public abstract class AbstractFetchSchedule extends Configured implements FetchSchedule
FetchSchedule
.Modifier and Type | Field and Description |
---|---|
protected int |
defaultInterval |
protected int |
maxInterval |
SECONDS_PER_DAY, STATUS_MODIFIED, STATUS_NOTMODIFIED, STATUS_UNKNOWN
Constructor and Description |
---|
AbstractFetchSchedule() |
AbstractFetchSchedule(Configuration conf) |
Modifier and Type | Method and Description |
---|---|
long |
calculateLastFetchTime(WebPage page)
This method return the last fetch time of the CrawlDatum
|
void |
forceRefetch(String url,
WebPage page,
boolean asap)
This method resets fetchTime, fetchInterval, modifiedTime,
retriesSinceFetch and page signature, so that it forces refetching.
|
Set<WebPage.Field> |
getFields() |
void |
initializeSchedule(String url,
WebPage page)
Initialize fetch schedule related data.
|
void |
setConf(Configuration conf) |
void |
setFetchSchedule(String url,
WebPage page,
long prevFetchTime,
long prevModifiedTime,
long fetchTime,
long modifiedTime,
int state)
Sets the
fetchInterval and fetchTime on a
successfully fetched page. |
void |
setPageGoneSchedule(String url,
WebPage page,
long prevFetchTime,
long prevModifiedTime,
long fetchTime)
This method specifies how to schedule refetching of pages marked as GONE.
|
void |
setPageRetrySchedule(String url,
WebPage page,
long prevFetchTime,
long prevModifiedTime,
long fetchTime)
This method adjusts the fetch schedule if fetching needs to be re-tried due
to transient errors.
|
boolean |
shouldFetch(String url,
WebPage page,
long curTime)
This method provides information whether the page is suitable for selection
in the current fetchlist.
|
getConf
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
getConf
public AbstractFetchSchedule()
public AbstractFetchSchedule(Configuration conf)
public void setConf(Configuration conf)
setConf
in interface Configurable
setConf
in class Configured
public void initializeSchedule(String url, WebPage page)
fetchTime
and fetchInterval
. The default
implementation sets the fetchTime
to now, using the default
fetchInterval
.initializeSchedule
in interface FetchSchedule
url
- URL of the page.page
- public void setFetchSchedule(String url, WebPage page, long prevFetchTime, long prevModifiedTime, long fetchTime, long modifiedTime, int state)
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.setFetchSchedule
in interface FetchSchedule
url
- url of the pageprevFetchTime
- previous value of fetch time, or -1 if not availableprevModifiedTime
- previous value of modifiedTime, or -1 if not availablefetchTime
- the latest time, when the page was recently re-fetched. Most
FetchSchedule implementations should update the value inmodifiedTime
- 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 instate
- 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.public void setPageGoneSchedule(String url, WebPage page, long prevFetchTime, long prevModifiedTime, long fetchTime)
maxInterval
.setPageGoneSchedule
in interface FetchSchedule
url
- URL of the pagepage
- datum
- , but implementations should make sure that it contains at least
all information fromdatum
- .public void setPageRetrySchedule(String url, WebPage page, long prevFetchTime, long prevModifiedTime, long fetchTime)
setPageRetrySchedule
in interface FetchSchedule
url
- URL of the pagepage
- prevFetchTime
- previous fetch timeprevModifiedTime
- previous modified timefetchTime
- current fetch timepublic long calculateLastFetchTime(WebPage page)
calculateLastFetchTime
in interface FetchSchedule
public boolean shouldFetch(String url, WebPage page, long curTime)
fetchTime
, if it is higher than theshouldFetch
in interface FetchSchedule
curTime
- it returns false, and true otherwise. It will also check that
fetchTime is not too remote (more than maxInterval
url
- URL of the pagepage
- curTime
- reference time (usually set to the time when the fetchlist
generation process was started).public void forceRefetch(String url, WebPage page, boolean asap)
forceRefetch
in interface FetchSchedule
url
- URL of the pagepage
- asap
- if true, force refetch as soon as possible - this sets the
fetchTime to now. If false, force refetch whenever the next fetch
time is set.public Set<WebPage.Field> getFields()
getFields
in interface FetchSchedule
Copyright © 2015 The Apache Software Foundation