Imported Upstream version 4.6.0.125

Former-commit-id: a2155e9bd80020e49e72e86c44da02a8ac0e57a4

mcs/class/referencesource/mscorlib/system/iappdomainpausemanager.cs

@@ -0,0 +1,116 @@
+//
+// Copyright (c) Microsoft Corporation.  All rights reserved.
+//
+/*=============================================================================
+**
+** Class: System.IAppDomainPauseConsumer and its implementation
+**
+** Purpose: Interface meant for CLR to participate in framework rundown.
+** AppDomainPauseManager is the class that encapsulates all Fx rundown work.
+**
+** Copyright (c) Microsoft
+**
+=============================================================================*/
+
+namespace System
+{
+    using System;
+    using System.Threading;
+    using System.Security;
+    using System.Diagnostics.Contracts;
+    using System.Runtime.Versioning;
+    using System.Runtime.CompilerServices;
+
+#if FEATURE_LEGACYNETCFFAS
+    [System.Security.SecurityCritical]
+    public interface IAppDomainPauseManager
+    {
+        void Pausing();
+        void Paused();
+        void Resuming();
+        void Resumed();
+    }
+#endif
+
+    [System.Security.SecurityCritical]
+#if FEATURE_LEGACYNETCFFAS
+    public class AppDomainPauseManager : IAppDomainPauseManager
+#else
+    internal class AppDomainPauseManager
+#endif
+    {
+        [System.Security.SecurityCritical]
+        public AppDomainPauseManager()
+        {
+            isPaused = false;
+        }
+
+        [System.Security.SecurityCritical]
+        static AppDomainPauseManager()
+        {
+        }
+        
+        static readonly AppDomainPauseManager instance = new AppDomainPauseManager();
+        internal static AppDomainPauseManager Instance
+        {
+            [System.Security.SecurityCritical]
+            get { return instance; }
+        }
+
+        // FAS: IAppDomainPauseConsumer interface implementation
+        // currently there is nothing we do here as the implementation
+        // of updating pause times have been moved to native CorHost2
+        [System.Security.SecurityCritical]
+        public void Pausing()
+        {
+        }
+
+        [System.Security.SecurityCritical]
+        public void Paused()
+        {
+            Contract.Assert(!isPaused);
+
+            if(ResumeEvent == null)
+                ResumeEvent = new ManualResetEvent(false);
+            else
+                ResumeEvent.Reset();
+
+            Timer.Pause();
+
+            // Set IsPaused at the last as other threads seeing it set, will expect a valid
+            // reset ResumeEvent. Also the requirement here is that only after Paused
+            // returns other threads should block on this event. So there is ---- here.
+            isPaused = true;
+        }
+
+        [System.Security.SecurityCritical]
+        public void Resuming()
+        {
+            Contract.Assert(isPaused);
+            isPaused = false;
+            ResumeEvent.Set();
+        }
+
+        [System.Security.SecurityCritical]
+        public void Resumed()
+        {
+            Timer.Resume();
+        }
+   
+        private static volatile bool isPaused;
+
+        internal static bool IsPaused
+        {
+            [System.Security.SecurityCritical]
+            get { return isPaused; }
+        }
+
+        internal static ManualResetEvent ResumeEvent
+        {
+            [System.Security.SecurityCritical]
+            get; 
+            [System.Security.SecurityCritical]
+            set;
+        }
+    }
+}