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.memory;
  
  import java.util.ArrayList;
  import java.util.Iterator;
  import java.util.LinkedHashMap;
  import java.util.List;
  import java.util.Map;
  import java.util.Map.Entry;
  
  import org.apache.activemq.command.Message;
  import org.apache.activemq.command.MessageId;
  import org.apache.activemq.store.MessageRecoveryListener;
  import org.apache.activemq.util.SubscriptionKey;
  
  /**
   * A holder for a durable subscriber
   */
  class MemoryTopicSub {
  
      private final Map<MessageId, Message> map = new LinkedHashMap<MessageId, Message>();
      private final SubscriptionKey subscriptionKey;
  
      private MessageId lastBatch;
  
      public MemoryTopicSub(SubscriptionKey subscriptionKey) {
          this.subscriptionKey = subscriptionKey;
      }
  
      void addMessage(MessageId id, Message message) {
          synchronized (this) {
              map.put(id, message);
          }
          message.incrementReferenceCount();
      }
  
      void removeMessage(MessageId id) {
          Message removed;
          synchronized (this) {
              removed = map.remove(id);
              if ((lastBatch != null && lastBatch.equals(id)) || map.isEmpty()) {
                  resetBatching();
              }
          }
          if (removed != null) {
              removed.decrementReferenceCount();
          }
      }
  
      List<Message> getStoredMessages() {
          synchronized (this) {
              return new ArrayList<Message>(map.values());
          }
      }
  
      synchronized int size() {
          return map.size();
      }
  
      synchronized long messageSize() {
          long messageSize = 0;
  
          for (Iterator<Entry<MessageId, Message>> iter = map.entrySet().iterator(); iter.hasNext();) {
              Entry<MessageId, Message> entry = iter.next();
              messageSize += entry.getValue().getSize();
          }
  
          return messageSize;
      }
  
      synchronized void recoverSubscription(MessageRecoveryListener listener) throws Exception {
          for (Iterator<Entry<MessageId, Message>> iter = map.entrySet().iterator(); iter.hasNext();) {
              Entry<MessageId, Message> entry = iter.next();
              Message msg = entry.getValue();
              listener.recoverMessage(msg);
          }
      }
  
      synchronized void recoverNextMessages(int maxReturned, MessageRecoveryListener listener) throws Exception {
          boolean pastLackBatch = lastBatch == null;
          MessageId lastId = null;
          // the message table is a synchronizedMap - so just have to synchronize here
          int count = 0;
          for (Iterator<Entry<MessageId, Message>> iter = map.entrySet().iterator(); iter.hasNext() && count < maxReturned;) {
              Entry<MessageId, Message> entry = iter.next();
              if (pastLackBatch) {
                  count++;
                  Message msg = entry.getValue();
                  lastId = entry.getKey();
                  listener.recoverMessage(msg);
              } else {
                  pastLackBatch = entry.getKey().equals(lastBatch);
              }
          }
  
          if (lastId != null) {
              lastBatch = lastId;
          }
      }
  
      synchronized void resetBatching() {
          lastBatch = null;
      }
  
      SubscriptionKey getSubscriptionKey() {
          return subscriptionKey;
      }
  }
  