srdb1/db_pool.c

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/* 
 * $Id$
 *
 * Copyright (C) 2001-2005 iptel.org
 * Copyright (C) 2007-2008 1&1 Internet AG
 *
 * This file is part of Kamailio, a free SIP server.
 *
 * Kamailio 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
 *
 * Kamailio 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
 */

#include "../../dprint.h"
#include "db_pool.h"


/* The head of the pool */
static struct pool_con* db_pool = 0;


/*
 * Search the pool for a connection with
 * the identifier equal to id, NULL is returned
 * when no connection is found
 */
struct pool_con* pool_get(const struct db_id* id)
{
        struct pool_con* ptr;

        if (!id) {
                LM_ERR("invalid parameter value\n");
                return 0;
        }

        ptr = db_pool;
        while (ptr) {
                if (cmp_db_id(id, ptr->id)) {
                        ptr->ref++;
                        return ptr;
                }
                ptr = ptr->next;
        }

        return 0;
}


/*
 * Insert a new connection into the pool
 */
void pool_insert(struct pool_con* con)
{
        if (!con) return;

        con->next = db_pool;
        db_pool = con;
}


/*
 * Release connection from the pool, the function
 * would return 1 when if the connection is not
 * referenced anymore and thus can be closed and
 * deleted by the backend. The function returns
 * 0 if the connection should still be kept open
 * because some other module is still using it.
 * The function returns -1 if the connection is
 * not in the pool.
 */
int pool_remove(struct pool_con* con)
{
        struct pool_con* ptr;

        if (!con) return -2;

        if (con->ref > 1) {
                     /* There are still other users, just
                      * decrease the reference count and return
                      */
                LM_DBG("connection still kept in the pool\n");
                con->ref--;
                return 0;
        }

        LM_DBG("removing connection from the pool\n");

        if (db_pool == con) {
                db_pool = db_pool->next;
        } else {
                ptr = db_pool;
                while(ptr) {
                        if (ptr->next == con) break;
                        ptr = ptr->next;
                }
                if (!ptr) {
                        LM_ERR("weird, connection not found in the pool\n");
                        return -1;
                } else {
                             /* Remove the connection from the pool */
                        ptr->next = con->next;
                }
        }

        return 1;
}