C# IAsyncResult WaitAll

Question

在WaitAll的一些实现中，我看到了以下代码

IAsyncResult result1 = Method.BeginInvoke(10, MyCallback, null)
IAsyncResult result2 = Method.BeginInvoke(20, MyCallback, null)
WaitHandle[] waitHandles = new WaitHandle[] { result1.AsyncWaitHandle, result2.AsyncWaitHandle};
WaitHandle.WaitAll(waitHandles)

这看起来对吗？在创建waitHandles数组之前，其中一个调用完成的可能性有多大？

你好，Dhananjay

Answer 1

对我来说很有意义。

// Begin invoking the first and second method, and give them a callback
IAsyncResult result1 = Method.BeginInvoke(10, MyCallback, null)
IAsyncResult result2 = Method.BeginInvoke(20, MyCallback, null)

// Any time past the point of invokation, MyCallback could be called.
// Get the wait handles of the async results, regardless of whether they have finished or not
WaitHandle[] waitHandles = new WaitHandle[] { result1.AsyncWaitHandle, result2.AsyncWaitHandle};

// Make sure to wait until the methods have finished.
// They could have finished immediately, and MyCallback could have already been called,
// but we will never get past this line unless they have finished.
WaitHandle.WaitAll(waitHandles)
// We may have waited on the function to finish, or they may have been done before we arrived at the previous line. Either way, they are done now.

你到底觉得奇怪的是什么？

问“机会有多大”不是一个好兆头。这种情况很有可能发生，这意味着如果方法在WaitAll之前完成，那么您需要考虑程序需要做什么。