[jira] [Updated] (ZOOKEEPER-3124) Add the correct comment to show why we need the special logic to handle cversion and pzxid

["Fangmin Lv (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/ZOOKEEPER-3124?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Fangmin Lv updated ZOOKEEPER-3124:
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    Summary: Add the correct comment to show why we need the special logic to handle cversion and pzxid  (was: Update the comment of special logic to handle cversion and pzxid in DataTree.processTxn)

> Add the correct comment to show why we need the special logic to handle cversion and pzxid
> ------------------------------------------------------------------------------------------
>
>                 Key: ZOOKEEPER-3124
>                 URL: https://issues.apache.org/jira/browse/ZOOKEEPER-3124
>             Project: ZooKeeper
>          Issue Type: Improvement
>          Components: server
>            Reporter: Fangmin Lv
>            Assignee: Fangmin Lv
>            Priority: Major
>              Labels: pull-request-available
>             Fix For: 3.6.0
>
>          Time Spent: 1.5h
>  Remaining Estimate: 0h
>
> There is special logic in the DataTree.processTxn to handle the NODEEXISTS when createNode, which is used to handle the cversion and pzxid not being updated due to fuzzy snapshot: 
> https://github.com/apache/zookeeper/blob/master/src/java/main/org/apache/zookeeper/server/DataTree.java#L962-L994. 
> But is this a real issue, or is it still an issue for now?
> In the current code, when serializing a parent node, we'll lock on it, and take a children snapshot at that time. If the child added after the parent is serialized to disk, then it won't be written out, so we shouldn't hit the issue where the child is in the snapshot but parent cversion and pzxid is not changed.
>  
>  
> I checked the JIRA ZOOKEEPER-1269 which added this code, it won't hit this issue as well, I'm not sure why we added this, am I missing anything? Can we just get rid of it?
>  



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