[jira] [Commented] (BOOKKEEPER-407) Hedwig client doesn't remove old topic2Host mapping in case of redirect

["Sijie Guo (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/BOOKKEEPER-407?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13456931#comment-13456931 ] 

Sijie Guo commented on BOOKKEEPER-407:
--------------------------------------

in most of case, putIfAbsent works OK, since the topic ownership will be cleared when a channel disconnected. only a corner case it would made bad, when a hub server failed to acquire ownership due to ZooKeeper failure and respond SERVICE_DOWN exception. since client could not tell whether it acquire the topic succeed or not and it might set a wrong owner. but it is trivial, since redirect could help find the right owner.

as my comment in https://issues.apache.org/jira/browse/BOOKKEEPER-392?focusedCommentId=13448270&page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#comment-13448270, I used replace instead of putIfAbsent for BOOKKEEPER-364.

besides that, I think it would be better to add specific exception for failure of getting ownership, so client could know whether it could set topic ownership or not.
                
> Hedwig client doesn't remove old topic2Host mapping in case of redirect
> -----------------------------------------------------------------------
>
>                 Key: BOOKKEEPER-407
>                 URL: https://issues.apache.org/jira/browse/BOOKKEEPER-407
>             Project: Bookkeeper
>          Issue Type: Bug
>    Affects Versions: 4.2.0
>            Reporter: Aniruddha
>
> In the storeTopic2HostMapping function, there is a topic2Host.putIfAbsent(). This doesn't seem correct as we should always update the mapping in case of a redirect. 

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