c# - 是否有等效于 Java CompletionService 的 C# 来响应已完成的线程？

Question

有很多关于如何等待所有“worker”作业完成的示例，但是如何在每个 worker 完成时以与 Java 的 CompletionService 相同的方式使用react呢？

我已经破解了一些有用的东西，但这看起来很脆弱:

int completedWorkers = 0;
while (completedWorkers < workerCount)
{
     int eventId = WaitHandle.WaitAny(eventArray);
     events[eventId].Reset();
     completedWorkers++;
     Console.WriteLine("Worker {0} has completed. {1} have now completed.", eventId, completedWorkers);
}
Console.WriteLine("All threads have finished");

这依赖于一组 ManualResetEvent 实例(在我的示例中为“eventArray”)，类似于 Microsoft 示例 http://msdn.microsoft.com/en-us/library/3dasc8as.aspx 中所示的数组(但是他们的代码使用 WaitAll() 来等待所有工作人员完成，而不是在每个工作人员完成时使用react)。

编辑:

我已经使用 TPL 接受了 Douglas 的回答，但作为引用，Delegates 为我们提供了这个开箱即用的功能:

IAsyncResult result = caller.BeginInvoke(
                new AsyncCallback(CallbackMethod),
                "The call executed on thread {0}, with return value \"{1}\".");

...

void CallbackMethod(IAsyncResult ar) 
{
    // 'react' to async delegates completing
}

Answer 1

如果您使用任务并行库，您可以为每个任务附加一个延续。

int completedWorkers = 0;
var continuations = tasks.Select((task, index) => task.ContinueWith(antecedent =>
{
    lock (tasks)   // only required if you want to avoid races between incrementing and writing
    {
        int _index = index;   // avoid closures issue
        completedWorkers++;   // if lock is removed, replace with: Interlocked.Increment(ref completedWorkers);
        Console.WriteLine("Worker {0} has completed. {1} have now completed.", _index, completedWorkers);
    }
}));
Task.WaitAll(continuations.ToArray());
Console.WriteLine("All threads have finished");