content: /**
   * 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.ArrayList;
  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.command.ConsumerId;
  import org.apache.activemq.command.ConsumerInfo;
  import org.apache.activemq.filter.MessageEvaluationContext;
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  /**
   * dispatch policy that ignores lower priority duplicate network consumers,
   * used in conjunction with network bridge suppresDuplicateTopicSubscriptions
   * 
   * @org.apache.xbean.XBean
   */
  public class PriorityNetworkDispatchPolicy extends SimpleDispatchPolicy {
  
      private static final Logger LOG = LoggerFactory.getLogger(PriorityNetworkDispatchPolicy.class);
      @Override
      public boolean dispatch(MessageReference node,
              MessageEvaluationContext msgContext,
              List<Subscription> consumers) throws Exception {
          
          List<Subscription> duplicateFreeSubs = new ArrayList<Subscription>();
          synchronized (consumers) {
              for (Subscription sub: consumers) {
                  ConsumerInfo info = sub.getConsumerInfo();
                  if (info.isNetworkSubscription()) {    
                      boolean highestPrioritySub = true;
                      for (Iterator<Subscription> it =  duplicateFreeSubs.iterator(); it.hasNext(); ) {
                          Subscription candidate = it.next();
                          if (matches(candidate, info)) {
                              if (hasLowerPriority(candidate, info)) {
                                  it.remove();
                              } else {
                                  // higher priority matching sub exists
                                  highestPrioritySub = false;
                                  LOG.debug("ignoring lower priority: {} [{}, {}] in favour of: {} [{}, {}]",
                                          candidate,
                                          candidate.getConsumerInfo().getNetworkConsumerIds(),
                                          candidate.getConsumerInfo().getNetworkConsumerIds(),
                                          sub,
                                          sub.getConsumerInfo().getNetworkConsumerIds(),
                                          sub.getConsumerInfo().getNetworkConsumerIds());
                              }
                          }
                      }
                      if (highestPrioritySub) {
                          duplicateFreeSubs.add(sub);
                      } 
                  } else {
                      duplicateFreeSubs.add(sub);
                  }
              }
          }
          
          return super.dispatch(node, msgContext, duplicateFreeSubs);
      }
  
      private boolean hasLowerPriority(Subscription candidate,
              ConsumerInfo info) {
         return candidate.getConsumerInfo().getPriority() < info.getPriority();
      }
  
      private boolean matches(Subscription candidate, ConsumerInfo info) {
          boolean matched = false;
          for (ConsumerId candidateId: candidate.getConsumerInfo().getNetworkConsumerIds()) {
              for (ConsumerId subId: info.getNetworkConsumerIds()) {
                  if (candidateId.equals(subId)) {
                      matched = true;
                      break;
                  }
              }
          }
          return matched;
      }
  
  }
  