Code:
/ DotNET / DotNET / 8.0 / untmp / whidbey / REDBITS / ndp / fx / src / xsp / System / Web / UI / PageAsyncTask.cs / 3 / PageAsyncTask.cs
//------------------------------------------------------------------------------ //// Copyright (c) Microsoft Corporation. All rights reserved. // //----------------------------------------------------------------------------- namespace System.Web.UI { using System; using System.Collections; using System.Security; using System.Security.Permissions; using System.Threading; using System.Web; using System.Web.UI; using System.Web.Util; [AspNetHostingPermission(SecurityAction.LinkDemand, Level=AspNetHostingPermissionLevel.Minimal)] public sealed class PageAsyncTask { private BeginEventHandler _beginHandler; private EndEventHandler _endHandler; private EndEventHandler _timeoutHandler; private Object _state; private bool _executeInParallel; private PageAsyncTaskManager _taskManager; private int _completionMethodLock; private bool _started; private bool _completed; private bool _completedSynchronously; private AsyncCallback _completionCallback; private IAsyncResult _asyncResult; private Exception _error; public PageAsyncTask(BeginEventHandler beginHandler, EndEventHandler endHandler, EndEventHandler timeoutHandler, Object state) : this(beginHandler, endHandler, timeoutHandler, state, false) { } public PageAsyncTask(BeginEventHandler beginHandler, EndEventHandler endHandler, EndEventHandler timeoutHandler, Object state, bool executeInParallel) { if (beginHandler == null) { throw new ArgumentNullException("beginHandler"); } if (endHandler == null) { throw new ArgumentNullException("endHandler"); } _beginHandler = beginHandler; _endHandler = endHandler; _timeoutHandler = timeoutHandler; _state = state; _executeInParallel = executeInParallel; } public BeginEventHandler BeginHandler { get { return _beginHandler; } } public EndEventHandler EndHandler { get { return _endHandler; } } public EndEventHandler TimeoutHandler { get { return _timeoutHandler; } } public Object State { get { return _state; } } public bool ExecuteInParallel { get { return _executeInParallel; } } internal bool Started { get { return _started; } } internal bool CompletedSynchronously { get { return _completedSynchronously; } } internal bool Completed { get { return _completed; } } internal IAsyncResult AsyncResult { get { return _asyncResult; } } internal Exception Error { get { return _error; } } internal void Start(PageAsyncTaskManager manager, Object source, EventArgs args) { Debug.Assert(!_started); _taskManager = manager; _completionCallback = new AsyncCallback(this.OnAsyncTaskCompletion); _started = true; Debug.Trace("Async", "Start task"); try { IAsyncResult ar = _beginHandler(source, args, _completionCallback, _state); if (ar == null) { throw new InvalidOperationException(SR.GetString(SR.Async_null_asyncresult)); } if (_asyncResult == null) { // _asyncResult could be not null if already completed _asyncResult = ar; } } catch (Exception e) { Debug.Trace("Async", "Task failed to start"); _error = e; _completed = true; _completedSynchronously = true; _taskManager.TaskCompleted(true /*onCallerThread*/); // notify TaskManager // it is ok to say false (onCallerThread) above because this kind of // error completion will never be the last in ResumeTasks() } } private void OnAsyncTaskCompletion(IAsyncResult ar) { Debug.Trace("Async", "Task completed, CompletedSynchronously=" + ar.CompletedSynchronously); if (_asyncResult == null) { // _asyncResult could be null if the code not yet returned from begin method _asyncResult = ar; } CompleteTask(false /*timedOut*/); } internal void ForceTimeout(bool syncCaller) { Debug.Trace("Async", "Task timed out"); CompleteTask(true /*timedOut*/, syncCaller /*syncTimeoutCaller*/); } private void CompleteTask(bool timedOut) { CompleteTask(timedOut, false /*syncTimeoutCaller*/); } private void CompleteTask(bool timedOut, bool syncTimeoutCaller) { if (Interlocked.Exchange(ref _completionMethodLock, 1) != 0) { return; } bool needSetupThreadContext; if (timedOut) { needSetupThreadContext = !syncTimeoutCaller; } else { _completedSynchronously = _asyncResult.CompletedSynchronously; needSetupThreadContext = !_completedSynchronously; } // call the completion or timeout handler // when neeeded setup the thread context and lock // catch and remember all exceptions try { if (needSetupThreadContext) { HttpApplication app = _taskManager.Application; lock (app) { HttpApplication.ThreadContext threadContext = null; try { threadContext = app.OnThreadEnter(); if (timedOut) { if (_timeoutHandler != null) { _timeoutHandler(_asyncResult); } } else { _endHandler(_asyncResult); } } finally { if (threadContext != null) { threadContext.Leave(); } } } } else { if (timedOut) { if (_timeoutHandler != null) { _timeoutHandler(_asyncResult); } } else { _endHandler(_asyncResult); } } } catch (Exception e) { _error = e; } _completed = true; _taskManager.TaskCompleted(_completedSynchronously /*onCallerThread*/); // notify TaskManager } } }
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