1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171
|
/* Copyright (c) 2000-2002 MySQL AB
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; version 2 of the License.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA */
/* Synchronization - readers / writer thread locks */
#include "mysys_priv.h"
#if defined(THREAD) && !defined(HAVE_PTHREAD_RWLOCK_RDLOCK) && !defined(HAVE_RWLOCK_INIT)
#include <errno.h>
/*
Source base from Sun Microsystems SPILT, simplified for MySQL use
-- Joshua Chamas
Some cleanup and additional code by Monty
*/
/*
* Multithreaded Demo Source
*
* Copyright (C) 1995 by Sun Microsystems, Inc.
* All rights reserved.
*
* This file is a product of SunSoft, Inc. and is provided for
* unrestricted use provided that this legend is included on all
* media and as a part of the software program in whole or part.
* Users may copy, modify or distribute this file at will.
*
* THIS FILE IS PROVIDED AS IS WITH NO WARRANTIES OF ANY KIND INCLUDING
* THE WARRANTIES OF DESIGN, MERCHANTIBILITY AND FITNESS FOR A PARTICULAR
* PURPOSE, OR ARISING FROM A COURSE OF DEALING, USAGE OR TRADE PRACTICE.
*
* This file is provided with no support and without any obligation on the
* part of SunSoft, Inc. to assist in its use, correction, modification or
* enhancement.
*
* SUNSOFT AND SUN MICROSYSTEMS, INC. SHALL HAVE NO LIABILITY WITH RESPECT
* TO THE INFRINGEMENT OF COPYRIGHTS, TRADE SECRETS OR ANY PATENTS BY THIS
* FILE OR ANY PART THEREOF.
*
* IN NO EVENT WILL SUNSOFT OR SUN MICROSYSTEMS, INC. BE LIABLE FOR ANY
* LOST REVENUE OR PROFITS OR OTHER SPECIAL, INDIRECT AND CONSEQUENTIAL
* DAMAGES, EVEN IF THEY HAVE BEEN ADVISED OF THE POSSIBILITY OF SUCH
* DAMAGES.
*
* SunSoft, Inc.
* 2550 Garcia Avenue
* Mountain View, California 94043
*/
int my_rwlock_init(rw_lock_t *rwp, void *arg __attribute__((unused)))
{
pthread_condattr_t cond_attr;
pthread_mutex_init( &rwp->lock, MY_MUTEX_INIT_FAST);
pthread_condattr_init( &cond_attr );
pthread_cond_init( &rwp->readers, &cond_attr );
pthread_cond_init( &rwp->writers, &cond_attr );
pthread_condattr_destroy(&cond_attr);
rwp->state = 0;
rwp->waiters = 0;
return(0);
}
int my_rwlock_destroy(rw_lock_t *rwp)
{
pthread_mutex_destroy( &rwp->lock );
pthread_cond_destroy( &rwp->readers );
pthread_cond_destroy( &rwp->writers );
return(0);
}
int my_rw_rdlock(rw_lock_t *rwp)
{
pthread_mutex_lock(&rwp->lock);
/* active or queued writers */
while (( rwp->state < 0 ) || rwp->waiters)
pthread_cond_wait( &rwp->readers, &rwp->lock);
rwp->state++;
pthread_mutex_unlock(&rwp->lock);
return(0);
}
int my_rw_tryrdlock(rw_lock_t *rwp)
{
int res;
pthread_mutex_lock(&rwp->lock);
if ((rwp->state < 0 ) || rwp->waiters)
res= EBUSY; /* Can't get lock */
else
{
res=0;
rwp->state++;
}
pthread_mutex_unlock(&rwp->lock);
return(res);
}
int my_rw_wrlock(rw_lock_t *rwp)
{
pthread_mutex_lock(&rwp->lock);
rwp->waiters++; /* another writer queued */
while (rwp->state)
pthread_cond_wait(&rwp->writers, &rwp->lock);
rwp->state = -1;
rwp->waiters--;
pthread_mutex_unlock(&rwp->lock);
return(0);
}
int my_rw_trywrlock(rw_lock_t *rwp)
{
int res;
pthread_mutex_lock(&rwp->lock);
if (rwp->state)
res= EBUSY; /* Can't get lock */
else
{
res=0;
rwp->state = -1;
}
pthread_mutex_unlock(&rwp->lock);
return(res);
}
int my_rw_unlock(rw_lock_t *rwp)
{
DBUG_PRINT("rw_unlock",
("state: %d waiters: %d", rwp->state, rwp->waiters));
pthread_mutex_lock(&rwp->lock);
if (rwp->state == -1) /* writer releasing */
{
rwp->state= 0; /* mark as available */
if ( rwp->waiters ) /* writers queued */
pthread_cond_signal( &rwp->writers );
else
pthread_cond_broadcast( &rwp->readers );
}
else
{
if ( --rwp->state == 0 ) /* no more readers */
pthread_cond_signal( &rwp->writers );
}
pthread_mutex_unlock( &rwp->lock );
return(0);
}
#endif
|