org.apache.nutch.crawl

Class LinkDbMerger

java.lang.Object

org.apache.hadoop.conf.Configured

org.apache.nutch.crawl.LinkDbMerger

All Implemented Interfaces:

Closeable, AutoCloseable, Configurable, JobConfigurable, Reducer<Text,Inlinks,Text,Inlinks>, Tool

public class LinkDbMerger
extends Configured
implements Tool, Reducer<Text,Inlinks,Text,Inlinks>

This tool merges several LinkDb-s into one, optionally filtering URLs through the current URLFilters, to skip prohibited URLs and links.

It's possible to use this tool just for filtering - in that case only one LinkDb should be specified in arguments.

If more than one LinkDb contains information about the same URL, all inlinks are accumulated, but only at most db.max.inlinks inlinks will ever be added.

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

Constructor Summary

Constructors

Constructor and Description
LinkDbMerger()
LinkDbMerger(Configuration conf)

Method Summary

Methods

Modifier and Type	Method and Description
void	close()
void	configure(JobConf job)
static JobConf	createMergeJob(Configuration config, Path linkDb, boolean normalize, boolean filter)
static void	main(String[] args)
void	merge(Path output, Path[] dbs, boolean normalize, boolean filter)
void	reduce(Text key, Iterator<Inlinks> values, OutputCollector<Text,Inlinks> output, Reporter reporter)
int	run(String[] args)

Methods inherited from class org.apache.hadoop.conf.Configured

getConf, setConf

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Methods inherited from interface org.apache.hadoop.conf.Configurable

getConf, setConf

Constructor Detail

LinkDbMerger

public LinkDbMerger()

LinkDbMerger

public LinkDbMerger(Configuration conf)

Method Detail

reduce

public void reduce(Text key,
          Iterator<Inlinks> values,
          OutputCollector<Text,Inlinks> output,
          Reporter reporter)
            throws IOException

Specified by:

reduce in interface Reducer<Text,Inlinks,Text,Inlinks>

Throws:

IOException

configure

public void configure(JobConf job)

Specified by:

configure in interface JobConfigurable

close

public void close()
           throws IOException

Specified by:

close in interface Closeable

Specified by:

close in interface AutoCloseable

Throws:

IOException

merge

public void merge(Path output,
         Path[] dbs,
         boolean normalize,
         boolean filter)
           throws Exception

Throws:

Exception

createMergeJob

public static JobConf createMergeJob(Configuration config,
                     Path linkDb,
                     boolean normalize,
                     boolean filter)

main

public static void main(String[] args)
                 throws Exception

Parameters:

args -

Throws:

Exception

run

public int run(String[] args)
        throws Exception

Specified by:

run in interface Tool

Throws:

Exception