OpenBSD-4.6/lib/libpthread/uthread/uthread_cond.c
/* $OpenBSD: uthread_cond.c,v 1.15 2007/04/27 19:40:08 kurt Exp $ */
/*
* 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: uthread_cond.c,v 1.18 1999/08/30 00:02:07 deischen Exp $
*/
#include <stdlib.h>
#include <errno.h>
#include <string.h>
#ifdef _THREAD_SAFE
#include <pthread.h>
#include "pthread_private.h"
/*
* Prototypes
*/
static inline pthread_t 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);
/* Reinitialize a condition variable to defaults. */
int
_cond_reinit(pthread_cond_t *cond)
{
int ret = 0;
if (cond == NULL)
ret = EINVAL;
else if (*cond == NULL)
ret = pthread_cond_init(cond, NULL);
else {
/*
* Initialize the condition variable structure:
*/
TAILQ_INIT(&(*cond)->c_queue);
(*cond)->c_flags = COND_FLAGS_INITED;
(*cond)->c_type = COND_TYPE_FAST;
(*cond)->c_mutex = NULL;
(*cond)->c_seqno = 0;
_SPINLOCK_INIT(&(*cond)->lock);
}
return (ret);
}
int
pthread_cond_init(pthread_cond_t * cond, const pthread_condattr_t * cond_attr)
{
enum pthread_cond_type type;
pthread_cond_t pcond;
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;
} else {
/* Default to a fast condition variable: */
type = COND_TYPE_FAST;
}
/* 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 {
/*
* 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;
_SPINLOCK_INIT(&pcond->lock);
*cond = pcond;
}
}
}
/* Return the completion status: */
return (rval);
}
int
pthread_cond_destroy(pthread_cond_t * cond)
{
int rval = 0;
if (cond == NULL || *cond == NULL)
rval = EINVAL;
else {
/* Lock the condition variable structure: */
_SPINLOCK(&(*cond)->lock);
/*
* Free the memory allocated for the condition
* variable structure:
*/
free(*cond);
/*
* NULL the caller's pointer now that the condition
* variable has been destroyed:
*/
*cond = NULL;
}
/* 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 seqno;
/* This is a cancellation point: */
_thread_enter_cancellation_point();
if (cond == NULL) {
/* No longer in a cancellation point: */
_thread_leave_cancellation_point();
return (EINVAL);
}
/*
* If the condition variable is statically initialized,
* perform the dynamic initialization:
*/
if (*cond == NULL &&
(rval = pthread_cond_init(cond, NULL)) != 0) {
/* No longer in a cancellation point: */
_thread_leave_cancellation_point();
return (rval);
}
/*
* 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: */
_SPINLOCK(&(*cond)->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: */
_SPINUNLOCK(&(*cond)->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 ((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: */
_SPINUNLOCK(&(*cond)->lock);
} else {
/*
* Schedule the next thread and unlock
* the condition variable structure:
*/
_thread_kern_sched_state_unlock(PS_COND_WAIT,
&(*cond)->lock, __FILE__, __LINE__);
done = (seqno != (*cond)->c_seqno);
interrupted = curthread->interrupted;
/*
* Check if the wait was interrupted
* (canceled) or needs to be resumed
* after handling a signal.
*/
if (interrupted != 0) {
/*
* Lock the mutex and ignore any
* errors. Note that even
* though this thread may have
* been canceled, POSIX requires
* that the mutex be reacquired
* prior to cancellation.
*/
(void)_mutex_cv_lock(mutex);
} else {
/*
* Lock the condition variable
* while removing the thread.
*/
_SPINLOCK(&(*cond)->lock);
cond_queue_remove(*cond,
curthread);
/* Check for no more waiters: */
if (TAILQ_FIRST(&(*cond)->c_queue) == NULL)
(*cond)->c_mutex = NULL;
_SPINUNLOCK(&(*cond)->lock);
/* Lock the mutex: */
rval = _mutex_cv_lock(mutex);
}
}
}
break;
/* Trap invalid condition variable types: */
default:
/* Unlock the condition variable structure: */
_SPINUNLOCK(&(*cond)->lock);
/* Return an invalid argument error: */
rval = EINVAL;
break;
}
if ((interrupted != 0) && (curthread->continuation != NULL))
curthread->continuation(curthread);
} while ((done == 0) && (rval == 0));
/* No longer in a cancellation point: */
_thread_leave_cancellation_point();
/* 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 rval = 0;
int done = 0;
int interrupted = 0;
int seqno;
/* This is a cancellation point: */
_thread_enter_cancellation_point();
if (cond == NULL ||
abstime == NULL || abstime->tv_sec < 0 || abstime->tv_nsec < 0 ||
abstime->tv_nsec >= 1000000000) {
/* No longer in a cancellation point: */
_thread_leave_cancellation_point();
return (EINVAL);
}
/*
* If the condition variable is statically initialized, perform dynamic
* initialization.
