ActiveMQ example source code file (FixedCountSubscriptionRecoveryPolicy.java)

This example ActiveMQ source code file (FixedCountSubscriptionRecoveryPolicy.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" ^TM.

Java - ActiveMQ tags/keywords

arraylist, destinationfilter, exception, exception, fixedcountsubscriptionrecoverypolicy, fixedcountsubscriptionrecoverypolicy, list, message, message, messagereference, messagereference, subscriptionrecovery, subscriptionrecoverypolicy, topic, util

The ActiveMQ FixedCountSubscriptionRecoveryPolicy.java source code

/**
 * 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.Broker;
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
 * 
 */
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<Message> 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()]);
    }

    public void setBroker(Broker broker) {        
    }

}