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  }