Now we assume instance may not respond if
- target state is Offline (non-graceful assumed)
- current state is Expelled

Up to this patch `instance_uuid` and `replicaset_uuid` were generated
using name-based UUID v3. So all instances named `i1` in all clusters
had the same UUID.

With this patch UUIDs become random v4. Particular UUID values are
generated in two locations:

1. `start_boot` (src/lib.rs)
2. `handle_join_request_and_wait` -> `build_instance` (src/rpc/join.rs)

Function `Instance::new()` is removed in favor of explicit struct
construction.

The main purpose is to reduce the usage of `Instance::new()` function.
It's going to be removed soon. No behavior changes are introduced yet.

Move vshard related fields from _pico_property to _pico_tier
and adapt it in governor algorithm

Closes #875

It's called proc_update_instance, not proc_replace_instance, duh!

Before this change we would silently replace an instance with current
grade not Online if a new instance with the same name wanted to join.
This was a mistake as it would allow a race condition when joining
several instances at once.

- Now we explicitly store the current & target vshard configuration in
  global storage

Transferred replication factor from Properties table to new Tier table

Instance and Replicaset belongs to tier via new field tier in _pico_instance and _pico_replicaset

New cli option init-cfg with path to configuration file in yaml format. For now contains only info about tiers.

Also fix some fresh clippy warnings

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

Also make `Default` trait implementation for `struct Instance` public.
Because keeping it private makes no sence for a public struct with
public fields.