一个简单的任务排队

    应一个同事之托，写了段简单的代码来完成排队执行的目的，环境为.net 2.0（vs2005），代码如下:

   1:          /// <summary>

   2:          /// 最大并发任务数

   3:          /// </summary>

   4:          private readonly int maxConcurrentTask = 10;

   5:          /// <summary>

   6:          /// 信号

   7:          /// </summary>

   8:          private readonly object semaphore = new object();

   9:          /// <summary>

  10:          /// 排队中的任务数

  11:          /// </summary>

  12:          private volatile int taskQueuing = 0;

  13:          /// <summary>

  14:          /// 执行中的任务数

  15:          /// </summary>

  16:          private volatile int taskRunning = 0;

  17:   

  18:          /// <summary>

  19:          /// 排任务

  20:          /// </summary>

  21:          /// <param name="task">任务</param>

  22:          public void QueueTask(object task)

  23:          {

  24:              do

  25:              {

  26:                  // 预防线程池过载

  27:                  if (taskQueuing + taskRunning < maxConcurrentTask)

  28:                  {

  29:                      System.Threading.Interlocked.Increment(ref taskQueuing);

  30:                      if (System.Threading.ThreadPool.QueueUserWorkItem(RunTask, task))

  31:                          return;

  32:                      System.Threading.Interlocked.Decrement(ref taskQueuing);

  33:                  }

  34:                  // 等待任务完成信号

  35:                  lock (semaphore)

  36:                      System.Threading.Monitor.Wait(semaphore, 1000);

  37:              }

  38:              while (true);

  39:          }

  40:   

  41:          /// <summary>

  42:          /// 等待所有任务执行完成

  43:          /// </summary>

  44:          public void WaitAllTaskCompleted()

  45:          {

  46:              while (taskQueuing > 0 && taskRunning > 0)

  47:                  lock (semaphore)

  48:                      if (taskQueuing > 0 && taskRunning > 0)

  49:                          System.Threading.Monitor.Wait(semaphore, 1000);

  50:          }

  51:   

  52:          private void RunTask(object task)

  53:          {

  54:              try

  55:              {

  56:                  System.Threading.Interlocked.Increment(ref taskRunning);

  57:                  System.Threading.Interlocked.Decrement(ref taskQueuing);

  58:                  RunTaskCore(task);

  59:              }

  60:              finally

  61:              {

  62:                  System.Threading.Interlocked.Decrement(ref taskRunning);

  63:                  // 发送任务完成信号

  64:                  lock (semaphore)

  65:                      System.Threading.Monitor.Pulse(semaphore);

  66:              }

  67:          }

  68:   

  69:          protected virtual void RunTaskCore(object task)

  70:          {

  71:              // todo : RunTaskCore

  72:          }

    比较简单，没有考虑取消等事情，另外QueueTask方法应该与WaitAllTaskCompleted方法在同一个线程中执行。