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 */
017package org.apache.activemq.broker.region.policy;
018
019import java.util.ArrayList;
020import java.util.Collections;
021import java.util.Comparator;
022import java.util.List;
023import org.apache.activemq.broker.region.MessageReference;
024import org.apache.activemq.broker.region.Subscription;
025import org.apache.activemq.filter.MessageEvaluationContext;
026
027/**
028 * Priority dispatch policy that sends a message to every subscription that
029 * matches the message in consumer priority order.
030 * 
031 * @org.apache.xbean.XBean
032 * 
033 */
034public class PriorityDispatchPolicy extends SimpleDispatchPolicy {
035
036    private final Comparator<? super Subscription> orderedCompare = new Comparator<Subscription>() {
037        @Override
038        public int compare(Subscription o1, Subscription o2) {
039            // We want the list sorted in descending order
040            return o2.getConsumerInfo().getPriority() - o1.getConsumerInfo().getPriority();
041        }
042    };
043
044    public boolean dispatch(MessageReference node, MessageEvaluationContext msgContext, List<Subscription> consumers)
045            throws Exception {
046        ArrayList<Subscription> ordered = new ArrayList<Subscription>(consumers);
047        Collections.sort(ordered, orderedCompare);
048
049        StringBuffer stringBuffer = new StringBuffer();
050        for (Subscription sub: ordered) {
051            stringBuffer.append(sub.getConsumerInfo().getPriority());
052            stringBuffer.append(',');
053        }
054        //System.err.println("Priority:" + stringBuffer.toString() + ", msg: " + node.getMessage());
055        return super.dispatch(node, msgContext, ordered);
056    }
057
058}