mirror of
https://git.FreeBSD.org/src.git
synced 2024-12-25 11:37:56 +00:00
100 lines
3.2 KiB
C
100 lines
3.2 KiB
C
/*
|
|
* Copyright (c) 2005, David Xu <davidxu@freebsd.org>
|
|
* 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 unmodified, 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.
|
|
*
|
|
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``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 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 "namespace.h"
|
|
#include <pthread.h>
|
|
#include "un-namespace.h"
|
|
|
|
#include "thr_private.h"
|
|
|
|
__weak_reference(_pthread_once, pthread_once);
|
|
|
|
#define ONCE_NEVER_DONE PTHREAD_NEEDS_INIT
|
|
#define ONCE_DONE PTHREAD_DONE_INIT
|
|
#define ONCE_IN_PROGRESS 0x02
|
|
#define ONCE_MASK 0x03
|
|
|
|
static pthread_mutex_t _thr_once_lock = PTHREAD_MUTEX_INITIALIZER;
|
|
static pthread_cond_t _thr_once_cv = PTHREAD_COND_INITIALIZER;
|
|
|
|
/*
|
|
* POSIX:
|
|
* The pthread_once() function is not a cancellation point. However,
|
|
* if init_routine is a cancellation point and is canceled, the effect
|
|
* on once_control shall be as if pthread_once() was never called.
|
|
*/
|
|
|
|
static void
|
|
once_cancel_handler(void *arg)
|
|
{
|
|
pthread_once_t *once_control = arg;
|
|
|
|
_pthread_mutex_lock(&_thr_once_lock);
|
|
once_control->state = ONCE_NEVER_DONE;
|
|
_pthread_mutex_unlock(&_thr_once_lock);
|
|
_pthread_cond_broadcast(&_thr_once_cv);
|
|
}
|
|
|
|
int
|
|
_pthread_once(pthread_once_t *once_control, void (*init_routine) (void))
|
|
{
|
|
int wakeup = 0;
|
|
|
|
if (once_control->state == ONCE_DONE)
|
|
return (0);
|
|
_pthread_mutex_lock(&_thr_once_lock);
|
|
while (*(volatile int *)&(once_control->state) == ONCE_IN_PROGRESS)
|
|
_pthread_cond_wait(&_thr_once_cv, &_thr_once_lock);
|
|
/*
|
|
* If previous thread was canceled, then the state still
|
|
* could be ONCE_NEVER_DONE, we need to check it again.
|
|
*/
|
|
if (*(volatile int *)&(once_control->state) == ONCE_NEVER_DONE) {
|
|
once_control->state = ONCE_IN_PROGRESS;
|
|
_pthread_mutex_unlock(&_thr_once_lock);
|
|
_pthread_cleanup_push(once_cancel_handler, once_control);
|
|
init_routine();
|
|
_pthread_cleanup_pop(0);
|
|
_pthread_mutex_lock(&_thr_once_lock);
|
|
once_control->state = ONCE_DONE;
|
|
wakeup = 1;
|
|
}
|
|
_pthread_mutex_unlock(&_thr_once_lock);
|
|
if (wakeup)
|
|
_pthread_cond_broadcast(&_thr_once_cv);
|
|
return (0);
|
|
}
|
|
|
|
void
|
|
_thr_once_init()
|
|
{
|
|
_thr_once_lock = PTHREAD_MUTEX_INITIALIZER;
|
|
_thr_once_cv = PTHREAD_COND_INITIALIZER;
|
|
}
|