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/*
fifo waitqueue for threads.(Multi-in, single out)
Copyright (C) 2000 Martin Vogt
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU Library General Public License as published by
the Free Software Foundation.
For more information look at the file COPYRIGHT in this package
*/
#ifndef __THREADTQUEUE_H
#define __THREADTQUEUE_H
#include "abs_thread.h"
class WaitThreadEntry {
public:
WaitThreadEntry();
~WaitThreadEntry();
abs_thread_cond_t waitCond;
};
/**
This class can be used as a general purpuse wrapper to
make C++ classes thread safe.
Mpeglib uses for every decoder a single thread which
reads from the input and write to one output type (video/audio)
To make the input and output classes thread safe you have
two solutions. First you can try to do it in every class
itsself, this is much work and needs understanding of
threads or you can use this wrapper class.
Normally you don't need two threads in one class, only
for the audio/video sync this is necessary, but for
the inputstream (file,http,..) this not necessary.
For the output this is the same.
This class offers two methods. waitForExclusiceAcess()
and releaseExlusiveAcess. Internally the thread who
calls waitFor.. in enqueued (if it does not get the exclusive
access) the thread who have the exclusive access calls
sometimes release.. with then pass the exclusive access
to the next thread.
Why it is needed?
Because we access the input/output streams from different
threads. A user of mpeglib may want to set mpeg video
in fullscreen mode, this means two threads call
methods in the output classes including: closing windows,
resizing windows ... now this is safley possible when
the threadSafeInputStream / threadSafeoutputStream wrappers
are used, which forward the calls to the real classes.
*/
class ThreadQueue {
abs_thread_mutex_t queueMut;
int insertPos;
int removePos;
int size;
WaitThreadEntry** waitThreadEntries;
public:
ThreadQueue();
~ThreadQueue();
void waitForExclusiveAccess();
void releaseExclusiveAccess();
};
#endif
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