edu.umd.cloud9.collection.line.NumberTextDocuments.java Source code

Introduction

Here is the source code for edu.umd.cloud9.collection.line.NumberTextDocuments.java

Source

/*
 * Cloud9: A MapReduce Library for Hadoop
 *
 * 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 edu.umd.cloud9.collection.line;

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

import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.conf.Configured;
import org.apache.hadoop.fs.FileSystem;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.io.IntWritable;
import org.apache.hadoop.io.LongWritable;
import org.apache.hadoop.io.Text;
import org.apache.hadoop.mapred.FileInputFormat;
import org.apache.hadoop.mapred.FileOutputFormat;
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.TextOutputFormat;
import org.apache.hadoop.util.Tool;
import org.apache.hadoop.util.ToolRunner;
import org.apache.log4j.Logger;

/**
 * <p>
 * Program that builds the mapping from docids (String identifiers) to
 * docnos (sequentially-numbered ints) for regular text documents. The program takes four command-line
 * arguments:
 * </p>
 * 
 * 
 * @author Ferhan Ture
 */
public class NumberTextDocuments extends Configured implements Tool {

    private static final Logger sLogger = Logger.getLogger(NumberTextDocuments.class);

    private static enum Count {
        DOCS
    };

    private static class MyMapper extends MapReduceBase
            implements Mapper<LongWritable, TextDocument, Text, IntWritable> {

        private final static Text sText = new Text();
        private final static IntWritable sInt = new IntWritable(1);

        public void map(LongWritable key, TextDocument doc, OutputCollector<Text, IntWritable> output,
                Reporter reporter) throws IOException {
            reporter.incrCounter(Count.DOCS, 1);

            sText.set(doc.getDocid());
            output.collect(sText, sInt);
        }
    }

    private static class MyReducer extends MapReduceBase implements Reducer<Text, IntWritable, Text, IntWritable> {

        private final static IntWritable sCnt = new IntWritable(1);

        public void reduce(Text key, Iterator<IntWritable> values, OutputCollector<Text, IntWritable> output,
                Reporter reporter) throws IOException {
            output.collect(key, sCnt);
            sCnt.set(sCnt.get() + 1);
        }
    }

    /**
     * Creates an instance of this tool.
     */
    public NumberTextDocuments() {
    }

    private static int printUsage() {
        System.out.println("usage: [input-path] [output-path] [output-file] [num-mappers]");
        ToolRunner.printGenericCommandUsage(System.out);
        return -1;
    }

    /**
     * Runs this tool.
     */
    public int run(String[] args) throws Exception {
        if (args.length != 4) {
            printUsage();
            return -1;
        }

        String inputPath = args[0];
        String outputPath = args[1];
        String outputFile = args[2];
        int mapTasks = Integer.parseInt(args[3]);

        sLogger.info("Tool: NumberTextDocuments");
        sLogger.info(" - Input path: " + inputPath);
        sLogger.info(" - Output path: " + outputPath);
        sLogger.info(" - Output file: " + outputFile);
        sLogger.info("Launching with " + mapTasks + " mappers...");

        JobConf conf = new JobConf(getConf(), NumberTextDocuments.class);
        conf.setJobName("NumberTextDocuments");

        conf.setNumMapTasks(mapTasks);
        conf.setNumReduceTasks(1);

        FileInputFormat.setInputPaths(conf, new Path(inputPath));
        FileOutputFormat.setOutputPath(conf, new Path(outputPath));
        FileOutputFormat.setCompressOutput(conf, false);

        conf.setInputFormat(TextDocumentInputFormat.class);
        conf.setOutputKeyClass(Text.class);
        conf.setOutputValueClass(IntWritable.class);
        conf.setOutputFormat(TextOutputFormat.class);

        conf.setMapperClass(MyMapper.class);
        conf.setReducerClass(MyReducer.class);

        // delete the output directory if it exists already
        FileSystem.get(conf).delete(new Path(outputPath), true);

        JobClient.runJob(conf);

        String input = outputPath + (outputPath.endsWith("/") ? "" : "/") + "/part-00000";
        TextDocnoMapping.writeDocnoData(input, outputFile, FileSystem.get(getConf()));

        return 0;
    }

    /**
     * Dispatches command-line arguments to the tool via the
     * <code>ToolRunner</code>.
     */
    public static void main(String[] args) throws Exception {
        int res = ToolRunner.run(new Configuration(), new NumberTextDocuments(), args);
        System.exit(res);
    }
}