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105 lines
2.7 KiB
C
105 lines
2.7 KiB
C
/* Copyright (C) 2002 MySQL AB & MySQL Finland AB & TCX DataKonsult 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; either version 2 of the License, or
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(at your option) any later version.
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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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/*
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Simple implementation of semaphores, needed to compile MySQL on systems
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that doesn't support semaphores.
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*/
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#include <my_global.h>
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#include <my_semaphore.h>
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#include <errno.h>
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#if !defined(__WIN__) && !defined(HAVE_SEMAPHORE_H) && defined(THREAD)
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int sem_init(sem_t * sem, int pshared, uint value)
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{
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sem->count=value;
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pthread_cond_init(&sem->cond, 0);
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pthread_mutex_init(&sem->mutex, 0);
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return 0;
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}
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int sem_destroy(sem_t * sem)
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{
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int err1,err2;
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err1=pthread_cond_destroy(&sem->cond);
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err2=pthread_mutex_destroy(&sem->mutex);
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if (err1 || err2)
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{
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errno=err1 ? err1 : err2;
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return -1;
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}
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return 0;
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}
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int sem_wait(sem_t * sem)
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{
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if ((errno=pthread_mutex_lock(&sem->mutex)))
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return -1;
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while (!sem->count)
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pthread_cond_wait(&sem->cond, &sem->mutex);
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if (errno)
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return -1;
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sem->count--; /* mutex is locked here */
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pthread_mutex_unlock(&sem->mutex);
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return 0;
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}
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int sem_trywait(sem_t * sem)
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{
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if ((errno=pthread_mutex_lock(&sem->mutex)))
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return -1;
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if (sem->count)
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sem->count--;
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else
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errno=EAGAIN;
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pthread_mutex_unlock(&sem->mutex);
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return errno ? -1 : 0;
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}
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int sem_post(sem_t * sem)
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{
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if ((errno=pthread_mutex_lock(&sem->mutex)))
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return -1;
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sem->count++;
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pthread_mutex_unlock(&sem->mutex); /* does it really matter what to do */
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pthread_cond_signal(&sem->cond); /* first: x_unlock or x_signal ? */
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return 0;
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}
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int sem_post_multiple(sem_t * sem, uint count)
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{
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if ((errno=pthread_mutex_lock(&sem->mutex)))
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return -1;
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sem->count+=count;
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pthread_mutex_unlock(&sem->mutex); /* does it really matter what to do */
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pthread_cond_broadcast(&sem->cond); /* first: x_unlock or x_broadcast ? */
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return 0;
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}
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int sem_getvalue(sem_t * sem, uint *sval)
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{
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if ((errno=pthread_mutex_lock(&sem->mutex)))
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return -1;
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*sval=sem->count;
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pthread_mutex_unlock(&sem->mutex);
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return 0;
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}
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#endif /* !defined(__WIN__) && !defined(HAVE_SEMAPHORE_H) && defined(THREAD) */
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