FreeBSD-5.3/lib/libpthread/thread/thr_cond.c
/*
* Copyright (c) 1995 John Birrell <jb@cimlogic.com.au>.
* 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, 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.
* 3. All advertising materials mentioning features or use of this software
* must display the following acknowledgement:
* This product includes software developed by John Birrell.
* 4. Neither the name of the author nor the names of any co-contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY JOHN BIRRELL AND CONTRIBUTORS ``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 OR CONTRIBUTORS 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: src/lib/libpthread/thread/thr_cond.c,v 1.51 2003/12/09 02:20:56 davidxu Exp $
*/
#include <stdlib.h>
#include <errno.h>
#include <string.h>
#include <pthread.h>
#include "thr_private.h"
#define THR_IN_CONDQ(thr) (((thr)->sflags & THR_FLAGS_IN_SYNCQ) != 0)
#define THR_CONDQ_SET(thr) (thr)->sflags |= THR_FLAGS_IN_SYNCQ
#define THR_CONDQ_CLEAR(thr) (thr)->sflags &= ~THR_FLAGS_IN_SYNCQ
/*
* Prototypes
*/
static inline struct pthread *cond_queue_deq(pthread_cond_t);
static inline void cond_queue_remove(pthread_cond_t, pthread_t);
static inline void cond_queue_enq(pthread_cond_t, pthread_t);
/*
* 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);
int
_pthread_cond_init(pthread_cond_t *cond, const pthread_condattr_t *cond_attr)
{
enum pthread_cond_type type;
pthread_cond_t pcond;
int flags;
int rval = 0;
if (cond == NULL)
rval = EINVAL;
else {
/*
* Check if a pointer to a condition variable attribute
* structure was passed by the caller:
*/
if (cond_attr != NULL && *cond_attr != NULL) {
/* Default to a fast condition variable: */
type = (*cond_attr)->c_type;
flags = (*cond_attr)->c_flags;
} else {
/* Default to a fast condition variable: */
type = COND_TYPE_FAST;
flags = 0;
}
/* Process according to condition variable type: */
switch (type) {
/* Fast condition variable: */
case COND_TYPE_FAST:
/* Nothing to do here. */
break;
/* Trap invalid condition variable types: */
default:
/* Return an invalid argument error: */
rval = EINVAL;
break;
}
/* Check for no errors: */
if (rval == 0) {
if ((pcond = (pthread_cond_t)
malloc(sizeof(struct pthread_cond))) == NULL) {
rval = ENOMEM;
} else if (_lock_init(&pcond->c_lock, LCK_ADAPTIVE,
_thr_lock_wait, _thr_lock_wakeup) != 0) {
free(pcond);
rval = ENOMEM;
} else {
/*
* Initialise the condition variable
* structure:
*/
TAILQ_INIT(&pcond->c_queue);
pcond->c_flags = COND_FLAGS_INITED;
pcond->c_type = type;
pcond->c_mutex = NULL;
pcond->c_seqno = 0;
*cond = pcond;
}
}
}
/* Return the completion status: */
return (rval);
}
int
_pthread_cond_destroy(pthread_cond_t *cond)
{
struct pthread_cond *cv;
struct pthread *curthread = _get_curthread();
int rval = 0;
if (cond == NULL || *cond == NULL)
rval = EINVAL;
else {
/* Lock the condition variable structure: */
THR_LOCK_ACQUIRE(curthread, &(*cond)->c_lock);
/*
* NULL the caller's pointer now that the condition
* variable has been destroyed:
*/
cv = *cond;
*cond = NULL;
/* Unlock the condition variable structure: */
THR_LOCK_RELEASE(curthread, &cv->c_lock);
/* Free the cond lock structure: */
_lock_destroy(&cv->c_lock);
/*
* Free the memory allocated for the condition
* variable structure:
*/
free(cv);
}
/* Return the completion status: */
return (rval);
}
int
_pthread_cond_wait(pthread_cond_t *cond, pthread_mutex_t *mutex)
{
struct pthread *curthread = _get_curthread();
int rval = 0;
int done = 0;
int interrupted = 0;
int unlock_mutex = 1;
int seqno;
if (cond == NULL)
return (EINVAL);
/*
* If the condition variable is statically initialized,
* perform the dynamic initialization:
*/
if (*cond == NULL &&
(rval = pthread_cond_init(cond, NULL)) != 0)
return (rval);
if (!_kse_isthreaded())
_kse_setthreaded(1);
/*
* Enter a loop waiting for a condition signal or broadcast
* to wake up this thread. A loop is needed in case the waiting
* thread is interrupted by a signal to execute a signal handler.
