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/**
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You 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.apache.activemq.broker.region.policy;
import java.util.ArrayList;
import java.util.List;
import org.apache.activemq.broker.ConnectionContext;
import org.apache.activemq.broker.region.MessageReference;
import org.apache.activemq.broker.region.SubscriptionRecovery;
import org.apache.activemq.broker.region.Topic;
import org.apache.activemq.command.ActiveMQDestination;
import org.apache.activemq.command.Message;
import org.apache.activemq.filter.DestinationFilter;
/**
* This implementation of {@link SubscriptionRecoveryPolicy} will keep a fixed
* count of last messages.
*
* @org.apache.xbean.XBean
* @version $Revision$
*/
public class FixedCountSubscriptionRecoveryPolicy implements SubscriptionRecoveryPolicy {
private volatile MessageReference messages[];
private int maximumSize = 100;
private int tail;
public SubscriptionRecoveryPolicy copy() {
FixedCountSubscriptionRecoveryPolicy rc = new FixedCountSubscriptionRecoveryPolicy();
rc.setMaximumSize(maximumSize);
return rc;
}
public synchronized boolean add(ConnectionContext context, MessageReference node) throws Exception {
messages[tail++] = node;
if (tail >= messages.length) {
tail = 0;
}
return true;
}
public synchronized void recover(ConnectionContext context, Topic topic, SubscriptionRecovery sub) throws Exception {
// Re-dispatch the last message seen.
int t = tail;
// The buffer may not have rolled over yet..., start from the front
if (messages[t] == null) {
t = 0;
}
// Well the buffer is really empty then.
if (messages[t] == null) {
return;
}
// Keep dispatching until t hit's tail again.
do {
MessageReference node = messages[t];
sub.addRecoveredMessage(context, node);
t++;
if (t >= messages.length) {
t = 0;
}
} while (t != tail);
}
public void start() throws Exception {
messages = new MessageReference[maximumSize];
}
public void stop() throws Exception {
messages = null;
}
public int getMaximumSize() {
return maximumSize;
}
/**
* Sets the maximum number of messages that this destination will hold
* around in RAM
*/
public void setMaximumSize(int maximumSize) {
this.maximumSize = maximumSize;
}
public synchronized Message[] browse(ActiveMQDestination destination) throws Exception {
List result = new ArrayList();
DestinationFilter filter = DestinationFilter.parseFilter(destination);
int t = tail;
if (messages[t] == null) {
t = 0;
}
if (messages[t] != null) {
do {
MessageReference ref = messages[t];
Message message = ref.getMessage();
if (filter.matches(message.getDestination())) {
result.add(message);
}
t++;
if (t >= messages.length) {
t = 0;
}
} while (t != tail);
}
return result.toArray(new Message[result.size()]);
}
}