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https://issues.apache.org/jira/browse/HBASE-10915?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13961369#comment-13961369
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Mikhail Antonov commented on HBASE-10915:
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Regarding the separation, since the handlers are kind of "leaf type of ZK
usage", I'm doing the separation bottom-up, and we have to manually construct
such objects full of ZK details, as we have to construct it somewhere.
Perhaps in next Jira I will outline the approach for consensus initialization
to avoid that. So in this patch I have this:
- RegionServer creates implementation of CloseRegionConsensus directly,
instance of CloseRegionDetails impl (so ZK leaks out)
- creates CloseRegionHandler with them and submits to executor.
How it needs to be, perhaps:
- hbase-site.xml has property hbase.consensus.provider(=ZOOKEEPER in our
current situation).
- when node starts, it starts service ConsensusNodeServices, which (in our
case) creates connection to ZK ensemble and keeps the only instance of
ZooKeeperWatcher (+ set of zk-level listeners)
- RegionServer class starts,calls ConsensusNodeServices.get() to get impl of
CloseRegionConsensus, which has reference to ZK watcher (instead of current
server.getZooKeeper()), and internally tracks the state of relevant znodes.
- so when RegionServer feels the need to close regions and calls
closeRegion(region1), it doesn't need to be passed reference to ZK watcher (it
already has it), and doesn't need to be _passed_ reference to things like znode
expected versions, because all operations on znodes only ever happen inside the
CloseRegionConsensus method calls, so it can maintain these data in the data
structures.
I will put in more details in the updated doc.
> Decouple CloseRegionHandler from ZooKeeper
> ------------------------------------------
>
> Key: HBASE-10915
> URL: https://issues.apache.org/jira/browse/HBASE-10915
> Project: HBase
> Issue Type: Sub-task
> Components: Zookeeper
> Reporter: Mikhail Antonov
> Assignee: Mikhail Antonov
> Attachments: HBASE-10915.patch
>
>
> Decouple CloseRegionHandler class from ZK API.
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