* It is not (currently) possible to remain in the waiting queue
* while running a handler. Instead, the thread is interrupted
* and backed out of the waiting queue prior to executing the
* signal handler.
*/
do {
/* Lock the condition variable structure: */
THR_LOCK_ACQUIRE(curthread, &(*cond)->c_lock);
/*
* If the condvar was statically allocated, properly
* initialize the tail queue.
*/
if (((*cond)->c_flags & COND_FLAGS_INITED) == 0) {
TAILQ_INIT(&(*cond)->c_queue);
(*cond)->c_flags |= COND_FLAGS_INITED;
}
/* Process according to condition variable type: */
switch ((*cond)->c_type) {
/* Fast condition variable: */
case COND_TYPE_FAST:
if ((mutex == NULL) || (((*cond)->c_mutex != NULL) &&
((*cond)->c_mutex != *mutex))) {
/* Unlock the condition variable structure: */
THR_LOCK_RELEASE(curthread, &(*cond)->c_lock);
/* Return invalid argument error: */
rval = EINVAL;
} else {
/* Reset the timeout and interrupted flags: */
curthread->timeout = 0;
curthread->interrupted = 0;
/*
* Queue the running thread for the condition
* variable:
*/
cond_queue_enq(*cond, curthread);
/* Remember the mutex and sequence number: */
(*cond)->c_mutex = *mutex;
seqno = (*cond)->c_seqno;
/* Wait forever: */
curthread->wakeup_time.tv_sec = -1;
/* Unlock the mutex: */
if ((unlock_mutex != 0) &&
((rval = _mutex_cv_unlock(mutex)) != 0)) {
/*
* Cannot unlock the mutex, so remove
* the running thread from the condition
* variable queue:
*/
cond_queue_remove(*cond, curthread);
/* Check for no more waiters: */
if (TAILQ_FIRST(&(*cond)->c_queue) == NULL)
(*cond)->c_mutex = NULL;
/* Unlock the condition variable structure: */
THR_LOCK_RELEASE(curthread, &(*cond)->c_lock);
}
else {
/*
* Don't unlock the mutex the next
* time through the loop (if the
* thread has to be requeued after
* handling a signal).
*/
unlock_mutex = 0;
/*
* This thread is active and is in a
* critical region (holding the cv
* lock); we should be able to safely
* set the state.
*/
THR_SCHED_LOCK(curthread, curthread);
THR_SET_STATE(curthread, PS_COND_WAIT);
/* Remember the CV: */
curthread->data.cond = *cond;
THR_SCHED_UNLOCK(curthread, curthread);
/* Unlock the CV structure: */
THR_LOCK_RELEASE(curthread,
&(*cond)->c_lock);
/* Schedule the next thread: */
_thr_sched_switch(curthread);
curthread->data.cond = NULL;
/*
* XXX - This really isn't a good check
* since there can be more than one
* thread waiting on the CV. Signals
* sent to threads waiting on mutexes
* or CVs should really be deferred
* until the threads are no longer
* waiting, but POSIX says that signals
* should be sent "as soon as possible".
*/
done = (seqno != (*cond)->c_seqno);
if (THR_IN_SYNCQ(curthread)) {
/*
* Lock the condition variable
* while removing the thread.
*/
THR_LOCK_ACQUIRE(curthread,
&(*cond)->c_lock);
cond_queue_remove(*cond,
curthread);
/* Check for no more waiters: */
if (TAILQ_FIRST(&(*cond)->c_queue) == NULL)
(*cond)->c_mutex = NULL;
THR_LOCK_RELEASE(curthread,
&(*cond)->c_lock);
}
/*
* Save the interrupted flag; locking
* the mutex may destroy it.
*/
interrupted = curthread->interrupted;
/*
* Note that even though this thread may
* have been canceled, POSIX requires
* that the mutex be reaquired prior to
* cancellation.
