2 This file is part of PulseAudio.
4 Copyright 2006 Lennart Poettering
6 PulseAudio is free software; you can redistribute it and/or modify
7 it under the terms of the GNU Lesser General Public License as published
8 by the Free Software Foundation; either version 2.1 of the License,
9 or (at your option) any later version.
11 PulseAudio is distributed in the hope that it will be useful, but
12 WITHOUT ANY WARRANTY; without even the implied warranty of
13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
14 General Public License for more details.
16 You should have received a copy of the GNU Lesser General Public License
17 along with PulseAudio; if not, see <http://www.gnu.org/licenses/>.
24 #include <pulsecore/macro.h>
28 /* See http://www.hpl.hp.com/research/linux/atomic_ops/example.php4 for the
29 * reference algorithm used here. */
31 bool pa_once_begin(pa_once *control) {
36 if (pa_atomic_load(&control->done))
39 /* Caveat: We have to make sure that the once func has completed
40 * before returning, even if the once func is not actually
41 * executed by us. Hence the awkward locking. */
43 m = pa_static_mutex_get(&control->mutex, false, false);
46 if (pa_atomic_load(&control->done)) {
54 void pa_once_end(pa_once *control) {
59 pa_assert(!pa_atomic_load(&control->done));
60 pa_atomic_store(&control->done, 1);
62 m = pa_static_mutex_get(&control->mutex, false, false);
66 /* Not reentrant -- how could it be? */
67 void pa_run_once(pa_once *control, pa_once_func_t func) {
71 if (pa_once_begin(control)) {