    001/*
    002 * Copyright (c) 2007-2016 Concurrent, Inc. All Rights Reserved.
    003 *
    004 * Project and contact information: http://www.cascading.org/
    005 *
    006 * This file is part of the Cascading project.
    007 *
    008 * Licensed under the Apache License, Version 2.0 (the "License");
    009 * you may not use this file except in compliance with the License.
    010 * You may obtain a copy of the License at
    011 *
    012 *     http://www.apache.org/licenses/LICENSE-2.0
    013 *
    014 * Unless required by applicable law or agreed to in writing, software
    015 * distributed under the License is distributed on an "AS IS" BASIS,
    016 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    017 * See the License for the specific language governing permissions and
    018 * limitations under the License.
    019 */
    020
    021package cascading.flow.hadoop.stream.element;
    022
    023import cascading.flow.FlowProcess;
    024import cascading.flow.hadoop.HadoopFlowProcess;
    025import cascading.flow.hadoop.HadoopGroupByClosure;
    026import cascading.flow.hadoop.stream.HadoopGroupGate;
    027import cascading.flow.stream.duct.Duct;
    028import cascading.flow.stream.graph.IORole;
    029import cascading.pipe.GroupBy;
    030import cascading.tuple.Tuple;
    031import cascading.tuple.io.TuplePair;
    032import org.apache.hadoop.mapred.OutputCollector;
    033
    034/**
    035 *
    036 */
    037public class HadoopGroupByGate extends HadoopGroupGate
    038  {
    039  public HadoopGroupByGate( FlowProcess flowProcess, GroupBy groupBy, IORole role )
    040    {
    041    super( flowProcess, groupBy, role );
    042    }
    043
    044  @Override
    045  protected HadoopGroupByClosure createClosure()
    046    {
    047    // todo: collapse keyFields here if an array size > 1
    048    return new HadoopGroupByClosure( flowProcess, keyFields, valuesFields );
    049    }
    050
    051  @Override
    052  protected void wrapGroupingAndCollect( Duct previous, Tuple valuesTuple, Tuple groupKey ) throws java.io.IOException
    053    {
    054    collector.collect( groupKey, valuesTuple );
    055    }
    056
    057  @Override
    058  protected Tuple unwrapGrouping( Tuple key )
    059    {
    060    return sortFields == null ? key : ( (TuplePair) key ).getLhs();
    061    }
    062
    063  protected OutputCollector createOutputCollector()
    064    {
    065    return ( (HadoopFlowProcess) flowProcess ).getOutputCollector();
    066    }
    067  }