internal readonly Dictionary<Guid, SceneEventProgress> SceneEventProgressTracking = new Dictionary<Guid, SceneEventProgress>();
 
         /// <summary>
@@ -469,8 +488,18 @@ namespace Unity.Netcode
                 var scenePath = SceneUtility.GetScenePathByBuildIndex(i);
                 var hash = XXHash.Hash32(scenePath);
                 var buildIndex = SceneUtility.GetBuildIndexByScenePath(scenePath);
-                HashToBuildIndex.Add(hash, buildIndex);
+
-                BuildIndexToHash.Add(buildIndex, hash);
+                // In the rare-case scenario where a programmatically generated build has duplicate
+                // scene entries, we will log an error and skip the entry
+                if (!HashToBuildIndex.ContainsKey(hash))
+                {
+                    HashToBuildIndex.Add(hash, buildIndex);
+                    BuildIndexToHash.Add(buildIndex, hash);
+                }
+                else
+                {
+                    Debug.LogError($"{nameof(NetworkSceneManager)} is skipping duplicate scene path entry {scenePath}. Make sure your scenes in build list does not contain duplicates!");
+                }
             }
         }
 
@@ -501,7 +530,8 @@ namespace Unity.Netcode
             }
             else
             {
-                throw new Exception($"Scene Hash {sceneHash} does not exist in the {nameof(HashToBuildIndex)} table!");
+                throw new Exception($"Scene Hash {sceneHash} does not exist in the {nameof(HashToBuildIndex)} table!  Verify that all scenes requiring" +
+                    $" server to client synchronization are in the scenes in build list.");
             }
         }
 
@@ -565,20 +595,8 @@ namespace Unity.Netcode
 
             GenerateScenesInBuild();
 
-            // If NetworkManager has this set to true, then we can get the DDOL (DontDestroyOnLoad) from its GaemObject
+            // Since NetworkManager is now always migrated to the DDOL we will use this to get the DDOL scene
-            if (networkManager.DontDestroy)
+            DontDestroyOnLoadScene = networkManager.gameObject.scene;
-            {
-                DontDestroyOnLoadScene = networkManager.gameObject.scene;
-            }
-            else
-            {
-                // Otherwise, we have to create a GameObject and move it into the DDOL in order to
-                // register the DDOL scene handle with NetworkSceneManager
-                var myDDOLObject = new GameObject("DDOL-NWSM");
-                UnityEngine.Object.DontDestroyOnLoad(myDDOLObject);
-                DontDestroyOnLoadScene = myDDOLObject.scene;
-                UnityEngine.Object.Destroy(myDDOLObject);
-            }
 
             ServerSceneHandleToClientSceneHandle.Add(DontDestroyOnLoadScene.handle, DontDestroyOnLoadScene.handle);
             ScenesLoaded.Add(DontDestroyOnLoadScene.handle, DontDestroyOnLoadScene);
@@ -735,10 +753,9 @@ namespace Unity.Netcode
             {
                 EventData = SceneEventDataStore[sceneEventId]
             };
-            var size = m_NetworkManager.SendMessage(message, k_DeliveryType, targetClientIds);
+            var size = m_NetworkManager.SendMessage(ref message, k_DeliveryType, targetClientIds);
 
-            m_NetworkManager.NetworkMetrics.TrackSceneEventSent(
+            m_NetworkManager.NetworkMetrics.TrackSceneEventSent(targetClientIds, (uint)SceneEventDataStore[sceneEventId].SceneEventType, SceneNameFromHash(SceneEventDataStore[sceneEventId].SceneHash), size);
-                targetClientIds, (uint)SceneEventDataStore[sceneEventId].SceneEventType, SceneNameFromHash(SceneEventDataStore[sceneEventId].SceneHash), size);
         }
 
         /// <summary>
@@ -801,7 +818,7 @@ namespace Unity.Netcode
         private SceneEventProgress ValidateSceneEvent(string sceneName, bool isUnloading = false)
         {
             // Return scene event already in progress if one is already in progress
-            if (s_IsSceneEventActive)
+            if (m_IsSceneEventActive)
             {
                 return new SceneEventProgress(null, SceneEventProgressStatus.SceneEventInProgress);
             }
@@ -830,7 +847,7 @@ namespace Unity.Netcode
                 IsSpawnedObjectsPendingInDontDestroyOnLoad = true;
             }
 
-            s_IsSceneEventActive = true;
+            m_IsSceneEventActive = true;
 
             // Set our callback delegate handler for completion
             sceneEventProgress.OnComplete = OnSceneEventProgressCompleted;
@@ -857,12 +874,12 @@ namespace Unity.Netcode
             {
                 EventData = sceneEventData
             };
-            var size = m_NetworkManager.SendMessage(message, k_DeliveryType, m_NetworkManager.ConnectedClientsIds);
+            var size = m_NetworkManager.SendMessage(ref message, k_DeliveryType, m_NetworkManager.ConnectedClientsIds);
 
             m_NetworkManager.NetworkMetrics.TrackSceneEventSent(
                 m_NetworkManager.ConnectedClientsIds,
                 (uint)sceneEventProgress.SceneEventType,
-               SceneNameFromHash(sceneEventProgress.SceneHash),
+                SceneNameFromHash(sceneEventProgress.SceneHash),
                 size);
 
             // Send a local notification to the server that all clients are done loading or unloading
@@ -870,7 +887,7 @@ namespace Unity.Netcode
             {
                 SceneEventType = sceneEventProgress.SceneEventType,
                 SceneName = SceneNameFromHash(sceneEventProgress.SceneHash),
-                ClientId = m_NetworkManager.ServerClientId,
+                ClientId = NetworkManager.ServerClientId,
                 LoadSceneMode = sceneEventProgress.LoadSceneMode,
                 ClientsThatCompleted = sceneEventProgress.DoneClients,
                 ClientsThatTimedOut = m_NetworkManager.ConnectedClients.Keys.Except(sceneEventProgress.DoneClients).ToList(),
@@ -929,8 +946,9 @@ namespace Unity.Netcode
 
             ScenesLoaded.Remove(scene.handle);
 
-            AsyncOperation sceneUnload = SceneManager.UnloadSceneAsync(scene);
+            var sceneUnload = SceneManagerHandler.UnloadSceneAsync(scene,
-            sceneUnload.completed += (AsyncOperation asyncOp2) => { OnSceneUnloaded(sceneEventData.SceneEventId); };
+                    new ISceneManagerHandler.SceneEventAction() { SceneEventId = sceneEventData.SceneEventId, EventAction = OnSceneUnloaded });
+
             sceneEventProgress.SetSceneLoadOperation(sceneUnload);
 
             // Notify local server that a scene is going to be unloaded
@@ -940,10 +958,10 @@ namespace Unity.Netcode
                 SceneEventType = sceneEventData.SceneEventType,
                 LoadSceneMode = sceneEventData.LoadSceneMode,
                 SceneName = sceneName,
-                ClientId = m_NetworkManager.ServerClientId  // Server can only invoke this
+                ClientId = NetworkManager.ServerClientId  // Server can only invoke this
             });
 
-            OnUnload?.Invoke(m_NetworkManager.ServerClientId, sceneName, sceneUnload);
+            OnUnload?.Invoke(NetworkManager.ServerClientId, sceneName, sceneUnload);
 
             //Return the status
             return sceneEventProgress.Status;
@@ -960,8 +978,10 @@ namespace Unity.Netcode
 
             if (!ServerSceneHandleToClientSceneHandle.ContainsKey(sceneEventData.SceneHandle))
             {
-                throw new Exception($"Client failed to unload scene {sceneName} " +
+                Debug.Log($"Client failed to unload scene {sceneName} " +
-                    $"because we are missing the client scene handle due to the server scene handle {sceneEventData.SceneHandle} not being found!");
+                    $"because we are missing the client scene handle due to the server scene handle {sceneEventData.SceneHandle} not being found.");
+                EndSceneEvent(sceneEventId);
+                return;
             }
 
             var sceneHandle = ServerSceneHandleToClientSceneHandle[sceneEventData.SceneHandle];
@@ -972,22 +992,11 @@ namespace Unity.Netcode
                 throw new Exception($"Client failed to unload scene {sceneName} " +
                     $"because the client scene handle {sceneHandle} was not found in ScenesLoaded!");
             }
-            s_IsSceneEventActive = true;
+            m_IsSceneEventActive = true;
-            var sceneUnload = (AsyncOperation)null;
+
-#if UNITY_INCLUDE_TESTS
+            var sceneUnload = SceneManagerHandler.UnloadSceneAsync(ScenesLoaded[sceneHandle],
-            if (m_IsRunningUnitTest)
+                new ISceneManagerHandler.SceneEventAction() { SceneEventId = sceneEventData.SceneEventId, EventAction = OnSceneUnloaded });
-            {
+
-                sceneUnload = new AsyncOperation();
-            }
-            else
-            {
-                sceneUnload = SceneManager.UnloadSceneAsync(ScenesLoaded[sceneHandle]);
-                sceneUnload.completed += asyncOp2 => OnSceneUnloaded(sceneEventId);
-            }
-#else
-            sceneUnload = SceneManager.UnloadSceneAsync(ScenesLoaded[sceneHandle]);
-            sceneUnload.completed += asyncOp2 => OnSceneUnloaded(sceneEventId);
-#endif
             ScenesLoaded.Remove(sceneHandle);
 
             // Remove our server to scene handle lookup
@@ -1004,13 +1013,6 @@ namespace Unity.Netcode
             });
 
