[infinispan-dev] Partial state transfer in Infinispan

[Bela Ban]

On 6/1/11 6:05 PM, Mircea Markus wrote:
>
>>>> Why are we actually using JGroups' state transfer with replication, but
>>>> use our own state transfer with distribution ?
>>>
>>> I don't know, but guess it's because each node has a different set of
>>> keys so no node has the same state as another ?
>>
>> You could still use JGroups state transfer; getState() would list the
>> state provider as target node.
>>
>> In general, partial state transfer involves transferring (1) the partial
>> state and (2) the digest, which is a vector of highest seqnos seen for
>> every member. When we get a partial state, we always overwrite our own
>> digest with the one received, and update our state accordingly. However,
>> when this is done a couple of times, for different partial states, I'm
>> not sure that we won't receive a few messages multiple times, due to the
>> digest overwriting...
>>
>> I think the cleanest solution would be for you guys to reuse the state
>> transfer you already use for state transfer in distribution mode.
> +1. There's also transaction logic* related to state transfer, which would need to be maintained in two implementations - not good!
>
> * actually the transaction-failover logic needs to be revisited especially after the new rebalancing code. Dan and I will go over it next week - we working at his place and this will make things easier.

Excellent ! Let us know what the outcome is, naturally I'm especially 
interested in the new rebalancing code since I wrote it ! :-)
Note that I'll be on vacation until June 11th.
Cheers,

-- 
Bela Ban
Lead JGroups / Clustering Team
JBoss