*/
if (done || interrupted) {
rval = _mutex_cv_lock(mutex);
unlock_mutex = 1;
}
}
}
break;
/* Trap invalid condition variable types: */
default:
/* Unlock the condition variable structure: */
THR_LOCK_RELEASE(curthread, &(*cond)->c_lock);
/* Return an invalid argument error: */
rval = EINVAL;
break;
}
if ((interrupted != 0) && (curthread->continuation != NULL))
curthread->continuation((void *) curthread);
} while ((done == 0) && (rval == 0));
/* Return the completion status: */
return (rval);
}
__strong_reference(_pthread_cond_wait, _thr_cond_wait);
int
__pthread_cond_wait(pthread_cond_t *cond, pthread_mutex_t *mutex)
{
struct pthread *curthread = _get_curthread();
int ret;
_thr_cancel_enter(curthread);
ret = _pthread_cond_wait(cond, mutex);
_thr_cancel_leave(curthread, 1);
return (ret);
}
int
_pthread_cond_timedwait(pthread_cond_t * cond, pthread_mutex_t * mutex,
const struct timespec * abstime)
{
struct pthread *curthread = _get_curthread();
int rval = 0;
int done = 0;
int interrupted = 0;
int unlock_mutex = 1;
int seqno;
THR_ASSERT(curthread->locklevel == 0,
"cv_timedwait: locklevel is not zero!");
if (abstime == NULL || abstime->tv_sec < 0 || abstime->tv_nsec < 0 ||
abstime->tv_nsec >= 1000000000)
return (EINVAL);
/*
* If the condition variable is statically initialized, perform dynamic
* initialization.
*/
if (*cond == NULL && (rval = pthread_cond_init(cond, NULL)) != 0)
return (rval);
if (!_kse_isthreaded())
_kse_setthreaded(1);
/*
* Enter a loop waiting for a condition signal or broadcast
* to wake up this thread. A loop is needed in case the waiting
* thread is interrupted by a signal to execute a signal handler.
* It is not (currently) possible to remain in the waiting queue
* while running a handler. Instead, the thread is interrupted
* and backed out of the waiting queue prior to executing the
* signal handler.
*/
do {
/* Lock the condition variable structure: */
THR_LOCK_ACQUIRE(curthread, &(*cond)->c_lock);
/*
* If the condvar was statically allocated, properly
* initialize the tail queue.
*/
if (((*cond)->c_flags & COND_FLAGS_INITED) == 0) {
TAILQ_INIT(&(*cond)->c_queue);
(*cond)->c_flags |= COND_FLAGS_INITED;
}
/* Process according to condition variable type: */
switch ((*cond)->c_type) {
/* Fast condition variable: */
case COND_TYPE_FAST:
if ((mutex == NULL) || (((*cond)->c_mutex != NULL) &&
((*cond)->c_mutex != *mutex))) {
/* Return invalid argument error: */
rval = EINVAL;
/* Unlock the condition variable structure: */
THR_LOCK_RELEASE(curthread, &(*cond)->c_lock);
} else {
/* Set the wakeup time: */
curthread->wakeup_time.tv_sec = abstime->tv_sec;
curthread->wakeup_time.tv_nsec =
abstime->tv_nsec;
/* Reset the timeout and interrupted flags: */
curthread->timeout = 0;
curthread->interrupted = 0;
/*
* Queue the running thread for the condition
* variable:
*/
cond_queue_enq(*cond, curthread);
/* Remember the mutex and sequence number: */
(*cond)->c_mutex = *mutex;
seqno = (*cond)->c_seqno;
/* Unlock the mutex: */
if ((unlock_mutex != 0) &&
((rval = _mutex_cv_unlock(mutex)) != 0)) {
/*
* Cannot unlock the mutex; remove the
* running thread from the condition
* variable queue:
*/
cond_queue_remove(*cond, curthread);
/* Check for no more waiters: */
if (TAILQ_FIRST(&(*cond)->c_queue) == NULL)
(*cond)->c_mutex = NULL;
/* Unlock the condition variable structure: */
THR_LOCK_RELEASE(curthread, &(*cond)->c_lock);
} else {
/*
* Don't unlock the mutex the next
* time through the loop (if the
* thread has to be requeued after
* handling a signal).
*/
unlock_mutex = 0;
/*
* This thread is active and is in a
* critical region (holding the cv
* lock); we should be able to safely
* set the state.
*/
THR_SCHED_LOCK(curthread, curthread);
THR_SET_STATE(curthread, PS_COND_WAIT);
/* Remember the CV: */
curthread->data.cond = *cond;
THR_SCHED_UNLOCK(curthread, curthread);
/* Unlock the CV structure: */
THR_LOCK_RELEASE(curthread,
&(*cond)->c_lock);
/* Schedule the next thread: */
_thr_sched_switch(curthread);
curthread->data.cond = NULL;
/*
* XXX - This really isn't a good check
* since there can be more than one
* thread waiting on the CV. Signals
* sent to threads waiting on mutexes
* or CVs should really be deferred
* until the threads are no longer
* waiting, but POSIX says that signals
* should be sent "as soon as possible".
