interface/wx/msgqueue.h

   1 /////////////////////////////////////////////////////////////////////////////
   2 // Name:        msgqueue.h
   3 // Purpose:     interface of wxMessageQueue<T>
   4 // Author:      wxWidgets team
   5 // RCS-ID:      $Id$
   6 // Licence:     wxWindows license
   7 /////////////////////////////////////////////////////////////////////////////
   8
   9 /**
  10
  11     wxMessageQueue allows passing messages between threads.
  12
  13     This class should be typically used to communicate between the main and worker
  14     threads. The main thread calls wxMessageQueue::Post and
  15     the worker thread calls wxMessageQueue::Receive.
  16
  17     For this class a message is an object of arbitrary type T. Notice that
  18     often there is a some special message indicating that the thread
  19     should terminate as there is no other way to gracefully shutdown a thread
  20     waiting on the message queue.
  21
  22     @nolibrary
  23     @category{FIXME}
  24
  25     @see wxThread
  26 */
  27 class wxMessageQueue<T>
  28 {
  29 public:
  30     /**
  31         Returns @true if the object had been initialized successfully, @false
  32         if an error occurred.
  33     */
  34     bool IsOk() const;
  35
  36     /**
  37         Add a message to this queue and signal the threads waiting for messages
  38         (i.e. the threads which called wxMessageQueue::Receive or
  39         wxMessageQueue::ReceiveTimeout).
  40         This method is safe to call from multiple threads in parallel.
  41     */
  42     wxMessageQueueError Post(T const& msg);
  43
  44     /**
  45         Block until a message becomes available in the queue. Waits indefinitely long
  46         or until an error occurs.
  47         The message is returned in @e msg.
  48     */
  49     wxMessageQueueError Receive(T& msg);
  50
  51     /**
  52         Block until a message becomes available in the queue, but no more than
  53         @a timeout milliseconds has elapsed.
  54         If no message is available after @a timeout milliseconds then returns
  55         @b wxMSGQUEUE_TIMEOUT.
  56         If @a timeout is 0 then checks for any messages present in the queue
  57         and returns immediately without waiting.
  58         The message is returned in @e msg.
  59     */
  60     wxMessageQueueError ReceiveTimeout(long timeout, T& msg);
  61
  62     /**
  63         Default and only constructor. Use wxMessageQueue::IsOk to check
  64         if the object was successfully initialized.
  65     */
  66     wxMessageQueue();
  67 };
  68