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ActiveMQ example source code file (OrderBasedMessageBuffer.java)

This example ActiveMQ source code file (OrderBasedMessageBuffer.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

iterator, linkedlist, linkedlist, messagebuffer, messagequeue, messagequeue, object, object, orderbasedmessagebuffer, orderbasedmessagebuffer, util

The ActiveMQ OrderBasedMessageBuffer.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.memory.buffer;

import java.util.Iterator;
import java.util.LinkedList;

/**
 * A {@link MessageBuffer} which evicts messages in arrival order so the oldest
 * messages are removed first.
 * 
 * 
 */
public class OrderBasedMessageBuffer implements MessageBuffer {

    private int limit = 100 * 64 * 1024;
    private LinkedList<MessageQueue> list = new LinkedList();
    private int size;
    private Object lock = new Object();

    public OrderBasedMessageBuffer() {
    }

    public OrderBasedMessageBuffer(int limit) {
        this.limit = limit;
    }

    public int getSize() {
        synchronized (lock) {
            return size;
        }
    }

    /**
     * Creates a new message queue instance
     */
    public MessageQueue createMessageQueue() {
        return new MessageQueue(this);
    }

    /**
     * After a message queue has changed we may need to perform some evictions
     * 
     * @param delta
     * @param queueSize
     */
    public void onSizeChanged(MessageQueue queue, int delta, int queueSize) {
        synchronized (lock) {
            list.addLast(queue);
            size += delta;
            while (size > limit) {
                MessageQueue biggest = list.removeFirst();
                size -= biggest.evictMessage();
            }
        }
    }

    public void clear() {
        synchronized (lock) {
            for (Iterator<MessageQueue> iter = list.iterator(); iter.hasNext();) {
                MessageQueue queue = iter.next();
                queue.clear();
            }
            size = 0;
        }
    }

}

Other ActiveMQ examples (source code examples)

Here is a short list of links related to this ActiveMQ OrderBasedMessageBuffer.java source code file:

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