/////////////////////////////////////////////////////////////////////////////
-// Name: msgqueue.h
+// Name: wx/msgqueue.h
// Purpose: interface of wxMessageQueue<T>
// Author: wxWidgets team
// RCS-ID: $Id$
-// Licence: wxWindows license
+// Licence: wxWindows licence
/////////////////////////////////////////////////////////////////////////////
/**
+ Error codes for wxMessageQueue<> operations.
+ This enum contains the possible return value of wxMessageQueue<> methods.
+
+ @since 2.9.0
+ @category{threading}
+ */
+enum wxMessageQueueError
+{
+ /// Indicates that the operation completed successfully.
+ wxMSGQUEUE_NO_ERROR = 0,
+
+ /**
+ Indicates that no messages were received before timeout expired.
+
+ This return value is only used by wxMessageQueue<>::ReceiveTimeout().
+ */
+ wxMSGQUEUE_TIMEOUT,
+
+ /// Some unexpected (and fatal) error has occurred.
+ wxMSGQUEUE_MISC_ERROR
+};
+
+/**
wxMessageQueue allows passing messages between threads.
This class should be typically used to communicate between the main and worker
- threads. The main thread calls wxMessageQueue::Post and
- the worker thread calls wxMessageQueue::Receive.
+ threads. The main thread calls wxMessageQueue::Post and the worker thread
+ calls wxMessageQueue::Receive.
- For this class a message is an object of arbitrary type T. Notice that
- often there is a some special message indicating that the thread
+ @tparam T
+ For this class a message is an object of arbitrary type T.
+
+ Notice that often there is a some special message indicating that the thread
should terminate as there is no other way to gracefully shutdown a thread
waiting on the message queue.
+ @since 2.9.0
+
@nolibrary
- @category{FIXME}
+ @category{threading}
@see wxThread
*/
+template <typename T>
class wxMessageQueue<T>
{
public:
+ /**
+ Default and only constructor.
+ Use wxMessageQueue::IsOk to check if the object was successfully initialized.
+ */
+ wxMessageQueue();
+
+ /**
+ Remove all messages from the queue.
+
+ This method is meant to be called from the same thread(s) that call
+ Post() to discard any still pending requests if they became
+ unnecessary.
+
+ @since 2.9.1
+ */
+ wxMessageQueueError Clear();
+
/**
Returns @true if the object had been initialized successfully, @false
if an error occurred.
Add a message to this queue and signal the threads waiting for messages
(i.e. the threads which called wxMessageQueue::Receive or
wxMessageQueue::ReceiveTimeout).
+
This method is safe to call from multiple threads in parallel.
*/
wxMessageQueueError Post(T const& msg);
/**
- Block until a message becomes available in the queue. Waits indefinitely long
- or until an error occurs.
- The message is returned in @e msg.
+ Block until a message becomes available in the queue.
+ Waits indefinitely long or until an error occurs.
+
+ The message is returned in @a msg.
*/
wxMessageQueueError Receive(T& msg);
/**
Block until a message becomes available in the queue, but no more than
@a timeout milliseconds has elapsed.
+
If no message is available after @a timeout milliseconds then returns
@b wxMSGQUEUE_TIMEOUT.
+
If @a timeout is 0 then checks for any messages present in the queue
and returns immediately without waiting.
- The message is returned in @e msg.
- */
- wxMessageQueueError ReceiveTimeout(long timeout, T& msg);
- /**
- Default and only constructor. Use wxMessageQueue::IsOk to check
- if the object was successfully initialized.
+ The message is returned in @a msg.
*/
- wxMessageQueue();
+ wxMessageQueueError ReceiveTimeout(long timeout, T& msg);
};