[Tarantool-patches] [PATCH] Trigger on vclock change

[Georgy Kirichenko]

On Thursday, November 14, 2019 10:48:06 PM MSK Konstantin Osipov wrote:
> * Georgy Kirichenko <georgy at tarantool.org> [19/11/14 22:42]:
> > A replica state is described by 2 vclocks - written and committed ones.
> > Right now it is not an issue to report them both as an applier submits
> > transaction asynchronously. In addition to these two vclocks (yes, the
> > both could be transferred from the WAL thread) applier will report a
> > reject vclock - the vclock where applying breaks, and this could be done
> > from TX. I do not like the idea to split transmission between 2 threads.
> > The write and reject vclocks are used to evaluate majority whereas commit
> > vclock instructs a whole cluster that majority was already reached. The
> > main point is that any replica member could commit a transaction - this
> > relaxes RAFT limitations and increases the whole cluster durability (and
> > it is simpler in design and implementation, really). Also the new
> > synchronous replication design has a lot of advantages in comparison with
> > RAFT but let us discuss it in another thread. If you interested please
> > ask for details as I have not enough time to write public document right
> > now.
> > Returning to the subject, I would like to conclude that wal on_commit and
> > on_write triggers are good source to initiate status transmission. And the
> > trigger implemented by Maria will be replaced by replica on_commit which
> > allows us not to change anything at higher levels.
> 
> Congratulations, Georgy, maybe you even get a Turing award for
> inventing a new protocol.
> 
> Wait... they don't give a Turing award for "protocols" which have
> no proof and yield inconsistent results, or do they?
You do not even know details of the protocol but make such suggestion, so I 
could only repeat your last statement: "what a shame", seriously.
Please, remember all my attempts to discuss it with you or, for instance, our 
one-per-2-week meetings which all (except the first one) were skipped by you.
> 
> Meanwhile, if you have a design in mind, you could send an RFC. I
> will respond to the RFC.
Anybody could see the design document after this protocol research will be 
done. Yes, the research requires to be implemented first.
> 
> PS What a shame...