| /* |
| * Licensed to the Apache Software Foundation (ASF) under one |
| * or more contributor license agreements. See the NOTICE file |
| * distributed with this work for additional information |
| * regarding copyright ownership. The ASF licenses this file |
| * to you 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 org.apache.tinkerpop.gremlin.hadoop.process.computer; |
| |
| import org.apache.commons.configuration.Configuration; |
| import org.apache.hadoop.mapreduce.Reducer; |
| import org.apache.tinkerpop.gremlin.hadoop.structure.HadoopGraph; |
| import org.apache.tinkerpop.gremlin.hadoop.structure.io.HadoopPools; |
| import org.apache.tinkerpop.gremlin.hadoop.structure.io.ObjectWritable; |
| import org.apache.tinkerpop.gremlin.hadoop.structure.util.ConfUtil; |
| import org.apache.tinkerpop.gremlin.process.computer.MapReduce; |
| import org.apache.tinkerpop.gremlin.structure.io.gryo.kryoshim.KryoShimServiceLoader; |
| import org.apache.tinkerpop.gremlin.util.iterator.IteratorUtils; |
| import org.slf4j.Logger; |
| import org.slf4j.LoggerFactory; |
| |
| import java.io.IOException; |
| |
| /** |
| * @author Marko A. Rodriguez (http://markorodriguez.com) |
| */ |
| public final class HadoopReduce extends Reducer<ObjectWritable, ObjectWritable, ObjectWritable, ObjectWritable> { |
| |
| private static final Logger LOGGER = LoggerFactory.getLogger(HadoopReduce.class); |
| private MapReduce mapReduce; |
| private final HadoopReduceEmitter<ObjectWritable, ObjectWritable> reduceEmitter = new HadoopReduceEmitter<>(); |
| |
| private HadoopReduce() { |
| |
| } |
| |
| @Override |
| public void setup(final Reducer<ObjectWritable, ObjectWritable, ObjectWritable, ObjectWritable>.Context context) { |
| final Configuration apacheConfiguration = ConfUtil.makeApacheConfiguration(context.getConfiguration()); |
| KryoShimServiceLoader.applyConfiguration(apacheConfiguration); |
| this.mapReduce = MapReduce.createMapReduce(HadoopGraph.open(apacheConfiguration), apacheConfiguration); |
| this.mapReduce.workerStart(MapReduce.Stage.REDUCE); |
| } |
| |
| @Override |
| public void reduce(final ObjectWritable key, final Iterable<ObjectWritable> values, final Reducer<ObjectWritable, ObjectWritable, ObjectWritable, ObjectWritable>.Context context) throws IOException, InterruptedException { |
| this.reduceEmitter.setContext(context); |
| this.mapReduce.reduce(key.get(), IteratorUtils.map(values.iterator(), ObjectWritable::get), this.reduceEmitter); |
| } |
| |
| @Override |
| public void cleanup(final Reducer<ObjectWritable, ObjectWritable, ObjectWritable, ObjectWritable>.Context context) { |
| this.mapReduce.workerEnd(MapReduce.Stage.REDUCE); |
| } |
| |
| |
| public class HadoopReduceEmitter<OK, OV> implements MapReduce.ReduceEmitter<OK, OV> { |
| |
| private Reducer<ObjectWritable, ObjectWritable, ObjectWritable, ObjectWritable>.Context context; |
| private final ObjectWritable<OK> keyWritable = new ObjectWritable<>(); |
| private final ObjectWritable<OV> valueWritable = new ObjectWritable<>(); |
| |
| public void setContext(final Reducer<ObjectWritable, ObjectWritable, ObjectWritable, ObjectWritable>.Context context) { |
| this.context = context; |
| } |
| |
| @Override |
| public void emit(final OK key, final OV value) { |
| this.keyWritable.set(key); |
| this.valueWritable.set(value); |
| try { |
| this.context.write(this.keyWritable, this.valueWritable); |
| } catch (final Exception e) { |
| LOGGER.error(e.getMessage()); |
| throw new IllegalStateException(e.getMessage(), e); |
| } |
| } |
| } |
| } |