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    
019    package org.apache.hadoop.mapred;
020    
021    import java.io.IOException;
022    
023    import org.apache.hadoop.classification.InterfaceAudience;
024    import org.apache.hadoop.classification.InterfaceStability;
025    import org.apache.hadoop.conf.Configuration;
026    import org.apache.hadoop.io.LongWritable;
027    import org.apache.hadoop.io.Text;
028    
029    /**
030     * This class treats a line in the input as a key/value pair separated by a 
031     * separator character. The separator can be specified in config file 
032     * under the attribute name mapreduce.input.keyvaluelinerecordreader.key.value.separator. The default
033     * separator is the tab character ('\t').
034     */
035    @InterfaceAudience.Public
036    @InterfaceStability.Stable
037    public class KeyValueLineRecordReader implements RecordReader<Text, Text> {
038      
039      private final LineRecordReader lineRecordReader;
040    
041      private byte separator = (byte) '\t';
042    
043      private LongWritable dummyKey;
044    
045      private Text innerValue;
046    
047      public Class getKeyClass() { return Text.class; }
048      
049      public Text createKey() {
050        return new Text();
051      }
052      
053      public Text createValue() {
054        return new Text();
055      }
056    
057      public KeyValueLineRecordReader(Configuration job, FileSplit split)
058        throws IOException {
059        
060        lineRecordReader = new LineRecordReader(job, split);
061        dummyKey = lineRecordReader.createKey();
062        innerValue = lineRecordReader.createValue();
063        String sepStr = job.get("mapreduce.input.keyvaluelinerecordreader.key.value.separator", "\t");
064        this.separator = (byte) sepStr.charAt(0);
065      }
066    
067      public static int findSeparator(byte[] utf, int start, int length, 
068          byte sep) {
069        return org.apache.hadoop.mapreduce.lib.input.
070          KeyValueLineRecordReader.findSeparator(utf, start, length, sep);
071      }
072    
073      /** Read key/value pair in a line. */
074      public synchronized boolean next(Text key, Text value)
075        throws IOException {
076        byte[] line = null;
077        int lineLen = -1;
078        if (lineRecordReader.next(dummyKey, innerValue)) {
079          line = innerValue.getBytes();
080          lineLen = innerValue.getLength();
081        } else {
082          return false;
083        }
084        if (line == null)
085          return false;
086        int pos = findSeparator(line, 0, lineLen, this.separator);
087        org.apache.hadoop.mapreduce.lib.input.KeyValueLineRecordReader.
088          setKeyValue(key, value, line, lineLen, pos);
089        return true;
090      }
091      
092      public float getProgress() throws IOException {
093        return lineRecordReader.getProgress();
094      }
095      
096      public synchronized long getPos() throws IOException {
097        return lineRecordReader.getPos();
098      }
099    
100      public synchronized void close() throws IOException { 
101        lineRecordReader.close();
102      }
103    }