cc24e83605
This eliminates ping-ponging of locks, where the idle KSE wakes up only to find the lock it needs is being held. This gives little or no gain to M:N mode but greatly speeds up 1:1 mode. Reviewed & Tested by: davidxu
818 lines
22 KiB
C
818 lines
22 KiB
C
/*
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* Copyright (c) 1995 John Birrell <jb@cimlogic.com.au>.
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. All advertising materials mentioning features or use of this software
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* must display the following acknowledgement:
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* This product includes software developed by John Birrell.
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* 4. Neither the name of the author nor the names of any co-contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY JOHN BIRRELL AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*
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* $FreeBSD$
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*/
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#include <stdlib.h>
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#include <errno.h>
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#include <string.h>
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#include <pthread.h>
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#include "thr_private.h"
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#define THR_IN_CONDQ(thr) (((thr)->sflags & THR_FLAGS_IN_SYNCQ) != 0)
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#define THR_IN_CONDQ(thr) (((thr)->sflags & THR_FLAGS_IN_SYNCQ) != 0)
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#define THR_CONDQ_SET(thr) (thr)->sflags |= THR_FLAGS_IN_SYNCQ
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#define THR_CONDQ_CLEAR(thr) (thr)->sflags &= ~THR_FLAGS_IN_SYNCQ
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/*
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* Prototypes
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*/
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static inline struct pthread *cond_queue_deq(pthread_cond_t);
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static inline void cond_queue_remove(pthread_cond_t, pthread_t);
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static inline void cond_queue_enq(pthread_cond_t, pthread_t);
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/*
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* Double underscore versions are cancellation points. Single underscore
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* versions are not and are provided for libc internal usage (which
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* shouldn't introduce cancellation points).
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*/
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__weak_reference(__pthread_cond_wait, pthread_cond_wait);
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__weak_reference(__pthread_cond_timedwait, pthread_cond_timedwait);
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__weak_reference(_pthread_cond_init, pthread_cond_init);
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__weak_reference(_pthread_cond_destroy, pthread_cond_destroy);
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__weak_reference(_pthread_cond_signal, pthread_cond_signal);
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__weak_reference(_pthread_cond_broadcast, pthread_cond_broadcast);
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int
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_pthread_cond_init(pthread_cond_t *cond, const pthread_condattr_t *cond_attr)
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{
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enum pthread_cond_type type;
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pthread_cond_t pcond;
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int flags;
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int rval = 0;
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if (cond == NULL)
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rval = EINVAL;
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else {
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/*
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* Check if a pointer to a condition variable attribute
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* structure was passed by the caller:
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*/
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if (cond_attr != NULL && *cond_attr != NULL) {
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/* Default to a fast condition variable: */
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type = (*cond_attr)->c_type;
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flags = (*cond_attr)->c_flags;
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} else {
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/* Default to a fast condition variable: */
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type = COND_TYPE_FAST;
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flags = 0;
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}
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/* Process according to condition variable type: */
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switch (type) {
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/* Fast condition variable: */
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case COND_TYPE_FAST:
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/* Nothing to do here. */
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break;
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/* Trap invalid condition variable types: */
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default:
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/* Return an invalid argument error: */
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rval = EINVAL;
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break;
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}
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/* Check for no errors: */
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if (rval == 0) {
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if ((pcond = (pthread_cond_t)
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malloc(sizeof(struct pthread_cond))) == NULL) {
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rval = ENOMEM;
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} else if (_lock_init(&pcond->c_lock, LCK_ADAPTIVE,
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_thr_lock_wait, _thr_lock_wakeup) != 0) {
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free(pcond);
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rval = ENOMEM;
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} else {
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/*
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* Initialise the condition variable
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* structure:
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*/
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TAILQ_INIT(&pcond->c_queue);
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pcond->c_flags |= COND_FLAGS_INITED;
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pcond->c_type = type;
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pcond->c_mutex = NULL;
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pcond->c_seqno = 0;
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*cond = pcond;
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}
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}
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}
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/* Return the completion status: */
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return (rval);
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}
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int
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_pthread_cond_destroy(pthread_cond_t *cond)
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{
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struct pthread_cond *cv;
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struct pthread *curthread = _get_curthread();
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int rval = 0;
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if (cond == NULL || *cond == NULL)
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rval = EINVAL;
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else {
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/* Lock the condition variable structure: */
