/**
*
* Copyright 2004 Protique Ltd
*
* 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.
*
**/
package org.activemq.store.bdb;
import com.sleepycat.je.CursorConfig;
import com.sleepycat.je.DatabaseEntry;
import com.sleepycat.je.DatabaseException;
import com.sleepycat.je.LockMode;
import com.sleepycat.je.OperationStatus;
import com.sleepycat.je.SecondaryCursor;
import com.sleepycat.je.SecondaryDatabase;
import com.sleepycat.je.SecondaryKeyCreator;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import javax.jms.JMSException;
/**
* @version $Revision: 1.1 $
*/
public class SequenceNumberCreator implements SecondaryKeyCreator {
private static final Log log = LogFactory.getLog(SequenceNumberCreator.class);
private long counter = 1;
private ThreadLocal lastKeyStore = new ThreadLocal();
private ThreadLocal deleteKeyStore = new ThreadLocal();
public synchronized void initialise(SecondaryDatabase database) throws JMSException, DatabaseException {
// lets calculate the size
counter = queryLatestKeyInDatabase(database);
}
public boolean createSecondaryKey(SecondaryDatabase secondaryDatabase, DatabaseEntry keyEntry, DatabaseEntry valueEntry, DatabaseEntry resultEntry) throws DatabaseException {
DatabaseEntry nextKey = (DatabaseEntry) deleteKeyStore.get();
if (nextKey != null) {
resultEntry.setData(nextKey.getData());
deleteKeyStore.set(null);
}
else {
long value = 1;
synchronized (this) {
value = ++counter;
}
//System.out.println("Creating new counter key of value: " + value);
resultEntry.setData(BDbHelper.asBytes(value));
}
lastKeyStore.set(resultEntry);
return true;
}
/**
* @return the last primary key we created
*/
public DatabaseEntry getLastKey() {
return (DatabaseEntry) lastKeyStore.get();
}
/**
* Sets the next primary key to return, such as doing a delete
*
* @param nextKey
*/
public void setDeleteKey(DatabaseEntry nextKey) {
this.deleteKeyStore.set(nextKey);
}
protected long queryLatestKeyInDatabase(SecondaryDatabase database) throws JMSException, DatabaseException {
CursorConfig cursorConfig = null;
SecondaryCursor cursor = null;
try {
cursor = database.openSecondaryCursor(BDbHelper.getTransaction(), cursorConfig);
DatabaseEntry sequenceNumberEntry = new DatabaseEntry();
DatabaseEntry keyEntry = new DatabaseEntry();
DatabaseEntry valueEntry = new DatabaseEntry();
OperationStatus status = cursor.getLast(sequenceNumberEntry, keyEntry, valueEntry, LockMode.DEFAULT);
long answer = 1;
if (status != OperationStatus.NOTFOUND) {
if (status == OperationStatus.SUCCESS) {
answer = extractLong(sequenceNumberEntry);
}
else {
throw new JMSException("Invalid status code: " + status + " cannot read last sequence number");
}
}
return answer;
}
finally {
if (cursor != null) {
try {
cursor.close();
}
catch (DatabaseException e) {
log.warn("Error closing cursor: " + e, e);
}
}
}
}
protected long extractLong(DatabaseEntry entry) {
return BDbHelper.longFromBytes(entry.getData());
}
}