001/*
002 * Copyright (c) 2007-2017 Xplenty, 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.tuple.hadoop.util;
022
023import java.io.InputStream;
024import java.util.Comparator;
025
026import cascading.CascadingException;
027import cascading.tuple.StreamComparator;
028import cascading.tuple.hadoop.io.HadoopTupleInputStream;
029import cascading.tuple.hadoop.io.HadoopTupleOutputStream;
030
031/**
032 *
033 */
034public class TupleElementStreamComparator implements StreamComparator<HadoopTupleInputStream>, Comparator<Object>
035  {
036  final StreamComparator comparator;
037
038  public TupleElementStreamComparator( StreamComparator comparator )
039    {
040    this.comparator = comparator;
041    }
042
043  @Override
044  public int compare( Object lhs, Object rhs )
045    {
046    return ( (Comparator<Object>) comparator ).compare( lhs, rhs );
047    }
048
049  @Override
050  public int compare( HadoopTupleInputStream lhsStream, HadoopTupleInputStream rhsStream )
051    {
052    try
053      {
054      // pop off element type, its assumed we know it as we have a stream comparator
055      // to delegate too
056      int lhsToken = lhsStream.readToken();
057      int rhsToken = rhsStream.readToken();
058
059      if( lhsToken == HadoopTupleOutputStream.WRITABLE_TOKEN )
060        lhsStream.readString();
061
062      if( rhsToken == HadoopTupleOutputStream.WRITABLE_TOKEN )
063        rhsStream.readString();
064
065      InputStream lhs = lhsToken == 0 ? null : lhsStream.getInputStream();
066      InputStream rhs = rhsToken == 0 ? null : rhsStream.getInputStream();
067
068      return comparator.compare( lhs, rhs );
069      }
070    catch( Exception exception )
071      {
072      throw new CascadingException( "unable to compare Tuples, likely a CoGroup is being attempted on fields of " +
073        "different types or custom comparators are incorrectly set on Fields", exception );
074      }
075    }
076  }