external/storm-beam/src/main/java/org/apache/storm/beam/translation/runtime/GroupByKeyInitBolt.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.beam.translation.runtime;

import org.apache.beam.sdk.util.WindowedValue;
import org.apache.beam.sdk.values.KV;
import org.apache.storm.task.OutputCollector;
import org.apache.storm.task.TopologyContext;
import org.apache.storm.topology.OutputFieldsDeclarer;
import org.apache.storm.topology.base.BaseRichBolt;
import org.apache.storm.tuple.Fields;
import org.apache.storm.tuple.Tuple;
import org.apache.storm.tuple.Values;

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

/**
 *
 */
public class GroupByKeyInitBolt extends BaseRichBolt {
    private OutputCollector collector;


    @Override
    public void prepare(Map stormConf, TopologyContext context, OutputCollector collector) {
        this.collector = collector;
    }

    public GroupByKeyInitBolt() {
    }

    @Override
    public void execute(Tuple input) {

        List<WindowedValue<KV>> values = (List<WindowedValue<KV>>)input.getValue(0);
        for(WindowedValue<KV> value : values) {
            KV kv = value.getValue();
            Object key = kv.getKey();
            this.collector.emit(input, new Values(key, value));
            this.collector.ack(input);
        }
    }

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