Task.WhenAny 和 SemaphoreSlim 类

使用时WaitHandle.WaitAny and Semaphore class像下面这样：

var s1 = new Semaphore(1, 1);
var s2 = new Semaphore(1, 1);

var handles = new [] { s1, s2 };

var index = WaitHandle.WaitAny(handles);

handles[index].Release();

似乎可以保证只有一个信号量被获取WaitHandle.WaitAny.

是否可以为异步（async/await）代码获得类似的行为？

我想不出内置的解决方案。我会这样做：

var s1 = new SemaphoreSlim(1, 1);
var s2 = new SemaphoreSlim(1, 1);

var waits = new [] { s1.WaitAsync(), s2.WaitAsync() };

var firstWait = await Task.WhenAny(waits);

//The wait is still running - perform compensation.
if (firstWait == waits[0])
 waits[1].ContinueWith(_ => s2.Release());
if (firstWait == waits[1])
 waits[0].ContinueWith(_ => s1.Release());

这会获取两个信号量，但会立即释放第二个信号量。这应该是等价的。我无法想象不必要地获取信号量的负面后果（当然性能除外）。