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.*; // Commons Logging imports import org.apache.commons.logging.Log; import org.apache.commons.logging.LogFactory; import org.apache.hadoop.io.*; import org.apache.hadoop.fs.*; import org.apache.hadoop.conf.*; import org.apache.hadoop.mapred.*; import org.apache.hadoop.util.*; 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; /** * This class takes the output of the fetcher and updates the * crawldb accordingly. */ public class CrawlDb extends Configured implements Tool { public static final Log LOG = LogFactory.getLog(CrawlDb.class); public static final String CRAWLDB_ADDITIONS_ALLOWED = "db.update.additions.allowed"; public static final String CURRENT_NAME = "current"; public static final String LOCK_NAME = ".locked"; public CrawlDb() { } public CrawlDb(Configuration conf) { setConf(conf); } public void update(Path crawlDb, Path[] segments, boolean normalize, boolean filter) throws IOException { boolean additionsAllowed = getConf().getBoolean(CRAWLDB_ADDITIONS_ALLOWED, true); update(crawlDb, segments, normalize, filter, additionsAllowed, false); } public void update(Path crawlDb, Path[] segments, boolean normalize, boolean filter, boolean additionsAllowed, boolean force) throws IOException { FileSystem fs = FileSystem.get(getConf()); Path lock = new Path(crawlDb, LOCK_NAME); LockUtil.createLockFile(fs, lock, force); SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss"); long start = System.currentTimeMillis(); if (LOG.isInfoEnabled()) { LOG.info("CrawlDb update: starting at " + sdf.format(start)); LOG.info("CrawlDb update: db: " + crawlDb); LOG.info("CrawlDb update: segments: " + Arrays.asList(segments)); LOG.info("CrawlDb update: additions allowed: " + additionsAllowed); LOG.info("CrawlDb update: URL normalizing: " + normalize); LOG.info("CrawlDb update: URL filtering: " + filter); } JobConf job = CrawlDb.createJob(getConf(), crawlDb); job.setBoolean(CRAWLDB_ADDITIONS_ALLOWED, additionsAllowed); job.setBoolean(CrawlDbFilter.URL_FILTERING, filter); job.setBoolean(CrawlDbFilter.URL_NORMALIZING, normalize); for (int i = 0; i < segments.length; i++) { Path fetch = new Path(segments[i], CrawlDatum.FETCH_DIR_NAME); Path parse = new Path(segments[i], CrawlDatum.PARSE_DIR_NAME); if (fs.exists(fetch) && fs.exists(parse)) { FileInputFormat.addInputPath(job, fetch); FileInputFormat.addInputPath(job, parse); } else { LOG.info(" - skipping invalid segment " + segments[i]); } } if (LOG.isInfoEnabled()) { LOG.info("CrawlDb update: Merging segment data into db."); } try { JobClient.runJob(job); } catch (IOException e) { LockUtil.removeLockFile(fs, lock); Path outPath = FileOutputFormat.getOutputPath(job); if (fs.exists(outPath)) fs.delete(outPath, true); throw e; } CrawlDb.install(job, crawlDb); long end = System.currentTimeMillis(); LOG.info("CrawlDb update: finished at " + sdf.format(end) + ", elapsed: " + TimingUtil.elapsedTime(start, end)); } public static JobConf createJob(Configuration config, Path crawlDb) throws IOException { Path newCrawlDb = new Path(crawlDb, Integer.toString(new Random().nextInt(Integer.MAX_VALUE))); JobConf job = new NutchJob(config); job.setJobName("crawldb " + crawlDb); Path current = new Path(crawlDb, CURRENT_NAME); if (FileSystem.get(job).exists(current)) { FileInputFormat.addInputPath(job, current); } job.setInputFormat(SequenceFileInputFormat.class); job.setMapperClass(CrawlDbFilter.class); job.setReducerClass(CrawlDbReducer.class); FileOutputFormat.setOutputPath(job, newCrawlDb); job.setOutputFormat(MapFileOutputFormat.class); job.setOutputKeyClass(Text.class); job.setOutputValueClass(CrawlDatum.class); return job; } public static void install(JobConf job, Path crawlDb) throws IOException { Path newCrawlDb = FileOutputFormat.getOutputPath(job); FileSystem fs = new JobClient(job).getFs(); Path old = new Path(crawlDb, "old"); Path current = new Path(crawlDb, CURRENT_NAME); if (fs.exists(current)) { if (fs.exists(old)) fs.delete(old, true); fs.rename(current, old); } fs.mkdirs(crawlDb); fs.rename(newCrawlDb, current); if (fs.exists(old)) fs.delete(old, true); Path lock = new Path(crawlDb, LOCK_NAME); LockUtil.removeLockFile(fs, lock); } public static void main(String[] args) throws Exception { int res = ToolRunner.run(NutchConfiguration.create(), new CrawlDb(), args); System.exit(res); } public int run(String[] args) throws Exception { if (args.length < 2) { System.err.println( "Usage: CrawlDb <crawldb> (-dir <segments> | <seg1> <seg2> ...) [-force] [-normalize] [-filter] [-noAdditions]"); System.err.println("\tcrawldb\tCrawlDb to update"); System.err.println("\t-dir segments\tparent directory containing all segments to update from"); System.err.println("\tseg1 seg2 ...\tlist of segment names to update from"); System.err.println("\t-force\tforce update even if CrawlDb appears to be locked (CAUTION advised)"); System.err .println("\t-normalize\tuse URLNormalizer on urls in CrawlDb and segment (usually not needed)"); System.err.println("\t-filter\tuse URLFilters on urls in CrawlDb and segment"); System.err.println( "\t-noAdditions\tonly update already existing URLs, don't add any newly discovered URLs"); return -1; } boolean normalize = false; boolean filter = false; boolean force = false; final FileSystem fs = FileSystem.get(getConf()); boolean additionsAllowed = getConf().getBoolean(CRAWLDB_ADDITIONS_ALLOWED, true); HashSet<Path> dirs = new HashSet<Path>(); for (int i = 1; i < args.length; i++) { if (args[i].equals("-normalize")) { normalize = true; } else if (args[i].equals("-filter")) { filter = true; } else if (args[i].equals("-force")) { force = true; } else if (args[i].equals("-noAdditions")) { additionsAllowed = false; } else if (args[i].equals("-dir")) { FileStatus[] paths = fs.listStatus(new Path(args[++i]), HadoopFSUtil.getPassDirectoriesFilter(fs)); dirs.addAll(Arrays.asList(HadoopFSUtil.getPaths(paths))); } else { dirs.add(new Path(args[i])); } } try { update(new Path(args[0]), dirs.toArray(new Path[dirs.size()]), normalize, filter, additionsAllowed, force); return 0; } catch (Exception e) { LOG.fatal("CrawlDb update: " + StringUtils.stringifyException(e)); return -1; } } }