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; 018 019 import java.io.IOException; 020 import java.util.List; 021 022 import javax.jms.JMSException; 023 024 import org.apache.activemq.broker.region.group.MessageGroupMap; 025 import org.apache.activemq.broker.region.policy.SimpleDispatchSelector; 026 import org.apache.activemq.command.ActiveMQDestination; 027 import org.apache.activemq.command.ActiveMQMessage; 028 import org.apache.activemq.command.ConsumerId; 029 import org.apache.activemq.command.Message; 030 import org.apache.commons.logging.Log; 031 import org.apache.commons.logging.LogFactory; 032 033 /** 034 * Queue dispatch policy that determines if a message can be sent to a subscription 035 * 036 * @org.apache.xbean.XBean 037 * @version $Revision$ 038 */ 039 public class QueueDispatchSelector extends SimpleDispatchSelector { 040 private static final Log LOG = LogFactory.getLog(QueueDispatchSelector.class); 041 private Subscription exclusiveConsumer; 042 043 044 /** 045 * @param destination 046 */ 047 public QueueDispatchSelector(ActiveMQDestination destination) { 048 super(destination); 049 } 050 051 public Subscription getExclusiveConsumer() { 052 return exclusiveConsumer; 053 } 054 public void setExclusiveConsumer(Subscription exclusiveConsumer) { 055 this.exclusiveConsumer = exclusiveConsumer; 056 } 057 058 public boolean isExclusiveConsumer(Subscription s) { 059 return s == this.exclusiveConsumer; 060 } 061 062 063 public boolean canSelect(Subscription subscription, 064 MessageReference m) throws Exception { 065 066 boolean result = super.canDispatch(subscription, m); 067 if (result && !subscription.isBrowser()) { 068 result = exclusiveConsumer == null 069 || exclusiveConsumer == subscription; 070 if (result) { 071 QueueMessageReference node = (QueueMessageReference) m; 072 // Keep message groups together. 073 String groupId = node.getGroupID(); 074 int sequence = node.getGroupSequence(); 075 if (groupId != null) { 076 MessageGroupMap messageGroupOwners = ((Queue) node 077 .getRegionDestination()).getMessageGroupOwners(); 078 079 // If we can own the first, then no-one else should own the 080 // rest. 081 if (sequence == 1) { 082 assignGroup(subscription, messageGroupOwners, node,groupId); 083 }else { 084 085 // Make sure that the previous owner is still valid, we may 086 // need to become the new owner. 087 ConsumerId groupOwner; 088 089 groupOwner = messageGroupOwners.get(groupId); 090 if (groupOwner == null) { 091 assignGroup(subscription, messageGroupOwners, node,groupId); 092 } else { 093 if (groupOwner.equals(subscription.getConsumerInfo().getConsumerId())) { 094 // A group sequence < 1 is an end of group signal. 095 if (sequence < 0) { 096 messageGroupOwners.removeGroup(groupId); 097 } 098 } else { 099 result = false; 100 } 101 } 102 } 103 } 104 } 105 } 106 return result; 107 } 108 109 protected void assignGroup(Subscription subs,MessageGroupMap messageGroupOwners, MessageReference n, String groupId) throws IOException { 110 messageGroupOwners.put(groupId, subs.getConsumerInfo().getConsumerId()); 111 Message message = n.getMessage(); 112 if (message instanceof ActiveMQMessage) { 113 ActiveMQMessage activeMessage = (ActiveMQMessage)message; 114 try { 115 activeMessage.setBooleanProperty("JMSXGroupFirstForConsumer", true, false); 116 } catch (JMSException e) { 117 LOG.warn("Failed to set boolean header: " + e, e); 118 } 119 } 120 } 121 122 123 124 125 }