refactor: rename UpdateInstanceRequest -> update_instance::Request, UpdateInstanceResponse -> update_instance::Response

Use direct structure names instead of aliases for better IDE code surfing

Use direct structure names instead of aliases
for better IDE code surfing

1

Georgy Moshkin authored 2 years ago and Yaroslav Dynnikov committed 2 years ago

Originally it was meant to be a key for distinguishing outdated peer
info. But this was never actually fully implemented. Now that we have
the governor and it's synchronizing mechanism there's even less point
to this field. And now that this legacy code impedes refactoring, we
remove it at least until we have a better idea of how to implement it.

Also prefix stored procedures names `raft_join` and `raft_interact`

When instance runs `postjoin` function, it's supposed to have both
target and current grade Offline. Taking a read barrier in that state
makes no sence. Instead, an instance should set target grade online
asap. Ensuring it syncs is the responsibility of the governor.

Excessive read barrier affects `restart_both` test. One of the instances
(i1 who becomes a follower) sends a `read_index` request to i2 (leader).
But i2 reveals  `self.commit_to_current_term()` condition isn't met and
drops the request. As a result, i1 is obliged to wait for 10s timeout
before retrying `read_index` request again, but the test timeouts even
sooner.