来自取消令牌的任务? [英] Task from cancellation token?

问题描述

给定一个取消令牌，我想从中创建一个可等待的任务，该任务永远不会完成但可以取消.我需要这样的模式，IMO 应该很常见:

Given a cancellation token, I'd like to create an awaitable task out of it, which is never complete but can be cancelled. I need it for a pattern like this, which IMO should be quite common:

async Task DoStuff(Task t, CancellationToken ct)
{
   // t was made from TaskCompletionSource, 
   // both t and ct are beyond my control

   Task t2 = TaskFromCancellationToken(ct);
   await Task.WhenAny(t, t2);

   // do stuff
}

到目前为止我得到的最好的想法是:

The best idea I've got so far is this:

Task TaskFromCancelationToken(CancellationToken ct)
{
    return Task.Delay(Timeout.Infinite, ct);
}

有没有更好的方法来实现这个逻辑?

Is there a better way to make this logic happen?

推荐答案

这不是非常常见的，但它很常见，足以成为我AsyncEx 库.我使用 类似这样的:

It's not extremely common, but it's common enough to be part of my AsyncEx library. I use something like this:

public static Task AsTask(this CancellationToken cancellationToken)
{
    var tcs = new TaskCompletionSource<object>();
    cancellationToken.Register(() => tcs.TrySetCanceled(),
        useSynchronizationContext: false);
    return tcs.Task;
}

更新:最近，我建议使用类似 CancellationTokenTaskSource，它可以正确处理所有生命周期，没有资源泄漏的可能性.

Update: These days, I recommend using something like CancellationTokenTaskSource, which properly handles all lifetimes with no possibility of resource leaks.

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