/**
* 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.text.SimpleDateFormat;
import java.util.*;
import java.util.Map.Entry;
// Commons Logging imports
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.FileSystem;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.io.Text;
import org.apache.hadoop.io.Writable;
import org.apache.hadoop.mapred.*;
import org.apache.hadoop.util.*;
import org.apache.hadoop.conf.*;
import org.apache.nutch.util.NutchConfiguration;
import org.apache.nutch.util.NutchJob;
import org.apache.nutch.util.TimingUtil;
/**
* This tool merges several CrawlDb-s into one, optionally filtering
* URLs through the current URLFilters, to skip prohibited
* pages.
*
* <p>It's possible to use this tool just for filtering - in that case
* only one CrawlDb should be specified in arguments.</p>
* <p>If more than one CrawlDb contains information about the same URL,
* only the most recent version is retained, as determined by the
* value of {@link org.apache.nutch.crawl.CrawlDatum#getFetchTime()}.
* However, all metadata information from all versions is accumulated,
* with newer values taking precedence over older values.
*
* @author Andrzej Bialecki
*/
public class CrawlDbMerger extends Configured implements Tool {
private static final Logger LOG = LoggerFactory.getLogger(CrawlDbMerger.class);
public static class Merger extends MapReduceBase implements Reducer<Text, CrawlDatum, Text, CrawlDatum> {
private org.apache.hadoop.io.MapWritable meta;
private CrawlDatum res = new CrawlDatum();
private FetchSchedule schedule;
public void close() throws IOException {}
public void configure(JobConf conf) {
schedule = FetchScheduleFactory.getFetchSchedule(conf);
}
public void reduce(Text key, Iterator<CrawlDatum> values, OutputCollector<Text, CrawlDatum> output, Reporter reporter)
throws IOException {
long resTime = 0L;
boolean resSet = false;
meta = new org.apache.hadoop.io.MapWritable();
while (values.hasNext()) {
CrawlDatum val = values.next();
if (!resSet) {
res.set(val);
resSet = true;
resTime = schedule.calculateLastFetchTime(res);
for (Entry<Writable, Writable> e : res.getMetaData().entrySet()) {
meta.put(e.getKey(), e.getValue());
}
continue;
}
// compute last fetch time, and pick the latest
long valTime = schedule.calculateLastFetchTime(val);
if (valTime > resTime) {
// collect all metadata, newer values override older values
for (Entry<Writable, Writable> e : val.getMetaData().entrySet()) {
meta.put(e.getKey(), e.getValue());
}
res.set(val);
resTime = valTime ;
} else {
// insert older metadata before newer
for (Entry<Writable, Writable> e : meta.entrySet()) {
val.getMetaData().put(e.getKey(), e.getValue());
}
meta = val.getMetaData();
}
}
res.setMetaData(meta);
output.collect(key, res);
}
}
public CrawlDbMerger() {
}
public CrawlDbMerger(Configuration conf) {
setConf(conf);
}
public void merge(Path output, Path[] dbs, boolean normalize, boolean filter) throws Exception {
SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
long start = System.currentTimeMillis();
LOG.info("CrawlDb merge: starting at " + sdf.format(start));
JobConf job = createMergeJob(getConf(), output, normalize, filter);
for (int i = 0; i < dbs.length; i++) {
if (LOG.isInfoEnabled()) { LOG.info("Adding " + dbs[i]); }
FileInputFormat.addInputPath(job, new Path(dbs[i], CrawlDb.CURRENT_NAME));
}
JobClient.runJob(job);
FileSystem fs = FileSystem.get(getConf());
if(fs.exists(output))
fs.delete(output,true);
fs.mkdirs(output);
fs.rename(FileOutputFormat.getOutputPath(job), new Path(output, CrawlDb.CURRENT_NAME));
long end = System.currentTimeMillis();
LOG.info("CrawlDb merge: finished at " + sdf.format(end) + ", elapsed: " + TimingUtil.elapsedTime(start, end));
}
public static JobConf createMergeJob(Configuration conf, Path output, boolean normalize, boolean filter) {
Path newCrawlDb = new Path("crawldb-merge-" + Integer.toString(new Random().nextInt(Integer.MAX_VALUE)));
JobConf job = new NutchJob(conf);
job.setJobName("crawldb merge " + output);
job.setInputFormat(SequenceFileInputFormat.class);
job.setMapperClass(CrawlDbFilter.class);
job.setBoolean(CrawlDbFilter.URL_FILTERING, filter);
job.setBoolean(CrawlDbFilter.URL_NORMALIZING, normalize);
job.setReducerClass(Merger.class);
FileOutputFormat.setOutputPath(job, newCrawlDb);
job.setOutputFormat(MapFileOutputFormat.class);
job.setOutputKeyClass(Text.class);
job.setOutputValueClass(CrawlDatum.class);
return job;
}
/**
* @param args
*/
public static void main(String[] args) throws Exception {
int res = ToolRunner.run(NutchConfiguration.create(), new CrawlDbMerger(), args);
System.exit(res);
}
public int run(String[] args) throws Exception {
if (args.length < 2) {
System.err.println("Usage: CrawlDbMerger <output_crawldb> <crawldb1> [<crawldb2> <crawldb3> ...] [-normalize] [-filter]");
System.err.println("\toutput_crawldb\toutput CrawlDb");
System.err.println("\tcrawldb1 ...\tinput CrawlDb-s (single input CrawlDb is ok)");
System.err.println("\t-normalize\tuse URLNormalizer on urls in the crawldb(s) (usually not needed)");
System.err.println("\t-filter\tuse URLFilters on urls in the crawldb(s)");
return -1;
}
Path output = new Path(args[0]);
ArrayList<Path> dbs = new ArrayList<Path>();
boolean filter = false;
boolean normalize = false;
FileSystem fs = FileSystem.get(getConf());
for (int i = 1; i < args.length; i++) {
if (args[i].equals("-filter")) {
filter = true;
continue;
} else if (args[i].equals("-normalize")) {
normalize = true;
continue;
}
final Path dbPath = new Path(args[i]);
if(fs.exists(dbPath))
dbs.add(dbPath);
}
try {
merge(output, dbs.toArray(new Path[dbs.size()]), normalize, filter);
return 0;
} catch (Exception e) {
LOG.error("CrawlDb merge: " + StringUtils.stringifyException(e));
return -1;
}
}
}