com.unity.netcode.gameobjects@1.0.0-pre.4

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.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)

### 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)

Runtime/NetworkVariable/NetworkVariable.cs

@@ -9,6 +9,55 @@ namespace Unity.Netcode
     [Serializable]
     public class NetworkVariable<T> : NetworkVariableBase where T : unmanaged
     {
+        // Functions that know how to serialize INetworkSerializable
+        internal static void WriteNetworkSerializable<TForMethod>(FastBufferWriter writer, ref TForMethod value)
+            where TForMethod : INetworkSerializable, new()
+        {
+            writer.WriteNetworkSerializable(value);
+        }
+        internal static void ReadNetworkSerializable<TForMethod>(FastBufferReader reader, out TForMethod value)
+            where TForMethod : INetworkSerializable, new()
+        {
+            reader.ReadNetworkSerializable(out value);
+        }
+
+        // Functions that serialize other types
+        private static void WriteValue<TForMethod>(FastBufferWriter writer, ref TForMethod value) where TForMethod : unmanaged
+        {
+            writer.WriteValueSafe(value);
+        }
+
+        private static void ReadValue<TForMethod>(FastBufferReader reader, out TForMethod value)
+            where TForMethod : unmanaged
+        {
+            reader.ReadValueSafe(out value);
+        }
+
+        internal delegate void WriteDelegate<TForMethod>(FastBufferWriter writer, ref TForMethod value);
+
+        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.
+        internal static WriteDelegate<T> Write = WriteValue;
+        internal static ReadDelegate<T> Read = ReadValue;
+
+
         /// <summary>
         /// Delegate type for value changed event
         /// </summary>
@@ -106,7 +155,7 @@ namespace Unity.Netcode
         public override void ReadDelta(FastBufferReader reader, bool keepDirtyDelta)
         {
             T previousValue = m_InternalValue;
-            reader.ReadValueSafe(out m_InternalValue);
+            Read(reader, out m_InternalValue);
 
             if (keepDirtyDelta)
             {
@@ -119,13 +168,13 @@ 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, ref m_InternalValue);
         }
     }
 }