             OnUnload?.Invoke(m_NetworkManager.LocalClientId, sceneName, sceneUnload);
-
-#if UNITY_INCLUDE_TESTS
-            if (m_IsRunningUnitTest)
-            {
-                OnSceneUnloaded(sceneEventId);
-            }
-#endif
         }
 
         /// <summary>
@@ -1026,12 +1028,12 @@ namespace Unity.Netcode
                 // Server sends the unload scene notification after unloading because it will despawn all scene relative in-scene NetworkObjects
                 // If we send this event to all clients before the server is finished unloading they will get warning about an object being
                 // despawned that no longer exists
-                SendSceneEventData(sceneEventId, m_NetworkManager.ConnectedClientsIds.Where(c => c != m_NetworkManager.ServerClientId).ToArray());
+                SendSceneEventData(sceneEventId, m_NetworkManager.ConnectedClientsIds.Where(c => c != NetworkManager.ServerClientId).ToArray());
 
-                //Second, server sets itself as having finished unloading
+                //Only if we are a host do we want register having loaded for the associated SceneEventProgress
-                if (SceneEventProgressTracking.ContainsKey(sceneEventData.SceneEventProgressId))
+                if (SceneEventProgressTracking.ContainsKey(sceneEventData.SceneEventProgressId) && m_NetworkManager.IsHost)
                 {
-                    SceneEventProgressTracking[sceneEventData.SceneEventProgressId].AddClientAsDone(m_NetworkManager.ServerClientId);
+                    SceneEventProgressTracking[sceneEventData.SceneEventProgressId].AddClientAsDone(NetworkManager.ServerClientId);
                 }
             }
 
@@ -1044,7 +1046,7 @@ namespace Unity.Netcode
                 SceneEventType = sceneEventData.SceneEventType,
                 LoadSceneMode = sceneEventData.LoadSceneMode,
                 SceneName = SceneNameFromHash(sceneEventData.SceneHash),
-                ClientId = m_NetworkManager.IsServer ? m_NetworkManager.ServerClientId : m_NetworkManager.LocalClientId
+                ClientId = m_NetworkManager.IsServer ? NetworkManager.ServerClientId : m_NetworkManager.LocalClientId
             });
 
             OnUnloadComplete?.Invoke(m_NetworkManager.LocalClientId, SceneNameFromHash(sceneEventData.SceneHash));
@@ -1052,12 +1054,17 @@ namespace Unity.Netcode
             // Clients send a notification back to the server they have completed the unload scene event
             if (!m_NetworkManager.IsServer)
             {
-                SendSceneEventData(sceneEventId, new ulong[] { m_NetworkManager.ServerClientId });
+                SendSceneEventData(sceneEventId, new ulong[] { NetworkManager.ServerClientId });
             }
 
             EndSceneEvent(sceneEventId);
             // This scene event is now considered "complete"
-            s_IsSceneEventActive = false;
+            m_IsSceneEventActive = false;
+        }
+
+        private void EmptySceneUnloadedOperation(uint sceneEventId)
+        {
+            // Do nothing (this is a stub call since it is only used to flush all currently loaded scenes)
         }
 
         /// <summary>
@@ -1065,21 +1072,25 @@ namespace Unity.Netcode
         /// Since we assume a single mode loaded scene will be considered the "currently active scene",
         /// we only unload any additively loaded scenes.
         /// </summary>
-        internal void UnloadAdditivelyLoadedScenes()
+        internal void UnloadAdditivelyLoadedScenes(uint sceneEventId)
         {
             // Unload all additive scenes while making sure we don't try to unload the base scene ( loaded in single mode ).
             var currentActiveScene = SceneManager.GetActiveScene();
             foreach (var keyHandleEntry in ScenesLoaded)
             {
-                if (currentActiveScene.name != keyHandleEntry.Value.name)
+                // Validate the scene as well as ignore the DDOL (which will have a negative buildIndex)
+                if (currentActiveScene.name != keyHandleEntry.Value.name && keyHandleEntry.Value.buildIndex >= 0)
                 {
+                    var sceneUnload = SceneManagerHandler.UnloadSceneAsync(keyHandleEntry.Value,
+                        new ISceneManagerHandler.SceneEventAction() { SceneEventId = sceneEventId, EventAction = EmptySceneUnloadedOperation });
+
                     OnSceneEvent?.Invoke(new SceneEvent()
                     {
-                        AsyncOperation = SceneManager.UnloadSceneAsync(keyHandleEntry.Value),
+                        AsyncOperation = sceneUnload,
                         SceneEventType = SceneEventType.Unload,
                         SceneName = keyHandleEntry.Value.name,
                         LoadSceneMode = LoadSceneMode.Additive, // The only scenes unloaded are scenes that were additively loaded
-                        ClientId = m_NetworkManager.ServerClientId
+                        ClientId = NetworkManager.ServerClientId
                     });
                 }
             }
@@ -1115,8 +1126,8 @@ namespace Unity.Netcode
             sceneEventData.LoadSceneMode = loadSceneMode;
 
             // This both checks to make sure the scene is valid and if not resets the active scene event
-            s_IsSceneEventActive = ValidateSceneBeforeLoading(sceneEventData.SceneHash, loadSceneMode);
+            m_IsSceneEventActive = ValidateSceneBeforeLoading(sceneEventData.SceneHash, loadSceneMode);
-            if (!s_IsSceneEventActive)
+            if (!m_IsSceneEventActive)
             {
                 EndSceneEvent(sceneEventData.SceneEventId);
                 return SceneEventProgressStatus.SceneFailedVerification;
@@ -1131,12 +1142,13 @@ namespace Unity.Netcode
                 MoveObjectsToDontDestroyOnLoad();
 
                 // Now Unload all currently additively loaded scenes
-                UnloadAdditivelyLoadedScenes();
+                UnloadAdditivelyLoadedScenes(sceneEventData.SceneEventId);
             }
 
             // Now start loading the scene
-            AsyncOperation sceneLoad = SceneManager.LoadSceneAsync(sceneName, loadSceneMode);
+            var sceneLoad = SceneManagerHandler.LoadSceneAsync(sceneName, loadSceneMode,
-            sceneLoad.completed += (AsyncOperation asyncOp2) => { OnSceneLoaded(sceneEventData.SceneEventId, sceneName); };
+                new ISceneManagerHandler.SceneEventAction() { SceneEventId = sceneEventData.SceneEventId, EventAction = OnSceneLoaded });
+
             sceneEventProgress.SetSceneLoadOperation(sceneLoad);
 
             // Notify the local server that a scene loading event has begun
@@ -1146,10 +1158,10 @@ namespace Unity.Netcode
                 SceneEventType = sceneEventData.SceneEventType,
                 LoadSceneMode = sceneEventData.LoadSceneMode,
                 SceneName = sceneName,
-                ClientId = m_NetworkManager.ServerClientId
+                ClientId = NetworkManager.ServerClientId
             });
 
-            OnLoad?.Invoke(m_NetworkManager.ServerClientId, sceneName, sceneEventData.LoadSceneMode, sceneLoad);
+            OnLoad?.Invoke(NetworkManager.ServerClientId, sceneName, sceneEventData.LoadSceneMode, sceneLoad);
 
             //Return our scene progress instance
             return sceneEventProgress.Status;
@@ -1172,44 +1184,13 @@ namespace Unity.Netcode
                 return;
             }
 
-#if UNITY_INCLUDE_TESTS
-            if (m_IsRunningUnitTest)
-            {
-                // Send the loading message
-                OnSceneEvent?.Invoke(new SceneEvent()
-                {
-                    AsyncOperation = new AsyncOperation(),
-                    SceneEventType = sceneEventData.SceneEventType,
-                    LoadSceneMode = sceneEventData.LoadSceneMode,
-                    SceneName = sceneName,
-                    ClientId = m_NetworkManager.LocalClientId
-                });
-
-                // Only for testing
-                OnLoad?.Invoke(m_NetworkManager.ServerClientId, sceneName, sceneEventData.LoadSceneMode, new AsyncOperation());
-
-                // Unit tests must mirror the server's scenes loaded dictionary, otherwise this portion will fail
-                if (ScenesLoaded.ContainsKey(sceneEventData.SceneHandle))
-                {
-                    OnClientLoadedScene(sceneEventId, ScenesLoaded[sceneEventData.SceneHandle]);
-                }
-                else
-                {
-                    EndSceneEvent(sceneEventId);
-                    throw new Exception($"Could not find the scene handle {sceneEventData.SceneHandle} for scene {sceneName} " +
-                        $"during unit test.  Did you forget to register this in the unit test?");
-                }
-                return;
-            }
-#endif
-
             if (sceneEventData.LoadSceneMode == LoadSceneMode.Single)
             {
                 // Move ALL NetworkObjects to the temp scene
                 MoveObjectsToDontDestroyOnLoad();
 
                 // Now Unload all currently additively loaded scenes
-                UnloadAdditivelyLoadedScenes();
+                UnloadAdditivelyLoadedScenes(sceneEventData.SceneEventId);
             }
 
             // The Condition: While a scene is asynchronously loaded in single loading scene mode, if any new NetworkObjects are spawned
@@ -1222,8 +1203,8 @@ namespace Unity.Netcode
                 IsSpawnedObjectsPendingInDontDestroyOnLoad = true;
             }
 
-            var sceneLoad = SceneManager.LoadSceneAsync(sceneName, sceneEventData.LoadSceneMode);
+            var sceneLoad = SceneManagerHandler.LoadSceneAsync(sceneName, sceneEventData.LoadSceneMode,
-            sceneLoad.completed += asyncOp2 => OnSceneLoaded(sceneEventId, sceneName);
+                new ISceneManagerHandler.SceneEventAction() { SceneEventId = sceneEventId, EventAction = OnSceneLoaded });
 
