interface/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     @class wxMessageQueueT
  11     @wxheader{msgqueue.h}
  12
  13     wxMessageQueue allows passing messages between threads.
  14
  15     This class should be typically used to communicate between the main and worker
  16     threads. The main thread calls wxMessageQueue::Post and
  17     the worker thread calls wxMessageQueue::Receive.
  18
  19     For this class a message is an object of arbitrary type T. Notice that
  20     often there is a some special message indicating that the thread
  21     should terminate as there is no other way to gracefully shutdown a thread
  22     waiting on the message queue.
  23
  24     @nolibrary
  25     @category{FIXME}
  26
  27     @see wxThread
  28 */
  29 class wxMessageQueue<T>
  30 {
  31 public:
  32     /**
  33         Returns @true if the object had been initialized successfully, @false
  34         if an error occurred.
  35     */
  36     bool IsOk() const;
  37
  38     /**
  39         Add a message to this queue and signal the threads waiting for messages
  40         (i.e. the threads which called wxMessageQueue::Receive or
  41         wxMessageQueue::ReceiveTimeout).
  42         This method is safe to call from multiple threads in parallel.
  43     */
  44     wxMessageQueueError Post(T const& msg);
  45
  46     /**
  47         Block until a message becomes available in the queue. Waits indefinitely long
  48         or until an error occurs.
  49         The message is returned in @e msg.
  50     */
  51     wxMessageQueueError Receive(T& msg);
  52
  53     /**
  54         Block until a message becomes available in the queue, but no more than
  55         @a timeout milliseconds has elapsed.
  56         If no message is available after @a timeout milliseconds then returns
  57         @b wxMSGQUEUE_TIMEOUT.
  58         If @a timeout is 0 then checks for any messages present in the queue
  59         and returns immediately without waiting.
  60         The message is returned in @e msg.
  61     */
  62     wxMessageQueueError ReceiveTimeout(long timeout, T& msg);
  63
  64     /**
  65         Default and only constructor. Use wxMessageQueue::IsOk to check
  66         if the object was successfully initialized.
  67     */
  68     wxMessageQueue();
  69 };
  70