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.store;
  
  import java.io.IOException;
  import java.util.ArrayList;
  import java.util.List;
  
  import org.apache.activemq.command.ActiveMQDestination;
  import org.apache.activemq.command.ActiveMQQueue;
  import org.apache.activemq.command.ActiveMQTopic;
  import org.apache.activemq.command.SubscriptionInfo;
  
  /**
   * Used to implement common PersistenceAdapter methods.
   */
  public class PersistenceAdapterSupport {
  
      private static final DestinationMatcher MATCH_ALL = new AlwaysMatches();
  
      /**
       * Provides an interface for a Destination matching object that can be used to
       * search for specific destinations from a persistence adapter.
       */
      public interface DestinationMatcher {
  
          /**
           * Given a Destination object, return true if the destination matches some defined
           * search criteria, false otherwise.
           *
           * @param destination
           *        the destination to inspect.
           *
           * @return true if the destination matches the target criteria, false otherwise.
           */
          boolean matches(ActiveMQDestination destination);
  
      }
  
      /**
       * Searches the set of subscriptions from the given persistence adapter and returns all those
       * that belong to the given ClientId value.
       *
       * @param adapter
       *        the persistence adapter instance to search within.
       * @param clientId
       *        the client ID value used to filter the subscription set.
       *
       * @return a list of all subscriptions belonging to the given client.
       *
       * @throws IOException if an error occurs while listing the stored subscriptions.
       */
      static public List<SubscriptionInfo> listSubscriptions(PersistenceAdapter adapter, String clientId) throws IOException {
          ArrayList<SubscriptionInfo> rc = new ArrayList<SubscriptionInfo>();
          for (ActiveMQDestination destination : adapter.getDestinations()) {
              if (destination.isTopic()) {
                  TopicMessageStore store = adapter.createTopicMessageStore((ActiveMQTopic) destination);
                  for (SubscriptionInfo sub : store.getAllSubscriptions()) {
                      if (clientId == sub.getClientId() || clientId.equals(sub.getClientId())) {
                          rc.add(sub);
                      }
                  }
              }
          }
          return rc;
      }
  
      /**
       * Provides a means of querying the persistence adapter for a list of ActiveMQQueue instances.
       *
       * @param adapter
       *        the persistence adapter instance to query.
       *
       * @return a List<ActiveMQQeue> with all the queue destinations.
       *
       * @throws IOException if an error occurs while reading the destinations.
       */
      static public List<ActiveMQQueue> listQueues(PersistenceAdapter adapter) throws IOException {
          return listQueues(adapter, MATCH_ALL);
      }
  
      /**
       * Provides a means of querying the persistence adapter for a list of ActiveMQQueue instances
       * that match some given search criteria.
       *
       * @param adapter
       *        the persistence adapter instance to query.
       * @param matcher
       *        the DestinationMatcher instance used to find the target destinations.
       *
       * @return a List<ActiveMQQeue> with all the matching destinations.
       *
       * @throws IOException if an error occurs while reading the destinations.
       */
      static public List<ActiveMQQueue> listQueues(PersistenceAdapter adapter, DestinationMatcher matcher) throws IOException {
          ArrayList<ActiveMQQueue> rc = new ArrayList<ActiveMQQueue>();
          for (ActiveMQDestination destination : adapter.getDestinations()) {
              if (destination.isQueue() && matcher.matches(destination)) {
                  rc.add((ActiveMQQueue) destination);
              }
          }
          return rc;
      }
  
      /**
       * Provides a means of querying the persistence adapter for a list of ActiveMQTopic instances.
       *
       * @param adapter
       *        the persistence adapter instance to query.
       *
       * @return a List<ActiveMQTopic> with all the topic destinations.
       *
       * @throws IOException if an error occurs while reading the destinations.
       */
      static public List<ActiveMQTopic> listTopics(PersistenceAdapter adapter) throws IOException {
          return listTopics(adapter, MATCH_ALL);
      }
  
      /**
       * Provides a means of querying the persistence adapter for a list of ActiveMQTopic instances
       * that match some given search criteria.
       *
       * @param adapter
       *        the persistence adapter instance to query.
       * @param matcher
       *        the DestinationMatcher instance used to find the target destinations.
       *
       * @return a List<ActiveMQTopic> with all the matching destinations.
       *
       * @throws IOException if an error occurs while reading the destinations.
       */
      static public List<ActiveMQTopic> listTopics(PersistenceAdapter adapter, DestinationMatcher matcher) throws IOException {
          ArrayList<ActiveMQTopic> rc = new ArrayList<ActiveMQTopic>();
          for (ActiveMQDestination destination : adapter.getDestinations()) {
              if (destination.isTopic() && matcher.matches(destination)) {
                  rc.add((ActiveMQTopic) destination);
              }
          }
          return rc;
      }
  
      private static class AlwaysMatches implements DestinationMatcher {
  
          @Override
          public boolean matches(ActiveMQDestination destination) {
              return true;
          }
      }
  }
  