c++ - waitforsingleobject 等待一个已经发出信号的事件

Question

我做 WaitForSingleObject(handle, timeout);如果在调用 WaitForSingleObject 之前 handle 已经发出信号，函数将返回什么？

我认为它应该立即返回一个 WAIT_OBJECT_0...但在我的例子中，它等待事件被设置并且因为这没有发生(事件已经设置)，它会计时出。

请指教。

Answer 1

取决于事件。您对手动重置事件的期望是正确的，而自动重置事件不会保持信号状态:Event Objects (Windows) .

Auto-reset event An event object whose state remains signaled until a single waiting thread is released, at which time the system automatically sets the state to nonsignaled.

If no threads are waiting, the event object's state remains signaled. If more than one thread is waiting, a waiting thread is selected. Do not assume a first-in, first-out (FIFO) order. External events such as kernel-mode APCs can change the wait order.