[Tarantool-patches] [PATCH 1/2] replication: introduce ballot.can_be_leader

[Konstantin Osipov]

* Vladislav Shpilevoy via Tarantool-patches <tarantool-patches at dev.tarantool.org> [21/07/16 11:23]:
> The flag tells whether the sender has election mode 'candidate' or
> 'manual'.
> 
> The new field during bootstrap will help to avoid selecting a
> 'voter' as a master. Voters can't write, they are unable to boot
> themselves nor register others.
> 
> @TarantoolBot document
> Title: New field - IPROTO_BALLOT_CAN_BE_LEADER
> It is sent as a part of `IPROTO_BALLOT (0x29)`. The field is a
> boolean flag which is true if the sender has `election_mode` in
> its config `'manual'` or `'candidate'`.
> 
> During bootstrap the nodes able to become a leader are preferred
> over the nodes configured as `'voter'`.

Curious why did you add this feature in the first place, I mean
"eligibility"? Each voter has to be able to become a leader,
otherwise raft liveness guarantees are violated. Raft has
learners, but learners neither vote nor can become leaders.


-- 
Konstantin Osipov, Moscow, Russia