Imported Upstream version 4.0.0~alpha1

Former-commit-id: 806294f5ded97629b74c85c09952f2a74fe182d9

external/referencesource/System.Activities/System/Activities/NoPersistProperty.cs

@@ -0,0 +1,60 @@
+//-----------------------------------------------------------------------------
+// Copyright (c) Microsoft Corporation.  All rights reserved.
+//-----------------------------------------------------------------------------
+
+namespace System.Activities
+{
+    using System;
+    using System.Activities.Runtime;
+    using System.Runtime;
+    using System.Runtime.Serialization;
+
+    // This does not need to be data contract since we'll never persist while one of these is active
+    class NoPersistProperty : IPropertyRegistrationCallback
+    {
+        public const string Name = "System.Activities.NoPersistProperty";
+
+        ActivityExecutor executor;
+        int refCount;
+
+        public NoPersistProperty(ActivityExecutor executor)
+        {
+            this.executor = executor;
+        }
+
+        public void Enter()
+        {
+            this.refCount++;
+            this.executor.EnterNoPersist();
+        }
+
+        public bool Exit()
+        {
+            Fx.Assert(this.refCount > 0, "We should guard against too many exits elsewhere.");
+
+            this.refCount--;
+            this.executor.ExitNoPersist();
+
+            return this.refCount == 0;
+        }
+
+        public void Register(RegistrationContext context)
+        {
+        }
+
+        public void Unregister(RegistrationContext context)
+        {
+            if (this.refCount > 0)
+            {
+                for (int i = 0; i < this.refCount; i++)
+                {
+                    this.executor.ExitNoPersist();
+                }
+
+                this.refCount = 0;
+            }
+        }
+    }
+}
+
+