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/ DotNET / DotNET / 8.0 / untmp / WIN_WINDOWS / lh_tools_devdiv_wpf / Windows / wcp / Speech / Src / Internal / AsyncSerializedWorker.cs / 1 / AsyncSerializedWorker.cs
//------------------------------------------------------------------ //// Copyright (c) Microsoft Corporation. All rights reserved. // // // Description: // Synchronization event dispatcher. // This module implements a helper class to facilitate switching between synchronous and asynchronous event // handling and callback. // // History: // 9/1/2005 [....] Created. //----------------------------------------------------------------- using System; using System.Collections; using System.Text; using System.ComponentModel; using System.Threading; namespace System.Speech.Internal { internal interface IAsyncDispatch { void Post(object evt); void Post(object[] evt); void PostOperation(Delegate callback, params object[] parameters); } internal class AsyncSerializedWorker : IAsyncDispatch { #region Constructors internal AsyncSerializedWorker(WaitCallback defaultCallback, AsyncOperation asyncOperation) { _asyncOperation = asyncOperation; _workerPostCallback = new SendOrPostCallback(WorkerProc); Initialize(defaultCallback); } private void Initialize(WaitCallback defaultCallback) { _queue = new Queue(); _hasPendingPost = false; _workerCallback = new WaitCallback(WorkerProc); _defaultCallback = defaultCallback; _isAsyncMode = true; _isEnabled = true; } #endregion #region Public Methods public void Post(object evt) { AddItem(new AsyncWorkItem(DefaultCallback, evt)); } public void Post(object[] evt) { int i; lock (_queue.SyncRoot) { if (Enabled) { for (i = 0; i < evt.Length; i++) { AddItem(new AsyncWorkItem(DefaultCallback, evt[i])); } } } } public void PostOperation(Delegate callback, params object[] parameters) { AddItem(new AsyncWorkItem(callback, parameters)); } #endregion #region Internal Properties and Methods internal bool Enabled { get { lock (_queue.SyncRoot) { return _isEnabled; } } set { lock (_queue.SyncRoot) { _isEnabled = value; } } } internal void Purge() { lock (_queue.SyncRoot) { _queue.Clear(); } } internal WaitCallback DefaultCallback { get { lock (_queue.SyncRoot) { return _defaultCallback; } } } internal AsyncWorkItem NextWorkItem() { lock (_queue.SyncRoot) { if (_queue.Count == 0) { return null; } else { AsyncWorkItem workItem = (AsyncWorkItem)_queue.Dequeue(); if (_queue.Count == 0) { _hasPendingPost = false; } return workItem; } } } internal void ConsumeQueue() { AsyncWorkItem workItem; while (null != (workItem = NextWorkItem())) { workItem.Invoke(); } } internal bool AsyncMode { set { bool notify = false; lock (_queue.SyncRoot) { if (_isAsyncMode != value) { _isAsyncMode = value; if (_queue.Count > 0) { notify = true; } } } // We need to resume the worker thread if there are post-events to process if (notify) { OnWorkItemPending(); } } get { lock (_queue.SyncRoot) { return _isAsyncMode; } } } // event handler of this event should execute quickly and must not acquire any lock internal event WaitCallback WorkItemPending; #endregion #region Private/Protected Methods private void AddItem(AsyncWorkItem item) { bool processing = true; lock (_queue.SyncRoot) { if (Enabled) { _queue.Enqueue(item); if (!_hasPendingPost || !_isAsyncMode) { processing = false; _hasPendingPost = true; } } } if (!processing) { OnWorkItemPending(); } } private void WorkerProc(object ignored) { AsyncWorkItem workItem; while (true) { lock (_queue.SyncRoot) { if (_queue.Count > 0 && _isAsyncMode) { workItem = (AsyncWorkItem)_queue.Dequeue(); } else { if (_queue.Count == 0) { _hasPendingPost = false; } break; } } workItem.Invoke(); } } private void OnWorkItemPending() { // No need to lock here if (_hasPendingPost) { if (AsyncMode) { if (_asyncOperation == null) { ThreadPool.QueueUserWorkItem(_workerCallback, null); } else { _asyncOperation.Post(_workerPostCallback, null); } } else if (WorkItemPending != null) { WorkItemPending(null); } } } #endregion #region Private Fields private AsyncOperation _asyncOperation; private SendOrPostCallback _workerPostCallback; private Queue _queue; private bool _hasPendingPost; private bool _isAsyncMode; private WaitCallback _workerCallback; private WaitCallback _defaultCallback; private bool _isEnabled; #endregion } internal class AsyncWorkItem { internal AsyncWorkItem(Delegate dynamicCallback, params object[] postData) { _dynamicCallback = dynamicCallback; _postData = postData; } internal void Invoke() { if (_dynamicCallback != null) { _dynamicCallback.DynamicInvoke(_postData); } } private Delegate _dynamicCallback; private object [] _postData; } } // File provided for Reference Use Only by Microsoft Corporation (c) 2007. // Copyright (c) Microsoft Corporation. All rights reserved.
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