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/*
* Copyright (c) 1995 John Birrell <jb@cimlogic.com.au>.
* 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, 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.
* 3. Neither the name of the author nor the names of any co-contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY JOHN BIRRELL AND CONTRIBUTORS ``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 OR CONTRIBUTORS 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 once_lock = PTHREAD_MUTEX_INITIALIZER;
static pthread_cond_t 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(&once_lock);
once_control->state = ONCE_NEVER_DONE;
_pthread_mutex_unlock(&once_lock);
_pthread_cond_broadcast(&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(&once_lock);
while (*(volatile int *)&(once_control->state) == ONCE_IN_PROGRESS)
_pthread_cond_wait(&once_cv, &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(&once_lock);
curthread = _get_curthread();
THR_CLEANUP_PUSH(curthread, once_cancel_handler, once_control);
init_routine();
THR_CLEANUP_POP(curthread, 0);
_pthread_mutex_lock(&once_lock);
once_control->state = ONCE_DONE;
wakeup = 1;
}
_pthread_mutex_unlock(&once_lock);
if (wakeup)
_pthread_cond_broadcast(&once_cv);
return (0);
}
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