com.twitter.heron.streamlet.impl.sources.ComplexSource Maven / Gradle / Ivy

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//  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.sources;

import java.io.Serializable;
import java.util.Collection;
import java.util.Map;

import com.twitter.heron.api.spout.SpoutOutputCollector;
import com.twitter.heron.api.state.State;
import com.twitter.heron.api.topology.TopologyContext;
import com.twitter.heron.api.tuple.Values;
import com.twitter.heron.streamlet.Context;
import com.twitter.heron.streamlet.Source;
import com.twitter.heron.streamlet.impl.ContextImpl;

/**
 * SupplierSource is a way to wrap a supplier function inside a Heron Spout.
 * The SupplierSource just calls the get method of the supplied function
 * to generate the next tuple.
 */
public class ComplexSource extends StreamletSource {
  private static final long serialVersionUID = -5086763670301450007L;
  private Source generator;

  private SpoutOutputCollector collector;
  private State state;

  public ComplexSource(Source generator) {
    this.generator = generator;
  }

  @Override
  public void initState(State startupState) {
    this.state = startupState;
  }

  @SuppressWarnings("rawtypes")
  @Override
  public void open(Map map, TopologyContext topologyContext,
                   SpoutOutputCollector outputCollector) {
    collector = outputCollector;
    Context context = new ContextImpl(topologyContext, map, state);
    generator.setup(context);
  }

  @Override
  public void nextTuple() {
    Collection val = generator.get();
    if (val != null) {
      for (R tuple : val) {
        collector.emit(new Values(tuple));
      }
    }
  }
}