*/
if (*cond == NULL && (rval = pthread_cond_init(cond, NULL)) != 0) {
/* No longer in a cancellation point: */
_thread_leave_cancellation_point();
return (rval);
}
/*
* 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: */
_SPINLOCK(&(*cond)->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: */
_SPINUNLOCK(&(*cond)->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 ((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: */
_SPINUNLOCK(&(*cond)->lock);
} else {
/*
* Schedule the next thread and unlock
* the condition variable structure:
*/
_thread_kern_sched_state_unlock(PS_COND_WAIT,
&(*cond)->lock, __FILE__, __LINE__);
done = (seqno != (*cond)->c_seqno);
interrupted = curthread->interrupted;
/*
* Check if the wait was interrupted
* (canceled) or needs to be resumed
* after handling a signal.
*/
if (interrupted != 0) {
/*
* Lock the mutex and ignore any
* errors. Note that even
* though this thread may have
* been canceled, POSIX requires
* that the mutex be reacquired
* prior to cancellation.
*/
(void)_mutex_cv_lock(mutex);
} else {
/*
* Lock the condition variable
* while removing the thread.
*/
_SPINLOCK(&(*cond)->lock);
cond_queue_remove(*cond,
curthread);
/* Check for no more waiters: */
if (TAILQ_FIRST(&(*cond)->c_queue) == NULL)
(*cond)->c_mutex = NULL;
_SPINUNLOCK(&(*cond)->lock);
/* Lock the mutex: */
rval = _mutex_cv_lock(mutex);
/*
* Return ETIMEDOUT if the wait
* timed out and there wasn't an
* error locking the mutex:
*/
if ((curthread->timeout != 0)
&& rval == 0)
rval = ETIMEDOUT;
}
}
}
break;
/* Trap invalid condition variable types: */
default:
/* Unlock the condition variable structure: */
_SPINUNLOCK(&(*cond)->lock);
/* Return an invalid argument error: */
rval = EINVAL;
break;
}
if ((interrupted != 0) && (curthread->continuation != NULL))
curthread->continuation(curthread);
} while ((done == 0) && (rval == 0));
/* No longer in a cancellation point: */
_thread_leave_cancellation_point();
/* Return the completion status: */
return (rval);
}
int
pthread_cond_signal(pthread_cond_t * cond)
{
int rval = 0;
pthread_t pthread;
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) {
/*
* Defer signals to protect the scheduling queues
* from access by the signal handler:
*/
_thread_kern_sig_defer();
/* Lock the condition variable structure: */
_SPINLOCK(&(*cond)->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++;
if ((pthread = cond_queue_deq(*cond)) != NULL) {
/*
* Unless the thread is currently suspended,
* allow it to run. If the thread is suspended,
* make a note that the thread isn't in a wait
* queue any more.
*/
if (pthread->state != PS_SUSPENDED)
PTHREAD_NEW_STATE(pthread,PS_RUNNING);
else
pthread->suspended = SUSP_NOWAIT;
}
/* 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: */
_SPINUNLOCK(&(*cond)->lock);
/*
* Undefer and handle pending signals, yielding if
* necessary:
*/
_thread_kern_sig_undefer();
}
/* Return the completion status: */
return (rval);
}
int
pthread_cond_broadcast(pthread_cond_t * cond)
{
int rval = 0;
pthread_t pthread;
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) {
/*
* Defer signals to protect the scheduling queues
* from access by the signal handler:
*/
_thread_kern_sig_defer();
/* Lock the condition variable structure: */
_SPINLOCK(&(*cond)->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 = cond_queue_deq(*cond)) != NULL) {
/*
* Unless the thread is currently suspended,
* allow it to run. If the thread is suspended,
* make a note that the thread isn't in a wait
* queue any more.
*/
if (pthread->state != PS_SUSPENDED)
PTHREAD_NEW_STATE(pthread,PS_RUNNING);
else
pthread->suspended = SUSP_NOWAIT;
}
/* 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: */
_SPINUNLOCK(&(*cond)->lock);
/*
* Undefer and handle pending signals, yielding if
* necessary:
*/
_thread_kern_sig_undefer();
}
/* Return the completion status: */
return (rval);
}
/*
* Dequeue a waiting thread from the head of a condition queue in
* descending priority order.
*/
static inline pthread_t
cond_queue_deq(pthread_cond_t cond)
{
pthread_t pthread;
while ((pthread = TAILQ_FIRST(&cond->c_queue)) != NULL) {
TAILQ_REMOVE(&cond->c_queue, pthread, sqe);
pthread->flags &= ~PTHREAD_FLAGS_IN_CONDQ;
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, pthread_t 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 (pthread->flags & PTHREAD_FLAGS_IN_CONDQ) {
TAILQ_REMOVE(&cond->c_queue, pthread, sqe);
pthread->flags &= ~PTHREAD_FLAGS_IN_CONDQ;
}
}
/*
* Enqueue a waiting thread to a condition queue in descending priority
* order.
*/
static inline void
cond_queue_enq(pthread_cond_t cond, pthread_t pthread)
{
pthread_t tid = TAILQ_LAST(&cond->c_queue, cond_head);
PTHREAD_ASSERT_NOT_IN_SYNCQ(pthread);
/*
* 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);
}
pthread->flags |= PTHREAD_FLAGS_IN_CONDQ;
pthread->data.cond = cond;
}
#endif