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.Collections;
  import java.util.Comparator;
  import java.util.List;
  import java.util.StringJoiner;
  
  import org.apache.activemq.broker.region.MessageReference;
  import org.apache.activemq.broker.region.Subscription;
  import org.apache.activemq.filter.MessageEvaluationContext;
  import org.apache.activemq.filter.XPathExpression;
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  /**
   * Priority dispatch policy that sends a message to every subscription that
   * matches the message in consumer priority order.
   * 
   * @org.apache.xbean.XBean
   * 
   */
  public class PriorityDispatchPolicy extends SimpleDispatchPolicy {
  
      private static final Logger LOG = LoggerFactory.getLogger(PriorityDispatchPolicy.class);
  
      private final Comparator<? super Subscription> orderedCompare = new Comparator<Subscription>() {
          @Override
          public int compare(Subscription o1, Subscription o2) {
              // We want the list sorted in descending order
              return o2.getConsumerInfo().getPriority() - o1.getConsumerInfo().getPriority();
          }
      };
  
      public boolean dispatch(MessageReference node, MessageEvaluationContext msgContext, List<Subscription> consumers)
              throws Exception {
          ArrayList<Subscription> ordered = new ArrayList<Subscription>(consumers);
          Collections.sort(ordered, orderedCompare);
  
          if (LOG.isTraceEnabled() && !ordered.isEmpty()) {
              StringJoiner stringJoiner = new StringJoiner(",");
              for (Subscription sub : ordered) {
                  stringJoiner.add(String.valueOf(sub.getConsumerInfo().getPriority()));
              }
              LOG.trace("Ordered priorities: {}", stringJoiner);
          }
          return super.dispatch(node, msgContext, ordered);
      }
  
  }
  