用并发队列(ConcurrentQueue)实现多线程任务中随时异步回调进度通知(.Net4.0)

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:TupleConcurrentQueueSemaphoreSlimTask...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http://mainz.cnblogs.com,转载请注明。)

   //异步操作,代替Thread, threadPool
   Task _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item
   ConcurrentQueue<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) =>
                   {  
                          //...
                    }

10.13

有问题请回复。本文结束,代码带注释。

posted on 2011-10-13 10:56  Mainz  阅读(6911)  评论(7编辑  收藏

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