org.apache.hadoop.mapred.KeyValueLineRecordReader.java Source code

Introduction

Here is the source code for org.apache.hadoop.mapred.KeyValueLineRecordReader.java

Source

/**
 * 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.mapred;

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.LongWritable;
import org.apache.hadoop.io.Text;

/**
 * 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 implements RecordReader<Text, Text> {

    private final LineRecordReader lineRecordReader;

    private byte separator = (byte) '\t';

    private LongWritable dummyKey;

    private Text innerValue;

    public Class getKeyClass() {
        return Text.class;
    }

    public Text createKey() {
        return new Text();
    }

    public Text createValue() {
        return new Text();
    }

    public KeyValueLineRecordReader(Configuration job, FileSplit split) throws IOException {

        lineRecordReader = new LineRecordReader(job, split);
        dummyKey = lineRecordReader.createKey();
        innerValue = lineRecordReader.createValue();
        String sepStr = job.get("mapreduce.input.keyvaluelinerecordreader.key.value.separator", "\t");
        this.separator = (byte) sepStr.charAt(0);
    }

    public static int findSeparator(byte[] utf, int start, int length, byte sep) {
        return org.apache.hadoop.mapreduce.lib.input.KeyValueLineRecordReader.findSeparator(utf, start, length,
                sep);
    }

    /** Read key/value pair in a line. */
    public synchronized boolean next(Text key, Text value) throws IOException {
        byte[] line = null;
        int lineLen = -1;
        if (lineRecordReader.next(dummyKey, innerValue)) {
            line = innerValue.getBytes();
            lineLen = innerValue.getLength();
        } else {
            return false;
        }
        if (line == null)
            return false;
        int pos = findSeparator(line, 0, lineLen, this.separator);
        org.apache.hadoop.mapreduce.lib.input.KeyValueLineRecordReader.setKeyValue(key, value, line, lineLen, pos);
        return true;
    }

    public float getProgress() throws IOException {
        return lineRecordReader.getProgress();
    }

    public synchronized long getPos() throws IOException {
        return lineRecordReader.getPos();
    }

    public synchronized void close() throws IOException {
        lineRecordReader.close();
    }
}