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 com.alibaba.wasp.messagequeue;
  
  import com.alibaba.wasp.FConstants;
  import com.alibaba.wasp.fserver.EntityGroup;
  import com.alibaba.wasp.fserver.OperationStatus;
  import com.alibaba.wasp.storage.StorageActionManager;
  import com.alibaba.wasp.storage.StorageTableNotFoundException;
  import org.apache.hadoop.hbase.HConstants.OperationStatusCode;
  import org.apache.hadoop.hbase.client.Delete;
  
  import java.io.IOException;
  import java.util.List;
  
  /**
   * Subscriber of message queue.
   */
  public class Subscriber implements MessageQueue<OperationStatus> {
  
    private final EntityGroup entityGroup;
  
    private byte[] currentMessageRow;
  
    private final MessageQueueClient client;
  
    private StorageActionManager action;
  
    /**
     * @param entityGroup
     */
    public Subscriber(EntityGroup entityGroup, StorageActionManager action) {
      super();
      this.entityGroup = entityGroup;
      this.client = new MessageQueueClient(this.entityGroup.getEntityGroupInfo(),
          action);
      this.action = action;
    }
  
    /**
     * @return the entityGroup
     */
    public EntityGroup getEntityGroup() {
      return entityGroup;
    }
  
    /**
     * @return the currentMessageRow
     */
    public byte[] getCurrentMessageRow() {
      return currentMessageRow;
    }
  
    /**
     * @param currentMessageRow
     *          the currentMessageRow to set
     */
    public void setCurrentMessageRow(byte[] currentMessageRow) {
      this.currentMessageRow = currentMessageRow;
    }
  
    /**
     * return recently messages.
     * 
     * @return
     * @throws java.io.IOException
     */
    public List<Message> receive() throws IOException {
      try {
        return client.receive();
      } catch (StorageTableNotFoundException e) {
        throw new IOException(e);
      }
    }
  
    /**
     * @see com.alibaba.wasp.messagequeue.MessageQueue#doAsynchronous()
     */
    @Override
    public OperationStatus doAsynchronous(Message message) {
      if (!message.isCommited()) {
        return OperationStatus.SUCCESS;
      }
      OperationStatus status = entityGroup.doAsynchronous(message);
      if (status.getOperationStatusCode() != OperationStatusCode.SUCCESS) {
        return status;
      } else {
        Delete delete = new Delete(currentMessageRow);
        try {
          this.action.delete(FConstants.MESSAGEQUEUE_TABLENAME, delete);
        } catch (Exception e) {
          return OperationStatus.FAILURE;
        }
        return OperationStatus.SUCCESS;
      }
    }
  }
  