[2020.2][VFX] Fix 1300320 - Infinite compilation loop (#3500)

* Some fixes in expression graph compilation

* Fix hack + reformat

* Add an invalidation cause EnableChanged

Author: julienf-unity

com.unity.visualeffectgraph/CHANGELOG.md

@@ -8,6 +8,8 @@ and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.
 ### Fixed
 - VFXEventBinderBase throwing a null reference exception in runtime
 - Unexpected compilation warning in VFXMouseBinder [Case 1313003](https://issuetracker.unity3d.com/product/unity/issues/guid/1313003/)
+- Prevent infinite compilation loop [Case 1298466](https://issuetracker.unity3d.com/product/unity/issues/guid/1298466/)
+- Remove some useless compilation triggers (modifying not connected or disabled nodes for instance)
 
 ## [10.3.1] - 2020-01-26
 

com.unity.visualeffectgraph/Editor/GraphView/VFXViewWindow.cs

@@ -280,7 +280,16 @@ void Update()
                         else
                             graph.RecompileIfNeeded(true, true);
 
+                        bool wasDirty = graph.IsExpressionGraphDirty();
+
                         controller.RecompileExpressionGraphIfNeeded();
+
+                        // Hack to avoid infinite recompilation due to UI triggering a recompile TODO: Fix problematic cases that trigger that error
+                        if (!wasDirty && graph.IsExpressionGraphDirty())
+                        {
+                            Debug.LogError("Expression graph was marked as dirty after compiling context for UI. Discard to avoid infinite compilation loop.");
+                            graph.SetExpressionGraphDirty(false);
+                        }
                     }
                 }
             }

com.unity.visualeffectgraph/Editor/GraphView/Views/Controller/VFXViewControllerExpressions.cs

@@ -45,7 +45,8 @@ public void InvalidateExpressionGraph(VFXModel model, VFXModel.InvalidationCause
         {
             if (cause != VFXModel.InvalidationCause.kStructureChanged &&
                 cause != VFXModel.InvalidationCause.kExpressionInvalidated &&
-                cause != VFXModel.InvalidationCause.kParamChanged)
+                cause != VFXModel.InvalidationCause.kParamChanged &&
+                cause != VFXModel.InvalidationCause.kEnableChanged)
             {
                 ExpressionGraphDirtyParamOnly = false;
                 return;

com.unity.visualeffectgraph/Editor/Models/Blocks/VFXBlock.cs

@@ -31,7 +31,7 @@ public bool enabled
             set
             {
                 m_Disabled = !value;
-                Invalidate(InvalidationCause.kStructureChanged);
+                Invalidate(InvalidationCause.kEnableChanged);
             }
         }
         public virtual bool isValid

com.unity.visualeffectgraph/Editor/Models/Contexts/VFXContext.cs

@@ -167,10 +167,28 @@ protected override void OnInvalidate(VFXModel model, InvalidationCause cause)
             if (cause == InvalidationCause.kStructureChanged ||
                 cause == InvalidationCause.kConnectionChanged ||
                 cause == InvalidationCause.kExpressionInvalidated ||
-                cause == InvalidationCause.kSettingChanged)
+                cause == InvalidationCause.kSettingChanged ||
+                cause == InvalidationCause.kEnableChanged)
             {
                 if (hasBeenCompiled || CanBeCompiled())
-                    Invalidate(InvalidationCause.kExpressionGraphChanged);
+                {
+                    bool skip = false;
+
+                    // Check if the invalidation comes from a disable block and in that case don't recompile
+                    if (cause != InvalidationCause.kEnableChanged)
+                    {
+                        VFXBlock block = null;
+                        if (model is VFXBlock)
+                            block = (VFXBlock)model;
+                        else if (model is VFXSlot)
+                            block = ((VFXSlot)model).owner as VFXBlock;
+
+                        skip = block != null && !block.enabled;
+                    }
+
+                    if (!skip)
+                        Invalidate(InvalidationCause.kExpressionGraphChanged);
+                }
             }
         }
 

com.unity.visualeffectgraph/Editor/Models/Operators/VFXOperator.cs

@@ -41,7 +41,7 @@ public override bool ResyncSlots(bool notify)
                 try
                 {
                     changed = base.ResyncSlots(notify);
-                    if (notify)
+                    if (changed && notify)
                         foreach (var slot in outputSlots) // invalidate expressions on output slots
                             slot.InvalidateExpressionTree();
                 }

com.unity.visualeffectgraph/Editor/Models/VFXGraph.cs

@@ -502,7 +502,7 @@ protected override void OnInvalidate(VFXModel model, VFXModel.InvalidationCause
                 EditorUtility.SetDirty(this);
             }
 
-            if (cause == VFXModel.InvalidationCause.kExpressionGraphChanged || cause == VFXModel.InvalidationCause.kConnectionChanged)
+            if (cause == VFXModel.InvalidationCause.kExpressionGraphChanged)
             {
                 m_ExpressionGraphDirty = true;
                 m_DependentDirty = true;
@@ -549,10 +549,10 @@ public bool IsExpressionGraphDirty()
             return m_ExpressionGraphDirty;
         }
 
-        public void SetExpressionGraphDirty()
+        public void SetExpressionGraphDirty(bool dirty = true)
         {
-            m_ExpressionGraphDirty = true;
-            m_DependentDirty = true;
+            m_ExpressionGraphDirty = dirty;
+            m_DependentDirty = dirty;
         }
 
         public void SetExpressionValueDirty()
@@ -646,8 +646,8 @@ void RecurseSubgraphRecreateCopy(IEnumerable<VFXModel> children)
                 else if (child is VFXSubgraphOperator operatorChild)
                 {
                     operatorChild.RecreateCopy();
-                    operatorChild.ResyncSlots(true);
-                    operatorChild.UpdateOutputExpressions();
+                    if (operatorChild.ResyncSlots(true))
+                        operatorChild.UpdateOutputExpressions();
                 }
             }
         }

com.unity.visualeffectgraph/Editor/Models/VFXModel.cs

@@ -51,6 +51,7 @@ public enum InvalidationCause
             kExpressionGraphChanged,// Expression graph must be recomputed
             kUIChanged,             // UI stuff has changed
             kUIChangedTransient,    // UI stuff has been changed be does not require serialization 
+            kEnableChanged,         // Node has been enabled/disabled
         }
 
         public new virtual string name  { get { return string.Empty; } }