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/*
Copyright (C) 2012 - 2015 Andreas Baumann <mail@andreasbaumann.cc>
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 3 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, see <http://www.gnu.org/licenses/>.
*/
#include "pool.h"
#include "util.h" /* common project utilities */
#include <string.h> /* for strlen, memcpy, strcmp */
#include <errno.h> /* for ENOENT and friends */
#include <stdlib.h> /* for malloc */
#include <syslog.h> /* for syslog */
#define USED 1
#define AVAILABLE 0
#define ERROR 3
int psql_pool_init( PgConnPool *pool, const char *conninfo, const size_t max_connections )
{
size_t i;
int res;
pool->conns = (PGconn **)malloc( sizeof( PGconn * ) * max_connections );
if( pool->conns == NULL ) {
return -ENOMEM;
}
pool->avail = (unsigned int *)malloc( sizeof( unsigned int ) * max_connections );
if( pool->avail == NULL ) {
free( pool->conns );
return -ENOMEM;
}
pool->thread = (pthread_t *)malloc( sizeof( pthread_t ) * max_connections );
if( pool->thread == NULL ) {
free( pool->avail );
free( pool->conns );
return -ENOMEM;
}
pool->size = max_connections;
res = pthread_mutex_init( &pool->lock, NULL );
if( res < 0 ) {
free( pool->thread );
free( pool->avail );
free( pool->conns );
return res;
}
res = pthread_cond_init( &pool->cond, NULL );
if( res < 0 ) {
(void)pthread_mutex_destroy( &pool->lock );
free( pool->thread );
free( pool->avail );
free( pool->conns );
return res;
}
for( i = 0; i < max_connections; i++ ) {
pool->conns[i] = PQconnectdb( conninfo );
if( PQstatus( pool->conns[i] ) == CONNECTION_OK ) {
pool->avail[i] = AVAILABLE;
} else {
syslog( LOG_ERR, "Connection to database failed: %s",
PQerrorMessage( pool->conns[i]) );
PQfinish( pool->conns[i] );
pool->avail[i] = ERROR;
}
}
return 0;
}
int psql_pool_destroy( PgConnPool *pool )
{
size_t i;
int res1;
int res2;
for( i = 0; i < pool->size; i++ ) {
switch( pool->avail[i] ) {
case AVAILABLE:
PQfinish( pool->conns[i] );
break;
case USED:
syslog( LOG_ERR, "Destroying pool connection to thread %p which is still in use",
(void *)pool->thread[i] );
PQfinish( pool->conns[i] );
break;
case ERROR:
// ignoring threads in error, asusming PQfinish will fail anyway
break;
}
}
free( pool->conns );
free( pool->avail );
free( pool->thread );
res1 = pthread_cond_destroy( &pool->cond );
res2 = pthread_mutex_destroy( &pool->lock );
return ( res1 < 0 ) ? res1 : res2;
}
PGconn *psql_pool_acquire( PgConnPool *pool )
{
int res;
size_t i;
for( ;; ) {
res = pthread_mutex_lock( &pool->lock );
if( res < 0 ) {
syslog( LOG_ERR, "Locking mutex failed for thread %p: %d",
THREAD_ID, res );
return NULL;
}
/* find a free connection, remember pid */
for( i = 0; i < pool->size; i++ ) {
if( pool->avail[i] == AVAILABLE ) {
if( PQstatus( pool->conns[i] ) == CONNECTION_OK ) {
pool->avail[i] = USED;
pool->thread[i] = pthread_self( );
(void)pthread_mutex_unlock( &pool->lock );
return pool->conns[i];
} else {
pool->avail[i] = ERROR;
}
}
}
/* wait on conditional till a free connection is signalled */
res = pthread_cond_wait( &pool->cond, &pool->lock );
if( res < 0 ) {
syslog( LOG_ERR, "Error waiting for free condition in thread %p: %d",
THREAD_ID, res );
(void)pthread_mutex_unlock( &pool->lock );
return NULL;
}
(void)pthread_mutex_unlock( &pool->lock );
}
return NULL;
}
int psql_pool_release( PgConnPool *pool, PGconn *conn )
{
int res;
int i;
res = pthread_mutex_lock( &pool->lock );
if( res < 0 ) return res;
for( i = pool->size-1; i >= 0; i-- ) {
if( pool->conns[i] == conn ) {
break;
}
}
if( i < 0 ) {
(void)pthread_mutex_unlock( &pool->lock );
return -EINVAL;
}
pool->avail[i] = AVAILABLE;
(void)pthread_mutex_unlock( &pool->lock );
(void)pthread_cond_signal( &pool->cond );
return 0;
}
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