*/
done = (seqno != (*cond)->c_seqno);
if (THR_IN_CONDQ(curthread)) {
/*
* Lock the condition variable
* while removing the thread.
*/
THR_LOCK_ACQUIRE(curthread,
&(*cond)->c_lock);
cond_queue_remove(*cond,
curthread);
/* Check for no more waiters: */
if (TAILQ_FIRST(&(*cond)->c_queue) == NULL)
(*cond)->c_mutex = NULL;
THR_LOCK_RELEASE(curthread,
&(*cond)->c_lock);
}
/*
* Save the interrupted flag; locking
* the mutex may destroy it.
*/
interrupted = curthread->interrupted;
if (curthread->timeout != 0) {
/* The wait timedout. */
rval = ETIMEDOUT;
(void)_mutex_cv_lock(mutex);
} else if (interrupted || done) {
rval = _mutex_cv_lock(mutex);
unlock_mutex = 1;
}
}
}
break;
/* Trap invalid condition variable types: */
default:
/* Unlock the condition variable structure: */
THR_LOCK_RELEASE(curthread, &(*cond)->c_lock);
/* Return an invalid argument error: */
rval = EINVAL;
break;
}
if ((interrupted != 0) && (curthread->continuation != NULL))
curthread->continuation((void *)curthread);
} while ((done == 0) && (rval == 0));
/* Return the completion status: */
return (rval);
}
int
__pthread_cond_timedwait(pthread_cond_t *cond, pthread_mutex_t *mutex,
const struct timespec *abstime)
{
struct pthread *curthread = _get_curthread();
int ret;
_thr_cancel_enter(curthread);
ret = _pthread_cond_timedwait(cond, mutex, abstime);
_thr_cancel_leave(curthread, 1);
return (ret);
}
int
_pthread_cond_signal(pthread_cond_t * cond)
{
struct pthread *curthread = _get_curthread();
struct pthread *pthread;
struct kse_mailbox *kmbx;
int rval = 0;
THR_ASSERT(curthread->locklevel == 0,
"cv_timedwait: locklevel is not zero!");
if (cond == NULL)
rval = EINVAL;
/*
* If the condition variable is statically initialized, perform dynamic
* initialization.
*/
else if (*cond != NULL || (rval = pthread_cond_init(cond, NULL)) == 0) {
/* Lock the condition variable structure: */
THR_LOCK_ACQUIRE(curthread, &(*cond)->c_lock);
/* Process according to condition variable type: */
switch ((*cond)->c_type) {
/* Fast condition variable: */
case COND_TYPE_FAST:
/* Increment the sequence number: */
(*cond)->c_seqno++;
/*
* Wakeups have to be done with the CV lock held;
* otherwise there is a race condition where the
* thread can timeout, run on another KSE, and enter
* another blocking state (including blocking on a CV).
*/
if ((pthread = TAILQ_FIRST(&(*cond)->c_queue))
!= NULL) {
THR_SCHED_LOCK(curthread, pthread);
cond_queue_remove(*cond, pthread);
if ((pthread->kseg == curthread->kseg) &&
(pthread->active_priority >
curthread->active_priority))
curthread->critical_yield = 1;
kmbx = _thr_setrunnable_unlocked(pthread);
THR_SCHED_UNLOCK(curthread, pthread);
if (kmbx != NULL)
kse_wakeup(kmbx);
}
/* Check for no more waiters: */
if (TAILQ_FIRST(&(*cond)->c_queue) == NULL)
(*cond)->c_mutex = NULL;
break;
/* Trap invalid condition variable types: */
default:
/* Return an invalid argument error: */
rval = EINVAL;
break;
}
/* Unlock the condition variable structure: */
THR_LOCK_RELEASE(curthread, &(*cond)->c_lock);
}
/* Return the completion status: */
return (rval);
}
__strong_reference(_pthread_cond_signal, _thr_cond_signal);
int
_pthread_cond_broadcast(pthread_cond_t * cond)
{
struct pthread *curthread = _get_curthread();
struct pthread *pthread;
struct kse_mailbox *kmbx;
int rval = 0;
THR_ASSERT(curthread->locklevel == 0,
"cv_timedwait: locklevel is not zero!");
if (cond == NULL)
rval = EINVAL;
/*
* If the condition variable is statically initialized, perform dynamic
* initialization.
