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From Raúl Gutiérrez Segalés <...@itevenworks.net>
Subject Re: Watch: One time event -> Loss of event
Date Thu, 12 Jun 2014 17:36:24 GMT

On 12 June 2014 08:40, Mudit Verma <mudit.f2004912@gmail.com> wrote:

> Hi All,
> In my last couple of projects, I have heavily used zookeeper watches.
> However, ZK watch is a one time event.
> I strongly feel that zookeeper should have a way to set a watch
> permanently (unless removed by the user through an API or the znode is
> deleted). This would guarantee that no data change event is missed by the
> client. Otherwise, we can miss data change event that occurs between
> receiving the call back from previous watch and resetting the new watch
> again.  This problem is also stated in documentation.
> I am sure even others might have felt this need sometime or the other.
>  This missing capability makes ZK watcher functionality best effort and not
> full proof.  Consequently, clients who can not afford to miss any event,
> can not use ZooKeeper reliably.
> I think we should have these APIs unless there is some theoretical or
> practical problem with these.
> 1. API to set a watch permanently.
> 2. Removing a watch when not needed.
> Looking forward for a discussion.

Perhaps: https://issues.apache.org/jira/browse/ZOOKEEPER-1416?


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