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From "Flavio Junqueira (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (ZOOKEEPER-1485) client xid overflow is not handled
Date Fri, 01 Jul 2016 21:10:12 GMT

    [ https://issues.apache.org/jira/browse/ZOOKEEPER-1485?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15359640#comment-15359640
] 

Flavio Junqueira commented on ZOOKEEPER-1485:
---------------------------------------------

I'm not entirely convinced that this is the right way to address this issue. I was having
another look at ZOOKEEPER-22, which is something I'd really like to see implemented eventually
and I'm concerned that this approach of allowing the same xid to appear twice in a session
could create problems. Not repeating xid values for a given session sounds like a cleaner
abstraction compared to wrapping around like this.

What if we fix by not making the xid static in the C client and getting a new handle?

Also, it is important that we added test cases specially when there is a change of behavior.
Even if the change is trivial, we want to be able to test that future changes won't break
it.

> client xid overflow is not handled
> ----------------------------------
>
>                 Key: ZOOKEEPER-1485
>                 URL: https://issues.apache.org/jira/browse/ZOOKEEPER-1485
>             Project: ZooKeeper
>          Issue Type: Bug
>          Components: c client, java client
>    Affects Versions: 3.4.3, 3.3.5
>            Reporter: Michi Mutsuzaki
>            Assignee: Martin Kuchta
>         Attachments: ZOOKEEPER-1485.patch
>
>
> Both Java and C clients use signed 32-bit int as XIDs. XIDs are assumed to be non-negative,
and zookeeper uses some negative values as special XIDs (e.g. -2 for ping, -4 for auth). However,
neither Java nor C client ensures the XIDs it generates are non-negative, and the server doesn't
reject negative XIDs.
> Pat had some suggestions on how to fix this:
> - (bin-compat) Expire the session when the client sends a negative XID.
> - (bin-incompat) In addition to expiring the session, use 64-bit int for XID so that
overflow will practically never happen.
> --Michi



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