Package org.apache.nutch.crawl

Class Injector.InjectReducer

java.lang.Object

org.apache.hadoop.mapreduce.Reducer<Text,CrawlDatum,Text,CrawlDatum>

org.apache.nutch.crawl.Injector.InjectReducer

Enclosing class:

Injector

public static class Injector.InjectReducer
extends Reducer<Text,CrawlDatum,Text,CrawlDatum>

Combine multiple new entries for a url.

Nested Class Summary

Nested classes/interfaces inherited from class org.apache.hadoop.mapreduce.Reducer

Reducer.Context

Constructor Summary

Constructors

Constructor	Description
InjectReducer()

Method Summary

Modifier and Type	Method	Description
void	reduce(Text key, Iterable<CrawlDatum> values, Reducer.Context context)	Merge the input records of one URL as per rules below :
void	setup(Reducer.Context context)

Methods inherited from class org.apache.hadoop.mapreduce.Reducer

cleanup, run

Methods inherited from class java.lang.Object

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

Constructor Detail

InjectReducer

public InjectReducer()

Method Detail

setup

public void setup(Reducer.Context context)

Overrides:

setup in class Reducer<Text,CrawlDatum,Text,CrawlDatum>

reduce

public void reduce(Text key,
                   Iterable<CrawlDatum> values,
                   Reducer.Context context)
            throws IOException,
                   InterruptedException

Merge the input records of one URL as per rules below :

 1. If there is ONLY new injected record ==> emit injected record
 2. If there is ONLY old record          ==> emit existing record
 3. If BOTH new and old records are present:
    (a) If 'overwrite' is true           ==> emit injected record
    (b) If 'overwrite' is false :
        (i)  If 'update' is false        ==> emit existing record
        (ii) If 'update' is true         ==> update existing record and emit it
 

For more details @see NUTCH-1405

Overrides:

reduce in class Reducer<Text,CrawlDatum,Text,CrawlDatum>

Throws:

IOException

InterruptedException