com.cotdp.hadoop.BrotliFileRecordReader.java Source code

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Here is the source code for com.cotdp.hadoop.BrotliFileRecordReader.java

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/**
 * 
 * Adapated from com.cotdp.hadoop Copyright 2011 Michael Cutler <m@cotdp.com>
 *
 * 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 com.cotdp.hadoop;

import java.io.IOException;
import java.util.Scanner;

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.mapreduce.RecordReader;
import org.apache.hadoop.mapreduce.InputSplit;
import org.apache.hadoop.mapreduce.TaskAttemptContext;
import org.apache.hadoop.mapreduce.lib.input.FileSplit;

public class BrotliFileRecordReader extends RecordReader<Text, Text> {
    /** InputStream used to read the ZIP file from the FileSystem */
    private FSDataInputStream fsin;

    /** Brotli file parser/decompresser */
    private Process decompressor;

    /** Uncompressed file name */
    private Text currentKey = new Text();

    /** Uncompressed file contents */
    private Text currentValue = new Text();

    /** Used to indicate progress */
    private boolean isFinished = false;

    private Scanner outputLines;

    /**
     * Initialize and open the ZIP file from the FileSystem
     */
    @Override
    public void initialize(InputSplit inputSplit, TaskAttemptContext taskAttemptContext)
            throws IOException, InterruptedException {
        FileSplit split = (FileSplit) inputSplit;
        Configuration conf = taskAttemptContext.getConfiguration();
        Path path = split.getPath();
        FileSystem fs = path.getFileSystem(conf);

        // Set the file path as the key
        currentKey.set(path.getName());
        // Open the stream
        fsin = fs.open(path);

        String cmd = "/bin/cat";
        ProcessBuilder pb = new ProcessBuilder();
        pb.redirectOutput();
        pb.command(cmd);

        try {
            decompressor = pb.start();

        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
    }

    /**
     * This is where the magic happens, each ZipEntry is decompressed and
     * readied for the Mapper. The contents of each file is held *in memory*
     * in a BytesWritable object.
     * 
     * If the ZipFileInputFormat has been set to Lenient (not the default),
     * certain exceptions will be gracefully ignored to prevent a larger job
     * from failing.
     */
    @Override
    public boolean nextKeyValue() throws IOException, InterruptedException {
        if (outputLines == null) {
            // First time through
            currentKey.set(""); // TODO: Fix This, should be filename?
            outputLines = new Scanner(decompressor.getInputStream());
        }

        if (outputLines.hasNextLine()) {
            currentValue.set(outputLines.nextLine());
            return true;
        } else {
            // At the end of the end of the file
            isFinished = true;
            return false;
        }

    }

    /**
     * Rather than calculating progress, we just keep it simple
     */
    @Override
    public float getProgress() throws IOException, InterruptedException {
        return isFinished ? 1 : 0;
    }

    /**
     * Returns the current key (name of the zipped file)
     */
    @Override
    public Text getCurrentKey() throws IOException, InterruptedException {
        return currentKey;
    }

    /**
     * Returns the current value (contents of the zipped file)
     */
    @Override
    public Text getCurrentValue() throws IOException, InterruptedException {
        return currentValue;
    }

    /**
     * Close quietly, ignoring any exceptions
     */
    @Override
    public void close() throws IOException {

        try {
            fsin.close();
        } catch (Exception ignore) {
        }
    }

}