/**
* 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.IOException;
import java.util.ArrayList;
import java.util.Iterator;
import java.util.Random;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
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.Text;
import org.apache.hadoop.mapred.FileInputFormat;
import org.apache.hadoop.mapred.FileOutputFormat;
import org.apache.hadoop.mapred.JobClient;
import org.apache.hadoop.mapred.JobConf;
import org.apache.hadoop.mapred.MapFileOutputFormat;
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.util.StringUtils;
import org.apache.hadoop.util.Tool;
import org.apache.hadoop.util.ToolRunner;
import org.apache.nutch.util.NutchConfiguration;
import org.apache.nutch.util.NutchJob;
/**
* This tool merges several LinkDb-s into one, optionally filtering
* URLs through the current URLFilters, to skip prohibited URLs and
* links.
*
* <p>It's possible to use this tool just for filtering - in that case
* only one LinkDb should be specified in arguments.</p>
* <p>If more than one LinkDb contains information about the same URL,
* all inlinks are accumulated, but only at most <code>db.max.inlinks</code>
* inlinks will ever be added.</p>
* <p>If activated, URLFilters will be applied to both the target URLs and
* to any incoming link URL. If a target URL is prohibited, all
* inlinks to that target will be removed, including the target URL. If
* some of incoming links are prohibited, only they will be removed, and they
* won't count when checking the above-mentioned maximum limit.
*
* @author Andrzej Bialecki
*/
public class LinkDbMerger extends Configured implements Tool, Reducer<Text, Inlinks, Text, Inlinks> {
private static final Log LOG = LogFactory.getLog(LinkDbMerger.class);
private int maxInlinks;
public LinkDbMerger() {
}
public LinkDbMerger(Configuration conf) {
setConf(conf);
}
public void reduce(Text key, Iterator<Inlinks> values, OutputCollector<Text, Inlinks> output, Reporter reporter) throws IOException {
Inlinks result = new Inlinks();
while (values.hasNext()) {
Inlinks inlinks = values.next();
int end = Math.min(maxInlinks - result.size(), inlinks.size());
Iterator<Inlink> it = inlinks.iterator();
int i = 0;
while(it.hasNext() && i++ < end) {
result.add(it.next());
}
}
if (result.size() == 0) return;
output.collect(key, result);
}
public void configure(JobConf job) {
maxInlinks = job.getInt("db.max.inlinks", 10000);
}
public void close() throws IOException { }
public void merge(Path output, Path[] dbs, boolean normalize, boolean filter) throws Exception {
JobConf job = createMergeJob(getConf(), output, normalize, filter);
for (int i = 0; i < dbs.length; i++) {
FileInputFormat.addInputPath(job, new Path(dbs[i], LinkDb.CURRENT_NAME));
}
JobClient.runJob(job);
FileSystem fs = FileSystem.get(getConf());
fs.mkdirs(output);
fs.rename(FileOutputFormat.getOutputPath(job), new Path(output, LinkDb.CURRENT_NAME));
}
public static JobConf createMergeJob(Configuration config, Path linkDb, boolean normalize, boolean filter) {
Path newLinkDb =
new Path("linkdb-merge-" +
Integer.toString(new Random().nextInt(Integer.MAX_VALUE)));
JobConf job = new NutchJob(config);
job.setJobName("linkdb merge " + linkDb);
job.setInputFormat(SequenceFileInputFormat.class);
job.setMapperClass(LinkDbFilter.class);
job.setBoolean(LinkDbFilter.URL_NORMALIZING, normalize);
job.setBoolean(LinkDbFilter.URL_FILTERING, filter);
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;
}
/**
* @param args
*/
public static void main(String[] args) throws Exception {
int res = ToolRunner.run(NutchConfiguration.create(), new LinkDbMerger(), args);
System.exit(res);
}
public int run(String[] args) throws Exception {
if (args.length < 2) {
System.err.println("Usage: LinkDbMerger <output_linkdb> <linkdb1> [<linkdb2> <linkdb3> ...] [-normalize] [-filter]");
System.err.println("\toutput_linkdb\toutput LinkDb");
System.err.println("\tlinkdb1 ...\tinput LinkDb-s (single input LinkDb is ok)");
System.err.println("\t-normalize\tuse URLNormalizer on both fromUrls and toUrls in linkdb(s) (usually not needed)");
System.err.println("\t-filter\tuse URLFilters on both fromUrls and toUrls in linkdb(s)");
return -1;
}
Path output = new Path(args[0]);
ArrayList<Path> dbs = new ArrayList<Path>();
boolean normalize = false;
boolean filter = false;
for (int i = 1; i < args.length; i++) {
if (args[i].equals("-filter")) {
filter = true;
} else if (args[i].equals("-normalize")) {
normalize = true;
} else dbs.add(new Path(args[i]));
}
try {
merge(output, dbs.toArray(new Path[dbs.size()]), normalize, filter);
return 0;
} catch (Exception e) {
LOG.fatal("LinkDbMerger: " + StringUtils.stringifyException(e));
return -1;
}
}
}