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.webgraph.driver.wt10g; import java.io.IOException; import java.io.UTFDataFormatException; import java.net.URI; import java.net.URISyntaxException; import org.apache.hadoop.conf.Configuration; import org.apache.hadoop.filecache.DistributedCache; import org.apache.hadoop.fs.FileStatus; import org.apache.hadoop.fs.FileSystem; import org.apache.hadoop.fs.Path; import org.apache.hadoop.io.LongWritable; import org.apache.hadoop.io.SequenceFile; import org.apache.hadoop.io.Text; 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.SequenceFileOutputFormat; import org.apache.log4j.Logger; import org.htmlparser.NodeFilter; import org.htmlparser.Parser; import org.htmlparser.filters.NodeClassFilter; import org.htmlparser.tags.BaseHrefTag; import org.htmlparser.tags.LinkTag; import org.htmlparser.util.NodeList; import org.htmlparser.util.ParserException; import edu.umd.cloud9.collection.DocnoMapping; import edu.umd.cloud9.collection.generic.WebDocument; import edu.umd.cloud9.io.array.ArrayListWritable; import edu.umd.cloud9.util.PowerTool; import edu.umd.cloud9.webgraph.data.AnchorText; import edu.umd.cloud9.webgraph.data.AnchorTextConstants; import edu.umd.cloud9.webgraph.normalizer.AnchorTextNormalizer; /** * * @author Nima Asadi * @author Fangyue Wang * @author metzler * */ public class GenericExtractLinks extends PowerTool { private static final Logger LOG = Logger.getLogger(GenericExtractLinks.class); public static class Map extends Mapper<LongWritable, WebDocument, Text, ArrayListWritable<AnchorText>> { public static enum LinkCounter { INPUT_DOCS, // number of input documents OUTPUT_DOCS, // number of output documents INVALID_DOCNO, // number of malformed documents INVALID_URL, // number of malformed URLs TEXT_TOO_LONG, // number of lines of anchor text that are abnormally // long PARSER_FAILED // number of times the HTML parser fails }; private static String base; // base URL for current document private static String baseHost; private static int docno; // docno of current document private static final Text keyWord = new Text(); // output key for the // mappers private static final ArrayListWritable<AnchorText> arrayList = new ArrayListWritable<AnchorText>(); // output value for the mappers private static DocnoMapping docnoMapping = null; private static final Parser parser = new Parser(); private static final NodeFilter filter = new NodeClassFilter(LinkTag.class); private static NodeList list; private static boolean includeInternalLinks; private static AnchorTextNormalizer normalizer; @Override public void setup(Mapper<LongWritable, WebDocument, Text, ArrayListWritable<AnchorText>>.Context context) throws IOException { Configuration conf = context.getConfiguration(); String docnoMappingClass = conf.get("Cloud9.DocnoMappingClass"); try { docnoMapping = (DocnoMapping) Class.forName(docnoMappingClass).newInstance(); } catch (Exception e) { throw new RuntimeException("Error initializing DocnoMapping class!"); } String docnoMappingFile = conf.get("Cloud9.DocnoMappingFile", null); if (docnoMappingFile != null) { Path docnoMappingPath = null; try { Path[] localFiles = DistributedCache.getLocalCacheFiles(conf); if (localFiles != null) { docnoMappingPath = localFiles[0]; } else { docnoMappingPath = new Path(conf.get("Cloud9.DocnoMappingFile")); } } catch (IOException e) { throw new RuntimeException("Unable to find DocnoMappingFile!"); } try { docnoMapping.loadMapping(docnoMappingPath, FileSystem.getLocal(conf)); } catch (Exception e) { e.printStackTrace(); throw new RuntimeException("Error initializing DocnoMapping!"); } } includeInternalLinks = conf.getBoolean("Cloud9.IncludeInternalLinks", false); try { normalizer = (AnchorTextNormalizer) Class.forName(conf.get("Cloud9.AnchorTextNormalizer")) .newInstance(); } catch (Exception e) { e.printStackTrace(); throw new RuntimeException("Error initializing AnchorTextNormalizer"); } } @Override public void map(LongWritable key, WebDocument doc, Mapper<LongWritable, WebDocument, Text, ArrayListWritable<AnchorText>>.Context context) throws IOException, InterruptedException { context.getCounter(LinkCounter.INPUT_DOCS).increment(1); try { docno = docnoMapping.getDocno(doc.getDocid()); } catch (NullPointerException e) { // Discard documents with an invalid document number context.getCounter(LinkCounter.INVALID_DOCNO).increment(1); return; } try { base = normalizeURL(doc.getURL()); } catch (Exception e) { // Discard documents with which there is no URL associated context.getCounter(LinkCounter.INVALID_URL).increment(1); return; } if (base == null) { context.getCounter(LinkCounter.INVALID_URL).increment(1); return; } try { baseHost = new URI(base).getHost(); } catch (Exception e) { context.getCounter(LinkCounter.INVALID_URL).increment(1); return; } if (baseHost == null) { context.getCounter(LinkCounter.INVALID_URL).increment(1); return; } try { parser.setInputHTML(doc.getContent()); // initializing the // parser with new HTML // content // Setting base URL for the current document NodeList nl = parser.parse(null); BaseHrefTag baseTag = new BaseHrefTag(); baseTag.setBaseUrl(base); nl.add(baseTag); // re-initializing the parser with the fixed content parser.setInputHTML(nl.toHtml()); // listing all LinkTag nodes list = parser.extractAllNodesThatMatch(filter); } catch (ParserException e) { context.getCounter(LinkCounter.PARSER_FAILED).increment(1); return; } catch (StackOverflowError e) { context.getCounter(LinkCounter.PARSER_FAILED).increment(1); return; } for (int i = 0; i < list.size(); i++) { LinkTag link = (LinkTag) list.elementAt(i); String anchor = link.getLinkText(); String url = normalizeURL(link.extractLink()); if (url == null) { continue; } if (url.equals(base)) { // discard self links continue; } String host = null; try { host = new URI(url).getHost(); } catch (Exception e) { continue; } if (host == null) { continue; } if (anchor == null) { anchor = ""; } // normalizing the anchor text anchor = normalizer.process(anchor); arrayList.clear(); if (baseHost.equals(host)) { if (!includeInternalLinks) continue; arrayList.add(new AnchorText(AnchorTextConstants.Type.INTERNAL_IN_LINK.val, anchor, docno)); } else { arrayList.add(new AnchorText(AnchorTextConstants.Type.EXTERNAL_IN_LINK.val, anchor, docno)); } try { keyWord.set(url); context.write(keyWord, arrayList); } catch (UTFDataFormatException e) { context.getCounter(LinkCounter.TEXT_TOO_LONG).increment(1); keyWord.set(url); byte flag = arrayList.get(0).getType(); arrayList.clear(); arrayList.add(new AnchorText(flag, AnchorTextConstants.EMPTY_STRING, docno)); context.write(keyWord, arrayList); } } arrayList.clear(); arrayList.add(new AnchorText(AnchorTextConstants.Type.DOCNO_FIELD.val, AnchorTextConstants.EMPTY_STRING, docno)); keyWord.set(base); context.write(keyWord, arrayList); // keeping track of the number of documents that have actually been // processed context.getCounter(LinkCounter.OUTPUT_DOCS).increment(1); } private static String normalizeURL(String url) { try { URI uri = URI.create(url).normalize(); // first apply built-in normalizer String scheme = uri.getScheme().toLowerCase(); // schemes are not case sensitive String host = uri.getHost().toLowerCase(); // hosts are not case sensitive String path = uri.getPath(); while (path != null && path.length() > 0 && path.charAt(path.length() - 1) == '/') { // remove trailing forward slashes from path path = path.substring(0, path.length() - 1); } return (new URI(scheme, host, path, null)).toString(); } catch (Exception e) { return null; } } } public static class Reduce extends Reducer<Text, ArrayListWritable<AnchorText>, Text, ArrayListWritable<AnchorText>> { private static final ArrayListWritable<AnchorText> arrayList = new ArrayListWritable<AnchorText>(); private static boolean pushed; @Override public void reduce(Text key, Iterable<ArrayListWritable<AnchorText>> values, Reducer<Text, ArrayListWritable<AnchorText>, Text, ArrayListWritable<AnchorText>>.Context context) throws IOException, InterruptedException { arrayList.clear(); for (ArrayListWritable<AnchorText> packet : values) { for (AnchorText data : packet) { pushed = false; for (int i = 0; i < arrayList.size(); i++) { if (arrayList.get(i).equalsIgnoreSources(data)) { arrayList.get(i).addDocumentsFrom(data); pushed = true; break; } } if (!pushed) arrayList.add(data.clone()); } } context.write(key, arrayList); } } public static final String[] RequiredParameters = { "Cloud9.InputPath", "Cloud9.OutputPath", "Cloud9.Mappers", "Cloud9.Reducers", "Cloud9.IncludeInternalLinks", "Cloud9.AnchorTextNormalizer", "Cloud9.DocnoMappingClass", "Cloud9.DocnoMappingFile" }; public String[] getRequiredParameters() { return RequiredParameters; } public GenericExtractLinks(Configuration conf) { super(conf); } CollectionConfigurationManager configer; public GenericExtractLinks(Configuration conf, CollectionConfigurationManager confer) { super(conf); this.configer = confer; } @Override public int runTool() throws Exception { Configuration conf = getConf(); Job job = new Job(conf); int numReducers = conf.getInt("Cloud9.Reducers", 200); String inputPath = conf.get("Cloud9.InputPath"); String outputPath = conf.get("Cloud9.OutputPath"); String mappingFile = conf.get("Cloud9.DocnoMappingFile"); FileSystem fs = FileSystem.get(conf); if (!fs.exists(new Path(mappingFile))) { throw new RuntimeException("Error: Docno mapping data file " + mappingFile + " doesn't exist!"); } DistributedCache.addCacheFile(new Path(mappingFile).toUri(), job.getConfiguration()); job.setJobName("ExtractLinks"); conf.set("mapred.child.java.opts", "-Xmx2048m"); conf.setInt("mapred.task.timeout", 60000000); job.setNumReduceTasks(numReducers); job.setMapperClass(GenericExtractLinks.Map.class); job.setCombinerClass(GenericExtractLinks.Reduce.class); job.setReducerClass(GenericExtractLinks.Reduce.class); job.setOutputKeyClass(Text.class); job.setOutputValueClass(ArrayListWritable.class); configer.applyJobConfig(job); job.setOutputFormatClass(SequenceFileOutputFormat.class); SequenceFileOutputFormat.setCompressOutput(job, true); SequenceFileOutputFormat.setOutputCompressionType(job, SequenceFile.CompressionType.BLOCK); recursivelyAddInputPaths(job, inputPath); FileOutputFormat.setOutputPath(job, new Path(outputPath)); LOG.info("ExtractLinks"); LOG.info(" - input path: " + inputPath); LOG.info(" - output path: " + outputPath); LOG.info(" - mapping file: " + mappingFile); LOG.info(" - include internal links? " + conf.getBoolean("Cloud9.IncludeInternalLinks", false)); job.waitForCompletion(true); return 0; } public static void recursivelyAddInputPaths(Job job, String path) throws IOException { FileSystem fs; try { fs = FileSystem.get(new URI(path), job.getConfiguration()); } catch (URISyntaxException e) { throw new RuntimeException("Error recursively adding path -- " + path); } FileStatus[] ls = fs.listStatus(new Path(path)); for (FileStatus status : ls) { // skip anything that starts with an underscore, as it often indicates // a log directory or another special type of Hadoop file if (status.getPath().getName().startsWith("_")) { continue; } if (status.isDir()) { recursivelyAddInputPaths(job, status.getPath().toString()); } else { FileInputFormat.addInputPath(job, status.getPath()); } } } }