Java tutorial
/* * StreamCruncher: Copyright (c) 2006-2008, Ashwin Jayaprakash. All Rights Reserved. * Contact: ashwin {dot} jayaprakash {at} gmail {dot} com * Web: http://www.StreamCruncher.com * * This file is part of StreamCruncher. * * StreamCruncher is free software: you can redistribute it and/or modify * it under the terms of the GNU Lesser General Public License as published by * the Free Software Foundation, either version 3 of the License, or * (at your option) any later version. * * StreamCruncher 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 Lesser General Public License for more details. * * You should have received a copy of the GNU Lesser General Public License * along with StreamCruncher. If not, see <http://www.gnu.org/licenses/>. */ package streamcruncher.innards.db; import java.sql.Connection; import java.sql.ResultSet; import java.sql.SQLException; import java.util.Properties; import java.util.Timer; import java.util.TimerTask; import java.util.concurrent.atomic.AtomicLong; import java.util.logging.Level; import java.util.logging.Logger; import org.apache.commons.dbcp.BasicDataSource; import streamcruncher.api.DBName; import streamcruncher.api.artifact.IndexSpec; import streamcruncher.api.artifact.MiscSpec; import streamcruncher.api.artifact.RowSpec; import streamcruncher.api.artifact.TableSpec; import streamcruncher.boot.Component; import streamcruncher.boot.ConfigKeys; import streamcruncher.boot.Registry; import streamcruncher.innards.core.partition.aggregate.AbstractAggregatedColumnDDLHelper; import streamcruncher.innards.impl.query.DDLHelper; import streamcruncher.innards.query.Parser; import streamcruncher.innards.util.Helper; import streamcruncher.util.AtomicX; import streamcruncher.util.LoggerManager; import streamcruncher.util.sysevent.SystemEvent; import streamcruncher.util.sysevent.SystemEventBus; import streamcruncher.util.sysevent.SystemEvent.Priority; /* * Author: Ashwin Jayaprakash Date: Jan 2, 2006 Time: 9:40:59 AM */ public abstract class DatabaseInterface implements Component { protected Properties properties; protected BasicDataSource dataSource; protected String schema; protected boolean preservesArtifactsOnShutdown; protected boolean privateVolatileInstance; /** * Auto-commit is <code>false</code>. */ protected Connection sentinelConnection; protected Timer sentinelConnectionKeeper; // --------------------- /** * {@inheritDoc} <code>params</code> requires the first parameter to be a * {@link java.util.Properties} object loaded with the necessary Database * properties. */ public void start(Object... params) throws Exception { this.properties = (Properties) params[0]; String driver = properties.getProperty(ConfigKeys.DB.DRIVER_CLASS_NAME); String url = properties.getProperty(ConfigKeys.DB.DRIVER_URL); String user = properties.getProperty(ConfigKeys.DB.USER); String password = properties.getProperty(ConfigKeys.DB.PASSWORD); Class.forName(driver); // ---------------------- schema = properties.getProperty(ConfigKeys.DB.SCHEMA); if (schema != null && schema.length() == 0) { schema = null; } String preservesArtifactsStr = properties.getProperty(ConfigKeys.DB.PRESERVES_ARTIFACTS_ON_SHUTDOWN); preservesArtifactsOnShutdown = Boolean.parseBoolean(preservesArtifactsStr); String maxPoolSizeStr = properties.getProperty(ConfigKeys.DB.CONNECTION_POOL_MAX_SIZE); int maxPoolSize = Integer.parseInt(maxPoolSizeStr); String privateVolatileInstanceStr = properties.getProperty(ConfigKeys.DB.PRIVATE_VOLATILE_INSTANCE); privateVolatileInstance = Boolean.parseBoolean(privateVolatileInstanceStr); dataSource = new BasicDataSource(); dataSource.setDriverClassName(driver); dataSource.setUrl(url); dataSource.setUsername(user); dataSource.setPassword(password); dataSource.setMaxActive(maxPoolSize); dataSource.setMaxIdle(maxPoolSize); dataSource.setTestOnBorrow(false); dataSource.setTestOnReturn(false); dataSource.setTimeBetweenEvictionRunsMillis(2 * 60 * 1000); dataSource.setMinEvictableIdleTimeMillis(30 * 1000); dataSource.setAccessToUnderlyingConnectionAllowed(true); dataSource.setPoolPreparedStatements(true); setupLastStandingConnection(); // ---------------------- Logger logger = Registry.getImplFor(LoggerManager.class).getLogger(DatabaseInterface.class.getName()); logger.log(Level.INFO, "Started"); } private void setupLastStandingConnection() throws SQLException { if (privateVolatileInstance == true) { sentinelConnection = createConnection(); sentinelConnection.setAutoCommit(false); sentinelConnectionKeeper = new Timer("SentinelConnectionKeeper", true); /* * Keep checking periodically and ensure that the sentinelConnection * does not timeout. */ TimerTask timerTask = new TimerTask() { @Override public void run() { boolean isClosed = false; Throwable error = null; try { isClosed = DatabaseInterface.this.sentinelConnection.isClosed(); } catch (SQLException e1) { error = e1; } if (error != null || isClosed) { Logger logger = Registry.getImplFor(LoggerManager.class) .getLogger(DatabaseInterface.class.getName()); String msg = "The Private/Volatile Database instance may be at" + " risk, because the sentinel Connection has been lost."; if (error == null) { logger.log(Level.SEVERE, msg); } else { logger.log(Level.SEVERE, msg, error); } SystemEventBus bus = Registry.getImplFor(SystemEventBus.class); SystemEvent event = new SystemEvent(DatabaseInterface.class.getName(), "Sentinel Connection Lost", error, Priority.SEVERE); bus.submit(event); // ----------- // Try and create a new one. try { Timer oldTimer = DatabaseInterface.this.sentinelConnectionKeeper; DatabaseInterface.this.setupLastStandingConnection(); // Cancel this old timer. oldTimer.cancel(); } catch (SQLException e) { logger.log(Level.SEVERE, "An error occurred while the sentinel" + " Connection was being re-created.", e); event = new SystemEvent(DatabaseInterface.class.getName(), "Sentinel Connection Re-creation Error", null, Priority.SEVERE); bus.submit(event); return; } } // ------------ try { DatabaseInterface.this.sentinelConnection.commit(); } catch (SQLException e) { Logger logger = Registry.getImplFor(LoggerManager.class) .getLogger(DatabaseInterface.class.getName()); logger.log(Level.SEVERE, "An error occurred while the sentinel" + " Connection was pinging the Database.", e); SystemEventBus bus = Registry.getImplFor(SystemEventBus.class); SystemEvent event = new SystemEvent(DatabaseInterface.class.getName(), "Sentinel Connection Ping Error", null, Priority.SEVERE); bus.submit(event); } } }; sentinelConnectionKeeper.scheduleAtFixedRate(timerTask, 10 * 1000, 30 * 1000); } } public void stop() throws Exception { if (privateVolatileInstance == true) { sentinelConnectionKeeper.cancel(); /* * Hold on to this until the very end. Otherwise, the In-mem DBs * will shutdown. */ Helper.closeConnection(sentinelConnection); sentinelConnection = null; } dataSource.close(); dataSource = null; // --------------------- Logger logger = Registry.getImplFor(LoggerManager.class).getLogger(DatabaseInterface.class.getName()); logger.log(Level.INFO, "Stopped"); } // --------------------- public Connection createConnection() throws SQLException { return dataSource.getConnection(); } // --------------------- public abstract Class<? extends Parser> getParser(); public abstract DBName getDBName(); public String getSchema() { return schema; } public abstract AbstractAggregatedColumnDDLHelper getAggregatedColumnDDLHelper(); public abstract DDLHelper getDDLHelper(); public TableSpec createUnpartitionedTableSpec(String schema, String name, RowSpec rowSpec, IndexSpec[] indexSpecs, MiscSpec[] otherClauses) { return new TableSpec(schema, name, rowSpec, indexSpecs, otherClauses); } public IndexSpec createIndexSpec(String schema, String name, String tableName, boolean unique, String columnName, boolean ascending) { return new IndexSpec(schema, name, tableName, unique, columnName, ascending); } public IndexSpec createIndexSpec(String schema, String name, String tableName, boolean unique, String[] columnNames, boolean[] ascending) { return new IndexSpec(schema, name, tableName, unique, columnNames, ascending); } public boolean dbPreservesArtifactsOnShutdown() { return preservesArtifactsOnShutdown; } public AtomicX createRowIdGenerator() { return new AtomicX(new AtomicLong(Constants.DEFAULT_MONOTONIC_ID_VALUE)); } public ResultSet wrapResultSet(ResultSet resultSet) throws SQLException { return resultSet; } }