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.tap.hadoop.io;
022
023import java.io.IOException;
024
025import org.apache.hadoop.conf.Configurable;
026import org.apache.hadoop.conf.Configuration;
027import org.apache.hadoop.mapred.FileInputFormat;
028import org.apache.hadoop.mapred.FileSplit;
029import org.apache.hadoop.mapred.JobConf;
030import org.apache.hadoop.mapred.RecordReader;
031import org.apache.hadoop.mapred.Reporter;
032import org.apache.hadoop.mapred.lib.CombineFileSplit;
033
034/**
035 * A wrapper class for a record reader that handles a single file split. It delegates most of the
036 * methods to the wrapped instance. We need this wrapper to satisfy the constructor requirement to
037 * be used with hadoop's CombineFileRecordReader class.
038 *
039 * @see org.apache.hadoop.mapred.lib.CombineFileRecordReader
040 * @see org.apache.hadoop.mapred.lib.CombineFileInputFormat
041 */
042public class CombineFileRecordReaderWrapper<K, V> implements RecordReader<K, V>
043  {
044  /** property that indicates how individual input format is to be interpreted */
045  public static final String INDIVIDUAL_INPUT_FORMAT = "cascading.individual.input.format";
046
047  private final RecordReader<K, V> delegate;
048
049  // this constructor signature is required by CombineFileRecordReader
050  public CombineFileRecordReaderWrapper( CombineFileSplit split, Configuration conf, Reporter reporter, Integer idx ) throws Exception
051    {
052    FileSplit fileSplit = new FileSplit(
053      split.getPath( idx ),
054      split.getOffset( idx ),
055      split.getLength( idx ),
056      split.getLocations()
057    );
058
059    Class<?> clz = conf.getClass( INDIVIDUAL_INPUT_FORMAT, null );
060    FileInputFormat<K, V> inputFormat = (FileInputFormat<K, V>) clz.newInstance();
061
062    if( inputFormat instanceof Configurable )
063      ( (Configurable) inputFormat ).setConf( conf );
064
065    delegate = inputFormat.getRecordReader( fileSplit, (JobConf) conf, reporter );
066    }
067
068  public boolean next( K key, V value ) throws IOException
069    {
070    return delegate.next( key, value );
071    }
072
073  public K createKey()
074    {
075    return delegate.createKey();
076    }
077
078  public V createValue()
079    {
080    return delegate.createValue();
081    }
082
083  public long getPos() throws IOException
084    {
085    return delegate.getPos();
086    }
087
088  public void close() throws IOException
089    {
090    delegate.close();
091    }
092
093  public float getProgress() throws IOException
094    {
095    return delegate.getProgress();
096    }
097  }