org.apache.nutch.crawl.LinkDbReader.java Source code

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Here is the source code for org.apache.nutch.crawl.LinkDbReader.java

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/**
 * 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;

// Commons Logging imports
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

import org.apache.hadoop.conf.Configured;
import org.apache.hadoop.io.*;
import org.apache.hadoop.fs.*;
import org.apache.hadoop.mapred.*;
import org.apache.hadoop.mapred.lib.HashPartitioner;
import org.apache.hadoop.util.*;
import org.apache.hadoop.conf.Configuration;

import org.apache.nutch.util.NutchConfiguration;
import org.apache.nutch.util.NutchJob;
import org.apache.nutch.util.TimingUtil;

import java.text.SimpleDateFormat;
import java.util.Iterator;

/** . */
public class LinkDbReader extends Configured implements Tool, Closeable {
    public static final Log LOG = LogFactory.getLog(LinkDbReader.class);

    private static final Partitioner<WritableComparable, Writable> PARTITIONER = new HashPartitioner<WritableComparable, Writable>();

    private FileSystem fs;
    private Path directory;
    private MapFile.Reader[] readers;

    public LinkDbReader() {

    }

    public LinkDbReader(Configuration conf, Path directory) throws Exception {
        setConf(conf);
        init(directory);
    }

    public void init(Path directory) throws Exception {
        this.fs = FileSystem.get(getConf());
        this.directory = directory;
    }

    public String[] getAnchors(Text url) throws IOException {
        Inlinks inlinks = getInlinks(url);
        if (inlinks == null)
            return null;
        return inlinks.getAnchors();
    }

    public Inlinks getInlinks(Text url) throws IOException {

        if (readers == null) {
            synchronized (this) {
                readers = MapFileOutputFormat.getReaders(fs, new Path(directory, LinkDb.CURRENT_NAME), getConf());
            }
        }

        return (Inlinks) MapFileOutputFormat.getEntry(readers, PARTITIONER, url, new Inlinks());
    }

    public void close() throws IOException {
        if (readers != null) {
            for (int i = 0; i < readers.length; i++) {
                readers[i].close();
            }
        }
    }

    public void processDumpJob(String linkdb, String output) throws IOException {
        SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
        long start = System.currentTimeMillis();
        if (LOG.isInfoEnabled()) {
            LOG.info("LinkDb dump: starting at " + sdf.format(start));
            LOG.info("LinkDb dump: db: " + linkdb);
        }
        Path outFolder = new Path(output);

        JobConf job = new NutchJob(getConf());
        job.setJobName("read " + linkdb);

        FileInputFormat.addInputPath(job, new Path(linkdb, LinkDb.CURRENT_NAME));
        job.setInputFormat(SequenceFileInputFormat.class);

        FileOutputFormat.setOutputPath(job, outFolder);
        job.setOutputFormat(TextOutputFormat.class);
        job.setOutputKeyClass(Text.class);
        job.setOutputValueClass(Inlinks.class);

        JobClient.runJob(job);

        long end = System.currentTimeMillis();
        LOG.info(
                "LinkDb dump: finished at " + sdf.format(end) + ", elapsed: " + TimingUtil.elapsedTime(start, end));
    }

    public static void main(String[] args) throws Exception {
        int res = ToolRunner.run(NutchConfiguration.create(), new LinkDbReader(), args);
        System.exit(res);
    }

    public int run(String[] args) throws Exception {
        if (args.length < 2) {
            System.err.println("Usage: LinkDbReader <linkdb> {-dump <out_dir> | -url <url>)");
            System.err.println("\t-dump <out_dir>\tdump whole link db to a text file in <out_dir>");
            System.err.println("\t-url <url>\tprint information about <url> to System.out");
            return -1;
        }
        try {
            if (args[1].equals("-dump")) {
                processDumpJob(args[0], args[2]);
                return 0;
            } else if (args[1].equals("-url")) {
                init(new Path(args[0]));
                Inlinks links = getInlinks(new Text(args[2]));
                if (links == null) {
                    System.out.println(" - no link information.");
                } else {
                    Iterator<Inlink> it = links.iterator();
                    while (it.hasNext()) {
                        System.out.println(it.next().toString());
                    }
                }
                return 0;
            } else {
                System.err.println("Error: wrong argument " + args[1]);
                return -1;
            }
        } catch (Exception e) {
            LOG.fatal("LinkDbReader: " + StringUtils.stringifyException(e));
            return -1;
        }
    }
}