本文讲述实现抽象出来的异步通知回调进度通知，用在多层组件中，支持一组task的任意进度回调通知。本文中用到几个.NET 4.0的新方法和TPL方法：Tuple，ConcurrentQueue，SemaphoreSlim，Task...说明：如果你是一个简单的Task可能无需这么复杂，用传入Action同步回调即可，但是注意NotifyProgress也就是在任务执行过程中随时同步通知进度，会造成你任务阻塞。如果你是在UI层，用BackgroundWorkder最简单了。(本文原创于，转载请注明。)
//异步操作，代替Thread, threadPoolTask _ProgressQueueTask = null;//限制并发访问资源的线程数，SemaphoreSlim开销低于Semaphore50倍SemaphoreSlim _ProgressCounter = null;//并发队列ConcurrentQueue，线程安全的队列//Tuple：元数据结构，可以方便的访问其itemConcurrentQueue<tuple<progressaction, string,="" int?="">> _ProgressQueue = new ConcurrentQueue<tuple<progressaction, string,="" int?="">>();Action<progressaction, string,="" int?=""> _OnProgress;public Action<progressaction, string,="" int?=""> OnProgress{get { return _OnProgress; }set{_OnProgress = value;if (_ProgressQueueTask == null){_ProgressQueueTask = new Task(() =>{while (true){Tuple<progressaction, string,="" int?=""> item;//查询队列if (_ProgressQueue.TryDequeue(out item)){OnProgress(item.Item1, item.Item2, item.Item3);}else{//线程等待信号，由NotifyProgress入队列并给予信号_ProgressCounter.Wait();}}},TaskCreationOptions.LongRunning);_ProgressCounter = new SemaphoreSlim(0, 10);//初始0，最大限制10_ProgressQueueTask.Start();}}}//在任何Task的执行过程中，或一组task的执行过程中，可以调用此方法来异步回调随时通知进度，而不会阻塞本任务public void NotifyProgress(ProgressAction action, string item = null, long? current = null, long? maxCount = null){if (OnProgress != null){int? percent = null;if (current.HasValue && maxCount.HasValue){percent = (int)((double)current.Value / (double)maxCount.Value * 100.0);}_ProgressQueue.Enqueue(Tuple.Create(action, item, percent));_ProgressCounter.Release();}return;}public enum ProgressAction{Adding,Extracting,Extracted,Validating,Validated,Deleting,Deleted,Restore};//用法：//中间层NotifyProgress(ProgressAction.Extracting, "abc");//界面层OnProgress = (action, file, percent) =>{ //...}
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