Merge pull request #343 from amcasey/DevDiv1094428

Manage the lifetime of DkmClrValue objects

src/ExpressionEvaluator/CSharp/Source/ExpressionCompiler/EvaluationContext.cs

-// Copyright (c) Microsoft.  All Rights Reserved.  Licensed under the Apache License, Version 2.0.  See License.txt in the project root for license information.
+// Copyright (c) Microsoft.  All Rights Reserved.  Licensed under the Apache License, Version 2.0.  See License.txt in the project root for license information.
 
 using System;
 using System.Collections.Generic;

src/ExpressionEvaluator/Core/Source/ResultProvider/Helpers/EnumContextDataItem.cs

+// Copyright (c) Microsoft.  All Rights Reserved.  Licensed under the Apache License, Version 2.0.  See License.txt in the project root for license information.
+
+using Microsoft.VisualStudio.Debugger;
+
+namespace Microsoft.CodeAnalysis.ExpressionEvaluator
+{
+    /// <summary>
+    /// This type exists to protect <see cref="ExpressionEvaluator.EvalResultDataItem"/> from
+    /// spurious <see cref="DkmDataItem.OnClose"/> calls.  We need to attach the same information
+    /// to <see cref="Microsoft.VisualStudio.Debugger.Evaluation.DkmEvaluationResult"/> and 
+    /// <see cref="Microsoft.VisualStudio.Debugger.Evaluation.DkmEvaluationResultEnumContext"/>
+    /// but they have different lifetimes.  Enum contexts (which are effectively child lists)
+    /// are closed before the corresponding evaluation results.  We don't want to actually clean
+    /// up until the evaluation result is closed.
+    /// </summary>
+    internal sealed class EnumContextDataItem : DkmDataItem
+    {
+        public readonly EvalResultDataItem EvalResultDataItem;
+
+        /// <remarks>
+        /// Only <see cref="ExpressionEvaluator.EvalResultDataItem"/> is expected to instantiate this type.
+        /// </remarks>
+        public EnumContextDataItem(EvalResultDataItem dataItem)
+        {
+            this.EvalResultDataItem = dataItem;
+        }
+    }
+}

src/ExpressionEvaluator/Core/Source/ResultProvider/Helpers/EvalResultDataItem.cs

@@ -110,5 +110,11 @@ private static DkmEvaluationResultFlags GetFlags(DkmClrValue value)
 
             return resultFlags;
         }
+
+        protected override void OnClose()
+        {
+            Debug.WriteLine("Closing " + FullName);
+            Value.Close();
+        }
     }
 }

src/ExpressionEvaluator/Core/Source/ResultProvider/ResultProvider.cs

@@ -89,7 +89,7 @@ void IDkmClrResultProvider.GetItems(DkmEvaluationResultEnumContext enumContext,
         {
             try
             {
-                var dataItem = enumContext.GetDataItem<EvalResultDataItem>();
+                var dataItem = enumContext.GetDataItem<EnumContextDataItem>();
                 if (dataItem == null)
                 {
                     // We don't know about this result.  Call next implementation
@@ -97,7 +97,7 @@ void IDkmClrResultProvider.GetItems(DkmEvaluationResultEnumContext enumContext,
                     return;
                 }
 
-                completionRoutine(GetItems(enumContext.InspectionContext, dataItem, startIndex, count));
+                completionRoutine(GetItems(enumContext.InspectionContext, dataItem.EvalResultDataItem, startIndex, count));
             }
             catch (Exception e) when (ExpressionEvaluatorFatalError.CrashIfFailFastEnabled(e))
             {
@@ -116,7 +116,7 @@ string IDkmClrResultProvider.GetUnderlyingString(DkmEvaluationResult result)
                     return result.GetUnderlyingString();
                 }
 
