[infinispan-dev] New events to reflect topology change Was: https://issues.jboss.org/browse/ISPN-977

[Michal Linhard]

On 05/13/2011 11:28 AM, Manik Surtani wrote:
> So this is related to ISPN-360 which is currently titled "create NodeJoinedEvent".
>
> Leaving names out for now, essentially, what we need is a notification to inform listeners that (a) a JGroups ViewChange has been detected (b) a rehash has started and (c) a rehash has completed.  Possibly, being more fine-grained, that (d) a new ConsistentHash view has been installed.  Does this cover it all?  If so, how about:
>
> @ViewChanged (same as we have now)
> @RehashStarted
> @RehashComplete
> @TopologyChanged // to reflect a new CH?
>
> Thoughts?
Covers my requirements. With RehashComplete we would be able build a 
monitoring component that would enable us to wait until rehash is 
complete during the cluster scale-in phase.

m.
> Cheers
> Manik
>
>
>
> On 11 May 2011, at 13:29, Sanne Grinovero wrote:
>
>> First thing I thought when reading your email was "OMG do we support
>> on-the-fly hash implementation changes? crazy!"
>>
>> That's obviously not the case, but if you name it as
>> @ConsistenHashChangeListene that's what I would think.
>>
>> Wouldn't it be better to change the exact timing of the viewchange
>> event? I don't see why Infinispan users might be more interested in
>> knowing about the topology details according to the transport than
>> what they are about the actual Infinispan hashing topology - I would
>> expect that when I receive which notification the new view is already
>> installed and ready to go; actually I thought that was the case since
>> ever.
>>
>> What would be the use cases to get the notification *before* the new
>> hash is installed?
>>
>> Cheers,
>> Sanne
>>
>> 2011/5/11 Mircea Markus<mircea.markus at jboss.com>:
>>> Hi,
>>> The basic problem behind this is that I need to be notified when a new
>>> consistent hash is installed.
>>>
>>> ATM there isn't any support (of which I know)  for  a
>>> "@ConsistenHashChangeListener".
>>>
>>> I'm thinking to add such notifications either:
>>> a) internally: Observer pattern on DistributionManager or even on
>>> DistributionManagerImpl
>>> b) more generically, as a fully flagged listener.
>>>
>>> I favor a) and then if more people ask for it we will expose it as a fully
>>> flagged listener.
>>>
>>> Suggestions?
>>>
>>> Cheers,
>>> Mircea
>>>
>>> _______________________________________________
>>> infinispan-dev mailing list
>>> infinispan-dev at lists.jboss.org
>>> https://lists.jboss.org/mailman/listinfo/infinispan-dev
>>>
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> --
> Manik Surtani
> manik at jboss.org
> twitter.com/maniksurtani
>
> Lead, Infinispan
> http://www.infinispan.org
>
>
>
>
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-- 
Michal Linhard
Quality Assurance Engineer

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