示例
你可以将一个 Win32 内核句柄注册到任务队列。当该句柄变为已发出信号状态时，你的回调将被提交到队列。通常，你会创建一个自动重置事件用于发出信号。如果句柄不是自动重置的，那么只要句柄仍处于已发出信号状态，当前回调完成后就会提交一个新的回调。 以下示例展示了如何使用任务队列等待器。void CreatingTaskQueueWaiter()
{
HANDLE waitEvent = CreateEvent(nullptr, FALSE, FALSE, nullptr);
if (waitEvent == nullptr)
{
printf("Error creating wait handle: %d\r\n", GetLastError());
return;
}
XTaskQueueHandle queue;
HRESULT hr = XTaskQueueCreate(
XTaskQueueDispatchMode::ThreadPool,
XTaskQueueDispatchMode::ThreadPool,
&queue);
if (FAILED(hr))
{
printf("Error creating task queue: %x\n", hr);
CloseHandle(waitEvent);
return;
}
auto callback = [](void*, bool)
{
printf("Callback invoked.\r\n");
};
XTaskQueueRegistrationToken token;
hr = XTaskQueueRegisterWaiter(
queue,
XTaskQueuePort::Completion,
waitEvent,
nullptr,
callback,
&token);
if (FAILED(hr))
{
printf("Error registering task queue waiter: %x\n", hr);
CloseHandle(waitEvent);
XTaskQueueCloseHandle(queue);
return;
}
// Now, whenever our wait event becomes signaled, the callback will be called.
for (uint32_t i = 0; i < 5; i++)
{
SetEvent(waitEvent);
Sleep(100);
}
// Note: Unregistering the waiter is optional.
XTaskQueueUnregisterWaiter(queue, token);
XTaskQueueCloseHandle(queue);
CloseHandle(waitEvent);
}
示例输出
Callback invoked.
Callback invoked.
Callback invoked.
Callback invoked.
Callback invoked.