             OnSceneEvent?.Invoke(new SceneEvent()
             {
@@ -1242,10 +1223,10 @@ namespace Unity.Netcode
         /// Client and Server:
         /// Generic on scene loaded callback method to be called upon a scene loading
         /// </summary>
-        private void OnSceneLoaded(uint sceneEventId, string sceneName)
+        private void OnSceneLoaded(uint sceneEventId)
         {
             var sceneEventData = SceneEventDataStore[sceneEventId];
-            var nextScene = GetAndAddNewlyLoadedSceneByName(sceneName);
+            var nextScene = GetAndAddNewlyLoadedSceneByName(SceneNameFromHash(sceneEventData.SceneHash));
             if (!nextScene.isLoaded || !nextScene.IsValid())
             {
                 throw new Exception($"Failed to find valid scene internal Unity.Netcode for {nameof(GameObject)}s error!");
@@ -1307,7 +1288,9 @@ namespace Unity.Netcode
                 {
                     if (!keyValuePairBySceneHandle.Value.IsPlayerObject)
                     {
-                        m_NetworkManager.SpawnManager.SpawnNetworkObjectLocally(keyValuePairBySceneHandle.Value, m_NetworkManager.SpawnManager.GetNetworkObjectId(), true, false, null, true);
+                        // All in-scene placed NetworkObjects default to being owned by the server
+                        m_NetworkManager.SpawnManager.SpawnNetworkObjectLocally(keyValuePairBySceneHandle.Value,
+                            m_NetworkManager.SpawnManager.GetNetworkObjectId(), true, false, NetworkManager.ServerClientId, true);
                     }
                 }
             }
@@ -1319,35 +1302,35 @@ namespace Unity.Netcode
             for (int j = 0; j < m_NetworkManager.ConnectedClientsList.Count; j++)
             {
                 var clientId = m_NetworkManager.ConnectedClientsList[j].ClientId;
-                if (clientId != m_NetworkManager.ServerClientId)
+                if (clientId != NetworkManager.ServerClientId)
                 {
                     sceneEventData.TargetClientId = clientId;
                     var message = new SceneEventMessage
                     {
                         EventData = sceneEventData
                     };
-                    var size = m_NetworkManager.SendMessage(message, k_DeliveryType, clientId);
+                    var size = m_NetworkManager.SendMessage(ref message, k_DeliveryType, clientId);
                     m_NetworkManager.NetworkMetrics.TrackSceneEventSent(clientId, (uint)sceneEventData.SceneEventType, scene.name, size);
                 }
             }
 
-            s_IsSceneEventActive = false;
+            m_IsSceneEventActive = false;
             //First, notify local server that the scene was loaded
             OnSceneEvent?.Invoke(new SceneEvent()
             {
                 SceneEventType = SceneEventType.LoadComplete,
                 LoadSceneMode = sceneEventData.LoadSceneMode,
                 SceneName = SceneNameFromHash(sceneEventData.SceneHash),
-                ClientId = m_NetworkManager.ServerClientId,
+                ClientId = NetworkManager.ServerClientId,
                 Scene = scene,
             });
 
-            OnLoadComplete?.Invoke(m_NetworkManager.ServerClientId, SceneNameFromHash(sceneEventData.SceneHash), sceneEventData.LoadSceneMode);
+            OnLoadComplete?.Invoke(NetworkManager.ServerClientId, SceneNameFromHash(sceneEventData.SceneHash), sceneEventData.LoadSceneMode);
 
-            //Second, set the server as having loaded for the associated SceneEventProgress
+            //Second, only if we are a host do we want register having loaded for the associated SceneEventProgress
-            if (SceneEventProgressTracking.ContainsKey(sceneEventData.SceneEventProgressId))
+            if (SceneEventProgressTracking.ContainsKey(sceneEventData.SceneEventProgressId) && m_NetworkManager.IsHost)
             {
-                SceneEventProgressTracking[sceneEventData.SceneEventProgressId].AddClientAsDone(m_NetworkManager.ServerClientId);
+                SceneEventProgressTracking[sceneEventData.SceneEventProgressId].AddClientAsDone(NetworkManager.ServerClientId);
             }
             EndSceneEvent(sceneEventId);
         }
@@ -1362,8 +1345,8 @@ namespace Unity.Netcode
             sceneEventData.DeserializeScenePlacedObjects();
 
             sceneEventData.SceneEventType = SceneEventType.LoadComplete;
-            SendSceneEventData(sceneEventId, new ulong[] { m_NetworkManager.ServerClientId });
+            SendSceneEventData(sceneEventId, new ulong[] { NetworkManager.ServerClientId });
-            s_IsSceneEventActive = false;
+            m_IsSceneEventActive = false;
 
             // Notify local client that the scene was loaded
             OnSceneEvent?.Invoke(new SceneEvent()
@@ -1433,9 +1416,8 @@ namespace Unity.Netcode
             {
                 EventData = sceneEventData
             };
-            var size = m_NetworkManager.SendMessage(message, k_DeliveryType, clientId);
+            var size = m_NetworkManager.SendMessage(ref message, k_DeliveryType, clientId);
-            m_NetworkManager.NetworkMetrics.TrackSceneEventSent(
+            m_NetworkManager.NetworkMetrics.TrackSceneEventSent(clientId, (uint)sceneEventData.SceneEventType, "", size);
-                clientId, (uint)sceneEventData.SceneEventType, "", size);
 
             // Notify the local server that the client has been sent the synchronize event
             OnSceneEvent?.Invoke(new SceneEvent()
@@ -1464,12 +1446,9 @@ namespace Unity.Netcode
 
             var loadSceneMode = sceneHash == sceneEventData.SceneHash ? sceneEventData.LoadSceneMode : LoadSceneMode.Additive;
 
-            // Always check to see if the scene needs to be validated
+            // Store the sceneHandle and hash
-            if (!ValidateSceneBeforeLoading(sceneHash, loadSceneMode))
+            sceneEventData.ClientSceneHandle = sceneHandle;
-            {
+            sceneEventData.ClientSceneHash = sceneHash;
-                EndSceneEvent(sceneEventId);
-                return;
-            }
 
             // If this is the beginning of the synchronization event, then send client a notification that synchronization has begun
             if (sceneHash == sceneEventData.SceneHash)
@@ -1486,6 +1465,17 @@ namespace Unity.Netcode
                 ScenePlacedObjects.Clear();
             }
 
+            // Always check to see if the scene needs to be validated
+            if (!ValidateSceneBeforeLoading(sceneHash, loadSceneMode))
+            {
+                HandleClientSceneEvent(sceneEventId);
+                if (m_NetworkManager.LogLevel == LogLevel.Developer)
+                {
+                    NetworkLog.LogInfo($"Client declined to load the scene {sceneName}, continuing with synchronization.");
+                }
+                return;
+            }
+
             var shouldPassThrough = false;
             var sceneLoad = (AsyncOperation)null;
 
@@ -1497,38 +1487,28 @@ namespace Unity.Netcode
                 shouldPassThrough = true;
             }
 
-#if UNITY_INCLUDE_TESTS
-            if (m_IsRunningUnitTest)
-            {
-                // In unit tests, we don't allow clients to load additional scenes since
-                // MultiInstance unit tests share the same scene space.
-                shouldPassThrough = true;
-                sceneLoad = new AsyncOperation();
-            }
-#endif
             if (!shouldPassThrough)
             {
                 // If not, then load the scene
-                sceneLoad = SceneManager.LoadSceneAsync(sceneName, loadSceneMode);
+                sceneLoad = SceneManagerHandler.LoadSceneAsync(sceneName, loadSceneMode,
-                sceneLoad.completed += asyncOp2 => ClientLoadedSynchronization(sceneEventId, sceneHash, sceneHandle);
+                new ISceneManagerHandler.SceneEventAction() { SceneEventId = sceneEventId, EventAction = ClientLoadedSynchronization });
+
+                // Notify local client that a scene load has begun
+                OnSceneEvent?.Invoke(new SceneEvent()
+                {
+                    AsyncOperation = sceneLoad,
+                    SceneEventType = SceneEventType.Load,
+                    LoadSceneMode = loadSceneMode,
+                    SceneName = sceneName,
+                    ClientId = m_NetworkManager.LocalClientId,
+                });
+
+                OnLoad?.Invoke(m_NetworkManager.LocalClientId, sceneName, loadSceneMode, sceneLoad);
             }
-
+            else
-            // Notify local client that a scene load has begun
-            OnSceneEvent?.Invoke(new SceneEvent()
-            {
-                AsyncOperation = sceneLoad,
-                SceneEventType = SceneEventType.Load,
-                LoadSceneMode = loadSceneMode,
-                SceneName = sceneName,
-                ClientId = m_NetworkManager.LocalClientId,
-            });
-
-            OnLoad?.Invoke(m_NetworkManager.LocalClientId, sceneName, loadSceneMode, sceneLoad);
-
-            if (shouldPassThrough)
             {
                 // If so, then pass through
-                ClientLoadedSynchronization(sceneEventId, sceneHash, sceneHandle);
+                ClientLoadedSynchronization(sceneEventId);
             }
         }
 
