146 lines
2.6 KiB
C
146 lines
2.6 KiB
C
/*
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* Asterisk -- An open source telephony toolkit.
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*
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* Copyright (C) 2013, Digium, Inc.
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*
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* David M. Lee, II <dlee@digium.com>
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*
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* See http://www.asterisk.org for more information about
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* the Asterisk project. Please do not directly contact
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* any of the maintainers of this project for assistance;
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* the project provides a web site, mailing lists and IRC
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* channels for your use.
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*
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* This program is free software, distributed under the terms of
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* the GNU General Public License Version 2. See the LICENSE file
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* at the top of the source tree.
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*/
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/*! \file
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*
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* \brief Asterisk semaphore support.
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*/
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#include "asterisk.h"
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#include "asterisk/sem.h"
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#include "asterisk/utils.h"
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#ifndef HAS_WORKING_SEMAPHORE
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/* DIY semaphores! */
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int ast_sem_init(struct ast_sem *sem, int pshared, unsigned int value)
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{
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if (pshared) {
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/* Don't need it... yet */
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errno = ENOSYS;
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return -1;
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}
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/* Since value is unsigned, this will also catch attempts to init with
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* a negative value */
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if (value > AST_SEM_VALUE_MAX) {
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errno = EINVAL;
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return -1;
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}
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sem->count = value;
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sem->waiters = 0;
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ast_mutex_init(&sem->mutex);
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ast_cond_init(&sem->cond, NULL);
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return 0;
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}
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int ast_sem_destroy(struct ast_sem *sem)
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{
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ast_mutex_destroy(&sem->mutex);
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ast_cond_destroy(&sem->cond);
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return 0;
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}
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int ast_sem_post(struct ast_sem *sem)
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{
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SCOPED_MUTEX(lock, &sem->mutex);
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ast_assert(sem->count >= 0);
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if (sem->count == AST_SEM_VALUE_MAX) {
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errno = EOVERFLOW;
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return -1;
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}
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/* Give it up! */
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++sem->count;
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/* Release a waiter, if needed */
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if (sem->waiters) {
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ast_cond_signal(&sem->cond);
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}
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return 0;
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}
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int ast_sem_wait(struct ast_sem *sem)
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{
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int res;
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SCOPED_MUTEX(lock, &sem->mutex);
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ast_assert(sem->count >= 0);
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/* Wait for a non-zero count */
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++sem->waiters;
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while (sem->count == 0) {
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res = ast_cond_wait(&sem->cond, &sem->mutex);
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/* Give up on error */
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if (res != 0) {
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--sem->waiters;
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return res;
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}
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}
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--sem->waiters;
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/* Take it! */
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--sem->count;
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return 0;
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}
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int ast_sem_timedwait(struct ast_sem *sem, const struct timespec *abs_timeout)
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{
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int res;
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SCOPED_MUTEX(lock, &sem->mutex);
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ast_assert(sem->count >= 0);
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/* Wait for a non-zero count */
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++sem->waiters;
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while (sem->count == 0) {
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res = ast_cond_timedwait(&sem->cond, &sem->mutex, abs_timeout);
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/* Give up on error */
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if (res != 0) {
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--sem->waiters;
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return res;
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}
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}
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--sem->waiters;
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/* Take it! */
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--sem->count;
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return 0;
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}
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int ast_sem_getvalue(struct ast_sem *sem, int *sval)
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{
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SCOPED_MUTEX(lock, &sem->mutex);
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ast_assert(sem->count >= 0);
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*sval = sem->count;
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return 0;
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}
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#endif
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