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freebsd-dev/lib/libc_r/uthread/uthread_cond.c
Alfred Perlstein 7285bccf1a add pthread_cancel, obtained from OpenBSD. 
eischen (Daniel Eischen) added wrappers to protect against cancled
threads orphaning internal resources.

the cancelability code is still a bit fuzzy but works for test
programs of my own, OpenBSD's and some examples from ORA's books.

add readdir_r to both libc and libc_r

add some 'const' attributes to function parameters

Reviewed by: eischen, jasone
1999-11-28 05:38:13 +00:00

621 lines
15 KiB
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/*
* 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.
*
* $FreeBSD$
*/
#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;
memset(&(*cond)->lock, 0, sizeof((*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;
memset(&pcond->lock,0,sizeof(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)
{
int rval = 0;
if (cond == NULL)
rval = EINVAL;
/*
* If the condition variable is statically initialized,
* perform the dynamic initialization:
*/
else if (*cond != NULL ||
(rval = pthread_cond_init(cond,NULL)) == 0) {
_thread_enter_cancellation_point();
/* 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: */
_thread_run->timeout = 0;
_thread_run->interrupted = 0;
/*
* Queue the running thread for the condition
* variable:
*/
cond_queue_enq(*cond, _thread_run);
/* Remember the mutex that is being used: */
(*cond)->c_mutex = *mutex;
/* Wait forever: */
_thread_run->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, _thread_run);
/* 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__);
if (_thread_run->interrupted != 0) {
/*
* Lock the condition variable
* while removing the thread.
*/
_SPINLOCK(&(*cond)->lock);
cond_queue_remove(*cond,
_thread_run);
/* Check for no more waiters: */
if (TAILQ_FIRST(&(*cond)->c_queue) == NULL)
(*cond)->c_mutex = NULL;
_SPINUNLOCK(&(*cond)->lock);
}
/*
* Note that even though this thread may have
* been canceled, POSIX requires that the mutex
* be reaquired prior to cancellation.
*/
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 ((_thread_run->cancelflags & PTHREAD_CANCEL_NEEDED) != 0) {
_thread_exit_cleanup();
pthread_exit(PTHREAD_CANCELED);
}
_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)
{
int rval = 0;
if (cond == NULL || abstime == NULL)
rval = EINVAL;
if (abstime->tv_sec < 0 ||
abstime->tv_nsec < 0 || abstime->tv_nsec >= 1000000000) {
errno = EINVAL;
return (-1);
}
/*
* If the condition variable is statically initialized,
* perform the dynamic initialization:
*/
if (*cond != NULL ||
(rval = pthread_cond_init(cond,NULL)) == 0) {
_thread_enter_cancellation_point();
/* 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: */
_thread_run->wakeup_time.tv_sec =
abstime->tv_sec;
_thread_run->wakeup_time.tv_nsec =
abstime->tv_nsec;
/* Reset the timeout and interrupted flags: */
_thread_run->timeout = 0;
_thread_run->interrupted = 0;
/*
* Queue the running thread for the condition
* variable:
*/
cond_queue_enq(*cond, _thread_run);
/* Remember the mutex that is being used: */
(*cond)->c_mutex = *mutex;
/* 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, _thread_run);
/* 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__);
/*
* Check if the wait timedout or was
* interrupted (canceled):
*/
if ((_thread_run->timeout == 0) &&
(_thread_run->interrupted == 0)) {
/* Lock the mutex: */
rval = _mutex_cv_lock(mutex);
} else {
/* Lock the condition variable structure: */
_SPINLOCK(&(*cond)->lock);
/*
* The wait timed out; remove
* the thread from the condition
* variable queue:
*/
cond_queue_remove(*cond,
_thread_run);
/* Check for no more waiters: */
if (TAILQ_FIRST(&(*cond)->c_queue) == NULL)
(*cond)->c_mutex = NULL;
/* Unock the condition variable structure: */
_SPINUNLOCK(&(*cond)->lock);
/* Return a timeout error: */
rval = ETIMEDOUT;
/*
* Lock the mutex and ignore any
* errors. Note that even though
* this thread may have been
* canceled, POSIX requires that
* the mutex be reaquired prior
* to cancellation.
*/
(void)_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 ((_thread_run->cancelflags & PTHREAD_CANCEL_NEEDED) != 0) {
_thread_exit_cleanup();
pthread_exit(PTHREAD_CANCELED);
}
_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 || *cond == NULL)
rval = EINVAL;
else {
/*
* 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:
if ((pthread = cond_queue_deq(*cond)) != NULL)
/* Allow the thread to run: */
PTHREAD_NEW_STATE(pthread,PS_RUNNING);
/* 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 || *cond == NULL)
rval = EINVAL;
else {
/*
* 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:
/*
* Enter a loop to bring all threads off the
* condition queue:
*/
while ((pthread = cond_queue_deq(*cond)) != NULL) {
PTHREAD_NEW_STATE(pthread,PS_RUNNING);
}
/* 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, qe);
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, qe);
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);
/*
* 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, qe);
else {
tid = TAILQ_FIRST(&cond->c_queue);
while (pthread->active_priority <= tid->active_priority)
tid = TAILQ_NEXT(tid, qe);
TAILQ_INSERT_BEFORE(tid, pthread, qe);
}
pthread->flags |= PTHREAD_FLAGS_IN_CONDQ;
}
#endif
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