[infinispan-dev] State transfer-related terms

[Radim Vansa]

Hi,

I've started (again) working on ISPN-5021 [1], and I'd like to get some 
common agreement on few terms. So below I summarize my understanding (or 
misunderstanding) of these, please state you opinion, thinking a bit 
more generally.

State transfer: whole process beginning with some ST-related event = 
node being detected to crash/sending join or leave request, and ending 
when this event is processed. When another event happens, the current ST 
can either be finished or canceled and then *another* ST can begin. 
State transfer is a cluster-wide process, though it cannot be started 
and ended absolutely simultaneously.

Rebalance: one phase of ST, when the data transfer occurs.

Data rehash: this is a bit painful point: we have DataRehashEvent where 
the name suggest that it is related rather to rebalance, but currently 
it fires when CacheTopology.getPendingCH() == null (that means when ST 
is complete), and the event itself also looks more like it should be 
fired at the end of state transfer. If we have something more to do 
after the rebalance, I am not sure how useful is firing that just 
because all data has been transferred (but for example before old data 
has been wiped out). Should I add another StateTransferEvent event (and 
appropriate listeners)? That would break the compatibility with tightly 
related implementations...

WDYT?

Radim

[1] https://issues.jboss.org/browse/ISPN-5021


-- 
Radim Vansa <rvansa at redhat.com>
JBoss Performance Team