001/**
002 * Licensed to the Apache Software Foundation (ASF) under one
003 * or more contributor license agreements.  See the NOTICE file
004 * distributed with this work for additional information
005 * regarding copyright ownership.  The ASF licenses this file
006 * to you under the Apache License, Version 2.0 (the
007 * "License"); you may not use this file except in compliance
008 * with the License.  You may obtain a copy of the License at
009 *
010 *     http://www.apache.org/licenses/LICENSE-2.0
011 *
012 * Unless required by applicable law or agreed to in writing, software
013 * distributed under the License is distributed on an "AS IS" BASIS,
014 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
015 * See the License for the specific language governing permissions and
016 * limitations under the License.
017 */
018
019package org.apache.hadoop.mapreduce.lib.input;
020
021import java.io.IOException;
022
023import org.apache.hadoop.classification.InterfaceAudience;
024import org.apache.hadoop.classification.InterfaceStability;
025import org.apache.hadoop.io.Text;
026import org.apache.hadoop.io.Writable;
027import org.apache.hadoop.io.WritableComparable;
028import org.apache.hadoop.mapreduce.InputSplit;
029import org.apache.hadoop.mapreduce.RecordReader;
030import org.apache.hadoop.mapreduce.TaskAttemptContext;
031
032/**
033 * This class converts the input keys and values to their String forms by
034 * calling toString() method. This class to SequenceFileAsTextInputFormat
035 * class is as LineRecordReader class to TextInputFormat class.
036 */
037@InterfaceAudience.Public
038@InterfaceStability.Stable
039public class SequenceFileAsTextRecordReader
040  extends RecordReader<Text, Text> {
041  
042  private final SequenceFileRecordReader<WritableComparable<?>, Writable>
043    sequenceFileRecordReader;
044
045  private Text key;
046  private Text value;
047
048  public SequenceFileAsTextRecordReader()
049    throws IOException {
050    sequenceFileRecordReader =
051      new SequenceFileRecordReader<WritableComparable<?>, Writable>();
052  }
053
054  public void initialize(InputSplit split, TaskAttemptContext context)
055      throws IOException, InterruptedException {
056    sequenceFileRecordReader.initialize(split, context);
057  }
058
059  @Override
060  public Text getCurrentKey() 
061      throws IOException, InterruptedException {
062    return key;
063  }
064  
065  @Override
066  public Text getCurrentValue() 
067      throws IOException, InterruptedException {
068    return value;
069  }
070  
071  /** Read key/value pair in a line. */
072  public synchronized boolean nextKeyValue() 
073      throws IOException, InterruptedException {
074    if (!sequenceFileRecordReader.nextKeyValue()) {
075      return false;
076    }
077    if (key == null) {
078      key = new Text(); 
079    }
080    if (value == null) {
081      value = new Text(); 
082    }
083    key.set(sequenceFileRecordReader.getCurrentKey().toString());
084    value.set(sequenceFileRecordReader.getCurrentValue().toString());
085    return true;
086  }
087  
088  public float getProgress() throws IOException,  InterruptedException {
089    return sequenceFileRecordReader.getProgress();
090  }
091  
092  public synchronized void close() throws IOException {
093    sequenceFileRecordReader.close();
094  }
095}