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https://issues.apache.org/jira/browse/HBASE-3257?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12989363#comment-12989363
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Mingjie Lai commented on HBASE-3257:
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Patch was put to review board, but it's not forwarded to jira.
Here is the review request:
https://review.cloudera.org/r/1515/
Summary:
Coprocessors: Extend server side integration API to include HLog operations
Coprocessor based extensions should be able to:
- Observe, rewrite, or skip WALEdits as they are being written to the WAL
- Write arbitrary content into WALEdits
- Act on contents of WALEdits in the regionserver context during reconstruction
Code changes:
- a new coprocessor interface WALCPObserver is added which provides
preWALWrite() and postWALWrite() upcalls to HLog, before and after
HLog.write.append(), at doWrite().
- added 2 new upcalls for RegionObserver for WAL replay, preWALRestore() and
postWALRestore().
- a sample implementation -- SampleRegionWALObserver -- was create which can
add, remove, modify WALEdit before writing it to WAL.
- test cases which use SampleRegionWALObserver to test WAL write and replay.
- added coprocessor loading at TestHLog to make sure it doesn't affect HLog.
I need feedback for:
- The new cp interface name -- WALCPObserver -- is not perfect. The ideal name
is WALObserver but it's been used already. Other options include HLogObserver(H
is not preferred), LogObserver(confusion).
- No support for monitor master log splitting. I don't have a use case to
support the requirement right now.
> Coprocessors: Extend server side integration API to include HLog operations
> ---------------------------------------------------------------------------
>
> Key: HBASE-3257
> URL: https://issues.apache.org/jira/browse/HBASE-3257
> Project: HBase
> Issue Type: Sub-task
> Components: coprocessors
> Reporter: Andrew Purtell
> Assignee: Mingjie Lai
> Fix For: 0.92.0
>
>
> Coprocessor based extensions should be able to:
> * Observe, rewrite, or skip WALEdits as they are being written to the WAL
> * Write arbitrary content into WALEdits
> * Act on contents of WALEdits in the regionserver context during
> reconstruction
> (update: remove WALEdit monitoring at master split. No need to use scope to
> control the behavior here, since it could be done by a coprocessor
> implementation.)
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