fix: this fixes issues with multi scene loading on server and client (#…

…965)

* fix: This fixes issues with multi scene loading on server and client. We never checked for when clients would unload from one scene and load to another scene and do it again over and over. This causes spawned list to null itself out because of lost references. This now allows ServerObjectManager and ClientObjectManager to check for it after scene changes.

* fix: stupid me did undo a test.

* fix: created a new test for the method we created. Also created a new removalCollection list we can keep reusing because constantly reallocating and deallocating during scene load might be bad. Not sure if this is better or worse.

* fix: james caught few gotchas. This is fix.

Assets/Mirage/Runtime/ClientObjectManager.cs

@@ -89,6 +89,8 @@ void OnClientDisconnected(ClientStoppedReason reason)
 
         void OnFinishedSceneChange(string scenePath, SceneOperation sceneOperation)
         {
+            Client.World.RemoveDestroyedObjects();
+
             PrepareToSpawnSceneObjects();
         }
 
@@ -314,6 +316,7 @@ public void DestroyAllClientObjects()
             // create copy so they can be removed inside loop
             // allocation here are fine because is part of clean up
             NetworkIdentity[] all = Client.World.SpawnedIdentities.ToArray();
+
             foreach (NetworkIdentity identity in all)
             {
                 if (identity != null && identity.gameObject != null)

Assets/Mirage/Runtime/NetworkWorld.cs

@@ -57,6 +57,17 @@ internal void RemoveIdentity(NetworkIdentity identity)
                 onUnspawn?.Invoke(identity);
         }
 
+        internal void RemoveDestroyedObjects()
+        {
+            var removalCollection = new List<NetworkIdentity>(SpawnedIdentities);
+
+            foreach (NetworkIdentity identity in removalCollection)
+            {
+                if (identity == null)
+                    SpawnedObjects.Remove(identity.NetId);
+            }
+        }
+
         internal void RemoveIdentity(uint netId)
         {
             if (netId == 0) throw new ArgumentException("id can not be zero", nameof(netId));

Assets/Mirage/Runtime/ServerObjectManager.cs

@@ -92,6 +92,8 @@ void OnServerStopped()
 
         void OnFinishedSceneChange(string scenePath, SceneOperation sceneOperation)
         {
+            Server.World.RemoveDestroyedObjects();
+
             SpawnOrActivate();
         }
 

Assets/Tests/Editor/NetworkWorldTests.cs

@@ -2,7 +2,6 @@
 using System.Collections.Generic;
 using NSubstitute;
 using NUnit.Framework;
-using NUnit.Framework.Internal;
 using UnityEngine;
 using Object = UnityEngine.Object;
 using Random = UnityEngine.Random;
@@ -299,5 +298,27 @@ public void ClearDoesNotInvokeEvent()
             world.ClearSpawnedObjects();
             unspawnListener.DidNotReceiveWithAnyArgs().Invoke(default);
         }
+
+        [Test]
+        public void ClearDestoryedObjects()
+        {
+            AddValidIdentity(out uint id1, out NetworkIdentity identity1);
+            AddValidIdentity(out uint id2, out NetworkIdentity identity2);
+            AddValidIdentity(out uint id3, out NetworkIdentity identity3);
+            AddValidIdentity(out uint id4, out NetworkIdentity nullIdentity);
+
+            Object.DestroyImmediate(nullIdentity);
+
+            Assert.That(world.SpawnedIdentities.Count, Is.EqualTo(4));
+
+            world.RemoveDestroyedObjects();
+
+            foreach (NetworkIdentity identity in world.SpawnedIdentities)
+            {
+                Assert.That(identity != null);
+            }
+
+            Assert.That(world.SpawnedIdentities.Count, Is.EqualTo(3));
+        }
     }
 }