[infinispan-dev] Hot Rod partial topology update processing with new segment info - Re: ISPN-4674
Hey Dan,
Re: https://issues.jboss.org/browse/ISPN-4674
If you remember, the topology updates that we send to clients are sometimes partial. This
happens when at the JGroups level we have a new view, but the HR address cache has not yet
been updated with the JGroups address to endpoint address. This logic works well with HR
protocol 1.x.
With HR 2.x, there’s a slight problem with this. The problem is that we now write segment
information in the topology, and when we have this partial set up, calls to
locateOwnersForSegment(), for a partial cluster of 2, it can quite possibly return 2.
The problem comes when the client reads the number of servers, discovers it’s one, but
reading the segment, it says that there’s two owners. That’s where the
ArrayIndexOutOfBoundsException comes from.
The question is: how shall we deal with this segment information in the even of a partial
topology update?
From a client perspective, one option might be to just ignore those
segment positions for which there’s no cluster member. IOW, if the number of owners is
bigger than the cluster view, it could just decide to create a smaller segment array, of
only cluster view size, and then ignore the index of a node that’s not present in the
cluster view.
Would this be the best way to solve it? Or could we just avoid sending segment information
that’s not right? IOW, directly send from the server segment information with all this
filtered.
Thoughts?
Cheers,
--
Galder Zamarreño
galder(a)redhat.com
twitter.com/galderz