*/
else if (*cond != NULL || (rval = pthread_cond_init(cond, NULL)) == 0) {
/* Lock the condition variable structure: */
THR_LOCK_ACQUIRE(curthread, &(*cond)->c_lock);
/* Process according to condition variable type: */
switch ((*cond)->c_type) {
/* Fast condition variable: */
case COND_TYPE_FAST:
/* Increment the sequence number: */
(*cond)->c_seqno++;
/*
* Enter a loop to bring all threads off the
* condition queue:
*/
while ((pthread = TAILQ_FIRST(&(*cond)->c_queue))
!= NULL) {
THR_SCHED_LOCK(curthread, pthread);
cond_queue_remove(*cond, pthread);
if ((pthread->kseg == curthread->kseg) &&
(pthread->active_priority >
curthread->active_priority))
curthread->critical_yield = 1;
kmbx = _thr_setrunnable_unlocked(pthread);
THR_SCHED_UNLOCK(curthread, pthread);
if (kmbx != NULL)
kse_wakeup(kmbx);
}
/* There are no more waiting threads: */
(*cond)->c_mutex = NULL;
break;
/* Trap invalid condition variable types: */
default:
/* Return an invalid argument error: */
rval = EINVAL;
break;
}
/* Unlock the condition variable structure: */
THR_LOCK_RELEASE(curthread, &(*cond)->c_lock);
}
/* Return the completion status: */
return (rval);
}
__strong_reference(_pthread_cond_broadcast, _thr_cond_broadcast);
void
_cond_wait_backout(struct pthread *curthread)
{
pthread_cond_t cond;
cond = curthread->data.cond;
if (cond != NULL) {
/* Lock the condition variable structure: */
THR_LOCK_ACQUIRE(curthread, &cond->c_lock);
/* Process according to condition variable type: */
switch (cond->c_type) {
/* Fast condition variable: */
case COND_TYPE_FAST:
cond_queue_remove(cond, curthread);
/* Check for no more waiters: */
if (TAILQ_FIRST(&cond->c_queue) == NULL)
cond->c_mutex = NULL;
break;
default:
break;
}
/* Unlock the condition variable structure: */
THR_LOCK_RELEASE(curthread, &cond->c_lock);
}
}
/*
* Dequeue a waiting thread from the head of a condition queue in
* descending priority order.
*/
static inline struct pthread *
cond_queue_deq(pthread_cond_t cond)
{
struct pthread *pthread;
while ((pthread = TAILQ_FIRST(&cond->c_queue)) != NULL) {
TAILQ_REMOVE(&cond->c_queue, pthread, sqe);
THR_CONDQ_CLEAR(pthread);
if ((pthread->timeout == 0) && (pthread->interrupted == 0))
/*
* Only exit the loop when we find a thread
* that hasn't timed out or been canceled;
* those threads are already running and don't
* need their run state changed.
*/
break;
}
return (pthread);
}
/*
* Remove a waiting thread from a condition queue in descending priority
* order.
*/
static inline void
cond_queue_remove(pthread_cond_t cond, struct pthread *pthread)
{
/*
* Because pthread_cond_timedwait() can timeout as well
* as be signaled by another thread, it is necessary to
* guard against removing the thread from the queue if
* it isn't in the queue.
*/
if (THR_IN_CONDQ(pthread)) {
TAILQ_REMOVE(&cond->c_queue, pthread, sqe);
THR_CONDQ_CLEAR(pthread);
}
}
/*
* Enqueue a waiting thread to a condition queue in descending priority
* order.
*/
static inline void
cond_queue_enq(pthread_cond_t cond, struct pthread *pthread)
{
struct pthread *tid = TAILQ_LAST(&cond->c_queue, cond_head);
THR_ASSERT(!THR_IN_SYNCQ(pthread),
"cond_queue_enq: thread already queued!");
/*
* For the common case of all threads having equal priority,
* we perform a quick check against the priority of the thread
* at the tail of the queue.
*/
if ((tid == NULL) || (pthread->active_priority <= tid->active_priority))
TAILQ_INSERT_TAIL(&cond->c_queue, pthread, sqe);
else {
tid = TAILQ_FIRST(&cond->c_queue);
while (pthread->active_priority <= tid->active_priority)
tid = TAILQ_NEXT(tid, sqe);
TAILQ_INSERT_BEFORE(tid, pthread, sqe);
}
THR_CONDQ_SET(pthread);
pthread->data.cond = cond;
}