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70 lines
1.9 KiB
C
70 lines
1.9 KiB
C
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/* $Id$ */
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/***
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This file is part of PulseAudio.
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PulseAudio is free software; you can redistribute it and/or modify
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it under the terms of the GNU Lesser General Public License as published
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by the Free Software Foundation; either version 2 of the License,
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or (at your option) any later version.
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PulseAudio is distributed in the hope that it will be useful, but
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WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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General Public License for more details.
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You should have received a copy of the GNU Lesser General Public License
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along with PulseAudio; if not, write to the Free Software
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Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307
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USA.
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***/
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#ifdef HAVE_CONFIG_H
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#include <config.h>
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#endif
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#include <pthread.h>
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#include <assert.h>
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#include <pulsecore/mutex.h>
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#include "once.h"
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#define ASSERT_SUCCESS(x) do { \
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int _r = (x); \
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assert(_r == 0); \
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} while(0)
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static pa_mutex *global_mutex;
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static pthread_once_t global_mutex_once = PTHREAD_ONCE_INIT;
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static void global_mutex_once_func(void) {
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global_mutex = pa_mutex_new(0);
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}
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void pa_once(pa_once_t *control, pa_once_func_t func) {
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assert(control);
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assert(func);
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/* Create the global mutex */
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ASSERT_SUCCESS(pthread_once(&global_mutex_once, global_mutex_once_func));
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/* Create the local mutex */
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pa_mutex_lock(global_mutex);
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if (!control->mutex)
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control->mutex = pa_mutex_new(1);
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pa_mutex_unlock(global_mutex);
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/* Execute function */
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pa_mutex_lock(control->mutex);
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if (!control->once_value) {
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control->once_value = 1;
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func();
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}
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pa_mutex_unlock(control->mutex);
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/* Caveat: We have to make sure that the once func has completed
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* before returning, even if the once func is not actually
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* executed by us. Hence the awkward locking. */
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}
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