StormProcessingItem.java

package org.apache.samoa.topology.impl;

/*
 * #%L
 * SAMOA
 * %%
 * Copyright (C) 2014 - 2015 Apache Software Foundation
 * %%
 * 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.
 * #L%
 */

import java.util.HashSet;
import java.util.Map;
import java.util.Set;
import java.util.UUID;

import org.apache.samoa.core.ContentEvent;
import org.apache.samoa.core.Processor;
import org.apache.samoa.topology.AbstractProcessingItem;
import org.apache.samoa.topology.ProcessingItem;
import org.apache.samoa.topology.Stream;
import org.apache.samoa.topology.impl.StormStream.InputStreamId;
import org.apache.samoa.utils.PartitioningScheme;

import backtype.storm.task.OutputCollector;
import backtype.storm.task.TopologyContext;
import backtype.storm.topology.BoltDeclarer;
import backtype.storm.topology.OutputFieldsDeclarer;
import backtype.storm.topology.TopologyBuilder;
import backtype.storm.topology.base.BaseRichBolt;
import backtype.storm.tuple.Fields;
import backtype.storm.tuple.Tuple;

/**
 * ProcessingItem implementation for Storm.
 * 
 * @author Arinto Murdopo
 * 
 */
class StormProcessingItem extends AbstractProcessingItem implements StormTopologyNode {
  private final ProcessingItemBolt piBolt;
  private BoltDeclarer piBoltDeclarer;

  // TODO: should we put parallelism hint here?
  // imo, parallelism hint only declared when we add this PI in the topology
  // open for dicussion :p

  StormProcessingItem(Processor processor, int parallelismHint) {
    this(processor, UUID.randomUUID().toString(), parallelismHint);
  }

  StormProcessingItem(Processor processor, String friendlyId, int parallelismHint) {
    super(processor, parallelismHint);
    this.piBolt = new ProcessingItemBolt(processor);
    this.setName(friendlyId);
  }

  @Override
  protected ProcessingItem addInputStream(Stream inputStream, PartitioningScheme scheme) {
    StormStream stormInputStream = (StormStream) inputStream;
    InputStreamId inputId = stormInputStream.getInputId();

    switch (scheme) {
    case SHUFFLE:
      piBoltDeclarer.shuffleGrouping(inputId.getComponentId(), inputId.getStreamId());
      break;
    case GROUP_BY_KEY:
      piBoltDeclarer.fieldsGrouping(
          inputId.getComponentId(),
          inputId.getStreamId(),
          new Fields(StormSamoaUtils.KEY_FIELD));
      break;
    case BROADCAST:
      piBoltDeclarer.allGrouping(
          inputId.getComponentId(),
          inputId.getStreamId());
      break;
    }
    return this;
  }

  @Override
  public void addToTopology(StormTopology topology, int parallelismHint) {
    if (piBoltDeclarer != null) {
      // throw exception that one PI only belong to one topology
    } else {
      TopologyBuilder stormBuilder = topology.getStormBuilder();
      this.piBoltDeclarer = stormBuilder.setBolt(this.getName(),
          this.piBolt, parallelismHint);
    }
  }

  @Override
  public StormStream createStream() {
    return piBolt.createStream(this.getName());
  }

  @Override
  public String getId() {
    return this.getName();
  }

  @Override
  public String toString() {
    StringBuilder sb = new StringBuilder(super.toString());
    sb.insert(0, String.format("id: %s, ", this.getName()));
    return sb.toString();
  }

  private final static class ProcessingItemBolt extends BaseRichBolt {

    private static final long serialVersionUID = -6637673741263199198L;

    private final Set<StormBoltStream> streams;
    private final Processor processor;

    private OutputCollector collector;

    ProcessingItemBolt(Processor processor) {
      this.streams = new HashSet<StormBoltStream>();
      this.processor = processor;
    }

    @Override
    public void prepare(@SuppressWarnings("rawtypes") Map stormConf, TopologyContext context,
        OutputCollector collector) {
      this.collector = collector;
      // Processor and this class share the same instance of stream
      for (StormBoltStream stream : streams) {
        stream.setCollector(this.collector);
      }

      this.processor.onCreate(context.getThisTaskId());
    }

    @Override
    public void execute(Tuple input) {
      Object sentObject = input.getValue(0);
      ContentEvent sentEvent = (ContentEvent) sentObject;
      processor.process(sentEvent);
    }

    @Override
    public void declareOutputFields(OutputFieldsDeclarer declarer) {
      for (StormStream stream : streams) {
        declarer.declareStream(stream.getOutputId(),
            new Fields(StormSamoaUtils.CONTENT_EVENT_FIELD,
                StormSamoaUtils.KEY_FIELD));
      }
    }

    StormStream createStream(String piId) {
      StormBoltStream stream = new StormBoltStream(piId);
      streams.add(stream);
      return stream;
    }
  }
}