/**
*
* 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;
import org.activemq.message.Packet;
import org.activemq.util.BitArrayBin;
import org.activemq.util.IdGenerator;
import org.activemq.util.LRUCache;
import javax.jms.JMSException;
import javax.jms.Message;
import java.util.LinkedHashMap;
/**
* Provides basic audit functions for Messages
*
* @version $Revision: 1.1.1.1 $
*/
public class ActiveMQMessageAudit {
private static final int DEFAULT_WINDOW_SIZE = 1024;
private static final int MAXIMUM_PRODUCER_COUNT = 128;
private int windowSize;
private LinkedHashMap map;
/**
* Default Constructor windowSize = 1024, maximumNumberOfProducersToTrack = 128
*/
public ActiveMQMessageAudit() {
this(DEFAULT_WINDOW_SIZE, MAXIMUM_PRODUCER_COUNT);
}
/**
* Construct a MessageAudit
*
* @param windowSize range of ids to track
* @param maximumNumberOfProducersToTrack
* number of producers expected in the system
*/
public ActiveMQMessageAudit(int windowSize, final int maximumNumberOfProducersToTrack) {
this.windowSize = windowSize;
map = new LRUCache(maximumNumberOfProducersToTrack);
}
/**
* Checks if this message has beeb seen before
*
* @param message
* @return true if the message is a duplicate
* @throws JMSException
*/
public boolean isDuplicate(Message message) throws JMSException {
return isDuplicate(message.getJMSMessageID());
}
/**
* checks whether this messageId has been seen before and adds this messageId to the list
*
* @param id
* @return true if the message is a duplicate
*/
public boolean isDuplicate(String id) {
boolean answer = false;
String seed = IdGenerator.getSeedFromId(id);
if (seed != null) {
BitArrayBin bab = (BitArrayBin) map.get(seed);
if (bab == null) {
bab = new BitArrayBin(windowSize);
map.put(seed, bab);
}
long index = IdGenerator.getCountFromId(id);
if (index >= 0) {
answer = bab.setBit(index, true);
}
}
return answer;
}
}