eco-heron-examples/src/java/org/apache/heron/examples/eco/StatefulConsumerBolt.java

/**
 * 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.heron.examples.eco;

import java.util.Map;

import org.apache.heron.api.bolt.BaseRichBolt;
import org.apache.heron.api.bolt.OutputCollector;
import org.apache.heron.api.state.State;
import org.apache.heron.api.topology.IStatefulComponent;
import org.apache.heron.api.topology.OutputFieldsDeclarer;
import org.apache.heron.api.topology.TopologyContext;
import org.apache.heron.api.tuple.Tuple;


public class StatefulConsumerBolt extends BaseRichBolt
    implements IStatefulComponent<Integer, Integer> {
  private static final long serialVersionUID = -5470591933906954522L;

  private OutputCollector collector;
  private State<Integer, Integer> myState;

  @Override
  public void initState(State<Integer, Integer> state) {
    this.myState = state;
  }

  @Override
  public void preSave(String checkpointId) {
    // Nothing really since we operate out of the system supplied state
  }

  @SuppressWarnings("rawtypes")
  public void prepare(Map map, TopologyContext topologyContext, OutputCollector outputCollector) {
    collector = outputCollector;
  }

  @Override
  public void execute(Tuple tuple) {
    int key = tuple.getInteger(0);
    System.out.println("looking in state for: " + key);
    if (myState.get(key) == null) {
      System.out.println("did not find " + key + " in state: ");
      myState.put(key, 1);
    } else {
      System.out.println("found in state: " + key);
      Integer val = myState.get(key);
      myState.put(key, ++val);
    }
  }

  @Override
  public void declareOutputFields(OutputFieldsDeclarer outputFieldsDeclarer) {
  }
}