/*
* 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.util.jdbc;
import java.sql.SQLException;
import java.util.HashMap;
import org.hyperic.util.ConfigPropertyException;
/**
* This factory is meant to be the central point of access for IDGenerator
* objects used by an application. It will hold the single IDGenerator in a
* private map and reuse it across repeated invocations of getNextId(). It is
* particularly useful for Entity bean scenarios, where multiple instances of an
* IDGenerator result in database row contention and SQL timeouts if more than
* one thread attempts to get a new id from the sequence at the same time.
*/
public class IDGeneratorFactory {
// the map stores a key with the sequence name, and a value of the
// IDGenerator itself
private static HashMap generatorMap = new HashMap();
private static int DEFAULT_INTERVAL = 50;
/**
* Get a new ID from the named sequence, accessible through the named
* datasource string.
* @param ctx - the logging context. Typically the name of the calling
* class
* @param sequenceName - the name of the sequence to retrieve the new id from
* @param dsName - the JNDI name of the datasource
*/
public static long getNextId(String ctx,
String sequenceName,
DBUtil dbUtil)
throws ConfigPropertyException,
SequenceRetrievalException,
SQLException {
IDGenerator theGenerator = getGenerator(ctx, sequenceName, dbUtil);
return theGenerator.getNewID();
}
private static IDGenerator getGenerator(String ctx, String sequenceName,
DBUtil dbUtil)
throws ConfigPropertyException,
SequenceRetrievalException,
SQLException {
IDGenerator result = null;
synchronized (generatorMap) {
result = (IDGenerator) generatorMap.get(sequenceName);
if (result == null) {
result = new IDGenerator(ctx, sequenceName,
DEFAULT_INTERVAL, dbUtil);
generatorMap.put(sequenceName, result);
}
}
return result;
}
}