Java tutorial
/** * Licensed to the Apache Software Foundation (ASF) under one or more * contributor license agreements. See the NOTICE file distributed with * this work for additional information regarding copyright ownership. * The ASF licenses this file to You 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 org.apache.nutch.crawl; import java.io.*; import java.text.SimpleDateFormat; import java.util.*; import java.net.*; // Commons Logging imports import org.slf4j.Logger; import org.slf4j.LoggerFactory; import org.apache.hadoop.io.*; import org.apache.hadoop.fs.*; import org.apache.hadoop.fs.FileSystem; import org.apache.hadoop.conf.*; import org.apache.hadoop.mapred.*; import org.apache.hadoop.util.*; import org.apache.nutch.net.URLFilters; import org.apache.nutch.net.URLNormalizers; import org.apache.nutch.parse.*; import org.apache.nutch.util.HadoopFSUtil; import org.apache.nutch.util.LockUtil; import org.apache.nutch.util.NutchConfiguration; import org.apache.nutch.util.NutchJob; import org.apache.nutch.util.TimingUtil; /** Maintains an inverted link map, listing incoming links for each url. */ public class LinkDb extends Configured implements Tool, Mapper<Text, ParseData, Text, Inlinks> { public static final Logger LOG = LoggerFactory.getLogger(LinkDb.class); public static final String IGNORE_INTERNAL_LINKS = "db.ignore.internal.links"; public static final String CURRENT_NAME = "current"; public static final String LOCK_NAME = ".locked"; private int maxAnchorLength; private boolean ignoreInternalLinks; private URLFilters urlFilters; private URLNormalizers urlNormalizers; public LinkDb() { } public LinkDb(Configuration conf) { setConf(conf); } public void configure(JobConf job) { maxAnchorLength = job.getInt("db.max.anchor.length", 100); ignoreInternalLinks = job.getBoolean(IGNORE_INTERNAL_LINKS, true); if (job.getBoolean(LinkDbFilter.URL_FILTERING, false)) { urlFilters = new URLFilters(job); } if (job.getBoolean(LinkDbFilter.URL_NORMALIZING, false)) { urlNormalizers = new URLNormalizers(job, URLNormalizers.SCOPE_LINKDB); } } public void close() { } public void map(Text key, ParseData parseData, OutputCollector<Text, Inlinks> output, Reporter reporter) throws IOException { String fromUrl = key.toString(); String fromHost = getHost(fromUrl); if (urlNormalizers != null) { try { fromUrl = urlNormalizers.normalize(fromUrl, URLNormalizers.SCOPE_LINKDB); // normalize the url } catch (Exception e) { LOG.warn("Skipping " + fromUrl + ":" + e); fromUrl = null; } } if (fromUrl != null && urlFilters != null) { try { fromUrl = urlFilters.filter(fromUrl); // filter the url } catch (Exception e) { LOG.warn("Skipping " + fromUrl + ":" + e); fromUrl = null; } } if (fromUrl == null) return; // discard all outlinks Outlink[] outlinks = parseData.getOutlinks(); Inlinks inlinks = new Inlinks(); for (int i = 0; i < outlinks.length; i++) { Outlink outlink = outlinks[i]; String toUrl = outlink.getToUrl(); if (ignoreInternalLinks) { String toHost = getHost(toUrl); if (toHost == null || toHost.equals(fromHost)) { // internal link continue; // skip it } } if (urlNormalizers != null) { try { toUrl = urlNormalizers.normalize(toUrl, URLNormalizers.SCOPE_LINKDB); // normalize the url } catch (Exception e) { LOG.warn("Skipping " + toUrl + ":" + e); toUrl = null; } } if (toUrl != null && urlFilters != null) { try { toUrl = urlFilters.filter(toUrl); // filter the url } catch (Exception e) { LOG.warn("Skipping " + toUrl + ":" + e); toUrl = null; } } if (toUrl == null) continue; inlinks.clear(); String anchor = outlink.getAnchor(); // truncate long anchors if (anchor.length() > maxAnchorLength) { anchor = anchor.substring(0, maxAnchorLength); } inlinks.add(new Inlink(fromUrl, anchor)); // collect inverted link output.collect(new Text(toUrl), inlinks); } } private String getHost(String url) { try { return new URL(url).getHost().toLowerCase(); } catch (MalformedURLException e) { return null; } } public void invert(Path linkDb, final Path segmentsDir, boolean normalize, boolean filter, boolean force) throws IOException { final FileSystem fs = FileSystem.get(getConf()); FileStatus[] files = fs.listStatus(segmentsDir, HadoopFSUtil.getPassDirectoriesFilter(fs)); invert(linkDb, HadoopFSUtil.getPaths(files), normalize, filter, force); } public void invert(Path linkDb, Path[] segments, boolean normalize, boolean filter, boolean force) throws IOException { JobConf job = LinkDb.createJob(getConf(), linkDb, normalize, filter); Path lock = new Path(linkDb, LOCK_NAME); FileSystem fs = FileSystem.get(getConf()); LockUtil.createLockFile(fs, lock, force); Path currentLinkDb = new