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.jstorm.transactional.state;
  
  import static org.slf4j.LoggerFactory.getLogger;
  
  import java.util.HashMap;
  import java.util.Map;
  import java.util.Map.Entry;
  
  import org.slf4j.Logger;
  
  import com.alibaba.jstorm.transactional.state.task.KeyRangeStateTaskInit;
  
  import backtype.storm.task.TopologyContext;
  import backtype.storm.utils.Utils;
  
  /**
   * This abstract class implements the interfaces of transaction state for current task
   * @param <K> Key type of KV-State
   * @param <V> Value type of KV-State
   */
  public abstract class TransactionStateOperator<K, V> implements ITransactionStateOperator {
      private static final long serialVersionUID = 2545142551840944928L;
  
      private static final Logger LOG = getLogger(TransactionStateOperator.class);
  
      private IRichCheckpointKvState<K, V, String> stateInstance;
  
      public IKvState<K, V> createState(TopologyContext context) {
          stateInstance = (IRichCheckpointKvState<K, V, String>) Utils.newInstance("com.alibaba.jstorm.hdfs.transaction.RocksDbHdfsState");
          stateInstance.setStateName(String.valueOf(context.getThisTaskId()));
          stateInstance.init(context);
          return stateInstance;
      }
  
      @Override
      public void initState(Object userState) {
          LOG.info("Begin to restore from state: {}", userState);
          restore((String) userState);
      }
  
      public abstract void checkpoint(long batchId, IKvState<K, V> state);
  
      @Override
      public Object finishBatch(long batchId) {
          checkpoint(batchId, stateInstance);
          stateInstance.checkpoint(batchId);
          return null;
      }
  
      @Override
      public Object commit(long batchId, Object userState) {
          String checkpointPath = stateInstance.backup(batchId);
          return checkpointPath;
      }
  
      @Override
      public void rollBack(Object userState) {
          restore((String) userState);
      }
  
      @Override
      public void ackCommit(long batchId, long timeStamp) {
          stateInstance.remove(batchId);
      }
  
      private void restore(String checkpointPath) {
          stateInstance.restore(checkpointPath);
      }
  }