Thanks to this change:
- all the maps bucket -> buffer are indexed by int's instead of
string. No need to do: byte[] -> string -> hash conversion on each
access.
- buckets are strongly typed in backend/mvcc API.
This makes (bbolt) backend a full feature snapshot in term of WAL/raft,
i.e. carries:
- commit : (applied_index)
- confState
Benefits:
- Backend will be a sufficient point in time definition sufficient to
start replaying WAL. We have applied_index & confState in consistent
state.
- In case of emergency a backend state can be used for recovery
correct 'backend' (bbolt) context in aspect of membership.
Prior to this change the 'restored' backend used to still contain:
- old memberid (mvcc deletion used, why the membership is in bolt
bucket, but not mvcc part):
```
mvs := mvcc.NewStore(s.lg, be, lessor, ci, mvcc.StoreConfig{CompactionBatchLimit: math.MaxInt32})
defer mvs.Close()
txn := mvs.Write(traceutil.TODO())
btx := be.BatchTx()
del := func(k, v []byte) error {
txn.DeleteRange(k, nil)
return nil
}
// delete stored members from old cluster since using new members
btx.UnsafeForEach([]byte("members"), del)
```
- didn't get new members added.
