ce9ba9b376
Note: I have cleared the original MessageQueue.cpp file from the inline documentation. When the storage kit comes up, we need to rediscuss the documentation policy. git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@24522 a95241bf-73f2-0310-859d-f6bbb57e9c96
165 lines
4.4 KiB
Plaintext
165 lines
4.4 KiB
Plaintext
/*
|
|
* Copyright 2007, Haiku, Inc. All Rights Reserved.
|
|
* Distributed under the terms of the MIT License.
|
|
*
|
|
* Authors:
|
|
* Niels Sascha Reedijk, niels.reedijk@gmail.com
|
|
*
|
|
* Corresponds to:
|
|
* /trunk/headers/os/app/MessageQueue.h rev 19956
|
|
* /trunk/src/kits/app/MessageQueue.cpp rev 19956
|
|
*/
|
|
|
|
/*!
|
|
\file MessageQueue.h
|
|
\brief Provides the BMessageQueue class.
|
|
*/
|
|
|
|
|
|
/*!
|
|
\class BMessageQueue
|
|
\ingroup app
|
|
\brief A container that maintains a queue of messages.
|
|
|
|
This class is used by BLooper to maintain a queue of messages that need to
|
|
be processed. This class has been designed as a first in, first out
|
|
container.
|
|
|
|
The default message handling of a BLooper probably suffices for most uses,
|
|
but if you want more control, you can perform operations using the methods
|
|
of this class. Use BLooper::MessageQueue() to retrieve the specific
|
|
BMessageQueue instance.
|
|
|
|
Note that you are encouraged to make sure that whichever operation you
|
|
perform, that you only do this after the object has been locked (see
|
|
Lock()). The most important method, NextMessage() will fail if you have not
|
|
complied with this requirement.
|
|
*/
|
|
|
|
|
|
/*!
|
|
\fn BMessageQueue::BMessageQueue()
|
|
\brief Constructs an empty message queue.
|
|
*/
|
|
|
|
|
|
/*!
|
|
\fn BMessageQueue::~BMessageQueue()
|
|
\brief Destruct the BMessageQueue. It iterates over any messages left on
|
|
the queue and deletes them.
|
|
|
|
The implementation is careful not to release the lock when the
|
|
BMessageQueue is deconstructed. If the lock is released, it is
|
|
possible another thread will start an AddMessage() operation before
|
|
the BLocker is deleted. The safe thing to do is not to unlock the
|
|
BLocker from the destructor once it is acquired. That way, any thread
|
|
waiting to do a AddMessage() will fail to acquire the lock since the
|
|
BLocker will be deleted before they can acquire it.
|
|
*/
|
|
|
|
|
|
/*!
|
|
\fn void BMessageQueue::AddMessage(BMessage* message)
|
|
\brief Add a \a message to the end of the queue.
|
|
|
|
The message has to be allocated on the heap with \c new, because the queue
|
|
claims ownership of the message. Messages that were constructed on the
|
|
stack will corrupt the queue.
|
|
|
|
Because a BMessageQueue claims ownership of the \a message, it is important
|
|
that the message does not belong to another BMessageQueue.
|
|
*/
|
|
|
|
|
|
/*!
|
|
\fn void BMessageQueue::RemoveMessage(BMessage* message)
|
|
\brief Remove a \a message from the queue.
|
|
|
|
If the \a message is indeed associated with this queue, it is removed from
|
|
it. This effectively means that you regain ownership of the message.
|
|
*/
|
|
|
|
|
|
/*!
|
|
\fn int32 BMessageQueue::CountMessages() const
|
|
\brief Return the number of messages waiting in the queue.
|
|
*/
|
|
|
|
|
|
/*!
|
|
\fn bool BMessageQueue::IsEmpty() const
|
|
\brief Check if there are messages waiting in the queue.
|
|
*/
|
|
|
|
|
|
/*!
|
|
\fn BMessage *BMessageQueue::FindMessage(int32 index) const
|
|
\brief Retrieve the message at the \a index of this queue.
|
|
|
|
\param index A zero-based index of the message you want to retrieve.
|
|
|
|
\return A pointer to a message, or \c NULL if the \a index is out of
|
|
bounds.
|
|
\see FindMessage(uint32, int32) for a variant that takes a specific \c what
|
|
identifier.
|
|
*/
|
|
|
|
|
|
/*!
|
|
\fn BMessage *BMessageQueue::FindMessage(uint32 what, int32 index) const
|
|
\brief Retrieve the message at the \a index of this queue, but only if it
|
|
has a specific \a what constant.
|
|
|
|
\param index A zero-based index of the message you want to retrieve.
|
|
\param what The \a what code of the message.
|
|
|
|
\return A pointer to a message, or \c NULL if there is no message at the
|
|
\a index with that \a what constant, or if the \a index is out of
|
|
bounds.
|
|
*/
|
|
|
|
|
|
/*!
|
|
\fn bool BMessageQueue::Lock()
|
|
\brief Lock the queue so no other thread can perform operations on it.
|
|
|
|
\see Unlock()
|
|
*/
|
|
|
|
|
|
/*!
|
|
\fn void BMessageQueue::Unlock()
|
|
\brief Unlock the queue after a Lock() request.
|
|
|
|
\see Lock()
|
|
*/
|
|
|
|
|
|
/*!
|
|
\fn bool BMessageQueue::IsLocked() const
|
|
\brief Check if the queue is locked.
|
|
|
|
\see Lock() and Unlock()
|
|
*/
|
|
|
|
|
|
/*!
|
|
\fn BMessage *BMessageQueue::NextMessage()
|
|
\brief Remove the first BMessage on the queue and return it to the caller.
|
|
|
|
After calling this method, you get the ownership of the message, so make
|
|
sure it is deleted after you are done.
|
|
|
|
\return A pointer to a message, or \c NULL if the queue is empty, or the
|
|
object has not been properly locked.
|
|
\see Lock()
|
|
\see IsNextMessage()
|
|
*/
|
|
|
|
|
|
/*!
|
|
\fn bool BMessageQueue::IsNextMessage(const BMessage* message) const
|
|
\brief Check if the pointer to a \a message points at the next message on
|
|
the queue.
|
|
*/
|