c# - 线程安全 FIFO 队列/缓冲区

Question

我需要实现一种任务缓冲区。基本要求是:

• 在单个后台线程中处理任务
• 从多个线程接收任务
• 处理所有收到的任务，即确保在收到停止信号后缓冲区中的缓冲任务被清空
• 必须保持每个线程接收任务的顺序

我正在考虑使用如下所示的队列来实现它。将不胜感激对实现的反馈。有没有其他更好的想法来实现这样的事情？

public class TestBuffer
{
    private readonly object queueLock = new object();
    private Queue<Task> queue = new Queue<Task>();
    private bool running = false;

    public TestBuffer()
    {
    }

    public void start()
    {
        Thread t = new Thread(new ThreadStart(run));
        t.Start();
    }

    private void run()
    {
        running = true;

        bool run = true;
        while(run)
        {
            Task task = null;
            // Lock queue before doing anything
            lock (queueLock)
            {
                // If the queue is currently empty and it is still running
                // we need to wait until we're told something changed
                if (queue.Count == 0 && running)
                {
                    Monitor.Wait(queueLock);
                }

                // Check there is something in the queue
                // Note - there might not be anything in the queue if we were waiting for something to change and the queue was stopped
                if (queue.Count > 0)
                {
                    task = queue.Dequeue();
                }
            }

            // If something was dequeued, handle it
            if (task != null)
            {
                handle(task);
            }

            // Lock the queue again and check whether we need to run again
            // Note - Make sure we drain the queue even if we are told to stop before it is emtpy
            lock (queueLock)
            {
                run = queue.Count > 0 || running;
            }
        }
    }

    public void enqueue(Task toEnqueue)
    {
        lock (queueLock)
        {
            queue.Enqueue(toEnqueue);
            Monitor.PulseAll(queueLock);
        }
    }

    public void stop()
    {
        lock (queueLock)
        {
            running = false;
            Monitor.PulseAll(queueLock);
        }
    }

    public void handle(Task dequeued)
    {
        dequeued.execute();
    }
}

Answer 1

您实际上可以使用开箱即用的 BlockingCollection 来处理这个问题.

它被设计成有 1 个或多个生产者，以及 1 个或多个消费者。在您的情况下，您将有多个生产者和一个消费者。

当您收到停止信号时，让该信号处理程序

• 信号生产者线程停止
• 在 BlockingCollection 实例上调用 CompleteAdding

消费者线程将继续运行，直到所有排队的项目都被移除和处理，然后它会遇到 BlockingCollection 完成的条件。当线程遇到该条件时，它就退出。