Java tutorial
/* * NOTE: This copyright does *not* cover user programs that use HQ * program services by normal system calls through the application * program interfaces provided as part of the Hyperic Plug-in Development * Kit or the Hyperic Client Development Kit - this is merely considered * normal use of the program, and does *not* fall under the heading of * "derived work". * * Copyright (C) [2004, 2005, 2006], Hyperic, Inc. * This file is part of HQ. * * HQ is free software; you can redistribute it and/or modify * it under the terms version 2 of the GNU General Public License as * published by the Free Software Foundation. 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, write to the Free Software * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 * USA. */ package org.hyperic.hq.product; import java.security.MessageDigest; import java.sql.Connection; import java.sql.ResultSet; import java.sql.ResultSetMetaData; import java.sql.SQLException; import java.sql.Statement; import java.util.ArrayList; import java.util.HashMap; import java.util.Iterator; import java.util.List; import java.util.Map.Entry; import java.util.Properties; import java.util.Queue; import java.util.Set; import java.util.Timer; import java.util.TimerTask; import java.util.concurrent.ConcurrentLinkedQueue; import org.apache.commons.logging.Log; import org.apache.commons.logging.LogFactory; import org.hyperic.util.config.ConfigResponse; import org.hyperic.util.config.ConfigSchema; import org.hyperic.util.config.SchemaBuilder; import org.hyperic.util.jdbc.DBUtil; /** * Base class for JDBC measurement plugins. * Abstracts the JDBC connection and query functionality. */ public abstract class JDBCMeasurementPlugin extends MeasurementPlugin { private static Log log = LogFactory.getLog(JDBCMeasurementPlugin.class); protected static final String AVAIL_ATTR = "availability"; public static final String PROP_URL = "jdbcUrl"; public static final String PROP_USER = "jdbcUser"; public static final String PROP_PASSWORD = "jdbcPassword"; public static final String PROP_TABLE = "table"; public static final String PROP_INDEX = "index"; private static final String USER_KEY = "user"; private static final String PASSWORD_KEY = "password"; public static final int COL_INVALID = 0; private static long FIVE_MINUTES_MILLIS = 5 * 60 * 1000; protected String _sqlLog; private Double _data; private HashMap _colMap = new HashMap(), _valMap = new HashMap(); private int _numRows; private final static HashMap<String, Queue> connectionPools = new HashMap<String, Queue>(); private final static Timer poolsShrinkTimer = new Timer("JDBCMeasurementPlugin.poolsShrink"); static { poolsShrinkTimer.scheduleAtFixedRate(new TimerTask() { @Override public void run() { log.debug("[poolsShrink] run"); Set<Entry<String, Queue>> pools = connectionPools.entrySet(); Iterator<Entry<String, Queue>> it = pools.iterator(); while (it.hasNext()) { Entry<String, Queue> entry = it.next(); Queue<Connection> pool = entry.getValue(); if (pool.size() > 1) { log.debug("[poolsShrink] '" + entry.getKey() + "' pool.size()=" + pool.size()); while (pool.size() > 1) { Connection conn = pool.poll(); DBUtil.closeJDBCObjects(log, conn, null, null); } } } } }, FIVE_MINUTES_MILLIS, FIVE_MINUTES_MILLIS); } /** * Config schema includes jdbc URL, database username and password. * These values will be used to obtain a connection from * DriverManager.getConnection. */ public ConfigSchema getConfigSchema(TypeInfo info, ConfigResponse config) { ConfigSchema schema = super.getConfigSchema(info, config); if (schema.getOptions().size() > 0) { return schema; //from hq-plugin.xml } SchemaBuilder builder = new SchemaBuilder(config); builder.add(PROP_URL, "JDBC URL", getDefaultURL()); builder.add(PROP_USER, "Database username", "username"); builder.addSecret(PROP_PASSWORD, "Database password").setOptional(true); return builder.getSchema(); } /** * Verifies that JDBC driver returned by the getDriver() method * can be loaded by the plugin. */ public void init(PluginManager manager) throws PluginException { super.init(manager); try { getDriver(); } catch (ClassNotFoundException e) { //driver is not loaded server-side //if the above fails client-side queries will fail with //"No suitable driver" so its okay to swallow this exception //throw new PluginException(e.getMessage(), e); } } /** * Close any cached connections. */ public void shutdown() throws PluginException { super.shutdown(); poolsShrinkTimer.cancel(); synchronized (connectionPools) { Set<Entry<String, Queue>> pools = connectionPools.entrySet(); Iterator<Entry<String, Queue>> it = pools.iterator(); while (it.hasNext()) { Entry<String, Queue> entry = it.next(); Queue<Connection> pool = entry.getValue(); Connection conn; while ((conn = pool.poll()) != null) { DBUtil.closeJDBCObjects(log, conn, null, null); } } connectionPools.clear(); } } /** * Dispatches to getQueryValue() */ public MetricValue getValue(Metric metric) throws PluginException, MetricUnreachableException, MetricInvalidException, MetricNotFoundException { double value = getQueryValue(metric); MetricValue mValue = new MetricValue(value, System.currentTimeMillis()); return mValue; } protected abstract void initQueries(); protected abstract String getQuery(Metric jdsn); /** * The plugin must preform the Class.forName so its * ClassLoader is used to find the driver. */ protected abstract void getDriver() throws ClassNotFoundException; /** * The plugin must preform the DriverManager.getConnection so its * ClassLoader is used to find the driver. */ protected abstract Connection getConnection(String url, String user, String password) throws SQLException; protected abstract String getDefaultURL(); /** * The column in the ResultSet that holds the measurement value. * For most plugins this will be 1, by some databases do not allow * a ResultSet with a single column to be returned (see MySQL) */ protected int getColumn(Metric jdsn) { return 1; } protected String getColumnName(Metric jdsn) { return ""; } protected Connection getCachedConnection(Metric metric) throws SQLException { Properties props = metric.getProperties(); String url = props.getProperty(PROP_URL), user = props.getProperty(PROP_USER), pass = props.getProperty(PROP_PASSWORD); return getCachedConnection(url, user, pass); } private static String calculateKey(String url, String user, String pass) { if (pass == null) { pass = ""; } try { MessageDigest md = MessageDigest.getInstance("MD5"); byte[] thedigest = md.digest(pass.getBytes("UTF-8")); pass = new String(thedigest, "UTF-8"); } catch (Exception ex) { log.debug(ex, ex); } String cacheKey = url + ":" + pass + "@" + user; return cacheKey; } protected Connection getCachedConnection(String url, String user, String pass) throws SQLException { String cacheKey = calculateKey(url, user, pass); Connection conn; Queue<Connection> pool; synchronized (connectionPools) { pool = connectionPools.get(cacheKey); if (pool == null) { pool = new ConcurrentLinkedQueue<Connection>(); connectionPools.put(cacheKey, pool); log.debug("[getCC] Pool for '" + cacheKey + "' created"); } } int count = 0; while (((conn = pool.poll()) == null) && (count++ < 5)) { try { Thread.sleep(100); } catch (InterruptedException ex) { log.error(ex, ex); } } if (conn == null) { conn = getConnection(url, user, pass); log.debug("[getCC] Connection for '" + cacheKey + "' created (pool.size=" + pool.size() + ")"); } log.debug("[getCC] Connection for '" + cacheKey + "' used (pool.size=" + pool.size() + ")"); return conn; } protected void removeCachedConnection(String url, String user, String pass) { String cacheKey = calculateKey(url, user, pass); Queue<Connection> pool = connectionPools.get(cacheKey); if (pool != null) { Connection conn; while ((conn = pool.poll()) != null) { DBUtil.closeJDBCObjects(log, conn, null, null); log.debug("[remCC] Connection for '" + cacheKey + "' closed (pool.size=" + pool.size() + ")"); } connectionPools.remove(cacheKey); } else { log.debug("[remCC] Pool for '" + cacheKey + "' not found"); } } protected void returnCachedConnection(String url, String user, String pass, Connection conn) { String cacheKey = calculateKey(url, user, pass); Queue<Connection> pool = connectionPools.get(cacheKey); if (pool != null) { pool.add(conn); log.debug("[retCC] Connection for '" + cacheKey + "' returned (pool.size=" + pool.size() + ")"); } else { DBUtil.closeJDBCObjects(log, conn, null, null); log.debug("[retCC] Pool for '" + cacheKey + "' not found, closing connection"); } } /** * Do the database query returned by the getQuery() method * and return the result. A cached connection will be used * if one exists, otherwise the created connection will be * cached for future use. */ protected double getQueryValue(Metric jdsn) throws MetricNotFoundException, PluginException, MetricUnreachableException { return getQueryValue(jdsn, false); } protected double getQueryValue(Metric jdsn, boolean logSql) throws MetricNotFoundException, PluginException, MetricUnreachableException { initQueries(); String query = getQuery(jdsn); String attr = jdsn.getAttributeName(); if (query == null) { //plugin bug or hq-plugin.xml typo bug String msg = "No SQL query mapped to: " + attr; throw new PluginException(msg); } //ignore case to allow the stanard