ErrEdgeUnavailable indicates failed concurrent edge computation.

ErrEmptyDump indicates an attempt to restore from empty dump.

ErrLogExists indicates a requested log already exists.

ErrLogNotFound indicates a requested log was not found.

ErrThreadExists indicates a thread already exists.

ErrThreadNotFound indicates a requested thread was not found.

AddrBook stores log addresses.

HeadBook stores log heads.

KeyBook stores log keys.

Logstore stores log keys, addresses, heads and thread meta data.

ThreadMetadata stores local thread metadata like name.