[jira] [Commented] (ZOOKEEPER-1622) session ids will be negative in the year 2022

["Patrick Hunt (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/ZOOKEEPER-1622?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13792777#comment-13792777 ] 

Patrick Hunt commented on ZOOKEEPER-1622:
-----------------------------------------

[~ecn] could you submit a patch? Thanks.

> session ids will be negative in the year 2022
> ---------------------------------------------
>
>                 Key: ZOOKEEPER-1622
>                 URL: https://issues.apache.org/jira/browse/ZOOKEEPER-1622
>             Project: ZooKeeper
>          Issue Type: Bug
>            Reporter: Eric Newton
>            Assignee: Eric Newton
>            Priority: Trivial
>
> Someone decided to use a large number for their myid file.  This cause session ids to go negative, and our software (Apache Accumulo) did not handle this very well.  While diagnosing the problem, I noticed this in SessionImpl:
> {noformat}
>    public static long initializeNextSession(long id) {
>         long nextSid = 0;
>         nextSid = (System.currentTimeMillis() << 24) >> 8;
>         nextSid =  nextSid | (id <<56);
>         return nextSid;
>     }
> {noformat}
> When the 40th bit in System.currentTimeMillis() is a one, sign extension will fill the upper 8 bytes of nextSid, and id will not make the session id unique.  I recommend changing the right shift to the logical shift:
> {noformat}
>    public static long initializeNextSession(long id) {
>         long nextSid = 0;
>         nextSid = (System.currentTimeMillis() << 24) >>> 8;
>         nextSid =  nextSid | (id <<56);
>         return nextSid;
>     }
> {noformat}
> But, we have until the year 2022 before we have to worry about it.



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