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code.delx.au - pulseaudio/blob - src/pulsecore/once.c
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, write to the Free Software
18 Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307
26 #include <pulsecore/macro.h>
30 /* See http://www.hpl.hp.com/research/linux/atomic_ops/example.php4 for the
31 * reference algorithm used here. */
33 bool pa_once_begin(pa_once
*control
) {
38 if (pa_atomic_load(&control
->done
))
41 /* Caveat: We have to make sure that the once func has completed
42 * before returning, even if the once func is not actually
43 * executed by us. Hence the awkward locking. */
45 m
= pa_static_mutex_get(&control
->mutex
, false, false);
48 if (pa_atomic_load(&control
->done
)) {
56 void pa_once_end(pa_once
*control
) {
61 pa_assert(!pa_atomic_load(&control
->done
));
62 pa_atomic_store(&control
->done
, 1);
64 m
= pa_static_mutex_get(&control
->mutex
, false, false);
68 /* Not reentrant -- how could it be? */
69 void pa_run_once(pa_once
*control
, pa_once_func_t func
) {
73 if (pa_once_begin(control
)) {