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.mapreduce.lib.input; 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.Text; 027 import org.apache.hadoop.mapreduce.InputSplit; 028 import org.apache.hadoop.mapreduce.RecordReader; 029 import org.apache.hadoop.mapreduce.TaskAttemptContext; 030 031 /** 032 * This class treats a line in the input as a key/value pair separated by a 033 * separator character. The separator can be specified in config file 034 * under the attribute name mapreduce.input.keyvaluelinerecordreader.key.value.separator. The default 035 * separator is the tab character ('\t'). 036 */ 037 @InterfaceAudience.Public 038 @InterfaceStability.Stable 039 public class KeyValueLineRecordReader extends RecordReader<Text, Text> { 040 public static final String KEY_VALUE_SEPERATOR = 041 "mapreduce.input.keyvaluelinerecordreader.key.value.separator"; 042 043 private final LineRecordReader lineRecordReader; 044 045 private byte separator = (byte) '\t'; 046 047 private Text innerValue; 048 049 private Text key; 050 051 private Text value; 052 053 public KeyValueLineRecordReader(Configuration conf) 054 throws IOException { 055 056 lineRecordReader = new LineRecordReader(); 057 String sepStr = conf.get(KEY_VALUE_SEPERATOR, "\t"); 058 this.separator = (byte) sepStr.charAt(0); 059 } 060 061 public void initialize(InputSplit genericSplit, 062 TaskAttemptContext context) throws IOException { 063 lineRecordReader.initialize(genericSplit, context); 064 } 065 066 public static int findSeparator(byte[] utf, int start, int length, 067 byte sep) { 068 for (int i = start; i < (start + length); i++) { 069 if (utf[i] == sep) { 070 return i; 071 } 072 } 073 return -1; 074 } 075 076 public static void setKeyValue(Text key, Text value, byte[] line, 077 int lineLen, int pos) { 078 if (pos == -1) { 079 key.set(line, 0, lineLen); 080 value.set(""); 081 } else { 082 key.set(line, 0, pos); 083 value.set(line, pos + 1, lineLen - pos - 1); 084 } 085 } 086 /** Read key/value pair in a line. */ 087 public synchronized boolean nextKeyValue() 088 throws IOException { 089 byte[] line = null; 090 int lineLen = -1; 091 if (lineRecordReader.nextKeyValue()) { 092 innerValue = lineRecordReader.getCurrentValue(); 093 line = innerValue.getBytes(); 094 lineLen = innerValue.getLength(); 095 } else { 096 return false; 097 } 098 if (line == null) 099 return false; 100 if (key == null) { 101 key = new Text(); 102 } 103 if (value == null) { 104 value = new Text(); 105 } 106 int pos = findSeparator(line, 0, lineLen, this.separator); 107 setKeyValue(key, value, line, lineLen, pos); 108 return true; 109 } 110 111 public Text getCurrentKey() { 112 return key; 113 } 114 115 public Text getCurrentValue() { 116 return value; 117 } 118 119 public float getProgress() throws IOException { 120 return lineRecordReader.getProgress(); 121 } 122 123 public synchronized void close() throws IOException { 124 lineRecordReader.close(); 125 } 126 }