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/* Linuxthreads - a simple clone()-based implementation of Posix */
/* threads for Linux. */
/* Copyright (C) 1996 Xavier Leroy (Xavier.Leroy@inria.fr) */
/* and Pavel Krauz (krauz@fsid.cvut.cz). */
/* */
/* This program is free software; you can redistribute it and/or */
/* modify it under the terms of the GNU Library General Public License */
/* as published by the Free Software Foundation; either version 2 */
/* of the License, or (at your option) any later version. */
/* */
/* This program is distributed in the hope that it will be useful, */
/* but WITHOUT ANY WARRANTY; without even the implied warranty of */
/* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the */
/* GNU Library General Public License for more details. */
/* Condition variables */
#include <errno.h>
#include <sched.h>
#include <stddef.h>
#include <sys/time.h>
#include "pthread.h"
#include "internals.h"
#include "spinlock.h"
#include "queue.h"
#include "restart.h"
int pthread_cond_init(pthread_cond_t *cond,
const pthread_condattr_t *cond_attr)
{
__pthread_init_lock(&cond->__c_lock);
cond->__c_waiting = NULL;
return 0;
}
int pthread_cond_destroy(pthread_cond_t *cond)
{
if (cond->__c_waiting != NULL) return EBUSY;
return 0;
}
int pthread_cond_wait(pthread_cond_t *cond, pthread_mutex_t *mutex)
{
volatile pthread_descr self = thread_self();
__pthread_lock(&cond->__c_lock, self);
enqueue(&cond->__c_waiting, self);
__pthread_unlock(&cond->__c_lock);
pthread_mutex_unlock(mutex);
suspend_with_cancellation(self);
pthread_mutex_lock(mutex);
/* This is a cancellation point */
if (THREAD_GETMEM(self, p_canceled)
&& THREAD_GETMEM(self, p_cancelstate) == PTHREAD_CANCEL_ENABLE) {
/* Remove ourselves from the waiting queue if we're still on it */
__pthread_lock(&cond->__c_lock, self);
remove_from_queue(&cond->__c_waiting, self);
__pthread_unlock(&cond->__c_lock);
pthread_exit(PTHREAD_CANCELED);
}
return 0;
}
static inline int
pthread_cond_timedwait_relative(pthread_cond_t *cond,
pthread_mutex_t *mutex,
const struct timespec * reltime)
{
volatile pthread_descr self = thread_self();
sigset_t unblock, initial_mask;
int retsleep;
sigjmp_buf jmpbuf;
/* Wait on the condition */
__pthread_lock(&cond->__c_lock, self);
enqueue(&cond->__c_waiting, self);
__pthread_unlock(&cond->__c_lock);
pthread_mutex_unlock(mutex);
continue_waiting:
/* Set up a longjmp handler for the restart and cancel signals */
if (sigsetjmp(jmpbuf, 1) == 0) {
THREAD_SETMEM(self, p_signal_jmp, &jmpbuf);
THREAD_SETMEM(self, p_cancel_jmp, &jmpbuf);
THREAD_SETMEM(self, p_signal, 0);
/* Check for cancellation */
if (THREAD_GETMEM(self, p_canceled)
&& THREAD_GETMEM(self, p_cancelstate) == PTHREAD_CANCEL_ENABLE) {
retsleep = -1;
} else {
/* Unblock the restart signal */
sigemptyset(&unblock);
sigaddset(&unblock, __pthread_sig_restart);
sigprocmask(SIG_UNBLOCK, &unblock, &initial_mask);
/* Sleep for the required duration */
retsleep = __libc_nanosleep(reltime, NULL);
/* Block the restart signal again */
sigprocmask(SIG_SETMASK, &initial_mask, NULL);
}
} else {
retsleep = -1;
}
THREAD_SETMEM(self, p_signal_jmp, NULL);
THREAD_SETMEM(self, p_cancel_jmp, NULL);
/* Here, either the condition was signaled (self->p_signal != 0)
or we got canceled (self->p_canceled != 0)
or the timeout occurred (retsleep == 0)
or another interrupt occurred (retsleep == -1) */
/* This is a cancellation point */
if (THREAD_GETMEM(self, p_canceled)
&& THREAD_GETMEM(self, p_cancelstate) == PTHREAD_CANCEL_ENABLE) {
__pthread_lock(&cond->__c_lock, self);
remove_from_queue(&cond->__c_waiting, self);
__pthread_unlock(&cond->__c_lock);
pthread_mutex_lock(mutex);
pthread_exit(PTHREAD_CANCELED);
}
/* If not signaled: also remove ourselves and return an error code, but
only if the timeout has elapsed. If not, jsut continue waiting. */
if (THREAD_GETMEM(self, p_signal) == 0) {
if (retsleep != 0)
goto continue_waiting;
__pthread_lock(&cond->__c_lock, self);
remove_from_queue(&cond->__c_waiting, self);
__pthread_unlock(&cond->__c_lock);
pthread_mutex_lock(mutex);
return ETIMEDOUT;
}
/* Otherwise, return normally */
pthread_mutex_lock(mutex);
return 0;
}
int pthread_cond_timedwait(pthread_cond_t *cond, pthread_mutex_t *mutex,
const struct timespec * abstime)
{
struct timeval now;
struct timespec reltime;
/* Compute a time offset relative to now */
__gettimeofday(&now, NULL);
reltime.tv_sec = abstime->tv_sec - now.tv_sec;
reltime.tv_nsec = abstime->tv_nsec - now.tv_usec * 1000;
if (reltime.tv_nsec < 0) {
reltime.tv_nsec += 1000000000;
reltime.tv_sec -= 1;
}
if (reltime.tv_sec < 0) return ETIMEDOUT;
return pthread_cond_timedwait_relative(cond, mutex, &reltime);
}
int pthread_cond_signal(pthread_cond_t *cond)
{
pthread_descr th;
__pthread_lock(&cond->__c_lock, NULL);
th = dequeue(&cond->__c_waiting);
__pthread_unlock(&cond->__c_lock);
if (th != NULL) restart(th);
return 0;
}
int pthread_cond_broadcast(pthread_cond_t *cond)
{
pthread_descr tosignal, th;
__pthread_lock(&cond->__c_lock, NULL);
/* Copy the current state of the waiting queue and empty it */
tosignal = cond->__c_waiting;
cond->__c_waiting = NULL;
__pthread_unlock(&cond->__c_lock);
/* Now signal each process in the queue */
while ((th = dequeue(&tosignal)) != NULL) restart(th);
return 0;
}
int pthread_condattr_init(pthread_condattr_t *attr)
{
return 0;
}
int pthread_condattr_destroy(pthread_condattr_t *attr)
{
return 0;
}
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