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/*
* Copyright 2008-2013 Various Authors
* Copyright 2004 Timo Hirvonen
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License as
* published by the Free Software Foundation; either version 2 of the
* License, or (at your option) any later version.
*
* This program 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 General Public License
* along with this program; if not, see <http://www.gnu.org/licenses/>.
*/
#include "locking.h"
#include "debug.h"
#include <string.h>
#include <stdatomic.h>
#include <stdbool.h>
struct fifo_waiter {
struct fifo_waiter * _Atomic next;
pthread_cond_t cond;
};
pthread_t main_thread;
void cmus_mutex_lock(pthread_mutex_t *mutex)
{
int rc = pthread_mutex_lock(mutex);
if (unlikely(rc))
BUG("error locking mutex: %s\n", strerror(rc));
}
void cmus_mutex_unlock(pthread_mutex_t *mutex)
{
int rc = pthread_mutex_unlock(mutex);
if (unlikely(rc))
BUG("error unlocking mutex: %s\n", strerror(rc));
}
void cmus_rwlock_rdlock(pthread_rwlock_t *lock)
{
int rc = pthread_rwlock_rdlock(lock);
if (unlikely(rc))
BUG("error locking mutex: %s\n", strerror(rc));
}
void cmus_rwlock_wrlock(pthread_rwlock_t *lock)
{
int rc = pthread_rwlock_wrlock(lock);
if (unlikely(rc))
BUG("error locking mutex: %s\n", strerror(rc));
}
void cmus_rwlock_unlock(pthread_rwlock_t *lock)
{
int rc = pthread_rwlock_unlock(lock);
if (unlikely(rc))
BUG("error unlocking mutex: %s\n", strerror(rc));
}
void fifo_mutex_lock(struct fifo_mutex *fifo)
{
struct fifo_waiter self = {
.cond = PTHREAD_COND_INITIALIZER,
.next = ATOMIC_VAR_INIT(NULL),
};
struct fifo_waiter *old_tail = atomic_exchange_explicit(&fifo->tail, &self,
memory_order_relaxed);
if (old_tail)
atomic_store_explicit(&old_tail->next, &self, memory_order_release);
cmus_mutex_lock(&fifo->mutex);
if (old_tail) {
while (fifo->head != &self)
pthread_cond_wait(&self.cond, &fifo->mutex);
pthread_cond_destroy(&self.cond);
}
struct fifo_waiter *self_addr = &self;
bool was_tail = atomic_compare_exchange_strong_explicit(&fifo->tail, &self_addr,
NULL, memory_order_relaxed, memory_order_relaxed);
struct fifo_waiter *next = NULL;
if (!was_tail) {
while (!(next = atomic_load_explicit(&self.next, memory_order_consume)))
;
}
fifo->head = next;
}
void fifo_mutex_unlock(struct fifo_mutex *fifo)
{
if (fifo->head)
pthread_cond_signal(&fifo->head->cond);
cmus_mutex_unlock(&fifo->mutex);
}
void fifo_mutex_yield(struct fifo_mutex *fifo)
{
if (fifo->head || atomic_load_explicit(&fifo->tail, memory_order_relaxed)) {
fifo_mutex_unlock(fifo);
fifo_mutex_lock(fifo);
}
}
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