org.apache.activemq.memory.buffer.OrderBasedMessageBuffer Maven / Gradle / Ivy
/**
* 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 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 iter = list.iterator(); iter.hasNext();) {
MessageQueue queue = iter.next();
queue.clear();
}
size = 0;
}
}
}