1 /***
2 This file is part of PulseAudio.
3
4 Copyright 2006 Lennart Poettering
5
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.
10
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.
15
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/>.
18 ***/
19
20 #ifdef HAVE_CONFIG_H
21 #include <config.h>
22 #endif
23
24 #include <errno.h>
25 #include <pthread.h>
26 #include <semaphore.h>
27
28 #include <pulse/xmalloc.h>
29 #include <pulsecore/macro.h>
30
31 #include "semaphore.h"
32
33 struct pa_semaphore {
34 sem_t sem;
35 };
36
pa_semaphore_new(unsigned value)37 pa_semaphore* pa_semaphore_new(unsigned value) {
38 pa_semaphore *s;
39
40 s = pa_xnew(pa_semaphore, 1);
41 pa_assert_se(sem_init(&s->sem, 0, value) == 0);
42 return s;
43 }
44
pa_semaphore_free(pa_semaphore * s)45 void pa_semaphore_free(pa_semaphore *s) {
46 pa_assert(s);
47 pa_assert_se(sem_destroy(&s->sem) == 0);
48 pa_xfree(s);
49 }
50
pa_semaphore_post(pa_semaphore * s)51 void pa_semaphore_post(pa_semaphore *s) {
52 pa_assert(s);
53 pa_assert_se(sem_post(&s->sem) == 0);
54 }
55
pa_semaphore_wait(pa_semaphore * s)56 void pa_semaphore_wait(pa_semaphore *s) {
57 int ret;
58 pa_assert(s);
59
60 do {
61 ret = sem_wait(&s->sem);
62 } while (ret < 0 && errno == EINTR);
63
64 pa_assert(ret == 0);
65 }
66
pa_static_semaphore_get(pa_static_semaphore * s,unsigned value)67 pa_semaphore* pa_static_semaphore_get(pa_static_semaphore *s, unsigned value) {
68 pa_semaphore *m;
69
70 pa_assert(s);
71
72 /* First, check if already initialized and short cut */
73 if ((m = pa_atomic_ptr_load(&s->ptr)))
74 return m;
75
76 /* OK, not initialized, so let's allocate, and fill in */
77 m = pa_semaphore_new(value);
78 if ((pa_atomic_ptr_cmpxchg(&s->ptr, NULL, m)))
79 return m;
80
81 pa_semaphore_free(m);
82
83 /* Him, filling in failed, so someone else must have filled in
84 * already */
85 pa_assert_se(m = pa_atomic_ptr_load(&s->ptr));
86 return m;
87 }
88