Imported Upstream version 4.6.0.125

Former-commit-id: a2155e9bd80020e49e72e86c44da02a8ac0e57a4

mcs/class/referencesource/System.Web/HttpTaskAsyncHandler.cs

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+//------------------------------------------------------------------------------
+// <copyright file="HttpTaskAsyncHandler.cs" company="Microsoft">
+//     Copyright (c) Microsoft Corporation.  All rights reserved.
+// </copyright>                                                                
+//------------------------------------------------------------------------------
+
+/*
+ * Assists in converting an HTTP Handler written using the Task Asynchronous Pattern to an IHttpAsyncHandler.
+ * 
+ * Copyright (c) 2010 Microsoft Corporation
+ */
+
+namespace System.Web {
+    using System;
+    using System.ComponentModel;
+    using System.Threading.Tasks;
+
+    public abstract class HttpTaskAsyncHandler : IHttpAsyncHandler {
+
+        public virtual bool IsReusable {
+            get {
+                // Default implementation - can be overridden by developer.
+                return false;
+            }
+        }
+
+        [EditorBrowsable(EditorBrowsableState.Never)]
+        public virtual void ProcessRequest(HttpContext context) {
+            // Default implementation is that this isn't synchronously callable - can be overridden by developer.
+            string errorMessage = SR.GetString(SR.HttpTaskAsyncHandler_CannotExecuteSynchronously, GetType());
+            throw new NotSupportedException(errorMessage);
+        }
+
+        // This is the method we actually expect developers to override.
+        public abstract Task ProcessRequestAsync(HttpContext context);
+
+        #region IHttpAsyncHandler methods
+        IAsyncResult IHttpAsyncHandler.BeginProcessRequest(HttpContext context, AsyncCallback cb, object extraData) {
+            return TaskAsyncHelper.BeginTask(() => ProcessRequestAsync(context), cb, extraData);
+        }
+
+        void IHttpAsyncHandler.EndProcessRequest(IAsyncResult result) {
+            TaskAsyncHelper.EndTask(result);
+        }
+        #endregion
+
+    }
+}