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From Jordan Zimmerman <jor...@jordanzimmerman.com>
Subject Re: Attaching a Fencing Token to a Leader Latch
Date Tue, 19 Jul 2016 12:21:11 GMT
Why not just create a new LeaderLatch each time? Other than that, a PR with a settable id would
be nice.

-Jordan

> On Jul 19, 2016, at 7:17 AM, Stephan Ewen <sewen@apache.org> wrote:
> 
> Hi!
> 
> From what I understood from the API docs, that id is the same every time that specific
contender becomes leader.
> 
> What I am looking for is a unique value for every time leader status changes (which is
when a different znode gets created). We need that to separate actions taken by a participant
across being leader, losing leadership, and re-gaining its leadership.
> 
> Stephan
> 
> 
> On Tue, Jul 19, 2016 at 1:51 PM, Jordan Zimmerman <jordan@jordanzimmerman.com <mailto:jordan@jordanzimmerman.com>>
wrote:
> There’s a constructor in LeaderLatch that takes an “id”. That id is the payload
for the lock node.
> 
> 	public LeaderLatch(CuratorFramework client, String latchPath, String id)
> 
> You can call getParticipants() to get the IDs of all participants in the latch.
> 
>> On Jul 19, 2016, at 5:31 AM, Stephan Ewen <sewen@apache.org <mailto:sewen@apache.org>>
wrote:
>> 
>> Hi Curators!
>> 
>> We are using the curator LeaderLatch recipe for leader election - so far works great!
>> 
>> We need to additionally attach a "fencing token" to the leader latch - basically
a random unique ID that can be used to identify actions taken under the assumption of a certain
node holding the leader latch. This token should be retrieved atomically with the leader status
and live and die with the leader status.
>> 
>> Its seems natural to use the leader latch znode for that.
>> We were thinking to either use the latch's znode zxid, or to write some bytes to
the znode (or attach a child node) to it.
>> 
>> The recipe does not provide any access to the znode, however. What would you recommend
to do here? Is it possible to add (read only) access to the znode in the LeaderLatch?
>> 
>> Greetings,
>> Stephan
>> 
> 
> 


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