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.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;
  
  /**
   * Dispatch policy that causes every subscription to see messages in the same
   * order.
   * 
   * @org.apache.xbean.XBean
   * 
   */
  public class StrictOrderDispatchPolicy implements DispatchPolicy {
  
      /**
       * @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 consumers) throws Exception {
          // Big synch here so that only 1 message gets dispatched at a time.
          // Ensures
          // Everyone sees the same order.
          synchronized (consumers) {
              int count = 0;
              for (Iterator iter = consumers.iterator(); iter.hasNext();) {
                  Subscription sub = (Subscription)iter.next();
  
                  // Only dispatch to interested subscriptions
                  if (!sub.matches(node, msgContext)) {
                      sub.unmatched(node);
                      continue;
                  }
  
                  sub.add(node);
                  count++;
              }
              return count > 0;
          }
      }
  
  }
  