Question

I have an application which second thread calls GetMessage() in a loop. At some point the first thread realizes that the user wants to quit the application and notifies the second thread that it should terminate. As the second thread is stuck on GetMessage(), the program never quits. Is there a way to wait for messages with a timeout?
I’m open to other ideas too.

EDIT: (additional explanations)

The second thread runs that snippet of code:

while ( !m_quit && GetMessage( &msg, NULL, 0, 0 ) )
{
    TranslateMessage( &msg );
    DispatchMessage( &msg );
}

The first thread sets m_quit to true.

Answer 1

The easiest way is to just call UINT_PTR timerId=SetTimer(NULL, NULL, 1000, NULL) before calling GetMessage. It will post a WM_TIMER message to the calling thread every second, so the GetMessage will return promptly. Then, call KillTimer(NULL, timerId) to cancel it.

UPDATE Sample code:

BOOL GetMessageWithTimeout(MSG *msg, UINT to)
{
    BOOL res;
    UINT_PTR timerId = SetTimer(NULL, NULL, to, NULL);
    res = GetMessage(msg);
    KillTimer(NULL, timerId);
    if (!res)
        return FALSE;
    if (msg->message == WM_TIMER && msg->hwnd == NULL && msg->wParam == timerId)
        return FALSE; //TIMEOUT! You could call SetLastError() or something...
    return TRUE;
}