diff options
Diffstat (limited to 'lib/libthr/thread/thr_cond.c')
| -rw-r--r-- | lib/libthr/thread/thr_cond.c | 476 |
1 files changed, 476 insertions, 0 deletions
diff --git a/lib/libthr/thread/thr_cond.c b/lib/libthr/thread/thr_cond.c new file mode 100644 index 0000000..a834711 --- /dev/null +++ b/lib/libthr/thread/thr_cond.c @@ -0,0 +1,476 @@ +/* + * Copyright (c) 2005 David Xu <davidxu@freebsd.org> + * All rights reserved. + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions + * are met: + * 1. Redistributions of source code must retain the above copyright + * notice unmodified, this list of conditions, and the following + * disclaimer. + * 2. Redistributions in binary form must reproduce the above copyright + * notice, this list of conditions and the following disclaimer in the + * documentation and/or other materials provided with the distribution. + * + * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR + * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES + * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. + * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, + * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT + * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, + * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY + * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT + * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF + * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. + * + * $FreeBSD$ + */ + +#include "namespace.h" +#include <stdlib.h> +#include <errno.h> +#include <string.h> +#include <pthread.h> +#include <limits.h> +#include "un-namespace.h" + +#include "thr_private.h" + +/* + * Prototypes + */ +int __pthread_cond_wait(pthread_cond_t *cond, pthread_mutex_t *mutex); +int __pthread_cond_timedwait(pthread_cond_t *cond, pthread_mutex_t *mutex, + const struct timespec * abstime); +static int cond_init(pthread_cond_t *cond, const pthread_condattr_t *attr); +static int cond_wait_common(pthread_cond_t *cond, pthread_mutex_t *mutex, + const struct timespec *abstime, int cancel); +static int cond_signal_common(pthread_cond_t *cond); +static int cond_broadcast_common(pthread_cond_t *cond); + +/* + * Double underscore versions are cancellation points. Single underscore + * versions are not and are provided for libc internal usage (which + * shouldn't introduce cancellation points). + */ +__weak_reference(__pthread_cond_wait, pthread_cond_wait); +__weak_reference(__pthread_cond_timedwait, pthread_cond_timedwait); + +__weak_reference(_pthread_cond_init, pthread_cond_init); +__weak_reference(_pthread_cond_destroy, pthread_cond_destroy); +__weak_reference(_pthread_cond_signal, pthread_cond_signal); +__weak_reference(_pthread_cond_broadcast, pthread_cond_broadcast); + +#define CV_PSHARED(cvp) (((cvp)->__flags & USYNC_PROCESS_SHARED) != 0) + +static int +cond_init(pthread_cond_t *cond, const pthread_condattr_t *cond_attr) +{ + struct pthread_cond *cvp; + int error = 0; + + if ((cvp = (pthread_cond_t) + calloc(1, sizeof(struct pthread_cond))) == NULL) { + error = ENOMEM; + } else { + /* + * Initialise the condition variable structure: + */ + if (cond_attr == NULL || *cond_attr == NULL) { + cvp->__clock_id = CLOCK_REALTIME; + } else { + if ((*cond_attr)->c_pshared) + cvp->__flags |= USYNC_PROCESS_SHARED; + cvp->__clock_id = (*cond_attr)->c_clockid; + } + *cond = cvp; + } + return (error); +} + +static int +init_static(struct pthread *thread, pthread_cond_t *cond) +{ + int ret; + + THR_LOCK_ACQUIRE(thread, &_cond_static_lock); + + if (*cond == NULL) + ret = cond_init(cond, NULL); + else + ret = 0; + + THR_LOCK_RELEASE(thread, &_cond_static_lock); + + return (ret); +} + +#define CHECK_AND_INIT_COND \ + if (__predict_false((cvp = (*cond)) <= THR_COND_DESTROYED)) { \ + if (cvp == THR_COND_INITIALIZER) { \ + int ret; \ + ret = init_static(_get_curthread(), cond); \ + if (ret) \ + return (ret); \ + } else if (cvp == THR_COND_DESTROYED) { \ + return (EINVAL); \ + } \ + cvp = *cond; \ + } + +int +_pthread_cond_init(pthread_cond_t *cond, const pthread_condattr_t *cond_attr) +{ + + *cond = NULL; + return (cond_init(cond, cond_attr)); +} + +int +_pthread_cond_destroy(pthread_cond_t *cond) +{ + struct pthread_cond *cvp; + int error = 0; + + if ((cvp = *cond) == THR_COND_INITIALIZER) + error = 0; + else if (cvp == THR_COND_DESTROYED) + error = EINVAL; + else { + cvp = *cond; + *cond = THR_COND_DESTROYED; + + /* + * Free the memory allocated for the condition + * variable structure: + */ + free(cvp); + } + return (error); +} + +/* + * Cancellation behaivor: + * Thread may be canceled at start, if thread is canceled, it means it + * did not get a wakeup from pthread_cond_signal(), otherwise, it is + * not canceled. + * Thread cancellation never cause wakeup from pthread_cond_signal() + * to be lost. + */ +static int +cond_wait_kernel(struct pthread_cond *cvp, struct pthread_mutex *mp, + const struct timespec *abstime, int cancel) +{ + struct pthread *curthread = _get_curthread(); + int recurse; + int error, error2 = 0; + + error = _mutex_cv_detach(mp, &recurse); + if (error != 0) + return (error); + + if (cancel) { + _thr_cancel_enter2(curthread, 0); + error = _thr_ucond_wait((struct ucond *)&cvp->__has_kern_waiters, + (struct umutex *)&mp->m_lock, abstime, + CVWAIT_ABSTIME|CVWAIT_CLOCKID); + _thr_cancel_leave(curthread, 0); + } else { + error = _thr_ucond_wait((struct ucond *)&cvp->__has_kern_waiters, + (struct umutex *)&mp->m_lock, abstime, + CVWAIT_ABSTIME|CVWAIT_CLOCKID); + } + + /* + * Note that PP mutex and ROBUST mutex may return + * interesting error codes. + */ + if (error == 0) { + error2 = _mutex_cv_lock(mp, recurse); + } else if (error == EINTR || error == ETIMEDOUT) { + error2 = _mutex_cv_lock(mp, recurse); + if (error2 == 0 && cancel) + _thr_testcancel(curthread); + if (error == EINTR) + error = 0; + } else { + /* We know that it didn't unlock the mutex. */ + error2 = _mutex_cv_attach(mp, recurse); + if (error2 == 0 && cancel) + _thr_testcancel(curthread); + } + return (error2 != 0 ? error2 : error); +} + +/* + * Thread waits in userland queue whenever possible, when thread + * is signaled or broadcasted, it is removed from the queue, and + * is saved in curthread's defer_waiters[] buffer, but won't be + * woken up until mutex is unlocked. + */ + +static int +cond_wait_user(struct pthread_cond *cvp, struct pthread_mutex *mp, + const struct timespec *abstime, int cancel) +{ + struct pthread *curthread = _get_curthread(); + struct sleepqueue *sq; + int recurse; + int error; + + if (curthread->wchan != NULL) + PANIC("thread was already on queue."); + + if (cancel) + _thr_testcancel(curthread); + + _sleepq_lock(cvp); + /* + * set __has_user_waiters before unlocking mutex, this allows + * us to check it without locking in pthread_cond_signal(). + */ + cvp->__has_user_waiters = 1; + curthread->will_sleep = 1; + (void)_mutex_cv_unlock(mp, &recurse); + curthread->mutex_obj = mp; + _sleepq_add(cvp, curthread); + for(;;) { + _thr_clear_wake(curthread); + _sleepq_unlock(cvp); + + if (cancel) { + _thr_cancel_enter2(curthread, 0); + error = _thr_sleep(curthread, cvp->__clock_id, abstime); + _thr_cancel_leave(curthread, 0); + } else { + error = _thr_sleep(curthread, cvp->__clock_id, abstime); + } + + _sleepq_lock(cvp); + if (curthread->wchan == NULL) { + error = 0; + break; + } else if (cancel && SHOULD_CANCEL(curthread)) { + sq = _sleepq_lookup(cvp); + cvp->__has_user_waiters = + _sleepq_remove(sq, curthread); + _sleepq_unlock(cvp); + curthread->mutex_obj = NULL; + _mutex_cv_lock(mp, recurse); + if (!THR_IN_CRITICAL(curthread)) + _pthread_exit(PTHREAD_CANCELED); + else /* this should not happen */ + return (0); + } else if (error == ETIMEDOUT) { + sq = _sleepq_lookup(cvp); + cvp->__has_user_waiters = + _sleepq_remove(sq, curthread); + break; + } + } + _sleepq_unlock(cvp); + curthread->mutex_obj = NULL; + _mutex_cv_lock(mp, recurse); + return (error); +} + +static int +cond_wait_common(pthread_cond_t *cond, pthread_mutex_t *mutex, + const struct timespec *abstime, int cancel) +{ + struct pthread *curthread = _get_curthread(); + struct pthread_cond *cvp; + struct pthread_mutex *mp; + int error; + + CHECK_AND_INIT_COND + + mp = *mutex; + + if ((error = _mutex_owned(curthread, mp)) != 0) + return (error); + + if (curthread->attr.sched_policy != SCHED_OTHER || + (mp->m_lock.m_flags & (UMUTEX_PRIO_PROTECT|UMUTEX_PRIO_INHERIT| + USYNC_PROCESS_SHARED)) != 0 || + (cvp->__flags & USYNC_PROCESS_SHARED) != 0) + return cond_wait_kernel(cvp, mp, abstime, cancel); + else + return cond_wait_user(cvp, mp, abstime, cancel); +} + +int +_pthread_cond_wait(pthread_cond_t *cond, pthread_mutex_t *mutex) +{ + + return (cond_wait_common(cond, mutex, NULL, 0)); +} + +int +__pthread_cond_wait(pthread_cond_t *cond, pthread_mutex_t *mutex) +{ + + return (cond_wait_common(cond, mutex, NULL, 1)); +} + +int +_pthread_cond_timedwait(pthread_cond_t *cond, pthread_mutex_t *mutex, + const struct timespec * abstime) +{ + + if (abstime == NULL || abstime->tv_sec < 0 || abstime->tv_nsec < 0 || + abstime->tv_nsec >= 1000000000) + return (EINVAL); + + return (cond_wait_common(cond, mutex, abstime, 0)); +} + +int +__pthread_cond_timedwait(pthread_cond_t *cond, pthread_mutex_t *mutex, + const struct timespec *abstime) +{ + + if (abstime == NULL || abstime->tv_sec < 0 || abstime->tv_nsec < 0 || + abstime->tv_nsec >= 1000000000) + return (EINVAL); + + return (cond_wait_common(cond, mutex, abstime, 1)); +} + +static int +cond_signal_common(pthread_cond_t *cond) +{ + struct pthread *curthread = _get_curthread(); + struct pthread *td; + struct pthread_cond *cvp; + struct pthread_mutex *mp; + struct sleepqueue *sq; + int *waddr; + int pshared; + + /* + * If the condition variable is statically initialized, perform dynamic + * initialization. + */ + CHECK_AND_INIT_COND + + pshared = CV_PSHARED(cvp); + + _thr_ucond_signal((struct ucond *)&cvp->__has_kern_waiters); + + if (pshared || cvp->__has_user_waiters == 0) + return (0); + + curthread = _get_curthread(); + waddr = NULL; + _sleepq_lock(cvp); + sq = _sleepq_lookup(cvp); + if (sq == NULL) { + _sleepq_unlock(cvp); + return (0); + } + + td = _sleepq_first(sq); + mp = td->mutex_obj; + cvp->__has_user_waiters = _sleepq_remove(sq, td); + if (mp->m_owner == curthread) { + if (curthread->nwaiter_defer >= MAX_DEFER_WAITERS) { + _thr_wake_all(curthread->defer_waiters, + curthread->nwaiter_defer); + curthread->nwaiter_defer = 0; + } + curthread->defer_waiters[curthread->nwaiter_defer++] = + &td->wake_addr->value; + mp->m_flags |= PMUTEX_FLAG_DEFERED; + } else { + waddr = &td->wake_addr->value; + } + _sleepq_unlock(cvp); + if (waddr != NULL) + _thr_set_wake(waddr); + return (0); +} + +struct broadcast_arg { + struct pthread *curthread; + unsigned int *waddrs[MAX_DEFER_WAITERS]; + int count; +}; + +static void +drop_cb(struct pthread *td, void *arg) +{ + struct broadcast_arg *ba = arg; + struct pthread_mutex *mp; + struct pthread *curthread = ba->curthread; + + mp = td->mutex_obj; + if (mp->m_owner == curthread) { + if (curthread->nwaiter_defer >= MAX_DEFER_WAITERS) { + _thr_wake_all(curthread->defer_waiters, + curthread->nwaiter_defer); + curthread->nwaiter_defer = 0; + } + curthread->defer_waiters[curthread->nwaiter_defer++] = + &td->wake_addr->value; + mp->m_flags |= PMUTEX_FLAG_DEFERED; + } else { + if (ba->count >= MAX_DEFER_WAITERS) { + _thr_wake_all(ba->waddrs, ba->count); + ba->count = 0; + } + ba->waddrs[ba->count++] = &td->wake_addr->value; + } +} + +static int +cond_broadcast_common(pthread_cond_t *cond) +{ + int pshared; + struct pthread_cond *cvp; + struct sleepqueue *sq; + struct broadcast_arg ba; + + /* + * If the condition variable is statically initialized, perform dynamic + * initialization. + */ + CHECK_AND_INIT_COND + + pshared = CV_PSHARED(cvp); + + _thr_ucond_broadcast((struct ucond *)&cvp->__has_kern_waiters); + + if (pshared || cvp->__has_user_waiters == 0) + return (0); + + ba.curthread = _get_curthread(); + ba.count = 0; + + _sleepq_lock(cvp); + sq = _sleepq_lookup(cvp); + if (sq == NULL) { + _sleepq_unlock(cvp); + return (0); + } + _sleepq_drop(sq, drop_cb, &ba); + cvp->__has_user_waiters = 0; + _sleepq_unlock(cvp); + if (ba.count > 0) + _thr_wake_all(ba.waddrs, ba.count); + return (0); +} + +int +_pthread_cond_signal(pthread_cond_t * cond) +{ + + return (cond_signal_common(cond)); +} + +int +_pthread_cond_broadcast(pthread_cond_t * cond) +{ + + return (cond_broadcast_common(cond)); +} |
