NetBSD/lib/libpthread/pthread_barrier.c

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2003-03-08 11:03:34 +03:00
/* $NetBSD: pthread_barrier.c,v 1.6 2003/03/08 08:03:35 lukem Exp $ */
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/*-
* Copyright (c) 2001, 2003 The NetBSD Foundation, Inc.
* All rights reserved.
*
* This code is derived from software contributed to The NetBSD Foundation
* by Nathan J. Williams, and by Jason R. Thorpe.
*
* 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. All advertising materials mentioning features or use of this software
* must display the following acknowledgement:
* This product includes software developed by the NetBSD
* Foundation, Inc. and its contributors.
* 4. Neither the name of The NetBSD Foundation nor the names of its
* contributors may be used to endorse or promote products derived
* from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. 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 FOUNDATION 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.
*/
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#include <sys/cdefs.h>
__RCSID("$NetBSD: pthread_barrier.c,v 1.6 2003/03/08 08:03:35 lukem Exp $");
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#include <errno.h>
#include <sys/cdefs.h>
#include "pthread.h"
#include "pthread_int.h"
#undef PTHREAD_BARRIER_DEBUG
#ifdef PTHREAD_BARRIER_DEBUG
#define SDPRINTF(x) DPRINTF(x)
#else
#define SDPRINTF(x)
#endif
int
pthread_barrier_init(pthread_barrier_t *barrier,
const pthread_barrierattr_t *attr, unsigned int count)
{
pthread_t self;
#ifdef ERRORCHECK
if ((barrier == NULL) ||
(attr && (attr->ptba_magic != _PT_BARRIERATTR_MAGIC)))
return EINVAL;
#endif
if (count == 0)
return EINVAL;
self = pthread__self();
if (barrier->ptb_magic == _PT_BARRIER_MAGIC) {
/*
* We're simply reinitializing the barrier to a
* new count.
*/
pthread_spinlock(self, &barrier->ptb_lock);
if (barrier->ptb_magic != _PT_BARRIER_MAGIC) {
pthread_spinunlock(self, &barrier->ptb_lock);
return EINVAL;
}
if (!PTQ_EMPTY(&barrier->ptb_waiters)) {
pthread_spinunlock(self, &barrier->ptb_lock);
return EBUSY;
}
barrier->ptb_initcount = count;
barrier->ptb_curcount = 0;
barrier->ptb_generation = 0;
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pthread_spinunlock(self, &barrier->ptb_lock);
return 0;
}
barrier->ptb_magic = _PT_BARRIER_MAGIC;
pthread_lockinit(&barrier->ptb_lock);
PTQ_INIT(&barrier->ptb_waiters);
barrier->ptb_initcount = count;
barrier->ptb_curcount = 0;
barrier->ptb_generation = 0;
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return 0;
}
int
pthread_barrier_destroy(pthread_barrier_t *barrier)
{
pthread_t self;
#ifdef ERRORCHECK
if ((barrier == NULL) || (barrier->ptb_magic != _PT_BARRIER_MAGIC))
return EINVAL;
#endif
self = pthread__self();
pthread_spinlock(self, &barrier->ptb_lock);
if (barrier->ptb_magic != _PT_BARRIER_MAGIC) {
pthread_spinunlock(self, &barrier->ptb_lock);
return EINVAL;
}
if (!PTQ_EMPTY(&barrier->ptb_waiters)) {
pthread_spinunlock(self, &barrier->ptb_lock);
return EBUSY;
}
barrier->ptb_magic = _PT_BARRIER_DEAD;
pthread_spinunlock(self, &barrier->ptb_lock);
return 0;
}
int
pthread_barrier_wait(pthread_barrier_t *barrier)
{
pthread_t self;
unsigned int gen;
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#ifdef ERRORCHECK
if ((barrier == NULL) || (barrier->ptb_magic != _PT_BARRIER_MAGIC))
return EINVAL;
#endif
self = pthread__self();
pthread_spinlock(self, &barrier->ptb_lock);
/*
* A single arbitrary thread is supposed to return
* PTHREAD_BARRIER_SERIAL_THREAD, and everone else
* is supposed to return 0. Since pthread_barrier_wait()
* is not a cancellation point, this is trivial; we
* simply elect that the thread that causes the barrier
* to be satisfied gets the special return value. Note
* that this final thread does not actually need to block,
* but instead is responsible for waking everyone else up.
*/
if (barrier->ptb_curcount + 1 == barrier->ptb_initcount) {
struct pthread_queue_t blockedq;
SDPRINTF(("(barrier wait %p) Satisfied %p\n",
self, barrier));
blockedq = barrier->ptb_waiters;
PTQ_INIT(&barrier->ptb_waiters);
barrier->ptb_curcount = 0;
barrier->ptb_generation++;
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pthread__sched_sleepers(self, &blockedq);
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pthread_spinunlock(self, &barrier->ptb_lock);
return PTHREAD_BARRIER_SERIAL_THREAD;
}
barrier->ptb_curcount++;
gen = barrier->ptb_generation;
while (gen == barrier->ptb_generation) {
SDPRINTF(("(barrier wait %p) Waiting on %p\n",
self, barrier));
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pthread_spinlock(self, &self->pt_statelock);
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self->pt_state = PT_STATE_BLOCKED_QUEUE;
self->pt_sleepobj = barrier;
self->pt_sleepq = &barrier->ptb_waiters;
self->pt_sleeplock = &barrier->ptb_lock;
pthread_spinunlock(self, &self->pt_statelock);
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PTQ_INSERT_TAIL(&barrier->ptb_waiters, self, pt_sleep);
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pthread__block(self, &barrier->ptb_lock);
SDPRINTF(("(barrier wait %p) Woke up on %p\n",
self, barrier));
/* Spinlock is unlocked on return */
pthread_spinlock(self, &barrier->ptb_lock);
}
pthread_spinunlock(self, &barrier->ptb_lock);
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return 0;
}
int
pthread_barrierattr_init(pthread_barrierattr_t *attr)
{
#ifdef ERRORCHECK
if (attr == NULL)
return EINVAL;
#endif
attr->ptba_magic = _PT_BARRIERATTR_MAGIC;
return 0;
}
int
pthread_barrierattr_destroy(pthread_barrierattr_t *attr)
{
#ifdef ERRORCHECK
if ((attr == NULL) ||
(attr->ptba_magic != _PT_BARRIERATTR_MAGIC))
return EINVAL;
#endif
attr->ptba_magic = _PT_BARRIERATTR_DEAD;
return 0;
}