| /** |
| * 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.ArrayList; |
| import java.util.Iterator; |
| import java.util.LinkedList; |
| import java.util.List; |
| |
| import org.apache.activemq.broker.region.MessageReference; |
| import org.apache.activemq.command.ActiveMQMessage; |
| import org.apache.activemq.command.Message; |
| |
| /** |
| * Allows messages to be added to the end of the buffer such that they are kept |
| * around and evicted in a FIFO manner. |
| * |
| * |
| */ |
| public class MessageQueue { |
| |
| private MessageBuffer buffer; |
| private LinkedList<MessageReference> list = new LinkedList<MessageReference>(); |
| private int size; |
| private Object lock = new Object(); |
| private int position; |
| |
| public MessageQueue(MessageBuffer buffer) { |
| this.buffer = buffer; |
| } |
| |
| public void add(MessageReference messageRef) { |
| Message message = messageRef.getMessageHardRef(); |
| int delta = message.getSize(); |
| int newSize = 0; |
| synchronized (lock) { |
| list.add(messageRef); |
| size += delta; |
| newSize = size; |
| } |
| buffer.onSizeChanged(this, delta, newSize); |
| } |
| |
| public void add(ActiveMQMessage message) { |
| int delta = message.getSize(); |
| int newSize = 0; |
| synchronized (lock) { |
| list.add(message); |
| size += delta; |
| newSize = size; |
| } |
| buffer.onSizeChanged(this, delta, newSize); |
| } |
| |
| public int evictMessage() { |
| synchronized (lock) { |
| if (!list.isEmpty()) { |
| ActiveMQMessage message = (ActiveMQMessage) list.removeFirst(); |
| int messageSize = message.getSize(); |
| size -= messageSize; |
| return messageSize; |
| } |
| } |
| return 0; |
| } |
| |
| /** |
| * Returns a copy of the list |
| */ |
| public List<MessageReference> getList() { |
| synchronized (lock) { |
| return new ArrayList<MessageReference>(list); |
| } |
| } |
| |
| public void appendMessages(List<MessageReference> answer) { |
| synchronized (lock) { |
| for (Iterator<MessageReference> iter = list.iterator(); iter.hasNext();) { |
| answer.add(iter.next()); |
| } |
| } |
| } |
| |
| public int getSize() { |
| synchronized (lock) { |
| return size; |
| } |
| } |
| |
| public int getPosition() { |
| return position; |
| } |
| |
| public void setPosition(int position) { |
| this.position = position; |
| } |
| |
| public void clear() { |
| synchronized (lock) { |
| list.clear(); |
| size = 0; |
| } |
| } |
| |
| } |