edu.umn.cs.spatialHadoop.operations.Shuffle.java Source code

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Here is the source code for edu.umn.cs.spatialHadoop.operations.Shuffle.java

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/***********************************************************************
* Copyright (c) 2015 by Regents of the University of Minnesota.
* All rights reserved. This program and the accompanying materials
* are made available under the terms of the Apache License, Version 2.0 which 
* accompanies this distribution and is available at
* http://www.opensource.org/licenses/apache2.0.php.
*
*************************************************************************/
package edu.umn.cs.spatialHadoop.operations;

import java.io.IOException;
import java.util.Collections;
import java.util.Iterator;
import java.util.Vector;

import org.apache.hadoop.fs.Path;
import org.apache.hadoop.io.IntWritable;
import org.apache.hadoop.io.LongWritable;
import org.apache.hadoop.io.NullWritable;
import org.apache.hadoop.io.Text;
import org.apache.hadoop.mapred.ClusterStatus;
import org.apache.hadoop.mapred.JobClient;
import org.apache.hadoop.mapred.JobConf;
import org.apache.hadoop.mapred.MapReduceBase;
import org.apache.hadoop.mapred.Mapper;
import org.apache.hadoop.mapred.OutputCollector;
import org.apache.hadoop.mapred.Reducer;
import org.apache.hadoop.mapred.Reporter;
import org.apache.hadoop.mapred.TextInputFormat;
import org.apache.hadoop.util.GenericOptionsParser;

import edu.umn.cs.spatialHadoop.OperationsParams;
import edu.umn.cs.spatialHadoop.mapred.TextOutputFormat;

/**
 * Shuffle the lines in an input text file.
 * @author Ahmed Eldawy
 *
 */
public class Shuffle {

    private static final String NumOfPartitions = "edu.umn.cs.spatialHadoop.operations.LineRandomizer";

    public static class Map extends MapReduceBase implements Mapper<LongWritable, Text, IntWritable, Text> {
        /**Total number of partitions to generate*/
        private int numOfPartitions;

        /**Temporary key used to generate intermediate records*/
        private IntWritable tempKey = new IntWritable();

        @Override
        public void configure(JobConf job) {
            super.configure(job);
            numOfPartitions = job.getInt(NumOfPartitions, 1);
        }

        public void map(LongWritable key, Text line, OutputCollector<IntWritable, Text> output, Reporter reporter)
                throws IOException {
            tempKey.set((int) (Math.random() * numOfPartitions));
            output.collect(tempKey, line);
        }
    }

    public static class Reduce extends MapReduceBase implements Reducer<IntWritable, Text, NullWritable, Text> {

        private NullWritable dummy = NullWritable.get();

        @Override
        public void reduce(IntWritable key, Iterator<Text> values, OutputCollector<NullWritable, Text> output,
                Reporter reporter) throws IOException {
            // Retrieve all lines in this reduce group
            Vector<Text> all_lines = new Vector<Text>();
            while (values.hasNext()) {
                Text t = values.next();
                all_lines.add(new Text(t));
            }

            // Randomize lines within this group
            Collections.shuffle(all_lines);

            // Output lines in the randomized order
            for (Text line : all_lines) {
                output.collect(dummy, line);
            }
        }
    }

    /**
     * Counts the exact number of lines in a file by issuing a MapReduce job
     * that does the thing
     * @param infile
     * @param outfile
     * @param params
     * @throws IOException
     */
    public static void randomizerMapReduce(Path infile, Path outfile, OperationsParams params) throws IOException {
        JobConf job = new JobConf(Shuffle.class);

        job.setJobName("Randomizer");
        job.setMapOutputKeyClass(IntWritable.class);
        job.setMapOutputValueClass(Text.class);

        job.setMapperClass(Map.class);
        ClusterStatus clusterStatus = new JobClient(job).getClusterStatus();
        job.setNumMapTasks(clusterStatus.getMaxMapTasks() * 5);

        job.setReducerClass(Reduce.class);
        job.setNumReduceTasks(Math.max(1, clusterStatus.getMaxReduceTasks()));

        job.setInt(NumOfPartitions, Math.max(1, clusterStatus.getMaxReduceTasks()));

        job.setInputFormat(TextInputFormat.class);
        TextInputFormat.setInputPaths(job, infile);

        job.setOutputFormat(TextOutputFormat.class);
        TextOutputFormat.setOutputPath(job, outfile);

        // Submit the job
        JobClient.runJob(job);
    }

    private static void printUsage() {
        System.out.println("Shuffles the lines of an input text file");
        System.out.println("Parameters: (* marks required parameters)");
        System.out.println("<input file>: (*) Path to input file");
        System.out.println("<output file>: (*) Path to output file");
        GenericOptionsParser.printGenericCommandUsage(System.out);
    }

    /**
     * @param args
     * @throws IOException 
     */
    public static void main(String[] args) throws IOException {
        OperationsParams params = new OperationsParams(new GenericOptionsParser(args));
        if (!params.checkInputOutput()) {
            printUsage();
            System.exit(1);
        }
        Path inputFile = params.getInputPath();
        Path outputFile = params.getOutputPath();
        randomizerMapReduce(inputFile, outputFile, params);
    }

}