- Eliminate a couple of ancient TODOs. Extend the test.
- Fix `ConnectionPool::send` docstring appropriately.
- Tweak timeouts in test because it used to fail on my machine.

NOTE: there's still a bug, because we set each new replicaset's weight
to 1 (even ones which don't satisfy replication factor)
before the bucket distribution is bootstrapped. But there must be at
least one replicaset with non zero weight in order for vshard.*.cfg to
work.

A potential solution would be to only configure vshard once a replicaset
is filled up.

Async callbacks support is very poor in rust, so using a macro is one of
the few ways to have somewhat friendly code.

The code inside process_topology_request_async has become too complex
therefore TopologyRequest has lost its utility

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Originally it was meant to be a key for distinguishing outdated peer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.