    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.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  }