Official RaftLogStore implementation

[akiradeveloper]

Implementing RaftLogStore needs some work. How about providing an official referential implementation?

In that case, what is the suitable backend? sled? redb? lmdb? or rocksdb?

[akiradeveloper]

Or, do we develop another database which focuses on being a Raft log.

Raft log rarely needs random write or random read: the write and read happens sequentially. Under this special condition, we can create more efficient database for sure.

[akiradeveloper]

redb doesn't have namespace so it doesn't allow us to separate log for each lane-id.

sled has Tree (https://docs.rs/sled/latest/sled/struct.Db.html#method.open_tree) which looks like namespace.

[akiradeveloper]

or sqlite perhaps