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by brian
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/* Copyright (C) 2000 MySQL AB
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; version 2 of the License.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program; if not, write to the Free Software
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Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA */
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/* Synchronization - readers / writer thread locks */
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#include "mysys_priv.h" |
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28.1.35
by Monty Taylor
Removed all references to THREAD. |
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#if !defined(HAVE_PTHREAD_RWLOCK_RDLOCK) && !defined(HAVE_RWLOCK_INIT)
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by brian
clean slate |
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#include <errno.h> |
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/*
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Source base from Sun Microsystems SPILT, simplified for MySQL use
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-- Joshua Chamas
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Some cleanup and additional code by Monty
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*/
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/*
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* Multithreaded Demo Source
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*
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* Copyright (C) 1995 by Sun Microsystems, Inc.
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* All rights reserved.
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*
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* This file is a product of SunSoft, Inc. and is provided for
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* unrestricted use provided that this legend is included on all
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* media and as a part of the software program in whole or part.
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* Users may copy, modify or distribute this file at will.
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*
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* THIS FILE IS PROVIDED AS IS WITH NO WARRANTIES OF ANY KIND INCLUDING
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* THE WARRANTIES OF DESIGN, MERCHANTIBILITY AND FITNESS FOR A PARTICULAR
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* PURPOSE, OR ARISING FROM A COURSE OF DEALING, USAGE OR TRADE PRACTICE.
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*
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* This file is provided with no support and without any obligation on the
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* part of SunSoft, Inc. to assist in its use, correction, modification or
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* enhancement.
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*
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* SUNSOFT AND SUN MICROSYSTEMS, INC. SHALL HAVE NO LIABILITY WITH RESPECT
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* TO THE INFRINGEMENT OF COPYRIGHTS, TRADE SECRETS OR ANY PATENTS BY THIS
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* FILE OR ANY PART THEREOF.
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*
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* IN NO EVENT WILL SUNSOFT OR SUN MICROSYSTEMS, INC. BE LIABLE FOR ANY
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* LOST REVENUE OR PROFITS OR OTHER SPECIAL, INDIRECT AND CONSEQUENTIAL
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* DAMAGES, EVEN IF THEY HAVE BEEN ADVISED OF THE POSSIBILITY OF SUCH
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* DAMAGES.
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*
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* SunSoft, Inc.
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* 2550 Garcia Avenue
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* Mountain View, California 94043
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*/
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int my_rwlock_init(rw_lock_t *rwp, void *arg __attribute__((unused))) |
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{
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pthread_condattr_t cond_attr; |
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pthread_mutex_init( &rwp->lock, MY_MUTEX_INIT_FAST); |
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pthread_condattr_init( &cond_attr ); |
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pthread_cond_init( &rwp->readers, &cond_attr ); |
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pthread_cond_init( &rwp->writers, &cond_attr ); |
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pthread_condattr_destroy(&cond_attr); |
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rwp->state = 0; |
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rwp->waiters = 0; |
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return(0); |
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}
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int my_rwlock_destroy(rw_lock_t *rwp) |
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{
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pthread_mutex_destroy( &rwp->lock ); |
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pthread_cond_destroy( &rwp->readers ); |
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pthread_cond_destroy( &rwp->writers ); |
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return(0); |
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}
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int my_rw_rdlock(rw_lock_t *rwp) |
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{
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pthread_mutex_lock(&rwp->lock); |
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/* active or queued writers */
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while (( rwp->state < 0 ) || rwp->waiters) |
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pthread_cond_wait( &rwp->readers, &rwp->lock); |
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rwp->state++; |
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pthread_mutex_unlock(&rwp->lock); |
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return(0); |
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}
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int my_rw_tryrdlock(rw_lock_t *rwp) |
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{
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int res; |
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pthread_mutex_lock(&rwp->lock); |
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if ((rwp->state < 0 ) || rwp->waiters) |
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res= EBUSY; /* Can't get lock */ |
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else
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{
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res=0; |
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rwp->state++; |
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}
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pthread_mutex_unlock(&rwp->lock); |
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return(res); |
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}
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int my_rw_wrlock(rw_lock_t *rwp) |
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{
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pthread_mutex_lock(&rwp->lock); |
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rwp->waiters++; /* another writer queued */ |
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while (rwp->state) |
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pthread_cond_wait(&rwp->writers, &rwp->lock); |
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rwp->state = -1; |
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rwp->waiters--; |
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pthread_mutex_unlock(&rwp->lock); |
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return(0); |
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}
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int my_rw_trywrlock(rw_lock_t *rwp) |
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{
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int res; |
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pthread_mutex_lock(&rwp->lock); |
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if (rwp->state) |
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res= EBUSY; /* Can't get lock */ |
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else
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{
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res=0; |
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rwp->state = -1; |
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}
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pthread_mutex_unlock(&rwp->lock); |
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return(res); |
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}
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int my_rw_unlock(rw_lock_t *rwp) |
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{
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pthread_mutex_lock(&rwp->lock); |
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if (rwp->state == -1) /* writer releasing */ |
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{
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rwp->state= 0; /* mark as available */ |
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if ( rwp->waiters ) /* writers queued */ |
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pthread_cond_signal( &rwp->writers ); |
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else
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pthread_cond_broadcast( &rwp->readers ); |
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}
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else
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{
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if ( --rwp->state == 0 ) /* no more readers */ |
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pthread_cond_signal( &rwp->writers ); |
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}
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pthread_mutex_unlock( &rwp->lock ); |
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return(0); |
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}
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#endif
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