Imported Upstream version 4.6.0.125

Former-commit-id: a2155e9bd80020e49e72e86c44da02a8ac0e57a4

mcs/class/referencesource/System.Web/Cache/DependencyChangeMonitor.cs

@@ -0,0 +1,50 @@
+// <copyright file="DependencyChangeMonitor.cs" company="Microsoft">
+//   Copyright (c) 2009 Microsoft Corporation.  All rights reserved.
+// </copyright>
+#if USE_MEMORY_CACHE
+using System;
+using System.Diagnostics.CodeAnalysis;
+using System.Runtime.Caching;
+using System.Web.Util;
+
+namespace System.Web.Caching {
+    internal sealed class DependencyChangeMonitor: ChangeMonitor, ICacheDependencyChanged {
+        private CacheDependency _dependency;
+        
+        public override string UniqueId { 
+            get {
+                return _dependency.GetUniqueID();
+            }
+        }
+
+        internal DependencyChangeMonitor(CacheDependency dependency) {
+            if (dependency == null) {
+                throw new ArgumentNullException("dependency");
+            }
+            if (!dependency.Use()) {
+                throw new InvalidOperationException(
+                    SR.GetString(SR.Cache_dependency_used_more_that_once));
+            }
+            _dependency = dependency;
+            _dependency.SetCacheDependencyChanged(this);
+            if (_dependency.HasChanged) {
+                OnChanged(null);
+            }
+            InitializationComplete();
+        }
+
+        void ICacheDependencyChanged.DependencyChanged(Object sender, EventArgs e) {
+            OnChanged(null);
+        }
+
+        [SuppressMessage("Microsoft.Usage", "CA2215:DisposeMethodsShouldCallBaseClassDispose", Justification="suppressed because fxcop is suffering from despotism")]
+        protected override void Dispose(bool disposing) {
+            if (disposing) {
+                if (_dependency != null) {
+                    _dependency.DisposeInternal();
+                }
+            }
+        }
+    }
+}
+#endif