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THR_LOCK_ACQUIRE(curthread, &(*cond)->c_lock);
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/*
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* NULL the caller's pointer now that the condition
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* variable has been destroyed:
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*/
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cv = *cond;
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*cond = NULL;
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/* Unlock the condition variable structure: */
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THR_LOCK_RELEASE(curthread, &cv->c_lock);
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/* Free the cond lock structure: */
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_lock_destroy(&cv->c_lock);
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/*
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* Free the memory allocated for the condition
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* variable structure:
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*/
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free(cv);
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}
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/* Return the completion status: */
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return (rval);
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}
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int
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_pthread_cond_wait(pthread_cond_t *cond, pthread_mutex_t *mutex)
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{
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struct pthread *curthread = _get_curthread();
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int rval = 0;
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int done = 0;
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int interrupted = 0;
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int unlock_mutex = 1;
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int seqno;
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if (cond == NULL)
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return (EINVAL);
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/*
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* If the condition variable is statically initialized,
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* perform the dynamic initialization:
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*/
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if (*cond == NULL &&
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(rval = pthread_cond_init(cond, NULL)) != 0)
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return (rval);
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if (!_kse_isthreaded())
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_kse_setthreaded(1);
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/*
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* Enter a loop waiting for a condition signal or broadcast
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* to wake up this thread. A loop is needed in case the waiting
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* thread is interrupted by a signal to execute a signal handler.
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* It is not (currently) possible to remain in the waiting queue
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* while running a handler. Instead, the thread is interrupted
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* and backed out of the waiting queue prior to executing the
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* signal handler.
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*/
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do {
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/* Lock the condition variable structure: */
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THR_LOCK_ACQUIRE(curthread, &(*cond)->c_lock);
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/*
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* If the condvar was statically allocated, properly
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* initialize the tail queue.
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*/
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if (((*cond)->c_flags & COND_FLAGS_INITED) == 0) {
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TAILQ_INIT(&(*cond)->c_queue);
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(*cond)->c_flags |= COND_FLAGS_INITED;
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}
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/* Process according to condition variable type: */
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switch ((*cond)->c_type) {
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/* Fast condition variable: */
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case COND_TYPE_FAST:
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if ((mutex == NULL) || (((*cond)->c_mutex != NULL) &&
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((*cond)->c_mutex != *mutex))) {
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/* Unlock the condition variable structure: */
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THR_LOCK_RELEASE(curthread, &(*cond)->c_lock);
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/* Return invalid argument error: */
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rval = EINVAL;
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} else {
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/* Reset the timeout and interrupted flags: */
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curthread->timeout = 0;
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curthread->interrupted = 0;
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/*
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* Queue the running thread for the condition
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* variable:
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*/
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cond_queue_enq(*cond, curthread);
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/* Remember the mutex and sequence number: */
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(*cond)->c_mutex = *mutex;
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seqno = (*cond)->c_seqno;
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/* Wait forever: */
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curthread->wakeup_time.tv_sec = -1;
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/* Unlock the mutex: */
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if ((unlock_mutex != 0) &&
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((rval = _mutex_cv_unlock(mutex)) != 0)) {
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/*
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* Cannot unlock the mutex, so remove
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* the running thread from the condition
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* variable queue:
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*/
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cond_queue_remove(*cond, curthread);
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/* Check for no more waiters: */
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if (TAILQ_FIRST(&(*cond)->c_queue) == NULL)
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(*cond)->c_mutex = NULL;
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/* Unlock the condition variable structure: */
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THR_LOCK_RELEASE(curthread, &(*cond)->c_lock);
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}
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else {
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/*
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* Don't unlock the mutex the next
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* time through the loop (if the
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* thread has to be requeued after
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* handling a signal).
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*/
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unlock_mutex = 0;
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/*
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* This thread is active and is in a
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* critical region (holding the cv
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* lock); we should be able to safely
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* set the state.
