| /** |
| * Licensed to the Apache Software Foundation (ASF) under one or more |
| * contributor license agreements. See the NOTICE file distributed with |
| * this work for additional information regarding copyright ownership. |
| * The ASF licenses this file to You under the Apache License, Version 2.0 |
| * (the "License"); you may not use this file except in compliance with |
| * the License. You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, software |
| * distributed under the License is distributed on an "AS IS" BASIS, |
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| * See the License for the specific language governing permissions and |
| * limitations under the License. |
| */ |
| package org.apache.activemq.broker.region.policy; |
| |
| import java.util.Iterator; |
| import java.util.List; |
| import org.apache.activemq.broker.region.MessageReference; |
| import org.apache.activemq.broker.region.Subscription; |
| import org.apache.activemq.filter.MessageEvaluationContext; |
| import org.slf4j.Logger; |
| import org.slf4j.LoggerFactory; |
| |
| /** |
| * Simple dispatch policy that sends a message to every subscription that |
| * matches the message. |
| * |
| * @org.apache.xbean.XBean |
| * |
| */ |
| public class RoundRobinDispatchPolicy implements DispatchPolicy { |
| static final Logger LOG = LoggerFactory.getLogger(RoundRobinDispatchPolicy.class); |
| |
| /** |
| * @param node |
| * @param msgContext |
| * @param consumers |
| * @return true if dispatched |
| * @throws Exception |
| * @see org.apache.activemq.broker.region.policy.DispatchPolicy#dispatch(org.apache.activemq.broker.region.MessageReference, |
| * org.apache.activemq.filter.MessageEvaluationContext, java.util.List) |
| */ |
| public boolean dispatch(MessageReference node, |
| MessageEvaluationContext msgContext, List<Subscription> consumers) |
| throws Exception { |
| int count = 0; |
| |
| Subscription firstMatchingConsumer = null; |
| synchronized (consumers) { |
| for (Iterator<Subscription> iter = consumers.iterator(); iter |
| .hasNext();) { |
| Subscription sub = iter.next(); |
| |
| // Only dispatch to interested subscriptions |
| if (!sub.matches(node, msgContext)) { |
| sub.unmatched(node); |
| continue; |
| } |
| |
| if (firstMatchingConsumer == null) { |
| firstMatchingConsumer = sub; |
| } |
| |
| sub.add(node); |
| count++; |
| } |
| |
| if (firstMatchingConsumer != null) { |
| // Rotate the consumer list. |
| try { |
| consumers.remove(firstMatchingConsumer); |
| consumers.add(firstMatchingConsumer); |
| } catch (Throwable bestEffort) { |
| } |
| } |
| } |
| return count > 0; |
| } |
| } |