    001    //$HeadURL: https://svn.wald.intevation.org/svn/deegree/base/branches/2.4_testing/src/org/deegree/io/DBPool.java $
    002    /*----------------------------------------------------------------------------
    003     This file is part of deegree, http://deegree.org/
    004     Copyright (C) 2001-2009 by:
    005     Department of Geography, University of Bonn
    006     and
    007     lat/lon GmbH
    008
    009     This library is free software; you can redistribute it and/or modify it under
    010     the terms of the GNU Lesser General Public License as published by the Free
    011     Software Foundation; either version 2.1 of the License, or (at your option)
    012     any later version.
    013     This library is distributed in the hope that it will be useful, but WITHOUT
    014     ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
    015     FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more
    016     details.
    017     You should have received a copy of the GNU Lesser General Public License
    018     along with this library; if not, write to the Free Software Foundation, Inc.,
    019     59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
    020
    021     Contact information:
    022
    023     lat/lon GmbH
    024     Aennchenstr. 19, 53177 Bonn
    025     Germany
    026     http://lat-lon.de/
    027
    028     Department of Geography, University of Bonn
    029     Prof. Dr. Klaus Greve
    030     Postfach 1147, 53001 Bonn
    031     Germany
    032     http://www.geographie.uni-bonn.de/deegree/
    033
    034     e-mail: info@deegree.org
    035     ----------------------------------------------------------------------------*/
    036
    037    package org.deegree.io;
    038
    039    import java.sql.Connection;
    040    import java.sql.Driver;
    041    import java.sql.DriverManager;
    042    import java.sql.SQLException;
    043    import java.util.Properties;
    044
    045    import org.deegree.framework.util.ObjectPool;
    046
    047    /**
    048     * class to manage a pool of database connections.
    049     *
    050     *
    051     * @version $Revision: 21456 $
    052     * @author <a href="mailto:poth@lat-lon.de">Andreas Poth</a>
    053     * @author last edited by: $Author: aschmitz $
    054     *
    055     * @version 1.0. $Revision: 21456 $, $Date: 2009-12-15 15:17:33 +0100 (Di, 15. Dez 2009) $
    056     *
    057     * @since 2.0
    058     */
    059    public class DBPool extends ObjectPool {
    060
    061        private String driver = null;
    062
    063        private String database = null;
    064
    065        private Properties properties = new Properties();
    066
    067        /**
    068         * initialize pool for defined connection parameters
    069         *
    070         * @param driver
    071         * @param database
    072         * @param user
    073         * @param password
    074         */
    075        public DBPool( final String driver, final String database, final String user, final String password ) {
    076
    077            this.driver = driver;
    078            this.database = database;
    079            properties.put( "user", user );
    080            properties.put( "password", password );
    081        }
    082
    083        /**
    084         * initialize pool for defined connection parameters
    085         *
    086         * @param driver
    087         * @param database
    088         * @param properties
    089         */
    090        public DBPool( final String driver, final String database, final Properties properties ) {
    091
    092            this.driver = driver;
    093            this.database = database;
    094            this.properties = properties;
    095        }
    096
    097        /**
    098         * get an object from the object pool
    099         *
    100         * @return the object
    101         *
    102         * @throws DBPoolException
    103         */
    104        public synchronized Object acquireObject()
    105                                throws DBPoolException {
    106            try {
    107                // if the maximum amount of instances are in use
    108                // wait until an instance has been released back
    109                // to the pool or 20 seconds has passed
    110                long timediff = 0;
    111                while ( in_use.size() == getMaxInstances() && timediff < 20000 ) {
    112                    Thread.sleep( 100 );
    113                    timediff += 100;
    114                }
    115                // if no instance has been released within 20 seconds
    116                // or can newly be instantiated return null
    117                if ( timediff >= 20000 )
    118                    return null;
    119
    120                // if a none used is available from the pool
    121                if ( available.size() > 0 ) {
    122
    123                    // get/remove ojebct from the pool
    124                    Object o = available.remove( available.size() - 1 );
    125                    if ( ( (Connection) o ).isClosed() ) {
    126                        startLifeTime.remove( o );
    127                        o = acquireObject();
    128                    }
    129
    130                    // add it to 'in use' container
    131                    if ( !in_use.contains( o ) )
    132                        in_use.add( o );
    133
    134                    // reset its start life time
    135                    startLifeTime.put( o, new Long( System.currentTimeMillis() ) );
    136                    // set the start of its usage
    137                    startUsageTime.put( o, new Long( System.currentTimeMillis() ) );
    138
    139                    // return the object
    140                    return o;
    141
    142                }
    143                // else instatiate a new object
    144                // create a new class instance
    145                DriverManager.registerDriver( (Driver) Class.forName( driver ).newInstance() );
    146
    147                Properties prop = (Properties) properties.clone();
    148                Object connection = DriverManager.getConnection( database, prop );
    149
    150                existingInstances++;
    151
    152                // add it to 'in use' container
    153                in_use.add( connection );
    154                // set the start of its life time
    155                startLifeTime.put( connection, new Long( System.currentTimeMillis() ) );
    156                // set the start of its usage
    157                startUsageTime.put( connection, new Long( System.currentTimeMillis() ) );
    158                // return the object
    159                return connection;
    160            } catch ( Exception e ) {
    161                e.printStackTrace();
    162                throw new DBPoolException( "Error while acquiring connection: " + e.getMessage(), e );
    163            }
    164        }
    165
    166        /**
    167         * will be called when the object is removed from the pool
    168         *
    169         * @param o
    170         */
    171        @Override
    172        public void onObjectKill( Object o ) {
    173            try {
    174                ( (Connection) o ).close();
    175            } catch ( SQLException e ) {
    176                // which is a bad thing
    177            }
    178        }
    179
    180    }