examples/storm-starter/src/jvm/org/apache/storm/starter/StatefulTopology.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.storm.starter;

import java.util.Map;
import org.apache.storm.Config;
import org.apache.storm.StormSubmitter;
import org.apache.storm.starter.spout.RandomIntegerSpout;
import org.apache.storm.state.KeyValueState;
import org.apache.storm.task.OutputCollector;
import org.apache.storm.task.TopologyContext;
import org.apache.storm.topology.BasicOutputCollector;
import org.apache.storm.topology.OutputFieldsDeclarer;
import org.apache.storm.topology.TopologyBuilder;
import org.apache.storm.topology.base.BaseBasicBolt;
import org.apache.storm.topology.base.BaseStatefulBolt;
import org.apache.storm.tuple.Fields;
import org.apache.storm.tuple.Tuple;
import org.apache.storm.tuple.Values;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/**
 * An example topology that demonstrates the use of {@link org.apache.storm.topology.IStatefulBolt} to manage state. To run the example,
 * <pre>
 * $ storm jar examples/storm-starter/storm-starter-topologies-*.jar storm.starter.StatefulTopology statetopology
 * </pre>
 * <p/>
 * The default state used is 'InMemoryKeyValueState' which does not persist the state across restarts. You could use 'RedisKeyValueState' to
 * test state persistence by setting below property in conf/storm.yaml
 * <pre>
 * topology.state.provider: org.apache.storm.redis.state.RedisKeyValueStateProvider
 * </pre>
 * <p/>
 * You should also start a local redis instance before running the 'storm jar' command. The default RedisKeyValueStateProvider parameters
 * can be overridden in conf/storm.yaml, for e.g.
 * <p/>
 * <pre>
 * topology.state.provider.config: '{"keyClass":"...", "valueClass":"...",
 *                                   "keySerializerClass":"...", "valueSerializerClass":"...",
 *                                   "jedisPoolConfig":{"host":"localhost", "port":6379,
 *                                      "timeout":2000, "database":0, "password":"xyz"}}'
 *
 * </pre>
 * </p>
 */
public class StatefulTopology {
    private static final Logger LOG = LoggerFactory.getLogger(StatefulTopology.class);

    public static void main(String[] args) throws Exception {
        TopologyBuilder builder = new TopologyBuilder();
        builder.setSpout("spout", new RandomIntegerSpout());
        builder.setBolt("partialsum", new StatefulSumBolt("partial"), 1).shuffleGrouping("spout");
        builder.setBolt("printer", new PrinterBolt(), 2).shuffleGrouping("partialsum");
        builder.setBolt("total", new StatefulSumBolt("total"), 1).shuffleGrouping("printer");
        Config conf = new Config();
        conf.setDebug(false);
        String topoName = "test";
        if (args != null && args.length > 0) {
            topoName = args[0];
        }
        conf.setNumWorkers(1);
        StormSubmitter.submitTopologyWithProgressBar(topoName, conf, builder.createTopology());
    }

    /**
     * A bolt that uses {@link KeyValueState} to save its state.
     */
    private static class StatefulSumBolt extends BaseStatefulBolt<KeyValueState<String, Long>> {
        String name;
        KeyValueState<String, Long> kvState;
        long sum;
        private OutputCollector collector;

        StatefulSumBolt(String name) {
            this.name = name;
        }

        @Override
        public void prepare(Map<String, Object> topoConf, TopologyContext context, OutputCollector collector) {
            this.collector = collector;
        }

        @Override
        public void execute(Tuple input) {
            sum += ((Number) input.getValueByField("value")).longValue();
            LOG.debug("{} sum = {}", name, sum);
            kvState.put("sum", sum);
            collector.emit(input, new Values(sum));
            collector.ack(input);
        }

        @Override
        public void initState(KeyValueState<String, Long> state) {
            kvState = state;
            sum = kvState.get("sum", 0L);
            LOG.debug("Initstate, sum from saved state = {} ", sum);
        }

        @Override
        public void declareOutputFields(OutputFieldsDeclarer declarer) {
            declarer.declare(new Fields("value"));
        }
    }

    public static class PrinterBolt extends BaseBasicBolt {
        @Override
        public void execute(Tuple tuple, BasicOutputCollector collector) {
            System.out.println(tuple);
            LOG.debug("Got tuple {}", tuple);
            collector.emit(tuple.getValues());
        }

        @Override
        public void declareOutputFields(OutputFieldsDeclarer ofd) {
            ofd.declare(new Fields("value"));
        }

    }
}