@@ -1537,10 +1517,10 @@ namespace Unity.Netcode
         /// This handles all of the in-scene and dynamically spawned NetworkObject synchronization
         /// </summary>
         /// <param name="sceneIndex">Netcode scene index that was loaded</param>
-        private void ClientLoadedSynchronization(uint sceneEventId, uint sceneHash, int sceneHandle)
+        private void ClientLoadedSynchronization(uint sceneEventId)
         {
             var sceneEventData = SceneEventDataStore[sceneEventId];
-            var sceneName = SceneNameFromHash(sceneHash);
+            var sceneName = SceneNameFromHash(sceneEventData.ClientSceneHash);
             var nextScene = GetAndAddNewlyLoadedSceneByName(sceneName);
 
             if (!nextScene.isLoaded || !nextScene.IsValid())
@@ -1548,7 +1528,7 @@ namespace Unity.Netcode
                 throw new Exception($"Failed to find valid scene internal Unity.Netcode for {nameof(GameObject)}s error!");
             }
 
-            var loadSceneMode = (sceneHash == sceneEventData.SceneHash ? sceneEventData.LoadSceneMode : LoadSceneMode.Additive);
+            var loadSceneMode = (sceneEventData.ClientSceneHash == sceneEventData.SceneHash ? sceneEventData.LoadSceneMode : LoadSceneMode.Additive);
 
             // For now, during a synchronization event, we will make the first scene the "base/master" scene that denotes a "complete scene switch"
             if (loadSceneMode == LoadSceneMode.Single)
@@ -1556,9 +1536,9 @@ namespace Unity.Netcode
                 SceneManager.SetActiveScene(nextScene);
             }
 
-            if (!ServerSceneHandleToClientSceneHandle.ContainsKey(sceneHandle))
+            if (!ServerSceneHandleToClientSceneHandle.ContainsKey(sceneEventData.ClientSceneHandle))
             {
-                ServerSceneHandleToClientSceneHandle.Add(sceneHandle, nextScene.handle);
+                ServerSceneHandleToClientSceneHandle.Add(sceneEventData.ClientSceneHandle, nextScene.handle);
             }
             else
             {
@@ -1573,16 +1553,16 @@ namespace Unity.Netcode
             var responseSceneEventData = BeginSceneEvent();
             responseSceneEventData.LoadSceneMode = loadSceneMode;
             responseSceneEventData.SceneEventType = SceneEventType.LoadComplete;
-            responseSceneEventData.SceneHash = sceneHash;
+            responseSceneEventData.SceneHash = sceneEventData.ClientSceneHash;
 
 
             var message = new SceneEventMessage
             {
                 EventData = responseSceneEventData
             };
-            var size = m_NetworkManager.SendMessage(message, k_DeliveryType, m_NetworkManager.ServerClientId);
+            var size = m_NetworkManager.SendMessage(ref message, k_DeliveryType, NetworkManager.ServerClientId);
 
-            m_NetworkManager.NetworkMetrics.TrackSceneEventSent(m_NetworkManager.ServerClientId, (uint)responseSceneEventData.SceneEventType, sceneName, size);
+            m_NetworkManager.NetworkMetrics.TrackSceneEventSent(NetworkManager.ServerClientId, (uint)responseSceneEventData.SceneEventType, sceneName, size);
 
             EndSceneEvent(responseSceneEventData.SceneEventId);
 
@@ -1636,7 +1616,7 @@ namespace Unity.Netcode
                             sceneEventData.SynchronizeSceneNetworkObjects(m_NetworkManager);
 
                             sceneEventData.SceneEventType = SceneEventType.SynchronizeComplete;
-                            SendSceneEventData(sceneEventId, new ulong[] { m_NetworkManager.ServerClientId });
+                            SendSceneEventData(sceneEventId, new ulong[] { NetworkManager.ServerClientId });
 
                             // All scenes are synchronized, let the server know we are done synchronizing
                             m_NetworkManager.IsConnectedClient = true;
@@ -1663,7 +1643,7 @@ namespace Unity.Netcode
                         OnSceneEvent?.Invoke(new SceneEvent()
                         {
                             SceneEventType = sceneEventData.SceneEventType,
-                            ClientId = m_NetworkManager.ServerClientId,  // Server sent this to client
+                            ClientId = NetworkManager.ServerClientId,  // Server sent this to client
                         });
 
                         EndSceneEvent(sceneEventId);
@@ -1678,7 +1658,7 @@ namespace Unity.Netcode
                             SceneEventType = sceneEventData.SceneEventType,
                             LoadSceneMode = sceneEventData.LoadSceneMode,
                             SceneName = SceneNameFromHash(sceneEventData.SceneHash),
-                            ClientId = m_NetworkManager.ServerClientId,
+                            ClientId = NetworkManager.ServerClientId,
                             ClientsThatCompleted = sceneEventData.ClientsCompleted,
                             ClientsThatTimedOut = sceneEventData.ClientsTimedOut,
                         });
@@ -1770,9 +1750,9 @@ namespace Unity.Netcode
                         // NetworkObjects
                         m_NetworkManager.InvokeOnClientConnectedCallback(clientId);
 
-                        // TODO: This check and associated code can be removed once we determine all
+                        // Check to see if the client needs to resynchronize and before sending the message make sure the client is still connected to avoid
-                        // snapshot destroy messages are being updated until the server receives ACKs
+                        // a potential crash within the MessageSystem (i.e. sending to a client that no longer exists)
-                        if (sceneEventData.ClientNeedsReSynchronization() && !DisableReSynchronization)
+                        if (sceneEventData.ClientNeedsReSynchronization() && !DisableReSynchronization && m_NetworkManager.ConnectedClients.ContainsKey(clientId))
                         {
                             sceneEventData.SceneEventType = SceneEventType.ReSynchronize;
                             SendSceneEventData(sceneEventId, new ulong[] { clientId });
@@ -1830,21 +1810,23 @@ namespace Unity.Netcode
         /// Moves all NetworkObjects that don't have the <see cref="NetworkObject.DestroyWithScene"/> set to
         /// the "Do not destroy on load" scene.
         /// </summary>
-        private void MoveObjectsToDontDestroyOnLoad()
+        internal void MoveObjectsToDontDestroyOnLoad()
         {
-            // Move ALL NetworkObjects to the temp scene
+            // Move ALL NetworkObjects marked to persist scene transitions into the DDOL scene
             var objectsToKeep = new HashSet<NetworkObject>(m_NetworkManager.SpawnManager.SpawnedObjectsList);
-
             foreach (var sobj in objectsToKeep)
             {
-                if (!sobj.DestroyWithScene || (sobj.IsSceneObject != null && sobj.IsSceneObject.Value && sobj.gameObject.scene == DontDestroyOnLoadScene))
+                if (sobj == null)
                 {
-                    // Only move objects with no parent as child objects will follow
+                    continue;
-                    if (sobj.gameObject.transform.parent == null)
+                }
+
+                if (!sobj.DestroyWithScene || sobj.gameObject.scene == DontDestroyOnLoadScene)
+                {
+                    // Only move dynamically spawned network objects with no parent as child objects will follow
+                    if (sobj.gameObject.transform.parent == null && sobj.IsSceneObject != null && !sobj.IsSceneObject.Value)
                     {
                         UnityEngine.Object.DontDestroyOnLoad(sobj.gameObject);
-                        // Since we are doing a scene transition, disable the GameObject until the next scene is loaded
-                        sobj.gameObject.SetActive(false);
                     }
                 }
                 else if (m_NetworkManager.IsServer)
@@ -1864,7 +1846,7 @@ namespace Unity.Netcode
         /// Using the local scene relative Scene.handle as a sub-key to the root dictionary allows us to
         /// distinguish between duplicate in-scene placed NetworkObjects
         /// </summary>
-        private void PopulateScenePlacedObjects(Scene sceneToFilterBy, bool clearScenePlacedObjects = true)
+        internal void PopulateScenePlacedObjects(Scene sceneToFilterBy, bool clearScenePlacedObjects = true)
         {
             if (clearScenePlacedObjects)
             {
@@ -1879,25 +1861,26 @@ namespace Unity.Netcode
             // at the end of scene loading we use this list to soft synchronize all in-scene placed NetworkObjects
             foreach (var networkObjectInstance in networkObjects)
             {
-                // We check to make sure the NetworkManager instance is the same one to be "MultiInstanceHelpers" compatible and filter the list on a per scene basis (additive scenes)
+                var globalObjectIdHash = networkObjectInstance.GlobalObjectIdHash;
-                if (networkObjectInstance.IsSceneObject == null && networkObjectInstance.NetworkManager == m_NetworkManager && networkObjectInstance.gameObject.scene == sceneToFilterBy &&
+                var sceneHandle = networkObjectInstance.gameObject.scene.handle;
-                    networkObjectInstance.gameObject.scene.handle == sceneToFilterBy.handle)
+                // We check to make sure the NetworkManager instance is the same one to be "NetcodeIntegrationTestHelpers" compatible and filter the list on a per scene basis (for additive scenes)
+                if (networkObjectInstance.IsSceneObject != false && networkObjectInstance.NetworkManager == m_NetworkManager && networkObjectInstance.gameObject.scene == sceneToFilterBy &&
+                    sceneHandle == sceneToFilterBy.handle)
                 {
-                    if (!ScenePlacedObjects.ContainsKey(networkObjectInstance.GlobalObjectIdHash))
+                    if (!ScenePlacedObjects.ContainsKey(globalObjectIdHash))
                     {
-                        ScenePlacedObjects.Add(networkObjectInstance.GlobalObjectIdHash, new Dictionary<int, NetworkObject>());
+                        ScenePlacedObjects.Add(globalObjectIdHash, new Dictionary<int, NetworkObject>());
                     }
 
