org.apache.nutch.crawl

Class DefaultFetchSchedule

java.lang.Object

org.apache.hadoop.conf.Configured

org.apache.nutch.crawl.AbstractFetchSchedule

org.apache.nutch.crawl.DefaultFetchSchedule

All Implemented Interfaces:

org.apache.hadoop.conf.Configurable, FetchSchedule

public class DefaultFetchSchedule
extends AbstractFetchSchedule

This class implements the default re-fetch schedule. That is, no matter if the page was changed or not, the fetchInterval remains unchanged, and the updated page fetchTime will always be set to fetchTime + fetchInterval * 1000.

Author:

Andrzej Bialecki

Field Summary

Fields inherited from class org.apache.nutch.crawl.AbstractFetchSchedule

defaultInterval, maxInterval

Fields inherited from interface org.apache.nutch.crawl.FetchSchedule

SECONDS_PER_DAY, STATUS_MODIFIED, STATUS_NOTMODIFIED, STATUS_UNKNOWN

Constructor Summary

Constructors

Constructor and Description
DefaultFetchSchedule()

Method Summary

Methods

Modifier and Type	Method and Description
CrawlDatum	setFetchSchedule(org.apache.hadoop.io.Text url, CrawlDatum datum, long prevFetchTime, long prevModifiedTime, long fetchTime, long modifiedTime, int state) Sets the fetchInterval and fetchTime on a successfully fetched page.

Methods inherited from class org.apache.nutch.crawl.AbstractFetchSchedule

calculateLastFetchTime, forceRefetch, initializeSchedule, setConf, setPageGoneSchedule, setPageRetrySchedule, shouldFetch

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

getConf

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

Constructor Detail

DefaultFetchSchedule

public DefaultFetchSchedule()

Method Detail

setFetchSchedule

public CrawlDatum setFetchSchedule(org.apache.hadoop.io.Text url,
                          CrawlDatum datum,
                          long prevFetchTime,
                          long prevModifiedTime,
                          long fetchTime,
                          long modifiedTime,
                          int state)

Description copied from class: AbstractFetchSchedule

Sets the fetchInterval and fetchTime on a successfully fetched page. NOTE: this implementation resets the retry counter - extending classes should call super.setFetchSchedule() to preserve this behavior.

Specified by:

setFetchSchedule in interface FetchSchedule

Overrides:

setFetchSchedule in class AbstractFetchSchedule

Parameters:

url - url of the page

datum - page description to be adjusted. NOTE: this instance, passed by reference, may be modified inside the method.

prevFetchTime - previous value of fetch time, or 0 if not available.

prevModifiedTime - previous value of modifiedTime, or 0 if not available.

fetchTime - the latest time, when the page was recently re-fetched. Most FetchSchedule implementations should update the value in @see CrawlDatum to something greater than this value.

modifiedTime - last time the content was modified. This information comes from the protocol implementations, or is set to < 0 if not available. Most FetchSchedule implementations should update the value in @see CrawlDatum to this value.

state - if FetchSchedule.STATUS_MODIFIED, then the content is considered to be "changed" before the fetchTime, if FetchSchedule.STATUS_NOTMODIFIED then the content is known to be unchanged. This information may be obtained by comparing page signatures before and after fetching. If this is set to FetchSchedule.STATUS_UNKNOWN, then it is unknown whether the page was changed; implementations are free to follow a sensible default behavior.

Returns:

adjusted page information, including all original information. NOTE: this may be a different instance than @see CrawlDatum, but implementations should make sure that it contains at least all information from @see CrawlDatum}.