BMessageQueue¶

Constructor and Destructor¶

BMessageQueue()

BMessageQueue::BMessageQueue()

Creates an empty BMessageQueue object.

~BMessageQueue()

virtual BMessageQueue::~BMessageQueue()

Deletes all the objects in the queue and all the data structures used to manage the queue.

Member Functions¶

AddMessage(), RemoveMessage()

void BMessageQueue::AddMessage(BMessage *message)

void BMessageQueue::RemoveMessage(BMessage *message)

AddMessage() adds message to the far end of the queue. RemoveMessage() removes a particular message from the queue and deletes it.

CountMessages(), IsEmpty()

int32 BMessageQueue::CountMessages() const

bool BMessageQueue::IsEmpty() const

CountMessages() returns the number of messages currently in the queue.

IsEmpty() returns true if the object doesn’t contain any messages, and false otherwise.

FindMessage()

BMessage *BMessageQueue::FindMessage(int32 index) const
BMessage *BMessageQueue::FindMessage(uint32 what, int32 index = 0) const

FindMessage() returns a pointer to the index’th BMessage in the queue, where index 0 signifies the message that’s been in the queue the longest. The second version lets you specify a what field value; in this case, only messages that match the what argument are counted. If no message matches the criteria, the functions return NULL.

The message is not removed from the message queue.

Lock(), Unlock()

bool BMessageQueue::Lock()

void BMessageQueue::Unlock()

These functions lock and unlock the BMessageQueue, so that another thread won’t alter the contents of the queue while it’s being read. Lock() doesn’t return until it has the queue locked; it always returns true. Unlock() releases the lock so that someone else can lock it. Calls to these functions can be nested.

NextMessage()

BMessage *BMessageQueue::NextMessage()

Removes and returns the oldest message from the queue. If the queue is empty, the function returns NULL.