Imported Upstream version 4.6.0.125

Former-commit-id: a2155e9bd80020e49e72e86c44da02a8ac0e57a4

mcs/class/referencesource/System.Activities/System/Activities/AsyncInvokeOperation.cs

@@ -0,0 +1,62 @@
+//-----------------------------------------------------------------------------
+// Copyright (c) Microsoft Corporation.  All rights reserved.
+//-----------------------------------------------------------------------------
+
+namespace System.Activities
+{
+    using System.Xml;
+    using System.Collections.Generic;
+    using System.Threading;
+    using System.Runtime;
+
+    class AsyncInvokeOperation
+    {
+        object thisLock;
+
+        public AsyncInvokeOperation(SynchronizationContext syncContext)
+        {
+            Fx.Assert(syncContext != null, "syncContext cannot be null");
+            this.SyncContext = syncContext;
+            thisLock = new object();
+        }
+
+        SynchronizationContext SyncContext
+        {
+            get;
+            set;
+        }
+
+        bool Completed
+        {
+            get;
+            set;
+        }
+
+        public void OperationStarted()
+        {
+            this.SyncContext.OperationStarted();
+        }
+
+        public void OperationCompleted()
+        {
+            lock (thisLock)
+            {
+                Fx.AssertAndThrowFatal(!this.Completed, "Async operation has already been completed");
+                this.Completed = true;
+            }
+            this.SyncContext.OperationCompleted();
+        }
+
+        public void PostOperationCompleted(SendOrPostCallback callback, object arg)
+        {
+            lock (thisLock)
+            {
+                Fx.AssertAndThrowFatal(!this.Completed, "Async operation has already been completed");
+                this.Completed = true;
+            }
+            Fx.Assert(callback != null, "callback cannot be null");
+            this.SyncContext.Post(callback, arg);
+            this.SyncContext.OperationCompleted();
+        }
+    }
+}