-                    if (!ScenePlacedObjects[networkObjectInstance.GlobalObjectIdHash].ContainsKey(networkObjectInstance.gameObject.scene.handle))
+                    if (!ScenePlacedObjects[globalObjectIdHash].ContainsKey(sceneHandle))
                     {
-                        ScenePlacedObjects[networkObjectInstance.GlobalObjectIdHash].Add(networkObjectInstance.gameObject.scene.handle, networkObjectInstance);
+                        ScenePlacedObjects[globalObjectIdHash].Add(sceneHandle, networkObjectInstance);
                     }
                     else
                     {
-                        var exitingEntryName = ScenePlacedObjects[networkObjectInstance.GlobalObjectIdHash][networkObjectInstance.gameObject.scene.handle] != null ?
+                        var exitingEntryName = ScenePlacedObjects[globalObjectIdHash][sceneHandle] != null ? ScenePlacedObjects[globalObjectIdHash][sceneHandle].name : "Null Entry";
-                            ScenePlacedObjects[networkObjectInstance.GlobalObjectIdHash][networkObjectInstance.gameObject.scene.handle].name : "Null Entry";
                         throw new Exception($"{networkObjectInstance.name} tried to registered with {nameof(ScenePlacedObjects)} which already contains " +
-                            $"the same {nameof(NetworkObject.GlobalObjectIdHash)} value {networkObjectInstance.GlobalObjectIdHash} for {exitingEntryName}!");
+                            $"the same {nameof(NetworkObject.GlobalObjectIdHash)} value {globalObjectIdHash} for {exitingEntryName}!");
                     }
                 }
             }
@@ -1907,24 +1890,26 @@ namespace Unity.Netcode
         /// Moves all spawned NetworkObjects (from do not destroy on load) to the scene specified
         /// </summary>
         /// <param name="scene">scene to move the NetworkObjects to</param>
-        private void MoveObjectsFromDontDestroyOnLoadToScene(Scene scene)
+        internal void MoveObjectsFromDontDestroyOnLoadToScene(Scene scene)
         {
             // Move ALL NetworkObjects to the temp scene
             var objectsToKeep = m_NetworkManager.SpawnManager.SpawnedObjectsList;
 
             foreach (var sobj in objectsToKeep)
             {
-                if (sobj.gameObject.scene == DontDestroyOnLoadScene && (sobj.IsSceneObject == null || sobj.IsSceneObject.Value))
+                if (sobj == null)
                 {
                     continue;
                 }
-
+                // If it is in the DDOL then
-                // Only move objects with no parent as child objects will follow
+                if (sobj.gameObject.scene == DontDestroyOnLoadScene)
-                if (sobj.gameObject.transform.parent == null)
                 {
-                    // set it back to active at this point
+                    // only move dynamically spawned network objects, with no parent as child objects will follow,
-                    sobj.gameObject.SetActive(true);
+                    // back into the currently active scene
-                    SceneManager.MoveGameObjectToScene(sobj.gameObject, scene);
+                    if (sobj.gameObject.transform.parent == null && sobj.IsSceneObject != null && !sobj.IsSceneObject.Value)
+                    {
+                        SceneManager.MoveGameObjectToScene(sobj.gameObject, scene);
+                    }
                 }
             }
         }

Runtime/SceneManagement/SceneEventData.cs

@@ -4,7 +4,6 @@ using System.Linq;
 using Unity.Collections;
 using UnityEngine.SceneManagement;
 
-
 namespace Unity.Netcode
 {
     /// <summary>
@@ -42,7 +41,6 @@ namespace Unity.Netcode
         /// <b>Invocation:</b> Server Side<br/>
         /// <b>Message Flow:</b> Server to client<br/>
         /// <b>Event Notification:</b> Both server and client receive a local notification<br/>
-        /// <em>Note: This will be removed once snapshot and buffered messages are finalized as it will no longer be needed at that point.</em>
         /// </summary>
         ReSynchronize,
         /// <summary>
@@ -93,13 +91,17 @@ namespace Unity.Netcode
     {
         internal SceneEventType SceneEventType;
         internal LoadSceneMode LoadSceneMode;
-        internal Guid SceneEventProgressId;
+        internal ForceNetworkSerializeByMemcpy<Guid> SceneEventProgressId;
         internal uint SceneEventId;
 
 
         internal uint SceneHash;
         internal int SceneHandle;
 
+        // Used by the client during synchronization
+        internal uint ClientSceneHash;
+        internal int ClientSceneHandle;
+
         /// Only used for <see cref="SceneEventType.Synchronize"/> scene events, this assures permissions when writing
         /// NetworkVariable information.  If that process changes, then we need to update this
         internal ulong TargetClientId;
@@ -230,7 +232,14 @@ namespace Unity.Netcode
 
         internal void AddSpawnedNetworkObjects()
         {
-            m_NetworkObjectsSync = m_NetworkManager.SpawnManager.SpawnedObjectsList.ToList();
+            m_NetworkObjectsSync.Clear();
+            foreach (var sobj in m_NetworkManager.SpawnManager.SpawnedObjectsList)
+            {
+                if (sobj.Observers.Contains(TargetClientId))
+                {
+                    m_NetworkObjectsSync.Add(sobj);
+                }
+            }
             m_NetworkObjectsSync.Sort(SortNetworkObjects);
         }
 
@@ -582,9 +591,6 @@ namespace Unity.Netcode
                         networkObject.IsSpawned = false;
                         if (m_NetworkManager.PrefabHandler.ContainsHandler(networkObject))
                         {
-                            // Since this is the client side and we have missed the delete message, until the Snapshot system is in place for spawn and despawn handling
-                            // we have to remove this from the list of spawned objects manually or when a NetworkObjectId is recycled the client will throw an error
-                            // about the id already being assigned.
                             if (m_NetworkManager.SpawnManager.SpawnedObjects.ContainsKey(networkObjectId))
                             {
                                 m_NetworkManager.SpawnManager.SpawnedObjects.Remove(networkObjectId);

Runtime/Serialization/BufferSerializer.cs

@@ -1,13 +1,16 @@
+using System;
+using UnityEngine;
+
 namespace Unity.Netcode
 {
     /// <summary>
     /// Two-way serializer wrapping FastBufferReader or FastBufferWriter.
-    /// 
+    ///
     /// Implemented as a ref struct for two reasons:
     /// 1. The BufferSerializer cannot outlive the FBR/FBW it wraps or using it will cause a crash
     /// 2. The BufferSerializer must always be passed by reference and can't be copied
     ///
-    /// Ref structs help enforce both of those rules: they can't out live the stack context in which they were
+    /// Ref structs help enforce both of those rules: they can't ref live the stack context in which they were
     /// created, and they're always passed by reference no matter what.
     ///
     /// BufferSerializer doesn't wrapp FastBufferReader or FastBufferWriter directly because it can't.
@@ -58,168 +61,63 @@ namespace Unity.Netcode
             return m_Implementation.GetFastBufferWriter();
         }
 
-        /// <summary>
+        public void SerializeValue(ref string s, bool oneByteChars = false) => m_Implementation.SerializeValue(ref s, oneByteChars);
-        /// Serialize an INetworkSerializable
+        public void SerializeValue(ref byte value) => m_Implementation.SerializeValue(ref value);
-        /// 
+        public void SerializeValue<T>(ref T value, FastBufferWriter.ForPrimitives unused = default) where T : unmanaged, IComparable, IConvertible, IComparable<T>, IEquatable<T> => m_Implementation.SerializeValue(ref value);
-        /// Throws OverflowException if the end of the buffer has been reached.
+        public void SerializeValue<T>(ref T[] value, FastBufferWriter.ForPrimitives unused = default) where T : unmanaged, IComparable, IConvertible, IComparable<T>, IEquatable<T> => m_Implementation.SerializeValue(ref value);
-        /// Write buffers will grow up to the maximum allowable message size before throwing OverflowException.
+        public void SerializeValue<T>(ref T value, FastBufferWriter.ForEnums unused = default) where T : unmanaged, Enum => m_Implementation.SerializeValue(ref value);
-        /// </summary>
+        public void SerializeValue<T>(ref T[] value, FastBufferWriter.ForEnums unused = default) where T : unmanaged, Enum => m_Implementation.SerializeValue(ref value);
-        /// <param name="value">Value to serialize</param>
+        public void SerializeValue<T>(ref T value, FastBufferWriter.ForStructs unused = default) where T : unmanaged, INetworkSerializeByMemcpy => m_Implementation.SerializeValue(ref value);
-        public void SerializeNetworkSerializable<T>(ref T value) where T : INetworkSerializable, new()
+        public void SerializeValue<T>(ref T[] value, FastBufferWriter.ForStructs unused = default) where T : unmanaged, INetworkSerializeByMemcpy => m_Implementation.SerializeValue(ref value);
-        {
+        public void SerializeValue<T>(ref T value, FastBufferWriter.ForNetworkSerializable unused = default) where T : INetworkSerializable, new() => m_Implementation.SerializeValue(ref value);
-            m_Implementation.SerializeNetworkSerializable(ref value);
+        public void SerializeValue<T>(ref T[] value, FastBufferWriter.ForNetworkSerializable unused = default) where T : INetworkSerializable, new() => m_Implementation.SerializeValue(ref value);
-        }
+        public void SerializeValue(ref Vector2 value) => m_Implementation.SerializeValue(ref value);
+        public void SerializeValue(ref Vector2[] value) => m_Implementation.SerializeValue(ref value);
+        public void SerializeValue(ref Vector3 value) => m_Implementation.SerializeValue(ref value);
+        public void SerializeValue(ref Vector3[] value) => m_Implementation.SerializeValue(ref value);
+        public void SerializeValue(ref Vector4 value) => m_Implementation.SerializeValue(ref value);
+        public void SerializeValue(ref Vector4[] value) => m_Implementation.SerializeValue(ref value);
+        public void SerializeValue(ref Quaternion value) => m_Implementation.SerializeValue(ref value);
+        public void SerializeValue(ref Quaternion[] value) => m_Implementation.SerializeValue(ref value);
+        public void SerializeValue(ref Color value) => m_Implementation.SerializeValue(ref value);
+        public void SerializeValue(ref Color[] value) => m_Implementation.SerializeValue(ref value);
+        public void SerializeValue(ref Color32 value) => m_Implementation.SerializeValue(ref value);
+        public void SerializeValue(ref Color32[] value) => m_Implementation.SerializeValue(ref value);
+        public void SerializeValue(ref Ray value) => m_Implementation.SerializeValue(ref value);
+        public void SerializeValue(ref Ray[] value) => m_Implementation.SerializeValue(ref value);
+        public void SerializeValue(ref Ray2D value) => m_Implementation.SerializeValue(ref value);
+        public void SerializeValue(ref Ray2D[] value) => m_Implementation.SerializeValue(ref value);
 