case "Availability" boolean isAvail = attr.equalsIgnoreCase(AVAIL_ATTR); Properties props = jdsn.getProperties(); String url = props.getProperty(PROP_URL), user = props.getProperty(PROP_USER), pass = props.getProperty(PROP_PASSWORD); Connection conn = null; Statement stmt = null; ResultSet rs = null; try { conn = getCachedConnection(url, user, pass); stmt = conn.createStatement(); stmt.execute(query); // If the query executed without error, we don't care if any // results were returned. if (isAvail) { return Metric.AVAIL_UP; } int column = getColumn(jdsn); if (logSql) { _data = null; _sqlLog = getSqlRow(stmt); } else if (column != COL_INVALID) { rs = stmt.getResultSet(); if (rs != null && rs.next()) { return rs.getDouble(column); } else { throw new MetricNotFoundException(attr); } } if (_data != null) { return _data.doubleValue(); } return rs.getDouble(getColumnName(jdsn)); } catch (SQLException e) { // Remove this connection from the cache. removeCachedConnection(url, user, pass); if (isAvail) { log.debug("AVAIL_DOWN", e); return Metric.AVAIL_DOWN; } String msg = "Query failed for " + attr + ", while attempting to issue query " + query + ":" + e.getMessage(); //XXX these two are oracle specific. // Catch divide by 0 errors and return 0 if (e.getErrorCode() == DBUtil.ORACLE_ERROR_DIVIDE_BY_ZERO || e.getErrorCode() == DBUtil.POSTGRES_ERROR_DIVIDE_BY_ZERO) return 0; if (e.getErrorCode() == DBUtil.ORACLE_ERROR_NOT_AVAILABLE || e.getErrorCode() == DBUtil.POSTGRES_CONNECTION_EXCEPTION || e.getErrorCode() == DBUtil.POSTGRES_CONNECTION_FAILURE || e.getErrorCode() == DBUtil.POSTGRES_UNABLE_TO_CONNECT || e.getErrorCode() == DBUtil.MYSQL_LOCAL_CONN_ERROR || e.getErrorCode() == DBUtil.MYSQL_REMOTE_CONN_ERROR) throw new MetricUnreachableException(msg, e); throw new MetricNotFoundException(msg, e); } finally { returnCachedConnection(url, user, pass, conn); DBUtil.closeJDBCObjects(log, null, stmt, rs); } } private String getSqlRow(Statement stmt) throws SQLException { StringBuffer buf = new StringBuffer(); do { ResultSet rs = stmt.getResultSet(); if (stmt.getUpdateCount() != -1) { continue; } if (rs == null) { break; } setData(rs); buf.append(getOutput(rs.getMetaData())); } while (stmt.getMoreResults() == true); return buf.toString(); } protected void setData(ResultSet rs) throws SQLException { clearObjects(); ResultSetMetaData md = rs.getMetaData(); processColumnHeader(md); processColumns(rs); } private void clearObjects() { _numRows = 0; _colMap.clear(); _valMap.clear(); } protected void processColumnHeader(ResultSetMetaData md) throws SQLException { for (int i = 1; i <= md.getColumnCount(); i++) { Integer ind = new Integer(i); int length = md.getColumnName(i).trim().length(); length = (length == 0) ? 1 : length; _colMap.put(ind, new Integer(length)); _valMap.put(ind, new ArrayList()); } } protected void processColumns(ResultSet rs) throws SQLException { while (rs.next()) { _numRows++; ResultSetMetaData rsmd = rs.getMetaData(); for (int i = 1; i <= rsmd.getColumnCount(); i++) { Integer ind = new Integer(i); String val = null; if (rs.getObject(i) == null) { val = "()"; } else { try { // XXX ignoring BLOBs for now if (rsmd.getColumnType(i) == -2) { } else { val = rs.getString(i).trim(); } if (_data == null) { _data = new Double(val); } } catch (Exception e) { val = ""; } } ((List) _valMap.get(ind)).add(val); if (val.length() > ((Integer) _colMap.get(ind)).intValue()) { _colMap.put(ind, new Integer(val.length())); } } } } private String getOutput(ResultSetMetaData md) throws SQLException { StringBuffer rtn = new StringBuffer(); for (int i = 1; i <= md.getColumnCount(); i++) { rtn.append(md.getColumnName(i)).append("="); for (int j = 0; j < _numRows; j++) { Integer jnd = new Integer(i); String val = ""; if (((List) _valMap.get(jnd)).size() > 0) { val = (String) ((List) _valMap.get(jnd)).remove(0); } rtn.append(val); if (j < (_numRows - 1)) { rtn.append(","); } } rtn.append("::"); } return rtn.toString(); } /** * Utility method that returns an instance of Properties containing the given * user and password keys. The Properties instance returned can be passed in * as the info argument to DriverManager.getConnection(url, info). * * @param user the username for the JDBC connection * @param password the password for the JDBC connection * @return an instance of Properties containing the user and password * JDBC Connection properties */ public static Properties getJDBCConnectionProperties(String user, String password) { Properties info = new Properties(); if (user != null) { info.put(USER_KEY, user); } if (password != null) { info.put(PASSWORD_KEY, password); } return info; } }