Add IPendingExecutionRequestState interface to expose completion state of SingleExecuteProtector

src/Microsoft.VisualStudio.Threading/IPendingExecutionRequestState.cs

@@ -0,0 +1,21 @@
+// Copyright (c) Microsoft Corporation. All rights reserved.
+// Licensed under the MIT license. See LICENSE file in the project root for full license information.
+
+using System.ComponentModel;
+using System.Diagnostics.CodeAnalysis;
+
+namespace Microsoft.VisualStudio.Threading
+{
+    /// <summary>
+    /// An optional interface implemented by pending request state posted to the underline synchronization context. It allows synchronization context to remove completed requests.
+    /// </summary>
+    [EditorBrowsable(EditorBrowsableState.Never)]
+    [Experimental("VSOnly")]
+    public interface IPendingExecutionRequestState
+    {
+        /// <summary>
+        /// Gets a value indicating whether the current request has been completed, and can be skipped.
+        /// </summary>
+        bool IsCompleted { get; }
+    }
+}

src/Microsoft.VisualStudio.Threading/JoinableTaskFactory.cs

@@ -1058,7 +1058,9 @@ public void Dispose()
     /// A delegate wrapper that ensures the delegate is only invoked at most once.
     /// </summary>
     [DebuggerDisplay("{DelegateLabel}")]
-    internal class SingleExecuteProtector
+#pragma warning disable VSOnly // Type is for evaluation purposes only and is subject to change or removal in future updates. Suppress this diagnostic to proceed.
+    internal class SingleExecuteProtector : IPendingExecutionRequestState
+#pragma warning restore VSOnly // Type is for evaluation purposes only and is subject to change or removal in future updates. Suppress this diagnostic to proceed.
     {
         /// <summary>
         /// Executes the delegate if it has not already executed.
@@ -1112,6 +1114,11 @@ private SingleExecuteProtector(JoinableTask job)
             this.job = job;
         }
 
+        /// <summary>
+        /// Gets a value indicating whether the current request has been completed, and can be skipped.
+        /// </summary>
+        bool IPendingExecutionRequestState.IsCompleted => this.HasBeenExecuted;
+
         /// <summary>
         /// Gets a value indicating whether this instance has already executed.
         /// </summary>

src/Microsoft.VisualStudio.Threading/net472/PublicAPI.Unshipped.txt

@@ -1,2 +1,4 @@
 Microsoft.VisualStudio.Threading.AsyncBarrier.SignalAndWait(System.Threading.CancellationToken cancellationToken) -> System.Threading.Tasks.ValueTask
+Microsoft.VisualStudio.Threading.IPendingExecutionRequestState
+Microsoft.VisualStudio.Threading.IPendingExecutionRequestState.IsCompleted.get -> bool
 static Microsoft.VisualStudio.Threading.JoinableTaskContext.CreateNoOpContext() -> Microsoft.VisualStudio.Threading.JoinableTaskContext!

src/Microsoft.VisualStudio.Threading/net8.0-windows/PublicAPI.Unshipped.txt

@@ -1,2 +1,4 @@
 Microsoft.VisualStudio.Threading.AsyncBarrier.SignalAndWait(System.Threading.CancellationToken cancellationToken) -> System.Threading.Tasks.ValueTask
+Microsoft.VisualStudio.Threading.IPendingExecutionRequestState
+Microsoft.VisualStudio.Threading.IPendingExecutionRequestState.IsCompleted.get -> bool
 static Microsoft.VisualStudio.Threading.JoinableTaskContext.CreateNoOpContext() -> Microsoft.VisualStudio.Threading.JoinableTaskContext!

src/Microsoft.VisualStudio.Threading/net8.0/PublicAPI.Unshipped.txt

@@ -1,2 +1,4 @@
 Microsoft.VisualStudio.Threading.AsyncBarrier.SignalAndWait(System.Threading.CancellationToken cancellationToken) -> System.Threading.Tasks.ValueTask
+Microsoft.VisualStudio.Threading.IPendingExecutionRequestState
+Microsoft.VisualStudio.Threading.IPendingExecutionRequestState.IsCompleted.get -> bool
 static Microsoft.VisualStudio.Threading.JoinableTaskContext.CreateNoOpContext() -> Microsoft.VisualStudio.Threading.JoinableTaskContext!

src/Microsoft.VisualStudio.Threading/netstandard2.0/PublicAPI.Unshipped.txt

@@ -1,2 +1,4 @@
 Microsoft.VisualStudio.Threading.AsyncBarrier.SignalAndWait(System.Threading.CancellationToken cancellationToken) -> System.Threading.Tasks.ValueTask
+Microsoft.VisualStudio.Threading.IPendingExecutionRequestState
+Microsoft.VisualStudio.Threading.IPendingExecutionRequestState.IsCompleted.get -> bool
 static Microsoft.VisualStudio.Threading.JoinableTaskContext.CreateNoOpContext() -> Microsoft.VisualStudio.Threading.JoinableTaskContext!