    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.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  }