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.Broker;
  import org.apache.activemq.broker.ConnectionContext;
  import org.apache.activemq.broker.region.MessageReference;
  import org.apache.activemq.broker.region.SubscriptionRecovery;
  import org.apache.activemq.broker.region.Topic;
  import org.apache.activemq.command.ActiveMQDestination;
  import org.apache.activemq.command.Message;
  import org.apache.activemq.memory.list.DestinationBasedMessageList;
  import org.apache.activemq.memory.list.MessageList;
  import org.apache.activemq.memory.list.SimpleMessageList;
  
  /**
   * This implementation of {@link SubscriptionRecoveryPolicy} will keep a fixed
   * amount of memory available in RAM for message history which is evicted in
   * time order.
   * 
   * @org.apache.xbean.XBean
   * 
   */
  public class FixedSizedSubscriptionRecoveryPolicy implements SubscriptionRecoveryPolicy {
  
      private MessageList buffer;
      private int maximumSize =  64 * 1024;
      private boolean useSharedBuffer = true;
  
      public FixedSizedSubscriptionRecoveryPolicy() {
          
      }
      
      public SubscriptionRecoveryPolicy copy() {
          FixedSizedSubscriptionRecoveryPolicy rc = new FixedSizedSubscriptionRecoveryPolicy();
          rc.setMaximumSize(maximumSize);
          rc.setUseSharedBuffer(useSharedBuffer);
          return rc;
      }
  
      public boolean add(ConnectionContext context, MessageReference message) throws Exception {
          buffer.add(message);
          return true;
      }
  
      public void recover(ConnectionContext context, Topic topic, SubscriptionRecovery sub) throws Exception {
          // Re-dispatch the messages from the buffer.
          List copy = buffer.getMessages(sub.getActiveMQDestination());
          if (!copy.isEmpty()) {
              for (Iterator iter = copy.iterator(); iter.hasNext();) {
                  MessageReference node = (MessageReference)iter.next();
                  sub.addRecoveredMessage(context, node);
              }
          }
      }
  
      public void start() throws Exception {
          buffer = createMessageList();
      }
  
      public void stop() throws Exception {
          buffer.clear();
      }
  
      // Properties
      // -------------------------------------------------------------------------
      public MessageList getBuffer() {
          return buffer;
      }
  
      public void setBuffer(MessageList buffer) {
          this.buffer = buffer;
      }
  
      public int getMaximumSize() {
          return maximumSize;
      }
  
      /**
       * Sets the maximum amount of RAM in bytes that this buffer can hold in RAM
       */
      public void setMaximumSize(int maximumSize) {
          this.maximumSize = maximumSize;
      }
  
      public boolean isUseSharedBuffer() {
          return useSharedBuffer;
      }
  
      public void setUseSharedBuffer(boolean useSharedBuffer) {
          this.useSharedBuffer = useSharedBuffer;
      }
  
      public Message[] browse(ActiveMQDestination destination) throws Exception {
          return buffer.browse(destination);
      }
      
      public void setBroker(Broker broker) {        
      }
  
      // Implementation methods
  
      // -------------------------------------------------------------------------
      protected MessageList createMessageList() {
          if (useSharedBuffer) {
              return new SimpleMessageList(maximumSize);
          } else {
              return new DestinationBasedMessageList(maximumSize);
          }
      }
  
  }
  