如何：使用事件来控制手动队列调度

示例

一个游戏可能希望将其用于任务队列的线程与该游戏中的其他工作共享。 以下示例显示了如何使用任务队列来在其具有要调度的项时指示一个条件变量。

// We use condition variables to signal when there's something for us  
// in the queue and a bool to signal when we want the whole thing to close.  
// Keep all this in a struct for convenient access.  
struct QueueControl  
{  
    std::condition_variable workActivity;  
    std::mutex workMutex;  
    std::condition_variable completionActivity;  
    std::mutex completionMutex;  
    bool terminate = false;  
} queueControl;  
  
void CALLBACK TaskQueueNewItemSubmitted(  
    void* context, XTaskQueueHandle, XTaskQueuePort port)  
{  
    // A new callback has been submitted. Notify the correct condition variable.  
    QueueControl* queueControl = static_cast<QueueControl*>(context);  
    switch (port)  
    {  
    case XTaskQueuePort::Work:  
        queueControl->workActivity.notify_all();  
        break;  
  
    case XTaskQueuePort::Completion:  
        queueControl->completionActivity.notify_all();  
        break;  
    }  
}  
  
void CreatingTaskQueueWithManualSignaling()  
{  
    // Create a manual task queue.  
    XTaskQueueHandle queue;  
    HRESULT hr = XTaskQueueCreate(  
        XTaskQueueDispatchMode::Manual,  
        XTaskQueueDispatchMode::Manual,  
        &queue);  
  
    if (FAILED(hr))  
    {  
        printf("Creating queue failed: 0x%x\r\n", hr);  
        return;  
    }  
  
    // Listen to callback-submitted notifications to signal  
    // our condition variable.  
    XTaskQueueRegistrationToken token;  
    hr = XTaskQueueRegisterMonitor(  
        queue, &queueControl,  
        TaskQueueNewItemSubmitted, &token);  
  
    std::thread workThread([&]()  
    {  
        std::unique_lock<std::mutex> lock(queueControl.workMutex);  
        while (!queueControl.terminate)  
        {  
            queueControl.workActivity.wait(lock);  
            XTaskQueueDispatch(queue, XTaskQueuePort::Work, 0);  
        }  
    });  
  
    std::thread completionThread([&]()  
    {  
        std::unique_lock<std::mutex> lock(queueControl.completionMutex);  
        while (!queueControl.terminate)  
        {  
            queueControl.completionActivity.wait(lock);  
            XTaskQueueDispatch(queue, XTaskQueuePort::Completion, 0);  
        }  
    });  
  
    SubmitCallbacks(queue);  
  
    // Wait a while for the callbacks to run.  
    Sleep(1000);  
  
    XTaskQueueTerminate(queue, true, nullptr, nullptr);  
  
    queueControl.terminate = true; 
    queueControl.workActivity.notify_all(); 
    queueControl.completionActivity.notify_all();  
  
    workThread.join();  
    completionThread.join();  
}  

另请参阅

设计任务队列