    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.tez;
    022
    023import java.util.Collection;
    024import java.util.Iterator;
    025
    026import cascading.flow.FlowProcess;
    027import cascading.flow.hadoop.HadoopCoGroupClosure;
    028import cascading.flow.hadoop.util.LazySpillableTupleCollection;
    029import cascading.flow.hadoop.util.ResettableCollection;
    030import cascading.tuple.Fields;
    031import cascading.tuple.Tuple;
    032
    033/**
    034 *
    035 */
    036public class TezCoGroupClosure extends HadoopCoGroupClosure
    037  {
    038  public TezCoGroupClosure( FlowProcess flowProcess, int numSelfJoins, Fields[] groupingFields, Fields[] valueFields )
    039    {
    040    super( flowProcess, numSelfJoins, groupingFields, valueFields );
    041    }
    042
    043  protected void build()
    044    {
    045    clearGroups();
    046
    047    for( int pos = 0; pos < values.length; pos++ )
    048      ( (ResettableCollection) collections[ pos ] ).reset( values[ pos ] );
    049
    050    // todo: prevent an initial iteration to populate the lazy collection
    051    if( numSelfJoins != 0 ) // force fill of lazy collection
    052      {
    053      Iterator<Tuple> iterator = collections[ 0 ].iterator();
    054
    055      while( iterator.hasNext() )
    056        iterator.next(); // do nothing, populates the lazy collection
    057      }
    058    }
    059
    060  @Override
    061  protected Collection<Tuple> createTupleCollection( Fields joinField )
    062    {
    063    return new LazySpillableTupleCollection( super.createTupleCollection( joinField ) );
    064    }
    065  }