Merge pull request #8607 from DustinCampbell/fix-codemodel-race

Fix race in Code Model cache

src/VisualStudio/Core/Impl/CodeModel/FileCodeModel.cs

@@ -196,30 +196,16 @@ internal void UpdateCodeElementNodeKey(AbstractKeyedCodeElement keyedElement, Sy
 
         internal void OnCodeElementCreated(SyntaxNodeKey nodeKey, EnvDTE.CodeElement element)
         {
-            _codeElementTable.Add(nodeKey, element);
-        }
-
-        internal void OnBeforeCodeElementCreated(SyntaxNode node)
-        {
-            // It's conceivable that a consumer is creating a code element with the same node key as a "dead" element
-            // that hasn't been removed from the cache yet. For example, the element could have been "deleted" by
-            // simply replacing its text in the underlying buffer. To handle this situation, we test to see if the
-            // element is "dead" by checking whether it's underlying node is invalid (that is, it can't be found by
-            // its node key). If the element is "dead", we'll go ahead and remove it from the cache here to avoid a
-            // collision with the new element.
+            // If we're creating an element with the same node key as an element that's already in the table, just remove
+            // the old element. The old element will continue to function but the new element will replace it in the cache.
 
-            var nodeKey = CodeModelService.TryGetNodeKey(node);
-            EnvDTE.CodeElement codeElement;
-            if (!nodeKey.IsEmpty && _codeElementTable.TryGetValue(nodeKey, out codeElement))
+            EnvDTE.CodeElement oldElement;
+            if (_codeElementTable.TryGetValue(nodeKey, out oldElement))
             {
-                var managedElement = ComAggregate.GetManagedObject<AbstractKeyedCodeElement>(codeElement);
-                Debug.Assert(managedElement != null, $"Could not get the underlying {nameof(AbstractKeyedCodeElement)} from {nameof(codeElement)} with {nameof(nodeKey)}: {nodeKey}");
-
-                if (managedElement?.IsValidNode() != true)
-                {
-                    _codeElementTable.Remove(nodeKey);
-                }
+                _codeElementTable.Remove(nodeKey);
             }
+
+            _codeElementTable.Add(nodeKey, element);
         }
 
         internal void OnCodeElementDeleted(SyntaxNodeKey nodeKey)

src/VisualStudio/Core/Impl/CodeModel/FileCodeModel_CodeGen.cs

@@ -62,8 +62,6 @@ private SyntaxNode InsertMember(SyntaxNode containerNode, SyntaxNode memberNode,
                 var resultNode = CodeModelService.InsertMember(
                     document, IsBatchOpen, insertionIndex, containerNode, memberNode, CancellationToken.None, out newDocument);
 
-                OnBeforeCodeElementCreated(resultNode);
-
                 return Tuple.Create(resultNode, newDocument);
             });
         }

src/VisualStudio/Core/Test/CodeModel/CSharp/CodeClassTests.vb

@@ -3854,6 +3854,8 @@ class C$$
                             Assert.False(True,
 $"Failed to add variable in loop iteration {i}!
 
+Exception: {ex.Message}
+
 Document text:
 {initialDocument.GetTextAsync(CancellationToken.None).Result}")
 

src/VisualStudio/Core/Test/CodeModel/VisualBasic/CodeClassTests.vb

@@ -3163,6 +3163,8 @@ End Class
                             Assert.False(True,
 $"Failed to add variable in loop iteration {i}!
 
+Exception: {ex.Message}
+
 Document text:
 {initialDocument.GetTextAsync(CancellationToken.None).Result}")