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 com.yahoo.semsearch.fastlinking.io; import java.io.IOException; import java.util.Random; 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.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.mapreduce.Job; import org.apache.hadoop.mapreduce.Mapper; import org.apache.hadoop.mapreduce.Reducer; import org.apache.hadoop.mapreduce.lib.input.FileInputFormat; import org.apache.hadoop.mapreduce.lib.output.FileOutputFormat; import org.apache.hadoop.mapreduce.lib.output.TextOutputFormat; import org.apache.hadoop.util.Tool; import org.apache.hadoop.util.ToolRunner; import org.apache.log4j.Logger; import edu.umd.cloud9.collection.DocnoMapping; import edu.umd.cloud9.collection.wikipedia.WikipediaPage; /** * From https://lintool.github.io/Cloud9/ * Tool for building the mapping between Wikipedia internal ids (docids) and sequentially-numbered * ints (docnos). * * @author Jimmy Lin * @author Peter Exner */ public class WikipediaDocnoMappingBuilder extends Configured implements Tool, DocnoMapping.Builder { private static final Logger LOG = Logger.getLogger(WikipediaDocnoMappingBuilder.class); private static final Random RANDOM = new Random(); private static enum PageTypes { TOTAL, REDIRECT, DISAMBIGUATION, EMPTY, ARTICLE, STUB, NON_ARTICLE, OTHER }; private static class MyMapper extends Mapper<LongWritable, WikipediaPage, IntWritable, IntWritable> { private final static IntWritable keyOut = new IntWritable(); private final static IntWritable valOut = new IntWritable(1); private boolean keepAll; @Override public void setup(Context context) { keepAll = context.getConfiguration().getBoolean(KEEP_ALL_OPTION, false); } @Override public void map(LongWritable key, WikipediaPage p, Context context) throws IOException, InterruptedException { // If we're keeping all pages, don't bother checking. if (keepAll) { if (p.getTitle().startsWith("Help:") || p.getTitle().startsWith("Wikipedia:") || p.getTitle().startsWith("User:")) return; context.getCounter(PageTypes.TOTAL).increment(1); keyOut.set(Integer.parseInt(p.getDocid())); context.write(keyOut, valOut); return; } context.getCounter(PageTypes.TOTAL).increment(1); if (p.isRedirect()) { context.getCounter(PageTypes.REDIRECT).increment(1); } else if (p.isEmpty()) { context.getCounter(PageTypes.EMPTY).increment(1); } else if (p.isDisambiguation()) { context.getCounter(PageTypes.DISAMBIGUATION).increment(1); } else if (p.isArticle()) { // heuristic: potentially template or stub article if (p.getTitle().length() > 0.3 * p.getContent().length()) { context.getCounter(PageTypes.OTHER).increment(1); return; } context.getCounter(PageTypes.ARTICLE).increment(1); if (p.isStub()) { context.getCounter(PageTypes.STUB).increment(1); } keyOut.set(Integer.parseInt(p.getDocid())); context.write(keyOut, valOut); } else { context.getCounter(PageTypes.NON_ARTICLE).increment(1); } } } private static class MyReducer extends Reducer<IntWritable, IntWritable, IntWritable, IntWritable> { private final static IntWritable cnt = new IntWritable(1); @Override public void reduce(IntWritable key, Iterable<IntWritable> values, Context context) throws IOException, InterruptedException { context.write(key, cnt); cnt.set(cnt.get() + 1); } } @Override public int build(Path src, Path dest, Configuration conf) throws IOException { super.setConf(conf); try { return run(new String[] { "-" + INPUT_OPTION + "=" + src.toString(), "-" + OUTPUT_FILE_OPTION + "=" + dest.toString() }); } catch (Exception e) { throw new IOException(e); } } public static final String INPUT_OPTION = "input"; 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("output file") .create(OUTPUT_FILE_OPTION)); options.addOption(OptionBuilder.withArgName("en|sv|de|cs|es|zh|ar|tr|it").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_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 outputFile = cmdline.getOptionValue(OUTPUT_FILE_OPTION); boolean keepAll = cmdline.hasOption(KEEP_ALL_OPTION); String tmpPath = "tmp-" + WikipediaDocnoMappingBuilder.class.getSimpleName() + "-" + RANDOM.nextInt(10000); LOG.info("Tool name: " + this.getClass().getName()); LOG.info(" - input: " + inputPath); LOG.info(" - output file: " + outputFile); LOG.info(" - keep all pages: " + keepAll); LOG.info(" - language: " + language); Job job = Job.getInstance(getConf()); job.setJarByClass(WikipediaDocnoMappingBuilder.class); job.setJobName(String.format("BuildWikipediaDocnoMapping[%s: %s, %s: %s, %s: %s]", INPUT_OPTION, inputPath, OUTPUT_FILE_OPTION, outputFile, LANGUAGE_OPTION, language)); job.getConfiguration().setBoolean(KEEP_ALL_OPTION, keepAll); if (language != null) { job.getConfiguration().set("wiki.language", language); } job.setNumReduceTasks(1); FileInputFormat.setInputPaths(job, new Path(inputPath)); FileOutputFormat.setOutputPath(job, new Path(tmpPath)); FileOutputFormat.setCompressOutput(job, false); job.setOutputKeyClass(IntWritable.class); job.setOutputValueClass(IntWritable.class); job.setInputFormatClass(WikipediaPageInputFormat.class); job.setOutputFormatClass(TextOutputFormat.class); job.setMapperClass(MyMapper.class); job.setReducerClass(MyReducer.class); // Delete the output directory if it exists already. FileSystem.get(getConf()).delete(new Path(tmpPath), true); if (job.waitForCompletion(true)) { // long cnt = keepAll ? job.getCounters().findCounter(PageTypes.TOTAL).getValue() : job.getCounters().findCounter(PageTypes.ARTICLE).getValue(); long cnt = job.getCounters() .findCounter("org.apache.hadoop.mapred.Task$Counter", "REDUCE_OUTPUT_RECORDS").getValue(); WikipediaDocnoMapping.writeDocnoMappingData(FileSystem.get(getConf()), tmpPath + "/part-r-00000", (int) cnt, outputFile); FileSystem.get(getConf()).delete(new Path(tmpPath), true); return 0; } else { return -1; } } public WikipediaDocnoMappingBuilder() { } public static void main(String[] args) throws Exception { ToolRunner.run(new WikipediaDocnoMappingBuilder(), args); } }