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https://issues.apache.org/jira/browse/HBASE-9489?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13833957#comment-13833957
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Gary Helmling commented on HBASE-9489:
--------------------------------------
I don't understand the API that this patch is adding:
{code}
+ void preMergeBeforePONR(final
ObserverContext<RegionServerCoprocessorEnvironment> ctx,
+ final HRegion regionA, final HRegion regionB, List<Mutation>
metaEntries) throws IOException;
+ void preMergeAfterPONR(final
ObserverContext<RegionServerCoprocessorEnvironment> ctx,
+ final HRegion regionA, final HRegion regionB, final HRegion
mergedRegion) throws IOException;
{code}
Generally, "before" and "after" are what the "pre" and "post" hooks are used
for respectively. Having a "pre...Before" and "pre...After" hook suggests to
me that the API is unclear. It instead looks to me like these 2 methods are
actually a "pre" and "post" hook around a single action. Maybe something like
preMergeCommit / postMergeCommit would be better?
I'm also not sure I understand the usage of ObserverContext.bypass() related to
these two methods. bypass() normally means "skip the normal processing". But
in preMergeBeforePONR(), according to the javadoc, it will actually _abort_ the
merge. It seems like using a return value to indicate whether to proceed or
abort would be more appropriate. For preMergeAfterPONR(), the javadoc says
that bypass is ignored, which is unusual for a "pre" method. It would make
more sense for bypass() to be ignored if this were a "post" method (say
"postMergeCommit").
> Add cp hooks in online merge before and after setting PONR
> ----------------------------------------------------------
>
> Key: HBASE-9489
> URL: https://issues.apache.org/jira/browse/HBASE-9489
> Project: HBase
> Issue Type: Sub-task
> Reporter: rajeshbabu
> Assignee: rajeshbabu
> Attachments: HBASE-9489.patch, HBASE-9489_v2.patch
>
>
> As we need to merge index region along with user region we need the hooks
> before and after setting PONR in region merge transtion.
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