KickJava   Java API By Example, From Geeks To Geeks.

Java > Open Source Codes > org > apache > activemq > broker > region > policy > OldestMessageWithLowestPriorityEvictionStrategy


1 /**
2  *
3  * Licensed to the Apache Software Foundation (ASF) under one or more
4  * contributor license agreements. See the NOTICE file distributed with
5  * this work for additional information regarding copyright ownership.
6  * The ASF licenses this file to You under the Apache License, Version 2.0
7  * (the "License"); you may not use this file except in compliance with
8  * the License. You may obtain a copy of the License at
9  *
10  * http://www.apache.org/licenses/LICENSE-2.0
11  *
12  * Unless required by applicable law or agreed to in writing, software
13  * distributed under the License is distributed on an "AS IS" BASIS,
14  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
15  * See the License for the specific language governing permissions and
16  * limitations under the License.
17  */
18 package org.apache.activemq.broker.region.policy;
19
20 import org.apache.activemq.broker.region.MessageReference;
21
22 import java.io.IOException JavaDoc;
23 import java.util.Iterator JavaDoc;
24 import java.util.LinkedList JavaDoc;
25
26 /**
27  * An eviction strategy which evicts the oldest message with the lowest priority first.
28  *
29  * @org.apache.xbean.XBean
30  *
31  * @version $Revision: 430023 $messageEvictionStrategy
32  */
33 public class OldestMessageWithLowestPriorityEvictionStrategy extends MessageEvictionStrategySupport {
34
35     public MessageReference[] evictMessages(LinkedList JavaDoc messages) throws IOException JavaDoc {
36         byte lowestPriority = Byte.MAX_VALUE;
37         int pivot = 0;
38         Iterator JavaDoc iter = messages.iterator();
39         for (int i = 0; iter.hasNext(); i++) {
40             MessageReference reference = (MessageReference) iter.next();
41             byte priority = reference.getMessage().getPriority();
42             if (priority < lowestPriority) {
43                 lowestPriority = priority;
44                 pivot = i;
45             }
46         }
47         return new MessageReference[] {(MessageReference) messages.remove(pivot)};
48     }
49 }
50
Popular Tags