了解MsgWaitForMultipleObjects [英] Understanding MsgWaitForMultipleObjects

问题描述

我有一个主gui线程，我希望对用户操作保持响应，例如，移动对话框，调整大小等，而我有一个后台线程来执行某些任务.过去，我在等待后台线程完成的同时使用带有超时的WaitForSingleObject来处理gui事件.最近，我读到有关MsgWaitForMultipleObjects的文章，该文章似乎正在解决我的清洁问题.

I have a main gui thread that I want to remain responsive to the users action such as moving the dialog around, resizing, etc while I have a background thread doing some task. In the past I've used WaitForSingleObject with a timeout in order to process gui events while waiting on the background thread to complete. I recently read about MsgWaitForMultipleObjects which looked to be solving the problem that I had a little bit cleaner.

有人可以告诉我以下代码中的错误吗?我在哪里错了?当我单击该按钮以启动线程时，gui没有响应.我制作了一个对话框应用程序，该应用程序具有在主ui线程上播放的avi.我有一个启动线程的按钮，并使用MsgWaitForMultipleObjects等待线程句柄，但允许处理所有消息，最终在线程完成/发出信号时中断.

Can someone tell me the bugs in the following code & where I'm going wrong here? The gui is unresponsive when I click the button to start the thread. I made a dialog app with an avi that is playing on the main ui thread. I have a button to start a thread and use MsgWaitForMultipleObjects to wait on the thread handle but allow all messages through to be processed ultimately breaking when the thread is finished/signaled.

谢谢.

UINT MyThreadProc( LPVOID pParam )
{
    ThreadData* pObject = (ThreadData*)pParam;

    if (pObject == NULL ||
        !pObject->IsKindOf(RUNTIME_CLASS(ThreadData)))
    return 1;   

    // Do some processing.
    int x = 0; 
    while (x++ < 5000)
    {
        for (int i=0; i<50000; i++)
            double sum = sqrt((double)i+1) * sqrt((double)i+2); 
    }

    return 0;
}

按钮处理程序

void Cmsgwait_demoDlg::OnBnClickedBtnStartThread()
{
    m_pThreadData = new ThreadData;
    CWinThread* pWorkThread = AfxBeginThread(MyThreadProc, m_pThreadData);

    m_status.SetWindowText("Status: Waiting for thread to complete."); 

    HANDLE handles[] = { pWorkThread->m_hThread }; 
    DWORD ret = 0; 

    do 
    {
        ret = MsgWaitForMultipleObjects(1, handles, FALSE, INFINITE, QS_ALLINPUT); 
        if (ret == WAIT_OBJECT_0)
        {
            m_status.SetWindowText("Status: Thread completed."); 
        }
        else if (WAIT_IO_COMPLETION)
        {
            m_status.SetWindowText("Status: User mode APC queued."); 
        }
        else if (WAIT_FAILED)
        {
            m_status.SetWindowText("Status: Wait failed"); 
        }
    }
    while (ret != WAIT_OBJECT_0 && ret != WAIT_FAILED);
}

推荐答案

您没有处理UI线程的传入消息，请使用此处)以获取示例.

You are not processing the incoming message of the UI thread, take a look at Raymond's blog (also see here) for a sample.

  while (true) {
    switch (MsgWaitForMultipleObjects(1, &h,
                         FALSE, INFINITE, QS_ALLINPUT)) {
    case WAIT_OBJECT_0:
      DoSomethingWith(h); // event has been signalled
      break;
    case WAIT_OBJECT_0+1:
      // we have a message - peek and dispatch it
      while (PeekMessage(&msg, NULL, 0, 0, PM_REMOVE)) {
        // TODO:  must handle WM_QUIT; see Raymond's blog for details
        TranslateMessage(&msg);
        DispatchMessage(&msg);
      }
      break;
    default:
      return FALSE; // unexpected failure
    }
  }

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