Imported Upstream version 4.0.0~alpha1

Former-commit-id: 806294f5ded97629b74c85c09952f2a74fe182d9

external/referencesource/System.Web/IdleTimeoutMonitor.cs

@@ -0,0 +1,83 @@
+//------------------------------------------------------------------------------
+// <copyright file="RequestTimeoutManager.cs" company="Microsoft">
+//     Copyright (c) Microsoft Corporation.  All rights reserved.
+// </copyright>                                                                
+//------------------------------------------------------------------------------
+
+/*
+ * Request timeout manager -- implements the request timeout mechanism
+ */
+namespace System.Web {
+    using System.Threading;
+    using System.Collections;
+    using System.Web.Hosting;
+    using System.Web.Util;
+
+    internal class IdleTimeoutMonitor {
+
+        private TimeSpan _idleTimeout;  // the timeout value
+        private DateTime _lastEvent;    // idle since this time
+        private Timer _timer;
+        private readonly TimeSpan _timerPeriod = new TimeSpan(0, 0, 30); // 30 secs
+
+        internal IdleTimeoutMonitor(TimeSpan timeout) {
+            _idleTimeout = timeout;
+            _timer = new Timer(new TimerCallback(this.TimerCompletionCallback), null, _timerPeriod, _timerPeriod);
+            _lastEvent = DateTime.UtcNow;
+        }
+
+        internal void Stop() {
+            // stop the timer
+            if (_timer != null) {
+                lock (this) {
+                    if (_timer != null) {
+                        ((IDisposable)_timer).Dispose();
+                        _timer = null;
+                    }
+                }
+            }
+        }
+
+        internal DateTime LastEvent { // thread-safe property
+            get {
+                DateTime t;
+                lock (this) { t = _lastEvent; }
+                return t;
+            }
+
+            set {
+                lock (this) { _lastEvent = value; }
+            }
+        }
+
+        private void TimerCompletionCallback(Object state) {
+            // user idle timer to trim the free list of app instanced
+            HttpApplicationFactory.TrimApplicationInstances();
+
+            // no idle timeout
+            if (_idleTimeout == TimeSpan.MaxValue)
+                return;
+
+            // don't do idle timeout if already shutting down
+            if (HostingEnvironment.ShutdownInitiated)
+                return;
+
+            // check if there are active requests
+            if (HostingEnvironment.BusyCount != 0)
+                return;
+
+            // check if enough time passed
+            if (DateTime.UtcNow <= LastEvent.Add(_idleTimeout))
+                return;
+
+            // check if debugger is attached
+            if (System.Diagnostics.Debugger.IsAttached)
+                return;
+
+            // shutdown
+            HttpRuntime.SetShutdownReason(ApplicationShutdownReason.IdleTimeout, 
+                                          SR.GetString(SR.Hosting_Env_IdleTimeout));
+            HostingEnvironment.InitiateShutdownWithoutDemand();
+        }
+    }
+}