有没有办法在非WPF线程上使用Dispatcher；对多线程不熟悉

Question

有没有办法在非WPF线程上使用Dispatcher；对多线程不熟悉

c#dispatcher

3

为什么这不起作用？

我的目标：我需要一种方法来运行特定线程中的特定方法，直到程序结束。

我的其他可能选择：我了解到一种可能的方法是实现一个队列。我可以将想要在特定线程中运行的方法推入该队列中。在特定线程中，我会旋转并睡眠/ monitor.pulse，以查看是否有委托等待在队列中运行。

我的目标：是避免创建委托队列、维护锁等所有繁重的工作。似乎在WPF世界中存在一种现成的解决方案，称为Dispatcher。大多数WPF控件都从DispatcherObject继承，整个过程似乎都很好。我该怎么做才能让它起作用？

using System;
using System.Threading;
using System.Windows.Threading;

namespace ThreadingTrials
{
    class Program
    {
        [STAThread]
        static void Main(string[] args)
        {
            Thread.CurrentThread.Name = "mainThread";
            Engine engine = new Engine();
            Console.WriteLine("initializing SpecialEngine from {0}", Thread.CurrentThread.Name);
            engine.initialize();
            engine.doWork();
        }
    }
    class Engine:DispatcherObject
    {
        private EventWaitHandle InitializationComplete;
        private EventWaitHandle newWorkComplete;
        //private Dispatcher dispatcher;
        public Engine()
        {

        }
        public void initialize()
        {
            InitializationComplete = new EventWaitHandle(false, EventResetMode.ManualReset);
            Thread thread = new Thread(new ParameterizedThreadStart((hwnd)=>
            {
                InitializeSpecialEngineObject();
                while (true) ;
            }));
            thread.Name = "Special Engine Thread";

            thread.SetApartmentState(ApartmentState.STA);
            thread.Priority = ThreadPriority.Normal;
            thread.Start();
            Console.WriteLine("waiting for initialize at {0}", Thread.CurrentThread.Name);
            InitializationComplete.WaitOne();
        }
        private void InitializeSpecialEngineObject()
        {
            Console.WriteLine("doing initialization at {0}", Thread.CurrentThread.Name);
            Thread.Sleep(500);
            //dispatcher = Dispatcher.CurrentDispatcher;
            InitializationComplete.Set();
        }

        internal void doWork()
        {
            newWorkComplete = new EventWaitHandle(false, EventResetMode.AutoReset);
            //Dispatcher.Thread.Suspend();
            Dispatcher.Invoke((SendOrPostCallback)delegate
                {
                    Console.WriteLine("dispatched to {0}", Thread.CurrentThread.Name);
                    Thread.Sleep(500);
                    newWorkComplete.Set();
                },DispatcherPriority.Background, null);
            Dispatcher.Thread.Resume();
            Console.WriteLine("waiting for new work to complete at {0}", Thread.CurrentThread.Name);
            newWorkComplete.WaitOne();
        }
        private void doingWork()
        {
            Console.WriteLine("Doing work in {0}", Thread.CurrentThread.Name);

            Thread.Sleep(500);
        }
    }
}

感谢您的输入。说得好。实际上，制作一个简单的工作线程等待一个事件来表示队列中有新任务的void()委托，并在它们变得可用时运行它们，这是非常少的工作。我从在线网站复制了大部分代码...抱歉，我丢失了参考资料。我在那天做了这件事，应该更早地编辑这篇文章。

using System;
using System.Threading;
using System.Collections.Generic;

class ProducerConsumerQueue : IDisposable
{
    EventWaitHandle _wh = new AutoResetEvent(false);
    Thread _worker;
    readonly object _locker = new object();
    Queue<Action> _tasks = new Queue<Action>();

    public delegate void Action();

    public ProducerConsumerQueue()
    {
        _worker = new Thread(Work);
        _worker.Start();
    }

    public void EnqueueTask(Action work)
    {
        lock (_locker) _tasks.Enqueue(work);
        _wh.Set();
    }

    public void Dispose()
    {
        EnqueueTask(null);     // Signal the consumer to exit.
        _worker.Join();         // Wait for the consumer's thread to finish.
        _wh.Close();            // Release any OS resources.
    }

    void Work()
    {
        while (true)
        {
            Action task = null;
            lock (_locker)
                if (_tasks.Count > 0)
                {
                    task = _tasks.Dequeue();
                    if (task == null) return;
                }
            if (task != null)
            {
                task.Invoke();
            }
            else
                _wh.WaitOne();         // No more tasks - wait for a signal
        }
    }

}
class Program
{
    static void Main()
    {
        using (ProducerConsumerQueue q = new ProducerConsumerQueue())
        {
            q.EnqueueTask(delegate 
            {
                Console.WriteLine("Performing task: Hello");
                Thread.Sleep(1000);  // simulate work...
            });
            for (int i = 0; i < 10; i++) q.EnqueueTask(delegate 
            {
                Console.WriteLine("Performing task: "+ i);
                Thread.Sleep(1000);  // simulate work...
            });
            q.EnqueueTask(delegate 
            {
                Console.WriteLine("Performing task: Goodbye!");
                Thread.Sleep(1000);  // simulate work...
            });
        }

        // Exiting the using statement calls q's Dispose method, which
        // enqueues a null task and waits until the consumer finishes.
    }
}

- schak

1个回答

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原文链接

- Stephen Cleary · Accepted Answer

您不需要调用Dispatcher.Run。您假设一个Dispatcher包含一个执行其工作的Thread，但这是错误的。当第一次调用Dispatcher.CurrentDispatcher时，会创建一个Dispatcher并将其绑定到当前线程。请注意，即使您的代码没有直接调用CurrentDispatcher，它也通过构造一个DispatcherObject（其中捕获了CurrentDispatcher）间接地调用它。

请查看WPF线程模型文档，其中包含您所需的所有详细信息。

如果您想在子线程中使用类似于Dispatcher的功能，但又不想依赖于WPF，则可以使用来自Nito.Async的ActionThread类，它与Dispatcher加上专用Thread大致相当。