-                return dataItem.Value != null ? dataItem.Value.GetUnderlyingString() : null;
+                return dataItem.Value?.GetUnderlyingString();
             }
             catch (Exception e) when (ExpressionEvaluatorFatalError.CrashIfFailFastEnabled(e))
             {
@@ -420,7 +420,7 @@ private DkmGetChildrenAsyncResult GetChildren(DkmInspectionContext inspectionCon
             var rows = builder.ToArrayAndFree();
             Debug.Assert(index >= rows.Length);
             Debug.Assert(initialRequestSize >= rows.Length);
-            var enumContext = DkmEvaluationResultEnumContext.Create(index, evaluationResult.StackFrame, evaluationResult.InspectionContext, dataItem);
+            var enumContext = DkmEvaluationResultEnumContext.Create(index, evaluationResult.StackFrame, evaluationResult.InspectionContext, new EnumContextDataItem(dataItem));
             return new DkmGetChildrenAsyncResult(rows, enumContext);
         }
 

src/ExpressionEvaluator/Core/Source/ResultProvider/ResultProvider.csproj

@@ -101,6 +101,7 @@
     <Compile Include="Helpers\ArrayBuilder.cs" />
     <Compile Include="Helpers\DkmClrValueFlagsExtensions.cs" />
     <Compile Include="Helpers\DkmEvaluationResultFlagsExtensions.cs" />
+    <Compile Include="Helpers\EnumContextDataItem.cs" />
     <Compile Include="Helpers\EvalResultDataItem.cs" />
     <Compile Include="Helpers\GeneratedMetadataNames.cs" />
     <Compile Include="Helpers\HashFunctions.cs" />
@@ -136,3 +137,4 @@
     <Import Project="$(SolutionDir)\.nuget\NuGet.targets" Condition="Exists('$(SolutionDir)\.nuget\NuGet.targets')" />
   </ImportGroup>
 </Project>
+

src/ExpressionEvaluator/Core/Test/ResultProvider/Debugger/Engine/DkmClrValue.cs

@@ -647,5 +647,9 @@ private unsafe static object Dereference(IntPtr ptr, Type elementType)
                     throw new InvalidOperationException();
             }
         }
+
+		public void Close()
+		{
+		}
     }
 }

src/ExpressionEvaluator/Core/Test/ResultProvider/Debugger/Engine/DkmDataItem.cs

+// Copyright (c) Microsoft.  All Rights Reserved.  Licensed under the Apache License, Version 2.0.  See License.txt in the project root for license information.
+#region Assembly Microsoft.VisualStudio.Debugger.Engine, Version=1.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a
+// References\Debugger\v2.0\Microsoft.VisualStudio.Debugger.Engine.dll
+#endregion
+
+namespace Microsoft.VisualStudio.Debugger
+{
+	public class DkmDataItem
+	{
+		protected virtual void OnClose() { }
+	}
+}
\ No newline at end of file

src/ExpressionEvaluator/Core/Test/ResultProvider/Debugger/Engine/DkmMisc.cs

@@ -7,7 +7,6 @@ namespace Microsoft.VisualStudio.Debugger
 {
     public delegate void DkmCompletionRoutine<TResult>(TResult result);
 
-    public class DkmDataItem { }
     public class DkmWorkList { }
 
     public enum DkmDataCreationDisposition

src/ExpressionEvaluator/Core/Test/ResultProvider/ResultProviderTestUtilities.csproj

@@ -120,6 +120,9 @@
     <Compile Include="..\..\Source\ResultProvider\Helpers\EvalResultDataItem.cs">
       <Link>ResultProvider\Helpers\EvalResultDataItem.cs</Link>
     </Compile>
+    <Compile Include="..\..\Source\ResultProvider\Helpers\EnumContextDataItem.cs">
+      <Link>ResultProvider\Helpers\EnumContextDataItem.cs</Link>
+    </Compile>
     <Compile Include="..\..\Source\ResultProvider\Helpers\GeneratedMetadataNames.cs">
       <Link>ResultProvider\Helpers\GeneratedMetadataNames.cs</Link>
     </Compile>
@@ -174,6 +177,7 @@
     <Compile Include="Debugger\Engine\DkmEvaluationResultFlags.cs" />
     <Compile Include="Debugger\Engine\DkmFailedEvaluationResult.cs" />
     <Compile Include="Debugger\Engine\DkmInspectionContext.cs" />
+    <Compile Include="Debugger\Engine\DkmDataItem.cs" />
     <Compile Include="Debugger\Engine\DkmMisc.cs" />
     <Compile Include="Debugger\Engine\DkmModule.cs" />
     <Compile Include="Debugger\Engine\DkmModuleInstance.cs" />
@@ -221,3 +225,4 @@
     <Import Project="$(SolutionDir)\.nuget\NuGet.targets" Condition="Exists('$(SolutionDir)\.nuget\NuGet.targets')" />
   </ImportGroup>
 </Project>
+