-        /// <summary>
+        public void SerializeNetworkSerializable<T>(ref T value) where T : INetworkSerializable, new() => m_Implementation.SerializeNetworkSerializable(ref value);
-        /// Serialize a string.
-        ///
-        /// Note: Will ALWAYS allocate a new string when reading.
-        /// 
-        /// Throws OverflowException if the end of the buffer has been reached.
-        /// Write buffers will grow up to the maximum allowable message size before throwing OverflowException.
-        /// </summary>
-        /// <param name="s">Value to serialize</param>
-        /// <param name="oneByteChars">
-        /// If true, will truncate each char to one byte.
-        /// This is slower than two-byte chars, but uses less bandwidth.
-        /// </param>
-        public void SerializeValue(ref string s, bool oneByteChars = false)
-        {
-            m_Implementation.SerializeValue(ref s, oneByteChars);
-        }
 
-        /// <summary>
-        /// Serialize an array value.
-        ///
-        /// Note: Will ALWAYS allocate a new array when reading.
-        /// If you have a statically-sized array that you know is large enough, it's recommended to
-        /// serialize the size yourself and iterate serializing array members.
-        /// 
-        /// (This is because C# doesn't allow setting an array's length value, so deserializing
-        /// into an existing array of larger size would result in an array that doesn't have as many values
-        /// as its Length indicates it should.)
-        /// 
-        /// Throws OverflowException if the end of the buffer has been reached.
-        /// Write buffers will grow up to the maximum allowable message size before throwing OverflowException.
-        /// </summary>
-        /// <param name="array">Value to serialize</param>
-        public void SerializeValue<T>(ref T[] array) where T : unmanaged
-        {
-            m_Implementation.SerializeValue(ref array);
-        }
-
-        /// <summary>
-        /// Serialize a single byte
-        /// 
-        /// Throws OverflowException if the end of the buffer has been reached.
-        /// Write buffers will grow up to the maximum allowable message size before throwing OverflowException.
-        /// </summary>
-        /// <param name="value">Value to serialize</param>
-        public void SerializeValue(ref byte value)
-        {
-            m_Implementation.SerializeValue(ref value);
-        }
-
-        /// <summary>
-        /// Serialize an unmanaged type. Supports basic value types as well as structs.
-        /// The provided type will be copied to/from the buffer as it exists in memory.
-        /// 
-        /// Throws OverflowException if the end of the buffer has been reached.
-        /// Write buffers will grow up to the maximum allowable message size before throwing OverflowException.
-        /// </summary>
-        /// <param name="value">Value to serialize</param>
-        public void SerializeValue<T>(ref T value) where T : unmanaged
-        {
-            m_Implementation.SerializeValue(ref value);
-        }
-
-        /// <summary>
-        /// Allows faster serialization by batching bounds checking.
-        /// When you know you will be writing multiple fields back-to-back and you know the total size,
-        /// you can call PreCheck() once on the total size, and then follow it with calls to
-        /// SerializeValuePreChecked() for faster serialization. Write buffers will grow during PreCheck()
-        /// if needed.
-        /// 
-        /// PreChecked serialization operations will throw OverflowException in editor and development builds if you
-        /// go past the point you've marked using PreCheck(). In release builds, OverflowException will not be thrown
-        /// for performance reasons, since the point of using PreCheck is to avoid bounds checking in the following
-        /// operations in release builds.
-        ///
-        /// To get the correct size to check for, use FastBufferWriter.GetWriteSize(value) or
-        /// FastBufferWriter.GetWriteSize&lt;type&gt;()
-        /// </summary>
-        /// <param name="amount">Number of bytes you plan to read or write</param>
-        /// <returns>True if the read/write can proceed, false otherwise.</returns>
         public bool PreCheck(int amount)
         {
             return m_Implementation.PreCheck(amount);
         }
 
-        /// <summary>
+        public void SerializeValuePreChecked(ref string s, bool oneByteChars = false) => m_Implementation.SerializeValuePreChecked(ref s, oneByteChars);
-        /// Serialize a string.
+        public void SerializeValuePreChecked(ref byte value) => m_Implementation.SerializeValuePreChecked(ref value);
-        /// 
+        public void SerializeValuePreChecked<T>(ref T value, FastBufferWriter.ForPrimitives unused = default) where T : unmanaged, IComparable, IConvertible, IComparable<T>, IEquatable<T> => m_Implementation.SerializeValuePreChecked(ref value);
-        /// Note: Will ALWAYS allocate a new string when reading.
+        public void SerializeValuePreChecked<T>(ref T[] value, FastBufferWriter.ForPrimitives unused = default) where T : unmanaged, IComparable, IConvertible, IComparable<T>, IEquatable<T> => m_Implementation.SerializeValuePreChecked(ref value);
-        ///
+        public void SerializeValuePreChecked<T>(ref T value, FastBufferWriter.ForEnums unused = default) where T : unmanaged, Enum => m_Implementation.SerializeValuePreChecked(ref value);
-        /// Using the PreChecked versions of these functions requires calling PreCheck() ahead of time, and they should only
+        public void SerializeValuePreChecked<T>(ref T[] value, FastBufferWriter.ForEnums unused = default) where T : unmanaged, Enum => m_Implementation.SerializeValuePreChecked(ref value);
-        /// be called if PreCheck() returns true. This is an efficiency option, as it allows you to PreCheck() multiple
+        public void SerializeValuePreChecked<T>(ref T value, FastBufferWriter.ForStructs unused = default) where T : unmanaged, INetworkSerializeByMemcpy => m_Implementation.SerializeValuePreChecked(ref value);
-        /// serialization operations in one function call instead of having to do bounds checking on every call.
+        public void SerializeValuePreChecked<T>(ref T[] value, FastBufferWriter.ForStructs unused = default) where T : unmanaged, INetworkSerializeByMemcpy => m_Implementation.SerializeValuePreChecked(ref value);
-        /// </summary>
+        public void SerializeValuePreChecked(ref Vector2 value) => m_Implementation.SerializeValuePreChecked(ref value);
-        /// <param name="s">Value to serialize</param>
+        public void SerializeValuePreChecked(ref Vector2[] value) => m_Implementation.SerializeValuePreChecked(ref value);
-        /// <param name="oneByteChars">
+        public void SerializeValuePreChecked(ref Vector3 value) => m_Implementation.SerializeValuePreChecked(ref value);
-        /// If true, will truncate each char to one byte.
+        public void SerializeValuePreChecked(ref Vector3[] value) => m_Implementation.SerializeValuePreChecked(ref value);
-        /// This is slower than two-byte chars, but uses less bandwidth.
+        public void SerializeValuePreChecked(ref Vector4 value) => m_Implementation.SerializeValuePreChecked(ref value);
-        /// </param>
+        public void SerializeValuePreChecked(ref Vector4[] value) => m_Implementation.SerializeValuePreChecked(ref value);
-        public void SerializeValuePreChecked(ref string s, bool oneByteChars = false)
+        public void SerializeValuePreChecked(ref Quaternion value) => m_Implementation.SerializeValuePreChecked(ref value);
-        {
+        public void SerializeValuePreChecked(ref Quaternion[] value) => m_Implementation.SerializeValuePreChecked(ref value);
-            m_Implementation.SerializeValuePreChecked(ref s, oneByteChars);
+        public void SerializeValuePreChecked(ref Color value) => m_Implementation.SerializeValuePreChecked(ref value);
-        }
+        public void SerializeValuePreChecked(ref Color[] value) => m_Implementation.SerializeValuePreChecked(ref value);
-
+        public void SerializeValuePreChecked(ref Color32 value) => m_Implementation.SerializeValuePreChecked(ref value);
-        /// <summary>
+        public void SerializeValuePreChecked(ref Color32[] value) => m_Implementation.SerializeValuePreChecked(ref value);
-        /// Serialize an array value.
+        public void SerializeValuePreChecked(ref Ray value) => m_Implementation.SerializeValuePreChecked(ref value);
-        ///
+        public void SerializeValuePreChecked(ref Ray[] value) => m_Implementation.SerializeValuePreChecked(ref value);
-        /// Note: Will ALWAYS allocate a new array when reading.
+        public void SerializeValuePreChecked(ref Ray2D value) => m_Implementation.SerializeValuePreChecked(ref value);
-        /// If you have a statically-sized array that you know is large enough, it's recommended to
+        public void SerializeValuePreChecked(ref Ray2D[] value) => m_Implementation.SerializeValuePreChecked(ref value);
-        /// serialize the size yourself and iterate serializing array members.
-        /// 
-        /// (This is because C# doesn't allow setting an array's length value, so deserializing
-        /// into an existing array of larger size would result in an array that doesn't have as many values
-        /// as its Length indicates it should.)
-        ///
-        /// Using the PreChecked versions of these functions requires calling PreCheck() ahead of time, and they should only
-        /// be called if PreCheck() returns true. This is an efficiency option, as it allows you to PreCheck() multiple
-        /// serialization operations in one function call instead of having to do bounds checking on every call.
-        /// </summary>
-        /// <param name="array">Value to serialize</param>
-        public void SerializeValuePreChecked<T>(ref T[] array) where T : unmanaged
-        {
-            m_Implementation.SerializeValuePreChecked(ref array);
-        }
-
-        /// <summary>
-        /// Serialize a single byte
-        ///
-        /// Using the PreChecked versions of these functions requires calling PreCheck() ahead of time, and they should only
-        /// be called if PreCheck() returns true. This is an efficiency option, as it allows you to PreCheck() multiple
-        /// serialization operations in one function call instead of having to do bounds checking on every call.
-        /// </summary>
-        /// <param name="value">Value to serialize</param>
-        public void SerializeValuePreChecked(ref byte value)
-        {
-            m_Implementation.SerializeValuePreChecked(ref value);
-        }
-
-        /// <summary>
-        /// Serialize an unmanaged type. Supports basic value types as well as structs.
-        /// The provided type will be copied to/from the buffer as it exists in memory.
-        ///
-        /// Using the PreChecked versions of these functions requires calling PreCheck() ahead of time, and they should only
-        /// be called if PreCheck() returns true. This is an efficiency option, as it allows you to PreCheck() multiple
-        /// serialization operations in one function call instead of having to do bounds checking on every call.
-        /// </summary>
-        /// <param name="value">Value to serialize</param>
-        public void SerializeValuePreChecked<T>(ref T value) where T : unmanaged
-        {
-            m_Implementation.SerializeValuePreChecked(ref value);
-        }
     }
 }