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*/
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THR_SCHED_LOCK(curthread, curthread);
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THR_SET_STATE(curthread, PS_COND_WAIT);
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/* Remember the CV: */
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curthread->data.cond = *cond;
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THR_SCHED_UNLOCK(curthread, curthread);
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/* Unlock the CV structure: */
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THR_LOCK_RELEASE(curthread,
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&(*cond)->c_lock);
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/* Schedule the next thread: */
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_thr_sched_switch(curthread);
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curthread->data.cond = NULL;
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/*
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* XXX - This really isn't a good check
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* since there can be more than one
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* thread waiting on the CV. Signals
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* sent to threads waiting on mutexes
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* or CVs should really be deferred
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* until the threads are no longer
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* waiting, but POSIX says that signals
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* should be sent "as soon as possible".
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*/
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done = (seqno != (*cond)->c_seqno);
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if (THR_IN_SYNCQ(curthread)) {
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/*
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* Lock the condition variable
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* while removing the thread.
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*/
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THR_LOCK_ACQUIRE(curthread,
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&(*cond)->c_lock);
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cond_queue_remove(*cond,
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curthread);
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/* Check for no more waiters: */
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if (TAILQ_FIRST(&(*cond)->c_queue) == NULL)
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(*cond)->c_mutex = NULL;
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THR_LOCK_RELEASE(curthread,
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&(*cond)->c_lock);
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}
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/*
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* Save the interrupted flag; locking
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* the mutex may destroy it.
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*/
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interrupted = curthread->interrupted;
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/*
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* Note that even though this thread may
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* have been canceled, POSIX requires
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* that the mutex be reaquired prior to
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* cancellation.
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*/
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if (done || interrupted) {
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rval = _mutex_cv_lock(mutex);
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unlock_mutex = 1;
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}
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}
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}
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break;
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/* Trap invalid condition variable types: */
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default:
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/* Unlock the condition variable structure: */
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THR_LOCK_RELEASE(curthread, &(*cond)->c_lock);
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/* Return an invalid argument error: */
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rval = EINVAL;
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break;
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}
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if ((interrupted != 0) && (curthread->continuation != NULL))
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curthread->continuation((void *) curthread);
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} while ((done == 0) && (rval == 0));
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/* Return the completion status: */
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return (rval);
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}
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__strong_reference(_pthread_cond_wait, _thr_cond_wait);
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int
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__pthread_cond_wait(pthread_cond_t *cond, pthread_mutex_t *mutex)
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{
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struct pthread *curthread = _get_curthread();
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int ret;
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_thr_enter_cancellation_point(curthread);
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ret = _pthread_cond_wait(cond, mutex);
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_thr_leave_cancellation_point(curthread);
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return (ret);
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}
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int
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_pthread_cond_timedwait(pthread_cond_t * cond, pthread_mutex_t * mutex,
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const struct timespec * abstime)
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{
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struct pthread *curthread = _get_curthread();
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int rval = 0;
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int done = 0;
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int interrupted = 0;
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int unlock_mutex = 1;
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int seqno;
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THR_ASSERT(curthread->locklevel == 0,
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"cv_timedwait: locklevel is not zero!");
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if (abstime == NULL || abstime->tv_sec < 0 || abstime->tv_nsec < 0 ||
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abstime->tv_nsec >= 1000000000)
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return (EINVAL);
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/*
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* If the condition variable is statically initialized, perform dynamic
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* initialization.
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*/
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if (*cond == NULL && (rval = pthread_cond_init(cond, NULL)) != 0)
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return (rval);
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if (!_kse_isthreaded())
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_kse_setthreaded(1);
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/*
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* Enter a loop waiting for a condition signal or broadcast
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* to wake up this thread. A loop is needed in case the waiting
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* thread is interrupted by a signal to execute a signal handler.
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* It is not (currently) possible to remain in the waiting queue
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* while running a handler. Instead, the thread is interrupted
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* and backed out of the waiting queue prior to executing the
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* signal handler.
