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https://issues.apache.org/jira/browse/HBASE-626?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12596838#action_12596838
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Jean-Daniel Cryans commented on HBASE-626:
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Well in fact I checked this and this is already uses a form of visitor. The
listener (usually called observer) reacts to events, which is not the case in
this piece of code. But this is the good place I think to do the modification.
What I plan is :
- Refactor the scanMetaRegion method so it uses RowResult.
- Modify the listener (renamed visitor) so it accepts a RowResult and a
HRegionInfo.
- Add a method to scan all the meta regions which will take a visitor in
argument and optionally a row start key.
- Modify all impacted code.
Question : In the TODO it says that it has to "Allow multiple Visitors". Since
the ScannerListener already has to be implemented, I don't see the purpose of
that comment. Am I missing something bigger?
> Use Visitor pattern in MetaRegion to reduce code clones in HTable and
> HConnectionManager
> ----------------------------------------------------------------------------------------
>
> Key: HBASE-626
> URL: https://issues.apache.org/jira/browse/HBASE-626
> Project: Hadoop HBase
> Issue Type: Improvement
> Components: master
> Reporter: Jean-Daniel Cryans
> Priority: Minor
> Fix For: 0.2.0
>
>
> HTable and HConnectionManager.TableServers both scan the meta region in the
> same way (but the later also retry one time if it fails). A Visitor pattern
> should be used in a new scanning method in MetaRegion to accept visitors that
> gather information such as region names for a table or the list of all tables.
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