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

[Manik Surtani]

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?

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
>> 
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>> 
> 
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--
Manik Surtani
manik at jboss.org
twitter.com/maniksurtani

Lead, Infinispan
http://www.infinispan.org