multithreading - 从 WaitHandle.Wait 构造任务

Question

我选择返回 Task<T>和 Task从我的对象方法中提供 gui 的简单使用。一些方法只是等待其他类型的 waithandles 的互斥锁。有没有办法构造Task来自 WaitHandle.Wait()这样我就不必为此阻塞一个线程。

Answer 1

有一种方法可以做到这一点:您可以使用 ThreadPool.RegisterWaitForSingleObject 订阅 WaitHandle方法并通过 TaskCompletionSource 包装它类(class):

public static class WaitHandleEx
{
    public static Task ToTask(this WaitHandle waitHandle)
    {
        var tcs = new TaskCompletionSource<object>();

        // Registering callback to wait till WaitHandle changes its state

        ThreadPool.RegisterWaitForSingleObject(
            waitObject: waitHandle,
            callBack:(o, timeout) => { tcs.SetResult(null); }, 
            state: null, 
            timeout: TimeSpan.MaxValue, 
            executeOnlyOnce: true);

        return tcs.Task;
    }
}

用法:

WaitHandle wh = new AutoResetEvent(true);
var task = wh.ToTask();
task.Wait();