fix: networkscenemanager not releasing buffers from pool (#1132)

* fix

Don't used pooled NetworkBuffers for SceneEventData, instead just allocate 1 dedicated NetworkBuffer per SceneEventData (which will yield 2 instances per NetworkSceneManager).
Make sure we dispose the scene manager so it will dispose the two SceneEventData instances so they will Dispose their NetworkBuffers.

* style

Adding comments

* refactor

Switching back to PooledNetworkBuffer.
Now it only gets a PooledNetworkBuffer when needed, and releases it back into the pool when it is no longer needed.

* style

Fixing one standards violation introduced in this PR and several more that were introduced when metrics were added.

* style and refactor

Removed a LF that was not intended.
Added comments to SetInternalBuffer and ReleaseInternalBuffer while also making them both private as nothing else needs to be calling these two methods.

* refactor

Removing standards check.

* style

Removing 1 LF from SceneEventData constructor.
Slightly improved constructor description.
Removed 1 LF between ReleaseInternalBuffer and SetInternalBuffer
Removed 1 LF between AddSceneToSynchronize and SceneHandlesToSynchronize property.

Author: NoelStephensUnity

com.unity.netcode.gameobjects/Runtime/Core/NetworkManager.cs

@@ -951,6 +951,8 @@ public void Shutdown()
 
             if (SceneManager != null)
             {
+                // Let the NetworkSceneManager clean up its two SceneEvenData instances
+                SceneManager.Dispose();
                 SceneManager = null;
             }
 

com.unity.netcode.gameobjects/Runtime/SceneManagement/NetworkSceneManager.cs

@@ -85,7 +85,7 @@ public class SceneEvent
     /// Main class for managing network scenes when <see cref="NetworkConfig.EnableSceneManagement"/> is enabled.
     /// Uses the <see cref="MessageQueueContainer.MessageType.SceneEvent"/> message to communicate <see cref="SceneEventData"/> between the server and client(s)
     /// </summary>
-    public class NetworkSceneManager
+    public class NetworkSceneManager : IDisposable
     {
         // Used to be able to turn re-synchronization off for future snapshot development purposes.
         internal static bool DisableReSynchronization;
@@ -202,6 +202,17 @@ public class NetworkSceneManager
 
         internal Scene DontDestroyOnLoadScene;
 
+        /// <summary>
+        /// Handle NetworkSeneManager clean up
+        /// </summary>
+        public void Dispose()
+        {
+            SceneEventData.Dispose();
+            SceneEventData = null;
+            ClientSynchEventData.Dispose();
+            ClientSynchEventData = null;
+        }
+
         /// <summary>
         /// Gets the scene name from full path to the scene
         /// </summary>

com.unity.netcode.gameobjects/Runtime/SceneManagement/SceneEventData.cs

@@ -485,6 +485,7 @@ internal void OnRead(NetworkReader reader)
                     }
                 case SceneEventTypes.S2C_Load:
                     {
+                        SetInternalBuffer();
                         // We store off the trailing in-scene placed serialized NetworkObject data to
                         // be processed once we are done loading.
                         InternalBuffer.Position = 0;
@@ -514,8 +515,8 @@ internal void OnRead(NetworkReader reader)
         /// <param name="reader"></param>
         internal void CopySceneSyncrhonizationData(NetworkReader reader)
         {
+            SetInternalBuffer();
             m_NetworkObjectsSync.Clear();
-
             ScenesToSynchronize = new Queue<uint>(reader.ReadUIntArrayPacked());
             SceneHandlesToSynchronize = new Queue<uint>(reader.ReadUIntArrayPacked());
             InternalBuffer.Position = 0;
@@ -548,6 +549,7 @@ internal void DeserializeScenePlacedObjects()
                 // Deserialize the NetworkObject
                 NetworkObject.DeserializeSceneObject(InternalBuffer as NetworkBuffer, reader, m_NetworkManager);
             }
+            ReleaseInternalBuffer();
         }
 
         /// <summary>
@@ -694,6 +696,7 @@ internal void SynchronizeSceneNetworkObjects(NetworkManager networkManager)
                     m_NetworkObjectsSync.Add(spawnedNetworkObject);
                 }
             }
+            ReleaseInternalBuffer();
         }
 
         /// <summary>
@@ -737,9 +740,20 @@ internal void ReadSceneEventProgressDone(NetworkReader reader)
         }
 
         /// <summary>
-        /// Used to release the pooled network buffer
+        /// Gets a PooledNetworkBuffer if needed
         /// </summary>
-        public void Dispose()
+        private void SetInternalBuffer()
+        {
+            if (InternalBuffer == null)
+            {
+                InternalBuffer = NetworkBufferPool.GetBuffer();
+            }
+        }
+
+        /// <summary>
+        /// Releases the PooledNetworkBuffer when no longer needed
+        /// </summary>
+        private void ReleaseInternalBuffer()
         {
             if (InternalBuffer != null)
             {
@@ -749,12 +763,19 @@ public void Dispose()
         }
 
         /// <summary>
-        /// Constructor
+        /// Used to release the pooled network buffer
+        /// </summary>
+        public void Dispose()
+        {
+            ReleaseInternalBuffer();
+        }
+
+        /// <summary>
+        /// Constructor for SceneEventData
         /// </summary>
         internal SceneEventData(NetworkManager networkManager)
         {
             m_NetworkManager = networkManager;
-            InternalBuffer = NetworkBufferPool.GetBuffer();
         }
     }
 }