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.util.ArrayList;
020    import java.util.Collections;
021    import java.util.Comparator;
022    import java.util.List;
023    import org.apache.activemq.broker.region.MessageReference;
024    import org.apache.activemq.broker.region.Subscription;
025    import 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     */
034    public 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    }