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/*
* 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))
{
struct pthread *curthread;
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);
curthread = _get_curthread();
THR_CLEANUP_PUSH(curthread, once_cancel_handler, once_control);
init_routine();
THR_CLEANUP_POP(curthread, 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;
}
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