/*  * Copyright 2004-2005 OpenSymphony  *  * Licensed under the Apache License, Version 2.0 (the "License"); you may not  * use this file except in compliance with the License. You may obtain a copy  * of the License at  *  *   http://www.apache.org/licenses/LICENSE-2.0  *    * Unless required by applicable law or agreed to in writing, software  * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT  * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the  * License for the specific language governing permissions and limitations  * under the License. *  *//* * Previously Copyright (c) 2001-2004 James House */package org.quartz.impl.jdbcjobstore;import java.sql.Connection;import java.sql.PreparedStatement;import java.sql.ResultSet;import java.sql.SQLException;/** * Internal database based lock handler for providing thread/resource locking  * in order to protect resources from being altered by multiple threads at the  * same time. *  * @author jhouse */public class StdRowLockSemaphore extends DBSemaphore {    /*     * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~     *      * Constants.     *      * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~     */    public static final String SELECT_FOR_LOCK = "SELECT * FROM "            + TABLE_PREFIX_SUBST + TABLE_LOCKS + " WHERE " + COL_LOCK_NAME            + " = ? FOR UPDATE";    /*     * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~     *      * Constructors.     *      * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~     */    /**     * This constructor is for using the <code>StdRowLockSemaphore</code> as     * a bean.     */    public StdRowLockSemaphore() {        super(DEFAULT_TABLE_PREFIX, null, SELECT_FOR_LOCK);    }        public StdRowLockSemaphore(String tablePrefix, String selectWithLockSQL) {        super(tablePrefix, selectWithLockSQL, SELECT_FOR_LOCK);    }    /*     * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~     *      * Interface.     *      * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~     */    /**     * Execute the SQL select for update that will lock the proper database row.     */    protected void executeSQL(Connection conn, String lockName, String expandedSQL) throws LockException {        PreparedStatement ps = null;        ResultSet rs = null;        try {            ps = conn.prepareStatement(expandedSQL);            ps.setString(1, lockName);                        if (getLog().isDebugEnabled()) {                getLog().debug(                    "Lock '" + lockName + "' is being obtained: " +                     Thread.currentThread().getName());            }            rs = ps.executeQuery();            if (!rs.next()) {                throw new SQLException(Util.rtp(                    "No row exists in table " + TABLE_PREFIX_SUBST +                     TABLE_LOCKS + " for lock named: " + lockName, getTablePrefix()));            }        } catch (SQLException sqle) {            //Exception src =            // (Exception)getThreadLocksObtainer().get(lockName);            //if(src != null)            //  src.printStackTrace();            //else            //  System.err.println("--- ***************** NO OBTAINER!");            if (getLog().isDebugEnabled()) {                getLog().debug(                    "Lock '" + lockName + "' was not obtained by: " +                     Thread.currentThread().getName());            }                        throw new LockException("Failure obtaining db row lock: "                    + sqle.getMessage(), sqle);        } finally {            if (rs != null) {                 try {                    rs.close();                } catch (Exception ignore) {                }            }            if (ps != null) {                try {                    ps.close();                } catch (Exception ignore) {                }            }        }    }    protected String getSelectWithLockSQL() {        return getSQL();    }    public void setSelectWithLockSQL(String selectWithLockSQL) {        setSQL(selectWithLockSQL);    }}