com.twitter.heron.streamlet.impl.operators.MapOperator Maven / Gradle / Ivy
// Copyright 2017 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.streamlet.impl.operators;
import java.util.Map;
import com.twitter.heron.api.bolt.OutputCollector;
import com.twitter.heron.api.topology.TopologyContext;
import com.twitter.heron.api.tuple.Tuple;
import com.twitter.heron.api.tuple.Values;
import com.twitter.heron.streamlet.SerializableFunction;
/**
* MapOperator is the class that implements the map functionality.
* It takes in the mapFunction Function as the input.
* For every tuple, it applies the mapFunction, and emits the resulting value
*/
public class MapOperator extends StreamletOperator {
private static final long serialVersionUID = -1303096133107278700L;
private SerializableFunction mapFn;
private OutputCollector collector;
public MapOperator(SerializableFunction mapFn) {
this.mapFn = mapFn;
}
@SuppressWarnings("rawtypes")
@Override
public void prepare(Map map, TopologyContext topologyContext, OutputCollector outputCollector) {
collector = outputCollector;
}
@SuppressWarnings("unchecked")
@Override
public void execute(Tuple tuple) {
R obj = (R) tuple.getValue(0);
T result = mapFn.apply(obj);
collector.emit(new Values(result));
collector.ack(tuple);
}
}