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https://issues.apache.org/jira/browse/HBASE-17652?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Appy updated HBASE-17652:
-------------------------
Component/s: Coprocessors
> Use 'default' keyword in Coprocessor Observer interfaces to get rid of
> 'Base...Observer' implementations.
> ---------------------------------------------------------------------------------------------------------
>
> Key: HBASE-17652
> URL: https://issues.apache.org/jira/browse/HBASE-17652
> Project: HBase
> Issue Type: Improvement
> Components: Coprocessors
> Reporter: Appy
> Assignee: Appy
> Labels: coprocessors, incompatible
> Attachments: HBASE-17652.master.001.patch
>
>
> In cases where one might need to use multiple observers, say region, master
> and regionserver; and the fact that only one class can be extended, it gives
> rise to following pattern:
> {noformat}
> public class BaseMasterAndRegionObserver
> extends BaseRegionObserver
> implements MasterObserver
> class AccessController
> extends BaseMasterAndRegionObserver
> implements RegionServerObserver
> {noformat}
> were BaseMasterAndRegionObserver is full copy of BaseMasterObserver.
> There is an example of simple case too where the current design fails.
> Say only one observer is needed by the coprocessor, but the design
> doesn't permit extending even that single observer (see
> RSGroupAdminEndpoint), that leads to full copy of Base...Observer class into
> coprocessor class leading to 1000s of lines of code and this ugly mix of 5
> main functions with 100 useless functions.
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