c# - C# IAsyncResult 等待所有

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 数组之前调用完成之一的机会是多少？

问候， 达南杰

Answer 1

我感觉合理。

// 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.

你到底觉得什么奇怪？

问“有什么机会”是一个不好的迹象。有可能发生这种情况，这意味着您需要考虑程序在 WaitAll 之前完成时以及方法完成时需要执行的操作。