zephyr/lib/posix/pthread_cond.c

65 lines
1.6 KiB
C

/*
* Copyright (c) 2017 Intel Corporation
*
* SPDX-License-Identifier: Apache-2.0
*/
#include <kernel.h>
#include <ksched.h>
#include <wait_q.h>
#include <posix/pthread.h>
extern struct k_spinlock z_pthread_spinlock;
int64_t timespec_to_timeoutms(const struct timespec *abstime);
static int cond_wait(pthread_cond_t *cv, pthread_mutex_t *mut,
k_timeout_t timeout)
{
__ASSERT(mut->lock_count == 1U, "");
int ret;
k_spinlock_key_t key = k_spin_lock(&z_pthread_spinlock);
mut->lock_count = 0U;
mut->owner = NULL;
_ready_one_thread(&mut->wait_q);
ret = z_sched_wait(&z_pthread_spinlock, key, &cv->wait_q, timeout, NULL);
/* FIXME: this extra lock (and the potential context switch it
* can cause) could be optimized out. At the point of the
* signal/broadcast, it's possible to detect whether or not we
* will be swapping back to this particular thread and lock it
* (i.e. leave the lock variable unchanged) on our behalf.
* But that requires putting scheduler intelligence into this
* higher level abstraction and is probably not worth it.
*/
pthread_mutex_lock(mut);
return ret == -EAGAIN ? ETIMEDOUT : ret;
}
int pthread_cond_signal(pthread_cond_t *cv)
{
z_sched_wake(&cv->wait_q, 0, NULL);
return 0;
}
int pthread_cond_broadcast(pthread_cond_t *cv)
{
z_sched_wake_all(&cv->wait_q, 0, NULL);
return 0;
}
int pthread_cond_wait(pthread_cond_t *cv, pthread_mutex_t *mut)
{
return cond_wait(cv, mut, K_FOREVER);
}
int pthread_cond_timedwait(pthread_cond_t *cv, pthread_mutex_t *mut,
const struct timespec *abstime)
{
int32_t timeout = (int32_t)timespec_to_timeoutms(abstime);
return cond_wait(cv, mut, K_MSEC(timeout));
}