[infinispan-dev] Trigger NBST for Auto-Placer

[Dan Berindei]

Hi Pedro

When I split off the RebalancePolicy I was thinking that when a
RebalancePolicy needs to collaborate with a ConsistentHashFactory, they
should do so via another cache manager-scoped component. But that doesn't
really work (yet?), because ConsistentHashFactory can't access any
components.

I think it would be better to extend
ClusterTopologyManager.triggerRebalance (and
ConsistentHashFactory.rebalance) to accept an arbitrary Object parameter.
Then RebalancePolicy could use this parameter to pass extra information to
the CHF, like your Mappings object, and then when
ClusterTopologyManagerImpl asks for a balanced CH, the CHF will include the
Mappings in the result CH. What do you think?

In order to trigger the rebalance you have to call startRebalance, and the
new ("balanced") consistent hash must not be equal to the existing
consistent hash. See
https://github.com/infinispan/infinispan/blob/master/core/src/main/java/org/infinispan/topology/ClusterTopologyManagerImpl.java#L389

Cheers
Dan




On Thu, Feb 7, 2013 at 10:05 PM, Pedro Ruivo <pruivo at gsd.inesc-id.pt> wrote:

> Hi,
>
> I'm working in a way to rebase auto-placer on top of NBST and I have one
> question...
> If you have already forgot, auto-placer analyzes the workload and tries
> to move the most remote accessed keys to the corresponding requester.
>
> After calculating the new mappings, I want to trigger the NBST with this
> mapping. I'm thinking to add a new method in the ClusterTopologyManager,
> something like:
>
> triggerAutoPlacer(String cacheName, Mappings newMappings);
>
> and this method it will be a duplicate of triggerRebalance but instead
> of doing chFactory.rebalance(CH) (in the startRebalance() method) I'm
> thinking to do chFactory.autoPlacer(CH, Mappings). The last method will
> override the defautl CH location.
>
> Question: will this solution trigger the NBST or do I have to create the
> triggerAutoPlacer() method in another class?
>
> ps. forget the methods names... I will think in better names later
>
> Thanks!!
>
> Cheers,
> Pedro
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