From 6b31a9cce9d9c85a896195bfdd4c7ff0b660470b Mon Sep 17 00:00:00 2001
From: Lifeng Lu <lifengl@microsoft.com>
Date: Sun, 7 Mar 2021 13:11:43 -0800
Subject: [PATCH] Use strong references for JTF dependencies.

---
 .../JoinableTaskDependencyGraph.cs                 | 14 +++++++-------
 1 file changed, 7 insertions(+), 7 deletions(-)

diff --git a/src/Microsoft.VisualStudio.Threading/JoinableTaskDependencyGraph.cs b/src/Microsoft.VisualStudio.Threading/JoinableTaskDependencyGraph.cs
index 4fa79a37e..90824c7b0 100644
--- a/src/Microsoft.VisualStudio.Threading/JoinableTaskDependencyGraph.cs
+++ b/src/Microsoft.VisualStudio.Threading/JoinableTaskDependencyGraph.cs
@@ -290,7 +290,7 @@ internal struct JoinableTaskDependentData
             /// When the value in an entry is decremented to 0, the entry is removed from the map.
             /// </remarks>
             [DebuggerBrowsable(DebuggerBrowsableState.Never)]
-            private WeakKeyDictionary<IJoinableTaskDependent, int> childDependentNodes;
+            private Dictionary<IJoinableTaskDependent, int> childDependentNodes;
 
             /// <summary>
             /// The head of a singly linked list of records to track which task may process events of this task.
@@ -301,7 +301,7 @@ internal struct JoinableTaskDependentData
             /// <summary>
             /// Gets a value indicating whether the <see cref="childDependentNodes"/> is empty.
             /// </summary>
-            internal bool HasNoChildDependentNode => this.childDependentNodes is null || this.childDependentNodes.Count == 0 || !this.childDependentNodes.Any();
+            internal bool HasNoChildDependentNode => this.childDependentNodes is null || this.childDependentNodes.Count == 0;
 
             /// <summary>
             /// Gets a snapshot of all joined tasks.
@@ -352,7 +352,7 @@ internal static JoinableTaskCollection.JoinRelease AddDependency(IJoinableTaskDe
                         ref JoinableTaskDependentData data = ref parentTaskOrCollection.GetJoinableTaskDependentData();
                         if (data.childDependentNodes is null)
                         {
-                            data.childDependentNodes = new WeakKeyDictionary<IJoinableTaskDependent, int>(capacity: 2);
+                            data.childDependentNodes = new Dictionary<IJoinableTaskDependent, int>(capacity: 2);
                         }
 
                         if (data.childDependentNodes.TryGetValue(joinChild, out int refCount) && !parentTaskOrCollection.NeedRefCountChildDependencies)
@@ -471,7 +471,7 @@ internal static void AddSelfAndDescendentOrJoinedJobs(IJoinableTaskDependent tas
                     }
                 }
 
-                WeakKeyDictionary<IJoinableTaskDependent, int>? childDependentNodes = taskOrCollection.GetJoinableTaskDependentData().childDependentNodes;
+                Dictionary<IJoinableTaskDependent, int>? childDependentNodes = taskOrCollection.GetJoinableTaskDependentData().childDependentNodes;
                 if (childDependentNodes is object)
                 {
                     foreach (KeyValuePair<IJoinableTaskDependent, int> item in childDependentNodes)
@@ -555,7 +555,7 @@ internal static void ComputeSelfAndDescendentOrJoinedJobsAndRemainTasks(IJoinabl
                             return;
                         }
 
-                        WeakKeyDictionary<IJoinableTaskDependent, int>? dependencies = taskOrCollection.GetJoinableTaskDependentData().childDependentNodes;
+                        Dictionary<IJoinableTaskDependent, int>? dependencies = taskOrCollection.GetJoinableTaskDependentData().childDependentNodes;
                         if (dependencies is object)
                         {
                             foreach (KeyValuePair<IJoinableTaskDependent, int> item in dependencies)
@@ -664,7 +664,7 @@ internal void OnTaskCompleted(IJoinableTaskDependent thisDependentNode)
 
                     if (this.childDependentNodes is object)
                     {
-                        var childrenTasks = new List<IJoinableTaskDependent>(this.childDependentNodes.Keys);
+                        Dictionary<IJoinableTaskDependent, int>.KeyCollection? childrenTasks = this.childDependentNodes.Keys;
                         while (existingTaskTracking is object)
                         {
                             RemoveDependingSynchronousTaskFrom(childrenTasks, existingTaskTracking.SynchronousTask, force: existingTaskTracking.SynchronousTask == thisDependentNode);
@@ -871,7 +871,7 @@ private static void RemoveDependingSynchronousTask(IJoinableTaskDependent taskOr
             /// <param name="tasks">A list of tasks we need update the tracking list.</param>
             /// <param name="syncTask">The synchronous task we want to remove.</param>
             /// <param name="force">We always remove it from the tracking list if it is true.  Otherwise, we keep tracking the reference count.</param>
-            private static void RemoveDependingSynchronousTaskFrom(IReadOnlyList<IJoinableTaskDependent> tasks, JoinableTask syncTask, bool force)
+            private static void RemoveDependingSynchronousTaskFrom(IReadOnlyCollection<IJoinableTaskDependent> tasks, JoinableTask syncTask, bool force)
             {
                 Requires.NotNull(tasks, nameof(tasks));
                 Requires.NotNull(syncTask, nameof(syncTask));