Path(linkDb, CURRENT_NAME); SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss"); long start = System.currentTimeMillis(); if (LOG.isInfoEnabled()) { LOG.info("LinkDb: starting at " + sdf.format(start)); LOG.info("LinkDb: linkdb: " + linkDb); LOG.info("LinkDb: URL normalize: " + normalize); LOG.info("LinkDb: URL filter: " + filter); if (job.getBoolean(IGNORE_INTERNAL_LINKS, true)) { LOG.info("LinkDb: internal links will be ignored."); } } for (int i = 0; i < segments.length; i++) { if (LOG.isInfoEnabled()) { LOG.info("LinkDb: adding segment: " + segments[i]); } FileInputFormat.addInputPath(job, new Path(segments[i], ParseData.DIR_NAME)); } try { JobClient.runJob(job); } catch (IOException e) { LockUtil.removeLockFile(fs, lock); throw e; } if (fs.exists(currentLinkDb)) { if (LOG.isInfoEnabled()) { LOG.info("LinkDb: merging with existing linkdb: " + linkDb); } // try to merge Path newLinkDb = FileOutputFormat.getOutputPath(job); job = LinkDbMerger.createMergeJob(getConf(), linkDb, normalize, filter); FileInputFormat.addInputPath(job, currentLinkDb); FileInputFormat.addInputPath(job, newLinkDb); try { JobClient.runJob(job); } catch (IOException e) { LockUtil.removeLockFile(fs, lock); fs.delete(newLinkDb, true); throw e; } fs.delete(newLinkDb, true); } LinkDb.install(job, linkDb); long end = System.currentTimeMillis(); LOG.info("LinkDb: finished at " + sdf.format(end) + ", elapsed: " + TimingUtil.elapsedTime(start, end)); } private static JobConf createJob(Configuration config, Path linkDb, boolean normalize, boolean filter) { Path newLinkDb = new Path("linkdb-" + Integer.toString(new Random().nextInt(Integer.MAX_VALUE))); JobConf job = new NutchJob(config); job.setJobName("linkdb " + linkDb); job.setInputFormat(SequenceFileInputFormat.class); job.setMapperClass(LinkDb.class); job.setCombinerClass(LinkDbMerger.class); // if we don't run the mergeJob, perform normalization/filtering now if (normalize || filter) { try { FileSystem fs = FileSystem.get(config); if (!fs.exists(linkDb)) { job.setBoolean(LinkDbFilter.URL_FILTERING, filter); job.setBoolean(LinkDbFilter.URL_NORMALIZING, normalize); } } catch (Exception e) { LOG.warn("LinkDb createJob: " + e); } } job.setReducerClass(LinkDbMerger.class); FileOutputFormat.setOutputPath(job, newLinkDb); job.setOutputFormat(MapFileOutputFormat.class); job.setBoolean("mapred.output.compress", true); job.setOutputKeyClass(Text.class); job.setOutputValueClass(Inlinks.class); return job; } public static void install(JobConf job, Path linkDb) throws IOException { Path newLinkDb = FileOutputFormat.getOutputPath(job); FileSystem fs = new JobClient(job).getFs(); Path old = new Path(linkDb, "old"); Path current = new Path(linkDb, CURRENT_NAME); if (fs.exists(current)) { if (fs.exists(old)) fs.delete(old, true); fs.rename(current, old); } fs.mkdirs(linkDb); fs.rename(newLinkDb, current); if (fs.exists(old)) fs.delete(old, true); LockUtil.removeLockFile(fs, new Path(linkDb, LOCK_NAME)); } public static void main(String[] args) throws Exception { int res = ToolRunner.run(NutchConfiguration.create(), new LinkDb(), args); System.exit(res); } public int run(String[] args) throws Exception { if (args.length < 2) { System.err.println( "Usage: LinkDb <linkdb> (-dir <segmentsDir> | <seg1> <seg2> ...) [-force] [-noNormalize] [-noFilter]"); System.err.println("\tlinkdb\toutput LinkDb to create or update"); System.err.println("\t-dir segmentsDir\tparent directory of several segments, OR"); System.err.println("\tseg1 seg2 ...\t list of segment directories"); System.err.println("\t-force\tforce update even if LinkDb appears to be locked (CAUTION advised)"); System.err.println("\t-noNormalize\tdon't normalize link URLs"); System.err.println("\t-noFilter\tdon't apply URLFilters to link URLs"); return -1; } Path segDir = null; final FileSystem fs = FileSystem.get(getConf()); Path db = new Path(args[0]); ArrayList<Path> segs = new ArrayList<Path>(); boolean filter = true; boolean normalize = true; boolean force = false; for (int i = 1; i < args.length; i++) { if (args[i].equals("-dir")) { FileStatus[] paths = fs.listStatus(new Path(args[++i]), HadoopFSUtil.getPassDirectoriesFilter(fs)); segs.addAll(Arrays.asList(HadoopFSUtil.getPaths(paths))); } else if (args[i].equalsIgnoreCase("-noNormalize")) { normalize = false; } else if (args[i].equalsIgnoreCase("-noFilter")) { filter = false; } else if (args[i].equalsIgnoreCase("-force")) { force = true; } else segs.add(new Path(args[i])); } try { invert(db, segs.toArray(new Path[segs.size()]), normalize, filter, force); return 0; } catch (Exception e) { LOG.error("LinkDb: " + StringUtils.stringifyException(e)); return -1; } } }