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/* $Id$ */
/***
This file is part of PulseAudio.
Copyright 2006 Lennart Poettering
PulseAudio is free software; you can redistribute it and/or modify
it under the terms of the GNU Lesser General Public License as published
by the Free Software Foundation; either version 2 of the License,
or (at your option) any later version.
PulseAudio 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 Lesser General Public License
along with PulseAudio; if not, write to the Free Software
Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307
USA.
***/
#ifdef HAVE_CONFIG_H
#include <config.h>
#endif
#include <pthread.h>
#include <assert.h>
#include <pulsecore/mutex.h>
#include "once.h"
#define ASSERT_SUCCESS(x) do { \
int _r = (x); \
assert(_r == 0); \
} while(0)
static pa_mutex *global_mutex;
static pthread_once_t global_mutex_once = PTHREAD_ONCE_INIT;
static void global_mutex_once_func(void) {
global_mutex = pa_mutex_new(0);
}
void pa_once(pa_once_t *control, pa_once_func_t func) {
assert(control);
assert(func);
/* Create the global mutex */
ASSERT_SUCCESS(pthread_once(&global_mutex_once, global_mutex_once_func));
/* Create the local mutex */
pa_mutex_lock(global_mutex);
if (!control->mutex)
control->mutex = pa_mutex_new(1);
pa_mutex_unlock(global_mutex);
/* Execute function */
pa_mutex_lock(control->mutex);
if (!control->once_value) {
control->once_value = 1;
func();
}
pa_mutex_unlock(control->mutex);
/* Caveat: We have to make sure that the once func has completed
* before returning, even if the once func is not actually
* executed by us. Hence the awkward locking. */
}
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