001/*
002 * HA-JDBC: High-Availability JDBC
003 * Copyright (C) 2012  Paul Ferraro
004 *
005 * This program is free software: you can redistribute it and/or modify
006 * it under the terms of the GNU Lesser General Public License as published by
007 * the Free Software Foundation, either version 3 of the License, or
008 * (at your option) any later version.
009 *
010 * This program is distributed in the hope that it will be useful,
011 * but WITHOUT ANY WARRANTY; without even the implied warranty of
012 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
013 * GNU Lesser General Public License for more details.
014 *
015 * You should have received a copy of the GNU Lesser General Public License
016 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
017 */
018package net.sf.hajdbc.cache.eager;
019
020import java.sql.Connection;
021import java.sql.DatabaseMetaData;
022import java.sql.SQLException;
023
024import net.sf.hajdbc.Database;
025import net.sf.hajdbc.DatabaseCluster;
026import net.sf.hajdbc.DatabaseProperties;
027import net.sf.hajdbc.Messages;
028import net.sf.hajdbc.cache.DatabaseMetaDataCache;
029import net.sf.hajdbc.dialect.Dialect;
030
031/**
032 * DatabaseMetaDataCache implementation that eagerly caches data when first flushed.
033 * To be used when performance more of a concern than memory usage.
034 * 
035 * @author Paul Ferraro
036 * @since 2.0
037 */
038public class SharedEagerDatabaseMetaDataCache<Z, D extends Database<Z>> implements DatabaseMetaDataCache<Z, D>
039{
040        private final DatabaseCluster<Z, D> cluster;
041
042        private volatile DatabaseProperties properties;
043        
044        public SharedEagerDatabaseMetaDataCache(DatabaseCluster<Z, D> cluster)
045        {
046                this.cluster = cluster;
047        }
048        
049        /**
050         * @see net.sf.hajdbc.cache.DatabaseMetaDataCache#flush()
051         */
052        @Override
053        public void flush() throws SQLException
054        {
055                D database = this.cluster.getBalancer().next();
056                
057                if (database == null)
058                {
059                        throw new SQLException(Messages.NO_ACTIVE_DATABASES.getMessage());
060                }
061                
062                this.setDatabaseProperties(database.connect(database.getConnectionSource(), database.decodePassword(this.cluster.getDecoder())));
063        }
064
065        /**
066         * {@inheritDoc}
067         * @see net.sf.hajdbc.cache.DatabaseMetaDataCache#getDatabaseProperties(net.sf.hajdbc.Database, java.sql.Connection)
068         */
069        @Override
070        public synchronized DatabaseProperties getDatabaseProperties(D database, Connection connection) throws SQLException
071        {
072                if (this.properties == null)
073                {
074                        this.setDatabaseProperties(connection);
075                }
076                
077                return this.properties;
078        }
079        
080        private synchronized void setDatabaseProperties(Connection connection) throws SQLException
081        {
082                DatabaseMetaData metaData = connection.getMetaData();
083                Dialect dialect = this.cluster.getDialect();
084                this.properties = new EagerDatabaseProperties(metaData, dialect);
085        }
086}