com.unity.netcode.gameobjects@1.0.0-pre.10

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.10] - 2022-06-21

### Added

- Added a new `OnTransportFailure` callback to `NetworkManager`. This callback is invoked when the manager's `NetworkTransport` encounters an unrecoverable error. Transport failures also cause the `NetworkManager` to shut down. Currently, this is only used by `UnityTransport` to signal a timeout of its connection to the Unity Relay servers. (#1994)
- Added `NetworkEvent.TransportFailure`, which can be used by implementations of `NetworkTransport` to signal to `NetworkManager` that an unrecoverable error was encountered. (#1994)
- Added test to ensure a warning occurs when nesting NetworkObjects in a NetworkPrefab (#1969)
- Added `NetworkManager.RemoveNetworkPrefab(...)` to remove a prefab from the prefabs list (#1950)

### Changed

- Updated `UnityTransport` dependency on `com.unity.transport` to 1.1.0. (#2025)
- (API Breaking) `ConnectionApprovalCallback` is no longer an `event` and will not allow more than 1 handler registered at a time. Also, `ConnectionApprovalCallback` is now a `Func<>` taking `ConnectionApprovalRequest` in and returning `ConnectionApprovalResponse` back out (#1972)

### Removed

### Fixed
- Fixed issue where dynamically spawned `NetworkObject`s could throw an exception if the scene of origin handle was zero (0) and the `NetworkObject` was already spawned. (#2017)
- Fixed issue where `NetworkObject.Observers` was not being cleared when despawned. (#2009)
- Fixed `NetworkAnimator` could not run in the server authoritative mode. (#2003)
- Fixed issue where late joining clients would get a soft synchronization error if any in-scene placed NetworkObjects were parented under another `NetworkObject`. (#1985)
- Fixed issue where `NetworkBehaviourReference` would throw a type cast exception if using `NetworkBehaviourReference.TryGet` and the component type was not found. (#1984)
- Fixed `NetworkSceneManager` was not sending scene event notifications for the currently active scene and any additively loaded scenes when loading a new scene in `LoadSceneMode.Single` mode. (#1975)
- Fixed issue where one or more clients disconnecting during a scene event would cause `LoadEventCompleted` or `UnloadEventCompleted` to wait until the `NetworkConfig.LoadSceneTimeOut` period before being triggered. (#1973)
- Fixed issues when multiple `ConnectionApprovalCallback`s were registered (#1972)
- Fixed a regression in serialization support: `FixedString`, `Vector2Int`, and `Vector3Int` types can now be used in NetworkVariables and RPCs again without requiring a `ForceNetworkSerializeByMemcpy<>` wrapper. (#1961)
- Fixed generic types that inherit from NetworkBehaviour causing crashes at compile time. (#1976)
- Fixed endless dialog boxes when adding a `NetworkBehaviour` to a `NetworkManager` or vice-versa. (#1947)
- Fixed `NetworkAnimator` issue where it was only synchronizing parameters if the layer or state changed or was transitioning between states. (#1946)
- Fixed `NetworkAnimator` issue where when it did detect a parameter had changed it would send all parameters as opposed to only the parameters that changed. (#1946)
- Fixed `NetworkAnimator` issue where it was not always disposing the `NativeArray` that is allocated when spawned. (#1946)
- Fixed `NetworkAnimator` issue where it was not taking the animation speed or state speed multiplier into consideration. (#1946)
- Fixed `NetworkAnimator` issue where it was not properly synchronizing late joining clients if they joined while `Animator` was transitioning between states. (#1946)
- Fixed `NetworkAnimator` issue where the server was not relaying changes to non-owner clients when a client was the owner. (#1946)
- Fixed issue where the `PacketLoss` metric for tools would return the packet loss over a connection lifetime instead of a single frame. (#2004)

Runtime/Transports/UTP/UnityTransport.cs

@@ -243,6 +243,15 @@ namespace Unity.Netcode.Transports.UTP
             PacketDropRate = 0
         };
 
+        private struct PacketLossCache
+        {
+            public int PacketsReceived;
+            public int PacketsDropped;
+            public float PacketLoss;
+        };
+
+        private PacketLossCache m_PacketLossCache = new PacketLossCache();
+
         private State m_State = State.Disconnected;
         private NetworkDriver m_Driver;
         private NetworkSettings m_NetworkSettings;
@@ -713,6 +722,15 @@ namespace Unity.Netcode.Transports.UTP
 
                 m_Driver.ScheduleUpdate().Complete();
 
+                if (m_ProtocolType == ProtocolType.RelayUnityTransport && m_Driver.GetRelayConnectionStatus() == RelayConnectionStatus.AllocationInvalid)
+                {
+                    Debug.LogError("Transport failure! Relay allocation needs to be recreated, and NetworkManager restarted. " +
+                        "Use NetworkManager.OnTransportFailure to be notified of such events programmatically.");
+
+                    InvokeOnTransportEvent(NetcodeNetworkEvent.TransportFailure, 0, default, Time.realtimeSinceStartup);
+                    return;
+                }
+
                 while (AcceptConnection() && m_Driver.IsCreated)
                 {
                     ;
@@ -839,11 +857,22 @@ namespace Unity.Netcode.Transports.UTP
             {
                 var sharedContext = (ReliableUtility.SharedContext*)sharedBuffer.GetUnsafePtr();
 
-                var packetReceived = (float)sharedContext->stats.PacketsReceived;
-                var packetDropped = (float)sharedContext->stats.PacketsDropped;
-                var packetLoss = packetReceived > 0 ? packetDropped / packetReceived : 0;
+                var packetReceivedDelta = (float)(sharedContext->stats.PacketsReceived - m_PacketLossCache.PacketsReceived);
+                var packetDroppedDelta = (float)(sharedContext->stats.PacketsDropped - m_PacketLossCache.PacketsDropped);
 
-                return packetLoss;
+                // There can be multiple update happening in a single frame where no packets have transitioned
+                // In those situation we want to return the last packet loss value instead of 0 to avoid invalid swings
+                if (packetDroppedDelta == 0 && packetReceivedDelta == 0)
+                {
+                    return m_PacketLossCache.PacketLoss;
+                }
+
+                m_PacketLossCache.PacketsReceived = sharedContext->stats.PacketsReceived;
+                m_PacketLossCache.PacketsDropped = sharedContext->stats.PacketsDropped;
+
+                m_PacketLossCache.PacketLoss = packetReceivedDelta > 0 ? packetDroppedDelta / packetReceivedDelta : 0;
+
+                return m_PacketLossCache.PacketLoss;
             }
         }
 
@@ -1106,6 +1135,8 @@ namespace Unity.Netcode.Transports.UTP
 
             DisposeInternals();
 
+            m_ReliableReceiveQueues.Clear();
+
             // We must reset this to zero because UTP actually re-uses clientIds if there is a clean disconnect
             m_ServerClientId = 0;
         }