Runtime/Serialization/BufferSerializerReader.cs

@@ -1,4 +1,5 @@
 using System;
+using UnityEngine;
 
 namespace Unity.Netcode
 {
@@ -24,54 +25,63 @@ namespace Unity.Netcode
             throw new InvalidOperationException("Cannot retrieve a FastBufferWriter from a serializer where IsWriter = false");
         }
 
-        public void SerializeValue(ref string s, bool oneByteChars = false)
+        public void SerializeValue(ref string s, bool oneByteChars = false) => m_Reader.ReadValueSafe(out s, oneByteChars);
-        {
+        public void SerializeValue(ref byte value) => m_Reader.ReadByteSafe(out value);
-            m_Reader.ReadValueSafe(out s, oneByteChars);
+        public void SerializeValue<T>(ref T value, FastBufferWriter.ForPrimitives unused = default) where T : unmanaged, IComparable, IConvertible, IComparable<T>, IEquatable<T> => m_Reader.ReadValueSafe(out value);
-        }
+        public void SerializeValue<T>(ref T[] value, FastBufferWriter.ForPrimitives unused = default) where T : unmanaged, IComparable, IConvertible, IComparable<T>, IEquatable<T> => m_Reader.ReadValueSafe(out value);
+        public void SerializeValue<T>(ref T value, FastBufferWriter.ForEnums unused = default) where T : unmanaged, Enum => m_Reader.ReadValueSafe(out value);
+        public void SerializeValue<T>(ref T[] value, FastBufferWriter.ForEnums unused = default) where T : unmanaged, Enum => m_Reader.ReadValueSafe(out value);
+        public void SerializeValue<T>(ref T value, FastBufferWriter.ForStructs unused = default) where T : unmanaged, INetworkSerializeByMemcpy => m_Reader.ReadValueSafe(out value);
+        public void SerializeValue<T>(ref T[] value, FastBufferWriter.ForStructs unused = default) where T : unmanaged, INetworkSerializeByMemcpy => m_Reader.ReadValueSafe(out value);
+        public void SerializeValue<T>(ref T value, FastBufferWriter.ForNetworkSerializable unused = default) where T : INetworkSerializable, new() => m_Reader.ReadValue(out value);
+        public void SerializeValue<T>(ref T[] value, FastBufferWriter.ForNetworkSerializable unused = default) where T : INetworkSerializable, new() => m_Reader.ReadValue(out value);
+        public void SerializeValue(ref Vector2 value) => m_Reader.ReadValueSafe(out value);
+        public void SerializeValue(ref Vector2[] value) => m_Reader.ReadValueSafe(out value);
+        public void SerializeValue(ref Vector3 value) => m_Reader.ReadValueSafe(out value);
+        public void SerializeValue(ref Vector3[] value) => m_Reader.ReadValueSafe(out value);
+        public void SerializeValue(ref Vector4 value) => m_Reader.ReadValueSafe(out value);
+        public void SerializeValue(ref Vector4[] value) => m_Reader.ReadValueSafe(out value);
+        public void SerializeValue(ref Quaternion value) => m_Reader.ReadValueSafe(out value);
+        public void SerializeValue(ref Quaternion[] value) => m_Reader.ReadValueSafe(out value);
+        public void SerializeValue(ref Color value) => m_Reader.ReadValueSafe(out value);
+        public void SerializeValue(ref Color[] value) => m_Reader.ReadValueSafe(out value);
+        public void SerializeValue(ref Color32 value) => m_Reader.ReadValueSafe(out value);
+        public void SerializeValue(ref Color32[] value) => m_Reader.ReadValueSafe(out value);
+        public void SerializeValue(ref Ray value) => m_Reader.ReadValueSafe(out value);
+        public void SerializeValue(ref Ray[] value) => m_Reader.ReadValueSafe(out value);
+        public void SerializeValue(ref Ray2D value) => m_Reader.ReadValueSafe(out value);
+        public void SerializeValue(ref Ray2D[] value) => m_Reader.ReadValueSafe(out value);
 
-        public void SerializeValue<T>(ref T[] array) where T : unmanaged
+        public void SerializeNetworkSerializable<T>(ref T value) where T : INetworkSerializable, new() => m_Reader.ReadNetworkSerializable(out value);
-        {
-            m_Reader.ReadValueSafe(out array);
-        }
-
-        public void SerializeValue(ref byte value)
-        {
-            m_Reader.ReadByteSafe(out value);
-        }
-
-        public void SerializeValue<T>(ref T value) where T : unmanaged
-        {
-            m_Reader.ReadValueSafe(out value);
-        }
-
-        public void SerializeNetworkSerializable<T>(ref T value) where T : INetworkSerializable, new()
-        {
-            m_Reader.ReadNetworkSerializable(out value);
-        }
 
         public bool PreCheck(int amount)
         {
             return m_Reader.TryBeginRead(amount);
         }
 
-        public void SerializeValuePreChecked(ref string s, bool oneByteChars = false)
+        public void SerializeValuePreChecked(ref string s, bool oneByteChars = false) => m_Reader.ReadValue(out s, oneByteChars);
-        {
+        public void SerializeValuePreChecked(ref byte value) => m_Reader.ReadByte(out value);
-            m_Reader.ReadValue(out s, oneByteChars);
+        public void SerializeValuePreChecked<T>(ref T value, FastBufferWriter.ForPrimitives unused = default) where T : unmanaged, IComparable, IConvertible, IComparable<T>, IEquatable<T> => m_Reader.ReadValue(out value);
-        }
+        public void SerializeValuePreChecked<T>(ref T[] value, FastBufferWriter.ForPrimitives unused = default) where T : unmanaged, IComparable, IConvertible, IComparable<T>, IEquatable<T> => m_Reader.ReadValue(out value);
-
+        public void SerializeValuePreChecked<T>(ref T value, FastBufferWriter.ForEnums unused = default) where T : unmanaged, Enum => m_Reader.ReadValue(out value);
-        public void SerializeValuePreChecked<T>(ref T[] array) where T : unmanaged
+        public void SerializeValuePreChecked<T>(ref T[] value, FastBufferWriter.ForEnums unused = default) where T : unmanaged, Enum => m_Reader.ReadValue(out value);
-        {
+        public void SerializeValuePreChecked<T>(ref T value, FastBufferWriter.ForStructs unused = default) where T : unmanaged, INetworkSerializeByMemcpy => m_Reader.ReadValue(out value);
-            m_Reader.ReadValue(out array);
+        public void SerializeValuePreChecked<T>(ref T[] value, FastBufferWriter.ForStructs unused = default) where T : unmanaged, INetworkSerializeByMemcpy => m_Reader.ReadValue(out value);
-        }
+        public void SerializeValuePreChecked(ref Vector2 value) => m_Reader.ReadValue(out value);
-
+        public void SerializeValuePreChecked(ref Vector2[] value) => m_Reader.ReadValue(out value);
-        public void SerializeValuePreChecked(ref byte value)
+        public void SerializeValuePreChecked(ref Vector3 value) => m_Reader.ReadValue(out value);
-        {
+        public void SerializeValuePreChecked(ref Vector3[] value) => m_Reader.ReadValue(out value);
-            m_Reader.ReadValue(out value);
+        public void SerializeValuePreChecked(ref Vector4 value) => m_Reader.ReadValue(out value);
-        }
+        public void SerializeValuePreChecked(ref Vector4[] value) => m_Reader.ReadValue(out value);
-
+        public void SerializeValuePreChecked(ref Quaternion value) => m_Reader.ReadValue(out value);
-        public void SerializeValuePreChecked<T>(ref T value) where T : unmanaged
+        public void SerializeValuePreChecked(ref Quaternion[] value) => m_Reader.ReadValue(out value);
-        {
+        public void SerializeValuePreChecked(ref Color value) => m_Reader.ReadValue(out value);
-            m_Reader.ReadValue(out value);
+        public void SerializeValuePreChecked(ref Color[] value) => m_Reader.ReadValue(out value);
-        }
+        public void SerializeValuePreChecked(ref Color32 value) => m_Reader.ReadValue(out value);
+        public void SerializeValuePreChecked(ref Color32[] value) => m_Reader.ReadValue(out value);
+        public void SerializeValuePreChecked(ref Ray value) => m_Reader.ReadValue(out value);
+        public void SerializeValuePreChecked(ref Ray[] value) => m_Reader.ReadValue(out value);
+        public void SerializeValuePreChecked(ref Ray2D value) => m_Reader.ReadValue(out value);
+        public void SerializeValuePreChecked(ref Ray2D[] value) => m_Reader.ReadValue(out value);
     }
 }

