src/pulsecore/semaphore-posix.c

/***
  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 2.1 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, see <http://www.gnu.org/licenses/>.
***/

#ifdef HAVE_CONFIG_H
#include <config.h>
#endif

#include <errno.h>
#include <pthread.h>
#include <semaphore.h>

#include <pulse/xmalloc.h>
#include <pulsecore/macro.h>

#include "semaphore.h"

struct pa_semaphore {
    sem_t sem;
};

pa_semaphore* pa_semaphore_new(unsigned value) {
    pa_semaphore *s;

    s = pa_xnew(pa_semaphore, 1);
    pa_assert_se(sem_init(&s->sem, 0, value) == 0);
    return s;
}

void pa_semaphore_free(pa_semaphore *s) {
    pa_assert(s);
    pa_assert_se(sem_destroy(&s->sem) == 0);
    pa_xfree(s);
}

void pa_semaphore_post(pa_semaphore *s) {
    pa_assert(s);
    pa_assert_se(sem_post(&s->sem) == 0);
}

void pa_semaphore_wait(pa_semaphore *s) {
    int ret;
    pa_assert(s);

    do {
        ret = sem_wait(&s->sem);
    } while (ret < 0 && errno == EINTR);

    pa_assert(ret == 0);
}

pa_semaphore* pa_static_semaphore_get(pa_static_semaphore *s, unsigned value) {
    pa_semaphore *m;

    pa_assert(s);

    /* First, check if already initialized and short cut */
    if ((m = pa_atomic_ptr_load(&s->ptr)))
        return m;

    /* OK, not initialized, so let's allocate, and fill in */
    m = pa_semaphore_new(value);
    if ((pa_atomic_ptr_cmpxchg(&s->ptr, NULL, m)))
        return m;

    pa_semaphore_free(m);

    /* Him, filling in failed, so someone else must have filled in
     * already */
    pa_assert_se(m = pa_atomic_ptr_load(&s->ptr));
    return m;
}