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/* Copyright (C) 2002 MySQL AB & MySQL Finland AB & TCX DataKonsult 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; either version 2 of the License, or
(at your option) any later version.
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., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA */
/*
Simple implementation of semaphores, needed to compile MySQL on systems
that doesn't support semaphores.
*/
#include <my_global.h>
#include <my_semaphore.h>
#include <errno.h>
#if !defined(__WIN__) && !defined(HAVE_SEMAPHORE_H)
int sem_init(sem_t * sem, int pshared, uint value)
{
sem->count=value;
pthread_cond_init(&sem->cond, 0);
pthread_mutex_init(&sem->mutex, 0);
return 0;
}
int sem_destroy(sem_t * sem)
{
int err1,err2;
err1=pthread_cond_destroy(&sem->cond);
err2=pthread_mutex_destroy(&sem->mutex);
if (err1 || err2)
{
errno=err1 ? err1 : err2;
return -1;
}
return 0;
}
int sem_wait(sem_t * sem)
{
if ((errno=pthread_mutex_lock(&sem->mutex)))
return -1;
while (!sem->count)
pthread_cond_wait(&sem->cond, &sem->mutex);
if (errno)
return -1;
sem->count--; /* mutex is locked here */
pthread_mutex_unlock(&sem->mutex);
return 0;
}
int sem_trywait(sem_t * sem)
{
if ((errno=pthread_mutex_lock(&sem->mutex)))
return -1;
if (sem->count)
sem->count--;
else
errno=EAGAIN;
pthread_mutex_unlock(&sem->mutex);
return errno ? -1 : 0;
}
int sem_post(sem_t * sem)
{
if ((errno=pthread_mutex_lock(&sem->mutex)))
return -1;
sem->count++;
pthread_mutex_unlock(&sem->mutex); /* does it really matter what to do */
pthread_cond_signal(&sem->cond); /* first: x_unlock or x_signal ? */
return 0;
}
int sem_post_multiple(sem_t * sem, uint count)
{
if ((errno=pthread_mutex_lock(&sem->mutex)))
return -1;
sem->count+=count;
pthread_mutex_unlock(&sem->mutex); /* does it really matter what to do */
pthread_cond_broadcast(&sem->cond); /* first: x_unlock or x_broadcast ? */
return 0;
}
int sem_getvalue(sem_t * sem, uint *sval)
{
if ((errno=pthread_mutex_lock(&sem->mutex)))
return -1;
*sval=sem->count;
pthread_mutex_unlock(&sem->mutex);
return 0;
}
#endif /* !defined(__WIN__) && !defined(HAVE_SEMAPHORE_H) */
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