Runtime/Serialization/BufferSerializerWriter.cs

@@ -1,4 +1,5 @@
 using System;
+using UnityEngine;
 
 namespace Unity.Netcode
 {
@@ -24,25 +25,32 @@ namespace Unity.Netcode
             return m_Writer;
         }
 
-        public void SerializeValue(ref string s, bool oneByteChars = false)
+        public void SerializeValue(ref string s, bool oneByteChars = false) => m_Writer.WriteValueSafe(s, oneByteChars);
-        {
+        public void SerializeValue(ref byte value) => m_Writer.WriteByteSafe(value);
-            m_Writer.WriteValueSafe(s, oneByteChars);
+        public void SerializeValue<T>(ref T value, FastBufferWriter.ForPrimitives unused = default) where T : unmanaged, IComparable, IConvertible, IComparable<T>, IEquatable<T> => m_Writer.WriteValueSafe(value);
-        }
+        public void SerializeValue<T>(ref T[] value, FastBufferWriter.ForPrimitives unused = default) where T : unmanaged, IComparable, IConvertible, IComparable<T>, IEquatable<T> => m_Writer.WriteValueSafe(value);
-
+        public void SerializeValue<T>(ref T value, FastBufferWriter.ForEnums unused = default) where T : unmanaged, Enum => m_Writer.WriteValueSafe(value);
-        public void SerializeValue<T>(ref T[] array) where T : unmanaged
+        public void SerializeValue<T>(ref T[] value, FastBufferWriter.ForEnums unused = default) where T : unmanaged, Enum => m_Writer.WriteValueSafe(value);
-        {
+        public void SerializeValue<T>(ref T value, FastBufferWriter.ForStructs unused = default) where T : unmanaged, INetworkSerializeByMemcpy => m_Writer.WriteValueSafe(value);
-            m_Writer.WriteValueSafe(array);
+        public void SerializeValue<T>(ref T[] value, FastBufferWriter.ForStructs unused = default) where T : unmanaged, INetworkSerializeByMemcpy => m_Writer.WriteValueSafe(value);
-        }
+        public void SerializeValue<T>(ref T value, FastBufferWriter.ForNetworkSerializable unused = default) where T : INetworkSerializable, new() => m_Writer.WriteValue(value);
-
+        public void SerializeValue<T>(ref T[] value, FastBufferWriter.ForNetworkSerializable unused = default) where T : INetworkSerializable, new() => m_Writer.WriteValue(value);
-        public void SerializeValue(ref byte value)
+        public void SerializeValue(ref Vector2 value) => m_Writer.WriteValueSafe(value);
-        {
+        public void SerializeValue(ref Vector2[] value) => m_Writer.WriteValueSafe(value);
-            m_Writer.WriteByteSafe(value);
+        public void SerializeValue(ref Vector3 value) => m_Writer.WriteValueSafe(value);
-        }
+        public void SerializeValue(ref Vector3[] value) => m_Writer.WriteValueSafe(value);
-
+        public void SerializeValue(ref Vector4 value) => m_Writer.WriteValueSafe(value);
-        public void SerializeValue<T>(ref T value) where T : unmanaged
+        public void SerializeValue(ref Vector4[] value) => m_Writer.WriteValueSafe(value);
-        {
+        public void SerializeValue(ref Quaternion value) => m_Writer.WriteValueSafe(value);
-            m_Writer.WriteValueSafe(value);
+        public void SerializeValue(ref Quaternion[] value) => m_Writer.WriteValueSafe(value);
-        }
+        public void SerializeValue(ref Color value) => m_Writer.WriteValueSafe(value);
+        public void SerializeValue(ref Color[] value) => m_Writer.WriteValueSafe(value);
+        public void SerializeValue(ref Color32 value) => m_Writer.WriteValueSafe(value);
+        public void SerializeValue(ref Color32[] value) => m_Writer.WriteValueSafe(value);
+        public void SerializeValue(ref Ray value) => m_Writer.WriteValueSafe(value);
+        public void SerializeValue(ref Ray[] value) => m_Writer.WriteValueSafe(value);
+        public void SerializeValue(ref Ray2D value) => m_Writer.WriteValueSafe(value);
+        public void SerializeValue(ref Ray2D[] value) => m_Writer.WriteValueSafe(value);
 
         public void SerializeNetworkSerializable<T>(ref T value) where T : INetworkSerializable, new()
         {
@@ -54,24 +62,30 @@ namespace Unity.Netcode
             return m_Writer.TryBeginWrite(amount);
         }
 
-        public void SerializeValuePreChecked(ref string s, bool oneByteChars = false)
+        public void SerializeValuePreChecked(ref string s, bool oneByteChars = false) => m_Writer.WriteValue(s, oneByteChars);
-        {
+        public void SerializeValuePreChecked(ref byte value) => m_Writer.WriteByte(value);
-            m_Writer.WriteValue(s, oneByteChars);
+        public void SerializeValuePreChecked<T>(ref T value, FastBufferWriter.ForPrimitives unused = default) where T : unmanaged, IComparable, IConvertible, IComparable<T>, IEquatable<T> => m_Writer.WriteValue(value);
-        }
+        public void SerializeValuePreChecked<T>(ref T[] value, FastBufferWriter.ForPrimitives unused = default) where T : unmanaged, IComparable, IConvertible, IComparable<T>, IEquatable<T> => m_Writer.WriteValue(value);
 
-        public void SerializeValuePreChecked<T>(ref T[] array) where T : unmanaged
+        public void SerializeValuePreChecked<T>(ref T value, FastBufferWriter.ForEnums unused = default) where T : unmanaged, Enum => m_Writer.WriteValue(value);
-        {
+        public void SerializeValuePreChecked<T>(ref T[] value, FastBufferWriter.ForEnums unused = default) where T : unmanaged, Enum => m_Writer.WriteValue(value);
-            m_Writer.WriteValue(array);
+        public void SerializeValuePreChecked<T>(ref T value, FastBufferWriter.ForStructs unused = default) where T : unmanaged, INetworkSerializeByMemcpy => m_Writer.WriteValue(value);
-        }
+        public void SerializeValuePreChecked<T>(ref T[] value, FastBufferWriter.ForStructs unused = default) where T : unmanaged, INetworkSerializeByMemcpy => m_Writer.WriteValue(value);
-
+        public void SerializeValuePreChecked(ref Vector2 value) => m_Writer.WriteValue(value);
-        public void SerializeValuePreChecked(ref byte value)
+        public void SerializeValuePreChecked(ref Vector2[] value) => m_Writer.WriteValue(value);
-        {
+        public void SerializeValuePreChecked(ref Vector3 value) => m_Writer.WriteValue(value);
-            m_Writer.WriteByte(value);
+        public void SerializeValuePreChecked(ref Vector3[] value) => m_Writer.WriteValue(value);
-        }
+        public void SerializeValuePreChecked(ref Vector4 value) => m_Writer.WriteValue(value);
-
+        public void SerializeValuePreChecked(ref Vector4[] value) => m_Writer.WriteValue(value);
-        public void SerializeValuePreChecked<T>(ref T value) where T : unmanaged
+        public void SerializeValuePreChecked(ref Quaternion value) => m_Writer.WriteValue(value);
-        {
+        public void SerializeValuePreChecked(ref Quaternion[] value) => m_Writer.WriteValue(value);
-            m_Writer.WriteValue(value);
+        public void SerializeValuePreChecked(ref Color value) => m_Writer.WriteValue(value);
-        }
+        public void SerializeValuePreChecked(ref Color[] value) => m_Writer.WriteValue(value);
+        public void SerializeValuePreChecked(ref Color32 value) => m_Writer.WriteValue(value);
+        public void SerializeValuePreChecked(ref Color32[] value) => m_Writer.WriteValue(value);
+        public void SerializeValuePreChecked(ref Ray value) => m_Writer.WriteValue(value);
+        public void SerializeValuePreChecked(ref Ray[] value) => m_Writer.WriteValue(value);
+        public void SerializeValuePreChecked(ref Ray2D value) => m_Writer.WriteValue(value);
+        public void SerializeValuePreChecked(ref Ray2D[] value) => m_Writer.WriteValue(value);
     }
 }