CustomGroupingTopology.java

// Copyright 2016 Twitter. All rights reserved.
//
// Licensed 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.twitter.heron.examples;

import java.util.ArrayList;
import java.util.List;
import java.util.Map;

import backtype.storm.Config;
import backtype.storm.StormSubmitter;
import backtype.storm.generated.GlobalStreamId;
import backtype.storm.grouping.CustomStreamGrouping;
import backtype.storm.task.OutputCollector;
import backtype.storm.task.TopologyContext;
import backtype.storm.task.WorkerTopologyContext;
import backtype.storm.topology.OutputFieldsDeclarer;
import backtype.storm.topology.TopologyBuilder;
import backtype.storm.topology.base.BaseRichBolt;
import backtype.storm.tuple.Tuple;

/**
 * This is a basic example of a Storm topology.
 */
public final class CustomGroupingTopology {

  private CustomGroupingTopology() {
  }

  public static void main(String[] args) throws Exception {
    TopologyBuilder builder = new TopologyBuilder();

    builder.setSpout("word", new TestWordSpout(), 2);
    builder.setBolt("mybolt", new MyBolt(), 2)
        .customGrouping("word", new MyCustomStreamGrouping());

    Config conf = new Config();

    conf.setNumWorkers(1);
    StormSubmitter.submitTopology(args[0], conf, builder.createTopology());
  }

  public static class MyBolt extends BaseRichBolt {
    private static final long serialVersionUID = 1913733461146490337L;
    private long nItems;

    @Override
    @SuppressWarnings("rawtypes")
    public void prepare(
        Map conf,
        TopologyContext context,
        OutputCollector acollector) {
      nItems = 0;
    }

    @Override
    public void execute(Tuple tuple) {
      if (++nItems % 10000 == 0) {
        System.out.println(tuple.getString(0));
      }
    }

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

  public static class MyCustomStreamGrouping implements CustomStreamGrouping {
    private static final long serialVersionUID = 5987557161936201860L;
    private List<Integer> taskIds;

    public MyCustomStreamGrouping() {
    }

    @Override
    public void prepare(
        WorkerTopologyContext context,
        GlobalStreamId stream,
        List<Integer> targetTasks) {
      this.taskIds = targetTasks;
    }

    @Override
    public List<Integer> chooseTasks(int taskId, List<Object> values) {
      List<Integer> ret = new ArrayList<>();
      ret.add(taskIds.get(0));
      return ret;
    }
  }
}