Core/Movement: delay movement update in MotionMaster until its owner signals AddToWorld

Port From (https://github.com/TrinityCore/TrinityCore/commit/dfb2221552048512b4fda0c7e0c97ecf808106f9)

Source/Framework/Constants/Movement/MovementConst.cs

@@ -66,7 +66,10 @@ namespace Framework.Constants
     {
         None = 0x0,
         Update = 0x1, // Update in progress
-        StaticInitializationPending = 0x2
+        StaticInitializationPending = 0x2, // Static movement (MOTION_SLOT_DEFAULT) hasn't been initialized
+        InitializationPending = 0x4, // MotionMaster is stalled until signaled
+
+        Delayed = StaticInitializationPending | InitializationPending
     }
 
     public enum MotionMasterDelayedActionType

Source/Game/Entities/Unit/Unit.cs

@@ -430,6 +430,7 @@ namespace Game.Entities
         public override void AddToWorld()
         {
             base.AddToWorld();
+            i_motionMaster.AddToWorld();
 
             RemoveAurasWithInterruptFlags(SpellAuraInterruptFlags.EnterWorld);
         }

Source/Game/Movement/MotionMaster.cs

@@ -106,7 +106,7 @@ namespace Game.Movement
 
         public void Initialize()
         {
-            if (HasFlag(MotionMasterFlags.Update))
+            if (HasFlag(MotionMasterFlags.Delayed))
             {
                 _delayedActions.Enqueue(new DelayedAction(() => Initialize(), MotionMasterDelayedActionType.Initialize));
                 return;
@@ -120,6 +120,16 @@ namespace Game.Movement
             Add(AI.AISelector.SelectMovementGenerator(_owner), MovementSlot.Default);
         }
 
+        public void AddToWorld()
+        {
+            if (!HasFlag(MotionMasterFlags.InitializationPending))
+                return;
+
+            ResolveDelayedActions();
+
+            RemoveFlag(MotionMasterFlags.InitializationPending);
+        }
+
         public bool Empty()
         {
             return _defaultGenerator == null && _generators.Empty();
@@ -287,6 +297,9 @@ namespace Game.Movement
             if (!_owner)
                 return;
 
+            if (HasFlag(MotionMasterFlags.InitializationPending))
+                return;
+
             Cypher.Assert(!Empty(), $"MotionMaster:Update: update called without Initializing! ({_owner.GetGUID()})");
 
             AddFlag(MotionMasterFlags.Update);
@@ -315,11 +328,7 @@ namespace Game.Movement
 
             RemoveFlag(MotionMasterFlags.Update);
 
-            while (_delayedActions.Count != 0)
+            ResolveDelayedActions();
-            {
-                _delayedActions.Peek().Resolve();
-                _delayedActions.Dequeue();
-            }
         }
 
         void Add(MovementGenerator movement, MovementSlot slot = MovementSlot.Active)
@@ -330,7 +339,7 @@ namespace Game.Movement
             if (IsInvalidMovementSlot(slot))
                 return;
 
-            if (HasFlag(MotionMasterFlags.Update))
+            if (HasFlag(MotionMasterFlags.Delayed))
                 _delayedActions.Enqueue(new DelayedAction(() => Add(movement, slot), MotionMasterDelayedActionType.Add));
             else
                 DirectAdd(movement, slot);
@@ -341,7 +350,7 @@ namespace Game.Movement
             if (movement == null || IsInvalidMovementSlot(slot))
                 return;
 
-            if (HasFlag(MotionMasterFlags.Update))
+            if (HasFlag(MotionMasterFlags.Delayed))
             {
                 _delayedActions.Enqueue(new DelayedAction(() => Remove(movement, slot), MotionMasterDelayedActionType.Remove));
                 return;
@@ -373,7 +382,7 @@ namespace Game.Movement
             if (IsInvalidMovementGeneratorType(type) || IsInvalidMovementSlot(slot))
                 return;
 
-            if (HasFlag(MotionMasterFlags.Update))
+            if (HasFlag(MotionMasterFlags.Delayed))
             {
                 _delayedActions.Enqueue(new DelayedAction(() => Remove(type, slot), MotionMasterDelayedActionType.RemoveType));
                 return;
@@ -403,7 +412,7 @@ namespace Game.Movement
 
         public void Clear()
         {
-            if (HasFlag(MotionMasterFlags.Update))
+            if (HasFlag(MotionMasterFlags.Delayed))
             {
                 _delayedActions.Enqueue(new DelayedAction(() => Clear(), MotionMasterDelayedActionType.Clear));
                 return;
@@ -418,7 +427,7 @@ namespace Game.Movement
             if (IsInvalidMovementSlot(slot))
                 return;
 
-            if (HasFlag(MotionMasterFlags.Update))
+            if (HasFlag(MotionMasterFlags.Delayed))
             {
                 _delayedActions.Enqueue(new DelayedAction(() => Clear(slot), MotionMasterDelayedActionType.ClearSlot));
                 return;
@@ -442,7 +451,7 @@ namespace Game.Movement
 
         public void Clear(MovementGeneratorMode mode)
         {
-            if (HasFlag(MotionMasterFlags.Update))
+            if (HasFlag(MotionMasterFlags.Delayed))
             {
                 _delayedActions.Enqueue(new DelayedAction(() => Clear(mode), MotionMasterDelayedActionType.ClearMode));
                 return;
@@ -457,7 +466,7 @@ namespace Game.Movement
         public void Clear(MovementGeneratorPriority priority)
         {
 
-            if (HasFlag(MotionMasterFlags.Update))
+            if (HasFlag(MotionMasterFlags.Delayed))
             {
                 _delayedActions.Enqueue(new DelayedAction(() => Clear(priority), MotionMasterDelayedActionType.ClearPriority));
                 return;
@@ -990,6 +999,15 @@ namespace Game.Movement
             Add(movement);
         }
 
+        void ResolveDelayedActions()
+        {
+            while (_delayedActions.Count != 0)
+            {
+                _delayedActions.Peek().Resolve();
+                _delayedActions.Dequeue();
+            }
+        }
+
         void Remove(MovementGenerator movement, bool active, bool movementInform)
         {
             _generators.Remove(movement);