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*/
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do {
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/* Lock the condition variable structure: */
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THR_LOCK_ACQUIRE(curthread, &(*cond)->c_lock);
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/*
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* If the condvar was statically allocated, properly
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* initialize the tail queue.
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*/
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if (((*cond)->c_flags & COND_FLAGS_INITED) == 0) {
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TAILQ_INIT(&(*cond)->c_queue);
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(*cond)->c_flags |= COND_FLAGS_INITED;
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}
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/* Process according to condition variable type: */
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switch ((*cond)->c_type) {
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/* Fast condition variable: */
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case COND_TYPE_FAST:
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if ((mutex == NULL) || (((*cond)->c_mutex != NULL) &&
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((*cond)->c_mutex != *mutex))) {
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/* Return invalid argument error: */
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rval = EINVAL;
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/* Unlock the condition variable structure: */
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THR_LOCK_RELEASE(curthread, &(*cond)->c_lock);
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} else {
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/* Set the wakeup time: */
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curthread->wakeup_time.tv_sec = abstime->tv_sec;
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curthread->wakeup_time.tv_nsec =
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abstime->tv_nsec;
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/* Reset the timeout and interrupted flags: */
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curthread->timeout = 0;
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curthread->interrupted = 0;
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/*
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* Queue the running thread for the condition
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* variable:
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*/
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cond_queue_enq(*cond, curthread);
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/* Remember the mutex and sequence number: */
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(*cond)->c_mutex = *mutex;
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seqno = (*cond)->c_seqno;
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/* Unlock the mutex: */
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if ((unlock_mutex != 0) &&
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((rval = _mutex_cv_unlock(mutex)) != 0)) {
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/*
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* Cannot unlock the mutex; remove the
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* running thread from the condition
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* variable queue:
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*/
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cond_queue_remove(*cond, curthread);
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/* Check for no more waiters: */
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if (TAILQ_FIRST(&(*cond)->c_queue) == NULL)
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(*cond)->c_mutex = NULL;
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/* Unlock the condition variable structure: */
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THR_LOCK_RELEASE(curthread, &(*cond)->c_lock);
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} else {
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/*
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* Don't unlock the mutex the next
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* time through the loop (if the
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* thread has to be requeued after
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* handling a signal).
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*/
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unlock_mutex = 0;
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/*
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* This thread is active and is in a
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* critical region (holding the cv
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* lock); we should be able to safely
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* set the state.
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*/
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THR_SCHED_LOCK(curthread, curthread);
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THR_SET_STATE(curthread, PS_COND_WAIT);
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/* Remember the CV: */
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curthread->data.cond = *cond;
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THR_SCHED_UNLOCK(curthread, curthread);
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/* Unlock the CV structure: */
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THR_LOCK_RELEASE(curthread,
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&(*cond)->c_lock);
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/* Schedule the next thread: */
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_thr_sched_switch(curthread);
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curthread->data.cond = NULL;
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/*
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* XXX - This really isn't a good check
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* since there can be more than one
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* thread waiting on the CV. Signals
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|
* sent to threads waiting on mutexes
|
|
* or CVs should really be deferred
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* until the threads are no longer
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|
* waiting, but POSIX says that signals
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* should be sent "as soon as possible".
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*/
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done = (seqno != (*cond)->c_seqno);
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if (THR_IN_CONDQ(curthread)) {
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/*
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* Lock the condition variable
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* while removing the thread.
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*/
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THR_LOCK_ACQUIRE(curthread,
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&(*cond)->c_lock);
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cond_queue_remove(*cond,
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curthread);
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/* Check for no more waiters: */
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if (TAILQ_FIRST(&(*cond)->c_queue) == NULL)
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(*cond)->c_mutex = NULL;
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THR_LOCK_RELEASE(curthread,
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&(*cond)->c_lock);
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}
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/*
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* Save the interrupted flag; locking
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* the mutex may destroy it.
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*/
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interrupted = curthread->interrupted;
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if (curthread->timeout != 0) {
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|
/* 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_enter_cancellation_point(curthread);
|
|
ret = _pthread_cond_timedwait(cond, mutex, abstime);
|
|
_thr_leave_cancellation_point(curthread);
|
|
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;
|
|
}
|