4a027d50c7
for the process, not a separate set for each thread). By default, the process now only has signal handlers installed for SIGVTALRM, SIGINFO and SIGCHLD. The thread kernel signal handler is installed for other signals on demand. This means that SIG_IGN and SIG_DFL processing is now left to the kernel, not the thread kernel. Change the signal dispatch to no longer use a signal thread, and call the signal handler using the stack of the thread that has the signal pending. Change the atomic lock method to use test-and-set asm code with a yield if blocked. This introduces separate locks for each type of object instead of blocking signals to prevent a context switch. It was this blocking of signals that caused the performance degradation the people have noted. This is a *big* change!
350 lines
8.8 KiB
C
350 lines
8.8 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 REGENTS 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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*/
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#include <stdlib.h>
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#include <errno.h>
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#ifdef _THREAD_SAFE
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#include <pthread.h>
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#include "pthread_private.h"
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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 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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} else {
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/* Default to a fast condition variable: */
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type = COND_TYPE_FAST;
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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 {
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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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_thread_queue_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->access_lock = 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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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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_spinlock(&(*cond)->access_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(*cond);
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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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*cond = NULL;
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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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int rval = 0;
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int status;
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if (cond == NULL)
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rval = 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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else if (*cond != NULL ||
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(rval = pthread_cond_init(cond,NULL)) == 0) {
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/* Lock the condition variable structure: */
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_spinlock(&(*cond)->access_lock);
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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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/*
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* Queue the running thread for the condition
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* variable:
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*/
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_thread_queue_enq(&(*cond)->c_queue, _thread_run);
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/* Unlock the mutex: */
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pthread_mutex_unlock(mutex);
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/* Wait forever: */
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_thread_run->wakeup_time.tv_sec = -1;
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/* Unlock the condition variable structure: */
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_atomic_unlock(&(*cond)->access_lock);
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/* Schedule the next thread: */
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_thread_kern_sched_state(PS_COND_WAIT,
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__FILE__, __LINE__);
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/* Lock the condition variable structure: */
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_spinlock(&(*cond)->access_lock);
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/* Lock the mutex: */
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rval = pthread_mutex_lock(mutex);
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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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/* Unlock the condition variable structure: */
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_atomic_unlock(&(*cond)->access_lock);
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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_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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int rval = 0;
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int status;
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if (cond == NULL)
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rval = 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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else if (*cond != NULL ||
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(rval = pthread_cond_init(cond,NULL)) == 0) {
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/* Lock the condition variable structure: */
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_spinlock(&(*cond)->access_lock);
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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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/* Set the wakeup time: */
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_thread_run->wakeup_time.tv_sec = abstime->tv_sec;
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_thread_run->wakeup_time.tv_nsec = abstime->tv_nsec;
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/* Reset the timeout flag: */
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_thread_run->timeout = 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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_thread_queue_enq(&(*cond)->c_queue, _thread_run);
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/* Unlock the mutex: */
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if ((rval = pthread_mutex_unlock(mutex)) != 0) {
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/*
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* Cannot unlock the mutex, so 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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_thread_queue_deq(&(*cond)->c_queue);
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} else {
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/* Unlock the condition variable structure: */
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_atomic_unlock(&(*cond)->access_lock);
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/* Schedule the next thread: */
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_thread_kern_sched_state(PS_COND_WAIT,
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__FILE__, __LINE__);
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/* Lock the condition variable structure: */
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_spinlock(&(*cond)->access_lock);
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/* Lock the mutex: */
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if ((rval = pthread_mutex_lock(mutex)) != 0) {
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}
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/* Check if the wait timed out: */
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else if (_thread_run->timeout) {
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/* Return a timeout error: */
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rval = ETIMEDOUT;
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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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/* Return an invalid argument error: */
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rval = EINVAL;
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break;
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}
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/* Unlock the condition variable structure: */
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_atomic_unlock(&(*cond)->access_lock);
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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_signal(pthread_cond_t * cond)
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{
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int rval = 0;
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int status;
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pthread_t pthread;
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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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_spinlock(&(*cond)->access_lock);
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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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/* Bring the next thread off the condition queue: */
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if ((pthread = _thread_queue_deq(&(*cond)->c_queue)) != NULL) {
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/* Allow the thread to run: */
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PTHREAD_NEW_STATE(pthread,PS_RUNNING);
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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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/* Return an invalid argument error: */
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rval = EINVAL;
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break;
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}
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/* Unlock the condition variable structure: */
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_atomic_unlock(&(*cond)->access_lock);
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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_broadcast(pthread_cond_t * cond)
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{
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int rval = 0;
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int status;
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pthread_t pthread;
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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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_spinlock(&(*cond)->access_lock);
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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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/*
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* Enter a loop to bring all threads off the
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* condition queue:
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*/
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while ((pthread =
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_thread_queue_deq(&(*cond)->c_queue)) != NULL) {
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/* Allow the thread to run: */
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PTHREAD_NEW_STATE(pthread,PS_RUNNING);
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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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/* Return an invalid argument error: */
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rval = EINVAL;
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break;
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}
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/* Unlock the condition variable structure: */
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_atomic_unlock(&(*cond)->access_lock);
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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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#endif
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