jstorm-core/src/main/java/backtype/storm/testing/KeyedSummingBatchBolt.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 backtype.storm.testing;

import backtype.storm.coordination.BatchOutputCollector;
import backtype.storm.task.TopologyContext;
import backtype.storm.topology.OutputFieldsDeclarer;
import backtype.storm.topology.base.BaseBatchBolt;
import backtype.storm.tuple.Fields;
import backtype.storm.tuple.Tuple;
import backtype.storm.tuple.Values;
import backtype.storm.utils.Utils;
import clojure.lang.Numbers;
import java.util.HashMap;
import java.util.Map;

public class KeyedSummingBatchBolt extends BaseBatchBolt {
    BatchOutputCollector _collector;
    Object _id;
    Map<Object, Number> _sums = new HashMap<Object, Number>();

    @Override
    public void prepare(Map conf, TopologyContext context, BatchOutputCollector collector, Object id) {
        _collector = collector;
        _id = id;
    }

    @Override
    public void execute(Tuple tuple) {
        Object key = tuple.getValue(1);
        Number curr = Utils.get(_sums, key, 0);
        _sums.put(key, Numbers.add(curr, tuple.getValue(2)));
    }

    @Override
    public void finishBatch() {
        for (Object key : _sums.keySet()) {
            _collector.emit(new Values(_id, key, _sums.get(key)));
        }
    }

    @Override
    public void declareOutputFields(OutputFieldsDeclarer declarer) {
        declarer.declare(new Fields("tx", "key", "sum"));
    }
}