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:
    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

    All Methods Instance Methods Concrete Methods
    Modifier and Type | Method and Description
    --- | ---
    `CrawlDatum` | `setFetchSchedule(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(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}.

Copyright © 2019 The Apache Software Foundation