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/*
Copyright (C) 2006 Adam Charrett
This program is free software; you can redistribute it and/or
modify it under the terms of the GNU General Public License
as published by the Free Software Foundation; either version 2
of the License, or (at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA
messageq.h
Thread safe message queue.
*/
#ifndef _DVBSTREAMER_MESSAGEQ_H
#define _DVBSTREAMER_MESSAGEQ_H
#include "types.h"
/**
* @defgroup MessageQ Thread safe message queue
*@{
*/
/**
* Message Queue handle.
*/
typedef struct MessageQ_s *MessageQ_t;
/**
* Creates a new double linked list.
* @return A new MessageQ_t instance or NULL if there is not enough memory.
*/
MessageQ_t MessageQCreate();
/**
* Frees the specified message queue.
* @param msgQ The message queue to free.
*/
void MessageQDestroy(MessageQ_t msgQ);
/**
* Sends the specified msg to the message queue. msg must be allocated
* using Object(Alloc/Create) as on adding to the queue they will have their
* reference count increased using ObjectRefInc and any messages are left in the
* queue when it is destroyed they will first be unref'ed using ObjectRefDec().
*
* @param msgQ The message queue to send the message to.
* @param msg The object to send.
*/
void MessageQSend(MessageQ_t msgQ, void *msg);
/**
* Returns the number of messages waiting in the queue.
* @param msgQ The message queue to count the waiting messages in.
* @return The number of waiting messages.
*/
int MessageQAvailable(MessageQ_t msgQ);
/**
* Receive a message from the queue, the return object should be unref'ed once
* finished with via ObjectRefDec.
* If the quit flag is set on the message queue NULL will be returned.
* @param msgQ The queue to receive a message from.
* @return A pointer to an object or NULL if quit is set.
*/
void *MessageQReceive(MessageQ_t msgQ);
/**
* Receive a message from the queue waiting for upto timeout milliseconds.
* The return object should be unref'ed once finished with via ObjectRefDec.
* If the quit flag is set on the message queue NULL will be returned.
* @param msgQ The queue to receive a message from.
* @param timeout The number of milliseconds to wait for a message.
* @return A pointer to an object or NULL if quit is set.
*/
void *MessageQReceiveTimed(MessageQ_t msgQ, ulong timeout);
/**
* Set the quit flag on the specified message queue. Once set all current and
* future calls to MessageQReceive will return NULL.
* @param msgQ The message queue to set the quit flag on.
*/
void MessageQSetQuit(MessageQ_t msgQ);
/**
* Reset the quit flag on the specified message queue so messages can once again
* be received.
* @param msgQ The message queue to reset the quit flag on.
*/
void MessageQResetQuit(MessageQ_t msgQ);
/**
* Test whether the quit flag is set on the specified message queue.
* @param msgQ The message queue to check.
* @return TRUE if the quit flag is set, FALSE otherwise.
*/
bool MessageQIsQuitSet(MessageQ_t msgQ);
/** @} */
#endif
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