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https://issues.apache.org/jira/browse/HBASE-5573?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13234254#comment-13234254
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nkeywal commented on HBASE-5573:
--------------------------------
For ZK and ZKW dependency, prefixing zk for the ZooKeeper api objects and hb
for the HBase objects:
a zk.ZooKeeper can be created with a zk.Watcher as a parameter for the
constructor. a hb.ZooKeeperWatcher implements the zk.Watcher interface. So we
have:
hb.ZooKeeperWatcher implements zk.ZooKeeper.
hb.ZooKeeperWatcher contains hb.RecoverableZooKeeper
hb.RecoverableZooKeeper contains zk.ZooKeeper
zk.ZooKeeper contains (hb.ZooKeeperWatcher implements zk.ZooKeeper)
loop done.
It was like this before my patch. After my patch there are two cases:
1) As above
2) for ZooKeeperHBaseNodes, the watcher is actually "null", so it becomes:
hb.ZooKeeperHBaseNodes contains hb.RecoverableZooKeeper
hb.RecoverableZooKeeper contains zk.ZooKeeper
zk.ZooKeeper contains null
It allows to share the code, but it makes it more complex.
bq. I see. ROZK has a RZK. Can RZK have a ZooKeeper only?
Yes, but it would lead to some code duplication and we would lose the
recoverable feature (or we would need to duplicate it as well).
bq. ZooKeeperHBaseNodes => ReadOnlyZooKeeper
It's not really a readonly zookeeper: you can write with it.
bq. Looks good
Ok, I am gonna finish it with this approach then.
> Replace client ZooKeeper watchers by simple ZooKeeper reads
> -----------------------------------------------------------
>
> Key: HBASE-5573
> URL: https://issues.apache.org/jira/browse/HBASE-5573
> Project: HBase
> Issue Type: Improvement
> Components: client, zookeeper
> Affects Versions: 0.96.0
> Reporter: nkeywal
> Assignee: nkeywal
> Priority: Minor
> Attachments: 5573.v1.patch, 5573.v2.patch
>
>
> Some code in the package needs to read data in ZK. This could be done by a
> simple read, but is actually implemented with a watcher. This holds ZK
> resources.
> Fixing this could also be an opportunity to remove the need for the client to
> provide the master address and port.
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