com.twitter.heron.streamlet.impl.streamlets.TransformStreamlet 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.Set;
import com.twitter.heron.api.topology.TopologyBuilder;
import com.twitter.heron.streamlet.SerializableTransformer;
import com.twitter.heron.streamlet.impl.StreamletImpl;
import com.twitter.heron.streamlet.impl.operators.TransformOperator;
/**
* TransformStreamlet represents a Streamlet that is made up of applying the user
* supplied transform function to each element of the parent streamlet. It differs
* from the simple MapStreamlet in the sense that it provides setup/cleanup flexibility
* for the users to setup things and cleanup before the beginning of the computation
*/
public class TransformStreamlet extends StreamletImpl {
private StreamletImpl parent;
private SerializableTransformer serializableTransformer;
public TransformStreamlet(StreamletImpl parent,
SerializableTransformer serializableTransformer) {
this.parent = parent;
this.serializableTransformer = serializableTransformer;
setNumPartitions(parent.getNumPartitions());
}
@Override
public boolean doBuild(TopologyBuilder bldr, Set stageNames) {
setDefaultNameIfNone(StreamletNamePrefix.TRANSFORM, stageNames);
bldr.setBolt(getName(), new TransformOperator(serializableTransformer),
getNumPartitions()).shuffleGrouping(parent.getName());
return true;
}
}