co.nubetech.hiho.dedup.DelimitedLineRecordReader.java Source code

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Here is the source code for co.nubetech.hiho.dedup.DelimitedLineRecordReader.java

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/**
 * Copyright 2011 Nube Technologies
 *
 * Licensed 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 co.nubetech.hiho.dedup;

import java.io.IOException;

import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.FSDataInputStream;
import org.apache.hadoop.fs.FileSystem;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.io.Text;
import org.apache.hadoop.io.compress.CompressionCodec;
import org.apache.hadoop.io.compress.CompressionCodecFactory;
import org.apache.hadoop.mapreduce.InputSplit;
import org.apache.hadoop.mapreduce.RecordReader;
import org.apache.hadoop.mapreduce.TaskAttemptContext;
import org.apache.hadoop.mapreduce.lib.input.FileSplit;
import org.apache.hadoop.util.LineReader;
import org.apache.log4j.Logger;

public class DelimitedLineRecordReader extends RecordReader<Text, Text> {

    final static Logger logger = Logger.getLogger(co.nubetech.hiho.dedup.DelimitedLineRecordReader.class);

    private String delimiter;
    private int column;
    private CompressionCodecFactory compressionCodecs = null;
    private long start;
    private long pos;
    private long end;
    private LineReader in;
    private int maxLineLength;
    private Text key = null;
    private Text value = null;

    /**
     * 
     * @param delimiter
     * @param column
     * 
     * 
     */

    @Override
    public void initialize(InputSplit genericSplit, TaskAttemptContext context) throws IOException {
        FileSplit split = (FileSplit) genericSplit;
        Configuration job = context.getConfiguration();
        this.delimiter = job.get(DelimitedTextInputFormat.DELIMITER_CONF);
        this.column = job.getInt(DelimitedTextInputFormat.COLUMN_CONF, 0);
        this.maxLineLength = job.getInt("mapred.linerecordreader.maxlength", Integer.MAX_VALUE);
        start = split.getStart();
        end = start + split.getLength();
        final Path file = split.getPath();
        compressionCodecs = new CompressionCodecFactory(job);
        final CompressionCodec codec = compressionCodecs.getCodec(file);

        // open the file and seek to the start of the split
        FileSystem fs = file.getFileSystem(job);
        FSDataInputStream fileIn = fs.open(split.getPath());
        boolean skipFirstLine = false;
        if (codec != null) {
            in = new LineReader(codec.createInputStream(fileIn), job);
            end = Long.MAX_VALUE;
        } else {
            if (start != 0) {
                skipFirstLine = true;
                --start;
                fileIn.seek(start);
            }
            in = new LineReader(fileIn, job);
        }
        if (skipFirstLine) { // skip first line and re-establish "start".
            start += in.readLine(new Text(), 0, (int) Math.min((long) Integer.MAX_VALUE, end - start));
        }
        this.pos = start;
    }

    public boolean nextKeyValue() throws IOException {

        if (value == null) {
            value = new Text();
        }
        int newSize = 0;
        while (pos < end) {
            newSize = in.readLine(value, maxLineLength,
                    Math.max((int) Math.min(Integer.MAX_VALUE, end - pos), maxLineLength));
            if (newSize == 0) {
                break;
            }
            pos += newSize;
            if (newSize < maxLineLength) {
                break;
            }

            // line too long. try again
            logger.info("Skipped line of size " + newSize + " at pos " + (pos - newSize));
        }
        if (newSize == 0) {
            key = null;
            value = null;
            return false;
        } else {
            // we calculate the key from the value here
            if (value != null) {
                logger.debug("Value is: " + value);
                logger.debug("Column is: " + column);
                logger.debug("Delimiter is: " + delimiter);

                key = getColumn(value, column, delimiter);

                logger.debug("Value after generating keyColumn: " + value);
                logger.debug("Key is: " + key);

            }
            return true;
        }
    }

    @Override
    public Text getCurrentKey() {
        return key;
    }

    @Override
    public Text getCurrentValue() {
        return value;
    }

    public synchronized void close() throws IOException {
        if (in != null) {
            in.close();
        }
    }

    /**
     * Get the progress within the split
     */
    public float getProgress() {
        if (start == end) {
            return 0.0f;
        } else {
            return Math.min(1.0f, (pos - start) / (float) (end - start));
        }
    }

    public Text getColumn(Text val, int column, String delimiter) throws IOException {
        if (delimiter == null || delimiter.equals("")) {
            throw new IOException("Value of delimiter is empty");
        }
        int lastOccurance = 0;
        int occurance = 0;
        for (int i = 0; i < column; i++) {
            occurance = val.find(delimiter, lastOccurance) - lastOccurance;
            lastOccurance = lastOccurance + occurance + delimiter.length();
        }

        logger.debug("text value is: " + val);
        int delimiterLength = delimiter.length();
        int startPosition = lastOccurance - (occurance + delimiterLength);
        Text keyColumn = new Text();
        keyColumn.set(val.getBytes(), startPosition, occurance);
        return keyColumn;
    }

}