chore: add second part of session restore (#2919)

* update

Skip initial in-scene object spawn pass and sending service the initial synchronization when restoring a session.
Allow same scene handle entries when restoring a session.
Don't spawn the player during connection approval during session restore.
Integration test helpers registers validation handler to exclude InitTestScene for all clients.
NetworkSceneManager always sends scene events to the service.
For now, session owner always uses PostSynchronizationSceneUnloading when processing a session restore synchronization.

Author: NoelStephensUnity

com.unity.netcode.gameobjects/Runtime/Messaging/Messages/ConnectionApprovedMessage.cs

@@ -236,16 +236,22 @@ public void Handle(ref NetworkContext context)
                     // Mark the client being connected
                     networkManager.IsConnectedClient = true;
 
-                    // Spawn any in-scene placed NetworkObjects
-                    networkManager.SpawnManager.ServerSpawnSceneObjectsOnStartSweep();
+                    networkManager.SceneManager.IsRestoringSession = IsRestoredSession;
 
-                    // Spawn the local player of the session owner
-                    if (networkManager.AutoSpawnPlayerPrefabClientSide)
+                    if (!IsRestoredSession)
                     {
-                        networkManager.ConnectionManager.CreateAndSpawnPlayer(OwnerClientId);
+                        // Spawn any in-scene placed NetworkObjects
+                        networkManager.SpawnManager.ServerSpawnSceneObjectsOnStartSweep();
+
+                        // Spawn the local player of the session owner
+                        if (networkManager.AutoSpawnPlayerPrefabClientSide)
+                        {
+                            networkManager.ConnectionManager.CreateAndSpawnPlayer(OwnerClientId);
+                        }
+
+                        // Synchronize the service with the initial session owner's loaded scenes and spawned objects
+                        networkManager.SceneManager.SynchronizeNetworkObjects(NetworkManager.ServerClientId);
                     }
-                    // Synchronize the service with the initial session owner's loaded scenes and spawned objects
-                    networkManager.SceneManager.SynchronizeNetworkObjects(NetworkManager.ServerClientId);
                 }
             }
             ConnectedClientIds.Dispose();

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

@@ -444,6 +444,7 @@ public List<Scene> GetSynchronizedScenes()
         internal Dictionary<int, int> ServerSceneHandleToClientSceneHandle = new Dictionary<int, int>();
         internal Dictionary<int, int> ClientSceneHandleToServerSceneHandle = new Dictionary<int, int>();
 
+        internal bool IsRestoringSession;
         /// <summary>
         /// Add the client to server (and vice versa) scene handle lookup.
         /// Add the client-side handle to scene entry in the HandleToScene table.
@@ -455,7 +456,7 @@ internal bool UpdateServerClientSceneHandle(int serverHandle, int clientHandle,
             {
                 ServerSceneHandleToClientSceneHandle.Add(serverHandle, clientHandle);
             }
-            else
+            else if (!IsRestoringSession)
             {
                 return false;
             }
@@ -464,7 +465,7 @@ internal bool UpdateServerClientSceneHandle(int serverHandle, int clientHandle,
             {
                 ClientSceneHandleToServerSceneHandle.Add(clientHandle, serverHandle);
             }
-            else
+            else if (!IsRestoringSession)
             {
                 return false;
             }
@@ -1045,7 +1046,7 @@ internal NetworkObject GetSceneRelativeInSceneNetworkObject(uint globalObjectIdH
         /// <param name="targetClientIds">array of client identifiers to receive the scene event message</param>
         private void SendSceneEventData(uint sceneEventId, ulong[] targetClientIds)
         {
-            if (targetClientIds.Length == 0)
+            if (targetClientIds.Length == 0 && !NetworkManager.DistributedAuthorityMode)
             {
                 // This would be the Host/Server with no clients connected
                 // Silently return as there is nothing to be done
@@ -1056,6 +1057,16 @@ private void SendSceneEventData(uint sceneEventId, ulong[] targetClientIds)
 
             if (NetworkManager.DistributedAuthorityMode && !NetworkManager.DAHost)
             {
+                if (NetworkManager.DistributedAuthorityMode && HasSceneAuthority())
+                {
+                    sceneEvent.TargetClientId = NetworkManager.ServerClientId;
+                    var message = new SceneEventMessage
+                    {
+                        EventData = sceneEvent,
+                    };
+                    var size = NetworkManager.ConnectionManager.SendMessage(ref message, k_DeliveryType, NetworkManager.ServerClientId);
+                    NetworkManager.NetworkMetrics.TrackSceneEventSent(NetworkManager.ServerClientId, (uint)sceneEvent.SceneEventType, SceneNameFromHash(sceneEvent.SceneHash), size);
+                }
                 foreach (var clientId in targetClientIds)
                 {
                     sceneEvent.TargetClientId = clientId;
@@ -2430,6 +2441,12 @@ private void HandleClientSceneEvent(uint sceneEventId)
                                 networkObject.InternalNetworkSessionSynchronized();
                             }
 
+                            if (NetworkManager.DistributedAuthorityMode && HasSceneAuthority() && IsRestoringSession)
+                            {
+                                IsRestoringSession = false;
+                                PostSynchronizationSceneUnloading = m_OriginalPostSynchronizationSceneUnloading;
+                            }
+
                             EndSceneEvent(sceneEventId);
                         }
                         break;
@@ -2616,6 +2633,8 @@ private void HandleSessionOwnerEvent(uint sceneEventId, ulong clientId)
         /// </summary>
         internal bool SkipSceneHandling;
 
+        private bool m_OriginalPostSynchronizationSceneUnloading;
+
         /// <summary>
         /// Both Client and Server: Incoming scene event entry point
         /// </summary>
@@ -2689,6 +2708,12 @@ internal void HandleSceneEvent(ulong clientId, FastBufferReader reader)
                         // Only if ClientSynchronizationMode is Additive and the client receives a synchronize scene event
                         if (ClientSynchronizationMode == LoadSceneMode.Additive)
                         {
+                            if (NetworkManager.DistributedAuthorityMode && HasSceneAuthority() && IsRestoringSession && clientId == NetworkManager.ServerClientId)
+                            {
+                                m_OriginalPostSynchronizationSceneUnloading = PostSynchronizationSceneUnloading;
+                                PostSynchronizationSceneUnloading = true;
+                            }
+
                             // Check for scenes already loaded and create a table of scenes already loaded (SceneEntries) that will be
                             // used if the server is synchronizing the same scenes (i.e. if a matching scene is already loaded on the
                             // client side, then that scene will be used as opposed to loading another scene). This allows for clients

com.unity.netcode.gameobjects/TestHelpers/Runtime/NetcodeIntegrationTestHelpers.cs

@@ -378,7 +378,8 @@ private static void SceneManagerValidationAndTestRunnerInitialization(NetworkMan
         {
             // If VerifySceneBeforeLoading is not already set, then go ahead and set it so the host/server
             // will not try to synchronize clients to the TestRunner scene.  We only need to do this for the server.
-            if (networkManager.IsServer && networkManager.SceneManager.VerifySceneBeforeLoading == null)
+            // All clients in distributed authority mode, should have this registered (since any one client can become the session owner).
+            if ((networkManager.IsServer && networkManager.SceneManager.VerifySceneBeforeLoading == null) || networkManager.DistributedAuthorityMode)
             {
                 networkManager.SceneManager.VerifySceneBeforeLoading = VerifySceneIsValidForClientsToLoad;