update

src/EcsWorld.cs

@@ -86,6 +86,7 @@ namespace DCFApixels.DragonECS
 
         private StructList<IEcsWorldEventListener> _listeners = new StructList<IEcsWorldEventListener>(2);
         private StructList<IEcsEntityEventListener> _entityListeners = new StructList<IEcsEntityEventListener>(2);
+        private bool _hasAnyEntityListener = false;
 
         #region Properties
         EcsWorld IEntityStorage.World
@@ -394,7 +395,10 @@ namespace DCFApixels.DragonECS
             {
                 slot.gen |= GEN_SLEEP_MASK;
             }
-            _entityListeners.InvokeOnNewEntity(entityID);
+            if (_hasAnyEntityListener)
+            {
+                _entityListeners.InvokeOnNewEntity(entityID);
+            }
             MoveToEmptyEntities(entityID);
         }
 
@@ -436,7 +440,10 @@ namespace DCFApixels.DragonECS
             _delEntBuffer[_delEntBufferCount++] = entityID;
             _entities[entityID].isUsed = false;
             _entitiesCount--;
-            _entityListeners.InvokeOnDelEntity(entityID);
+            if (_hasAnyEntityListener)
+            {
+                _entityListeners.InvokeOnDelEntity(entityID);
+            }
         }
         [MethodImpl(MethodImplOptions.AggressiveInlining)]
         private void MoveToEmptyEntities(int entityID)
@@ -1045,10 +1052,12 @@ namespace DCFApixels.DragonECS
         public void AddListener(IEcsEntityEventListener entityEventListener)
         {
             _entityListeners.Add(entityEventListener);
+            _hasAnyEntityListener = _entityListeners.Count > 0;
         }
         public void RemoveListener(IEcsEntityEventListener entityEventListener)
         {
             _entityListeners.Remove(entityEventListener);
+            _hasAnyEntityListener = _entityListeners.Count > 0;
         }
         #endregion
 
@@ -1374,6 +1383,7 @@ namespace DCFApixels.DragonECS
     public interface IEcsEntityEventListener
     {
         void OnNewEntity(int entityID);
+        void OnMigrateEntity(int entityID);
         void OnDelEntity(int entityID);
     }
     internal static class WorldEventListExtensions
@@ -1411,6 +1421,14 @@ namespace DCFApixels.DragonECS
             }
         }
         [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        public static void InvokeOnMigrateEntity(this ref StructList<IEcsEntityEventListener> self, int entityID)
+        {
+            for (int i = 0, iMax = self.Count; i < iMax; i++)
+            {
+                self[i].OnMigrateEntity(entityID);
+            }
+        }
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
         public static void InvokeOnDelEntity(this ref StructList<IEcsEntityEventListener> self, int entityID)
         {
             for (int i = 0, iMax = self.Count; i < iMax; i++)

src/EcsWorld.pools.cs

@@ -286,6 +286,10 @@ namespace DCFApixels.DragonECS
                 RemoveFromEmptyEntities(entityID);
             }
             _entityComponentMasks[(entityID << _entityComponentMaskLengthBitShift) + maskBit.chunkIndex] |= maskBit.mask;
+            if (_hasAnyEntityListener)
+            {
+                _entityListeners.InvokeOnMigrateEntity(entityID);
+            }
         }
         [MethodImpl(MethodImplOptions.AggressiveInlining)]
         private void UnregisterEntityComponent(int entityID, int componentTypeID, EcsMaskChunck maskBit)
@@ -296,12 +300,15 @@ namespace DCFApixels.DragonECS
             slot.version++;
             var count = --_entities[entityID].componentsCount;
             _entityComponentMasks[(entityID << _entityComponentMaskLengthBitShift) + maskBit.chunkIndex] &= ~maskBit.mask;
-
             if (count == 0 && IsUsed(entityID))
             {
                 MoveToEmptyEntities(entityID);
             }
             CheckUnregisterValid(count, entityID);
+            if (_hasAnyEntityListener)
+            {
+                _entityListeners.InvokeOnMigrateEntity(entityID);
+            }
         }
         [MethodImpl(MethodImplOptions.AggressiveInlining)]
         private bool TryRegisterEntityComponent(int entityID, int componentTypeID, EcsMaskChunck maskBit)
@@ -320,6 +327,10 @@ namespace DCFApixels.DragonECS
                 {
                     RemoveFromEmptyEntities(entityID);
                 }
+                if (_hasAnyEntityListener)
+                {
+                    _entityListeners.InvokeOnMigrateEntity(entityID);
+                }
                 return true;
             }
             return false;
@@ -343,6 +354,10 @@ namespace DCFApixels.DragonECS
                     MoveToEmptyEntities(entityID);
                 }
                 CheckUnregisterValid(count, entityID);
+                if (_hasAnyEntityListener)
+                {
+                    _entityListeners.InvokeOnMigrateEntity(entityID);
+                }
                 return true;
             }
             return false;

src/Executors/EcsWhereExecutor.cs

@@ -160,6 +160,7 @@ namespace DCFApixels.DragonECS.Core.Internal
             SortHalper.Sort(_filteredEntities.AsSpan(_filteredEntitiesCount), comparison);
             return new EcsUnsafeSpan(World.ID, _filteredEntities.Ptr, _filteredEntitiesCount);
         }
+        public override EcsSpan Snapshot() { return Execute(); }
         #endregion
     }
 }

src/Executors/EcsWhereToGroupExecutor.cs

@@ -117,6 +117,7 @@ namespace DCFApixels.DragonECS.Core.Internal
             ExecuteFor_Iternal(span);
             return _filteredGroup;
         }
+        public override EcsSpan Snapshot() { return Execute(); }
         #endregion
     }
 }

src/Executors/MaskQueryExecutor.cs

@@ -105,6 +105,7 @@ namespace DCFApixels.DragonECS.Core
         }
         protected abstract void OnInitialize();
         protected abstract void OnDestroy();
+        public abstract EcsSpan Snapshot();
     }
 
 #if ENABLE_IL2CPP