Java tutorial
/* * 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.wikipedia; import java.io.IOException; import java.util.Iterator; import org.apache.commons.cli.CommandLine; import org.apache.commons.cli.CommandLineParser; import org.apache.commons.cli.GnuParser; import org.apache.commons.cli.HelpFormatter; import org.apache.commons.cli.OptionBuilder; import org.apache.commons.cli.Options; import org.apache.commons.cli.ParseException; 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.mapred.Counters; 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.RunningJob; import org.apache.hadoop.mapred.TextOutputFormat; import org.apache.hadoop.util.Tool; import org.apache.hadoop.util.ToolRunner; import org.apache.log4j.Logger; /** * Tool for building the mapping between Wikipedia internal ids (docids) and sequentially-numbered * ints (docnos). * * @author Jimmy Lin * @author Peter Exner */ public class BuildWikipediaDocnoMapping extends Configured implements Tool { private static final Logger LOG = Logger.getLogger(BuildWikipediaDocnoMapping.class); private static enum PageTypes { TOTAL, REDIRECT, DISAMBIGUATION, EMPTY, ARTICLE, STUB, NON_ARTICLE, OTHER }; private static class MyMapper extends MapReduceBase implements Mapper<LongWritable, WikipediaPage, IntWritable, IntWritable> { private final static IntWritable keyOut = new IntWritable(); private final static IntWritable valOut = new IntWritable(1); private boolean keepAll; public void configure(JobConf job) { keepAll = job.getBoolean(KEEP_ALL_OPTION, false); } public void map(LongWritable key, WikipediaPage p, OutputCollector<IntWritable, IntWritable> output, Reporter reporter) throws IOException { reporter.incrCounter(PageTypes.TOTAL, 1); // If we're keeping all pages, don't bother checking. if (keepAll) { keyOut.set(Integer.parseInt(p.getDocid())); output.collect(keyOut, valOut); return; } if (p.isRedirect()) { reporter.incrCounter(PageTypes.REDIRECT, 1); } else if (p.isEmpty()) { reporter.incrCounter(PageTypes.EMPTY, 1); } else if (p.isDisambiguation()) { reporter.incrCounter(PageTypes.DISAMBIGUATION, 1); } else if (p.isArticle()) { // heuristic: potentially template or stub article if (p.getTitle().length() > 0.3 * p.getContent().length()) { reporter.incrCounter(PageTypes.OTHER, 1); return; } reporter.incrCounter(PageTypes.ARTICLE, 1); if (p.isStub()) { reporter.incrCounter(PageTypes.STUB, 1); } keyOut.set(Integer.parseInt(p.getDocid())); output.collect(keyOut, valOut); } else { reporter.incrCounter(PageTypes.NON_ARTICLE, 1); } } } private static class MyReducer extends MapReduceBase implements Reducer<IntWritable, IntWritable, IntWritable, IntWritable> { private final static IntWritable cnt = new IntWritable(1); public void reduce(IntWritable key, Iterator<IntWritable> values, OutputCollector<IntWritable, IntWritable> output, Reporter reporter) throws IOException { output.collect(key, cnt); cnt.set(cnt.get() + 1); } } public static final String INPUT_OPTION = "input"; public static final String OUTPUT_PATH_OPTION = "output_path"; public static final String OUTPUT_FILE_OPTION = "output_file"; public static final String KEEP_ALL_OPTION = "keep_all"; public static final String LANGUAGE_OPTION = "wiki_language"; @SuppressWarnings("static-access") @Override public int run(String[] args) throws Exception { Options options = new Options(); options.addOption( OptionBuilder.withArgName("path").hasArg().withDescription("XML dump file").create(INPUT_OPTION)); options.addOption(OptionBuilder.withArgName("path").hasArg().withDescription("tmp output directory") .create(OUTPUT_PATH_OPTION)); options.addOption(OptionBuilder.withArgName("path").hasArg().withDescription("output file") .create(OUTPUT_FILE_OPTION)); options.addOption(OptionBuilder.withArgName("en|sv|de|cs|es|zh|ar|tr").hasArg() .withDescription("two-letter language code").create(LANGUAGE_OPTION)); options.addOption(KEEP_ALL_OPTION, false, "keep all pages"); CommandLine cmdline; CommandLineParser parser = new GnuParser(); try { cmdline = parser.parse(options, args); } catch (ParseException exp) { System.err.println("Error parsing command line: " + exp.getMessage()); return -1; } if (!cmdline.hasOption(INPUT_OPTION) || !cmdline.hasOption(OUTPUT_PATH_OPTION) || !cmdline.hasOption(OUTPUT_FILE_OPTION)) { HelpFormatter formatter = new HelpFormatter(); formatter.printHelp(this.getClass().getName(), options); ToolRunner.printGenericCommandUsage(System.out); return -1; } String language = null; if (cmdline.hasOption(LANGUAGE_OPTION)) { language = cmdline.getOptionValue(LANGUAGE_OPTION); if (language.length() != 2) { System.err.println("Error: \"" + language + "\" unknown language!"); return -1; } } String inputPath = cmdline.getOptionValue(INPUT_OPTION); String outputPath = cmdline.getOptionValue(OUTPUT_PATH_OPTION); String outputFile = cmdline.getOptionValue(OUTPUT_FILE_OPTION); boolean keepAll = cmdline.hasOption(KEEP_ALL_OPTION); LOG.info("Tool name: " + this.getClass().getName()); LOG.info(" - input: " + inputPath); LOG.info(" - output path: " + outputPath); LOG.info(" - output file: " + outputFile); LOG.info(" - keep all pages: " + keepAll); LOG.info(" - language: " + language); JobConf conf = new JobConf(getConf(), BuildWikipediaDocnoMapping.class); conf.setJobName(String.format("BuildWikipediaDocnoMapping[%s: %s, %s: %s, %s: %s]", INPUT_OPTION, inputPath, OUTPUT_FILE_OPTION, outputFile, LANGUAGE_OPTION, language)); conf.setBoolean(KEEP_ALL_OPTION, keepAll); if (language != null) { conf.set("wiki.language", language); } conf.setNumReduceTasks(1); FileInputFormat.setInputPaths(conf, new Path(inputPath)); FileOutputFormat.setOutputPath(conf, new Path(outputPath)); FileOutputFormat.setCompressOutput(conf, false); conf.setInputFormat(WikipediaPageInputFormat.class); conf.setOutputKeyClass(IntWritable.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); RunningJob job = JobClient.runJob(conf); Counters c = job.getCounters(); long cnt = keepAll ? c.getCounter(PageTypes.TOTAL) : c.getCounter(PageTypes.ARTICLE); WikipediaDocnoMapping.writeDocnoMappingData(FileSystem.get(conf), outputPath + "/part-00000", (int) cnt, outputFile); return 0; } public BuildWikipediaDocnoMapping() { } public static void main(String[] args) throws Exception { ToolRunner.run(new BuildWikipediaDocnoMapping(), args); } }