com.twitter.heron.streamlet.impl.streamlets.RemapStreamlet 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.streamlets;
import java.util.List;
import java.util.Set;
import com.twitter.heron.api.topology.TopologyBuilder;
import com.twitter.heron.streamlet.SerializableBiFunction;
import com.twitter.heron.streamlet.impl.StreamletImpl;
import com.twitter.heron.streamlet.impl.groupings.RemapCustomGrouping;
import com.twitter.heron.streamlet.impl.operators.MapOperator;
/**
* RemapStreamlet represents a Streamlet that is the result of
* applying user supplied remapFn on all elements of its parent Streamlet.
* RemapStreamlet as such is a generalized version of the Map/FlatMapStreamlets
* that give users more flexibility over the operation. The remapFn allows for
* users to choose which destination shards every transformed element can go.
*/
public class RemapStreamlet extends StreamletImpl {
private StreamletImpl parent;
private SerializableBiFunction> remapFn;
public RemapStreamlet(StreamletImpl parent,
SerializableBiFunction> remapFn) {
this.parent = parent;
this.remapFn = remapFn;
setNumPartitions(parent.getNumPartitions());
}
@Override
public boolean doBuild(TopologyBuilder bldr, Set stageNames) {
setDefaultNameIfNone(StreamletNamePrefix.REMAP, stageNames);
bldr.setBolt(getName(), new MapOperator((a) -> a),
getNumPartitions())
.customGrouping(parent.getName(), new RemapCustomGrouping(remapFn));
return true;
}
}