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; import java.io.IOException; import java.io.UTFDataFormatException; import java.net.URI; import java.util.Iterator; import org.apache.hadoop.filecache.DistributedCache; import org.apache.hadoop.fs.FileSystem; import org.apache.hadoop.fs.Path; import org.apache.hadoop.conf.Configuration; import org.apache.hadoop.io.IntWritable; import org.apache.hadoop.io.Text; import org.apache.hadoop.io.SequenceFile; 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.SequenceFileInputFormat; import org.apache.hadoop.mapred.SequenceFileOutputFormat; import org.apache.log4j.Logger; import edu.umd.cloud9.collection.clue.ClueWarcDocnoMapping; import edu.umd.cloud9.collection.clue.ClueWarcRecord; 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; import org.htmlparser.NodeFilter; import org.htmlparser.Parser; import org.htmlparser.filters.NodeClassFilter; import org.htmlparser.tags.LinkTag; import org.htmlparser.tags.BaseHrefTag; import org.htmlparser.util.NodeList; import org.htmlparser.util.ParserException; /** * * @author Nima Asadi * */ @SuppressWarnings("deprecation") public class ExtractLinks extends PowerTool { private static final Logger LOG = Logger.getLogger(ExtractLinks.class); public static class Map extends MapReduceBase implements Mapper<IntWritable, ClueWarcRecord, 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 final ClueWarcDocnoMapping docnoMapping = new ClueWarcDocnoMapping(); // docno // mapping // file 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; public void configure(JobConf job) { Path[] localFiles; try { localFiles = DistributedCache.getLocalCacheFiles(job); } catch (IOException e) { throw new RuntimeException("Local cache files not read properly."); } try { docnoMapping.loadMapping(localFiles[0], FileSystem.getLocal(job)); } catch (Exception e) { e.printStackTrace(); throw new RuntimeException("Error initializing DocnoMapping!"); } includeInternalLinks = job.getBoolean("Cloud9.IncludeInternalLinks", false); try { normalizer = (AnchorTextNormalizer) Class.forName(job.get("Cloud9.AnchorTextNormalizer")) .newInstance(); } catch (Exception e) { e.printStackTrace(); throw new RuntimeException("Error initializing AnchorTextNormalizer"); } } public void map(IntWritable key, ClueWarcRecord doc, OutputCollector<Text, ArrayListWritable<AnchorText>> output, Reporter reporter) throws IOException { reporter.incrCounter(LinkCounter.INPUT_DOCS, 1); try { docno = docnoMapping.getDocno(doc.getHeaderMetadataItem("WARC-TREC-ID")); } catch (NullPointerException e) { // Discard documents with an invalid document number reporter.incrCounter(LinkCounter.INVALID_DOCNO, 1); return; } try { base = doc.getHeaderMetadataItem("WARC-Target-URI"); } catch (NullPointerException e) { // Discard documents with which there is no URL associated reporter.incrCounter(LinkCounter.INVALID_URL, 1); return; } if (base == null) { reporter.incrCounter(LinkCounter.INVALID_URL, 1); return; } try { baseHost = new URI(base).getHost(); } catch (Exception e) { reporter.incrCounter(LinkCounter.INVALID_URL, 1); return; } if (baseHost == null) { reporter.incrCounter(LinkCounter.INVALID_URL, 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) { reporter.incrCounter(LinkCounter.PARSER_FAILED, 1); return; } catch (StackOverflowError e) { reporter.incrCounter(LinkCounter.PARSER_FAILED, 1); return; } for (int i = 0; i < list.size(); i++) { LinkTag link = (LinkTag) list.elementAt(i); String anchor = link.getLinkText(); String url = 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); output.collect(keyWord, arrayList); } catch (UTFDataFormatException e) { reporter.incrCounter(LinkCounter.TEXT_TOO_LONG, 1); keyWord.set(url); byte flag = arrayList.get(0).getType(); arrayList.clear(); arrayList.add(new AnchorText(flag, AnchorTextConstants.EMPTY_STRING, docno)); output.collect(keyWord, arrayList); } } arrayList.clear(); arrayList.add(new AnchorText(AnchorTextConstants.Type.DOCNO_FIELD.val, AnchorTextConstants.EMPTY_STRING, docno)); keyWord.set(base); output.collect(keyWord, arrayList); // keeping track of the number of documents that have actually been // processed reporter.incrCounter(LinkCounter.OUTPUT_DOCS, 1); } } public static class Reduce extends MapReduceBase implements Reducer<Text, ArrayListWritable<AnchorText>, Text, ArrayListWritable<AnchorText>> { private static final ArrayListWritable<AnchorText> arrayList = new ArrayListWritable<AnchorText>(); private static ArrayListWritable<AnchorText> packet; private static boolean pushed; public void reduce(Text key, Iterator<ArrayListWritable<AnchorText>> values, OutputCollector<Text, ArrayListWritable<AnchorText>> output, Reporter reporter) throws IOException { arrayList.clear(); while (values.hasNext()) { packet = values.next(); 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()); } } output.collect(key, arrayList); } } public static final String[] RequiredParameters = { "Cloud9.InputPath", "Cloud9.OutputPath", "Cloud9.Mappers", "Cloud9.Reducers", "Cloud9.DocnoMappingFile", "Cloud9.IncludeInternalLinks", "Cloud9.AnchorTextNormalizer", }; public String[] getRequiredParameters() { return RequiredParameters; } public ExtractLinks(Configuration conf) { super(conf); } public int runTool() throws Exception { JobConf conf = new JobConf(getConf(), ExtractLinks.class); FileSystem fs = FileSystem.get(conf); int numMappers = conf.getInt("Cloud9.Mappers", 1); 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"); if (!fs.exists(new Path(mappingFile))) throw new RuntimeException("Error: Docno mapping data file " + mappingFile + " doesn't exist!"); DistributedCache.addCacheFile(new URI(mappingFile), conf); conf.setJobName("ExtractLinks"); conf.set("mapred.child.java.opts", "-Xmx2048m"); conf.setInt("mapred.task.timeout", 60000000); conf.setNumMapTasks(numMappers); conf.setNumReduceTasks(numReducers); conf.setMapperClass(Map.class); conf.setCombinerClass(Reduce.class); conf.setReducerClass(Reduce.class); conf.setOutputKeyClass(Text.class); conf.setOutputValueClass(ArrayListWritable.class); conf.setInputFormat(SequenceFileInputFormat.class); conf.setOutputFormat(SequenceFileOutputFormat.class); SequenceFileOutputFormat.setCompressOutput(conf, true); SequenceFileOutputFormat.setOutputCompressionType(conf, SequenceFile.CompressionType.BLOCK); SequenceFileInputFormat.setInputPaths(conf, inputPath); FileOutputFormat.setOutputPath(conf, 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)); if (!fs.exists(new Path(outputPath))) { JobClient.runJob(conf); } else { LOG.info(outputPath + " already exists! Skipping this step..."); } return 0; } }