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KeyValueLineRecordReader.java
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KeyValueLineRecordReader.java
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/**
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance
* with the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.hadoop.mapreduce.lib.input;
import java.io.IOException;
import org.apache.hadoop.classification.InterfaceAudience;
import org.apache.hadoop.classification.InterfaceStability;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.io.Text;
import org.apache.hadoop.mapreduce.InputSplit;
import org.apache.hadoop.mapreduce.RecordReader;
import org.apache.hadoop.mapreduce.TaskAttemptContext;
/**
* This class treats a line in the input as a key/value pair separated by a
* separator character. The separator can be specified in config file
* under the attribute name mapreduce.input.keyvaluelinerecordreader.key.value.separator. The default
* separator is the tab character ('\t').
*/
@InterfaceAudience.Public
@InterfaceStability.Stable
public class KeyValueLineRecordReader extends RecordReader<Text, Text> {
public static final String KEY_VALUE_SEPARATOR =
"mapreduce.input.keyvaluelinerecordreader.key.value.separator";
/**
* @deprecated Use {@link #KEY_VALUE_SEPARATOR}
*/
@Deprecated
public static final String KEY_VALUE_SEPERATOR = KEY_VALUE_SEPARATOR;
private final LineRecordReader lineRecordReader;
private byte separator = (byte) '\t';
private Text innerValue;
private Text key;
private Text value;
public Class getKeyClass() { return Text.class; }
public KeyValueLineRecordReader(Configuration conf)
throws IOException {
lineRecordReader = new LineRecordReader();
String sepStr = conf.get(KEY_VALUE_SEPARATOR, "\t");
this.separator = (byte) sepStr.charAt(0);
}
public void initialize(InputSplit genericSplit,
TaskAttemptContext context) throws IOException {
lineRecordReader.initialize(genericSplit, context);
}
public static int findSeparator(byte[] utf, int start, int length,
byte sep) {
for (int i = start; i < (start + length); i++) {
if (utf[i] == sep) {
return i;
}
}
return -1;
}
public static void setKeyValue(Text key, Text value, byte[] line,
int lineLen, int pos) {
if (pos == -1) {
key.set(line, 0, lineLen);
value.set("");
} else {
key.set(line, 0, pos);
value.set(line, pos + 1, lineLen - pos - 1);
}
}
/** Read key/value pair in a line. */
public synchronized boolean nextKeyValue()
throws IOException {
byte[] line = null;
int lineLen = -1;
if (lineRecordReader.nextKeyValue()) {
innerValue = lineRecordReader.getCurrentValue();
line = innerValue.getBytes();
lineLen = innerValue.getLength();
} else {
return false;
}
if (line == null)
return false;
if (key == null) {
key = new Text();
}
if (value == null) {
value = new Text();
}
int pos = findSeparator(line, 0, lineLen, this.separator);
setKeyValue(key, value, line, lineLen, pos);
return true;
}
public Text getCurrentKey() {
return key;
}
public Text getCurrentValue() {
return value;
}
public float getProgress() throws IOException {
return lineRecordReader.getProgress();
}
public synchronized void close() throws IOException {
lineRecordReader.close();
}
}