Anoop Sam John created HBASE-19047:
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Summary: CP exposed Scanner types should not extend Shipper
Key: HBASE-19047
URL: https://issues.apache.org/jira/browse/HBASE-19047
Project: HBase
Issue Type: Sub-task
Reporter: Anoop Sam John
Assignee: Anoop Sam John
Fix For: 2.0.0-alpha-4
Shipper is a IA.Private interface and very much internal..
Right now CP exposed RegionScanner is extending this and so exposing the
shipped() method. This by mistake is called, can harm the correctness of the
cells in the Results.
preScannerOpen() allowing to return a new Scanner is also problematic now.
This can allow users to create a Region scanner from Region and then wrap it
and return back (Well same can be done by postScannerOpen also), it can so
happen that the wrapper is not implementing the shipped() properly. In any way
exposing the shipped () is problematic.
Solution
1. Remove preScannerOpen() , the use case I can think of is wrapping the
original scanner. The original scanner can be created by Region.getScanner way
only.. May be no need to remove this hook. Just remove the ability for it to
return a RegionScanner instance. Call this with the Scan object and the CP can
change the Scan object if they want.
2. Let RegionScanner not extending Shipper but only RegionScannerImpl
implements this
3. We have ref to the RegionScanner created by core and let that be used by
RegionScannerShippedCallBack when the post hook doing a wrap.
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