001 /** 002 * Licensed to the Apache Software Foundation (ASF) under one or more 003 * contributor license agreements. See the NOTICE file distributed with 004 * this work for additional information regarding copyright ownership. 005 * The ASF licenses this file to You under the Apache License, Version 2.0 006 * (the "License"); you may not use this file except in compliance with 007 * the License. You may obtain a copy of the License at 008 * 009 * http://www.apache.org/licenses/LICENSE-2.0 010 * 011 * Unless required by applicable law or agreed to in writing, software 012 * distributed under the License is distributed on an "AS IS" BASIS, 013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 014 * See the License for the specific language governing permissions and 015 * limitations under the License. 016 */ 017 package org.apache.activemq.broker.region.policy; 018 019 import java.io.IOException; 020 import java.util.Iterator; 021 import java.util.LinkedList; 022 023 import org.apache.activemq.broker.region.MessageReference; 024 025 /** 026 * An eviction strategy which evicts the oldest message with the lowest priority first. 027 * 028 * @org.apache.xbean.XBean 029 * 030 * messageEvictionStrategy 031 */ 032 public class OldestMessageWithLowestPriorityEvictionStrategy extends MessageEvictionStrategySupport { 033 034 public MessageReference[] evictMessages(LinkedList messages) throws IOException { 035 byte lowestPriority = Byte.MAX_VALUE; 036 int pivot = 0; 037 Iterator iter = messages.iterator(); 038 for (int i = 0; iter.hasNext(); i++) { 039 MessageReference reference = (MessageReference) iter.next(); 040 byte priority = reference.getMessage().getPriority(); 041 if (priority < lowestPriority) { 042 lowestPriority = priority; 043 pivot = i; 044 } 045 } 046 return new MessageReference[] {(MessageReference) messages.remove(pivot)}; 047 } 048 }