The GC procedure consists of two tiers: lookahead and purge. The
lookahead tier runs less frequently (default 12 hours) than the purge
tier (default 5 minutes).
A lookahead round traverses the entire store and picks entries that
need to be visited in the current lookahead window, pinning those
entries in a separate region in the KV store, indexed by the next visit
timestamp.
A purge round iterates over the lookahead window only, and refreshes
the entries that require a visit. It removes them from the lookahead
region unless the entry requires another visit within the current
window.
Each entry in the address book KV store now represents a full peer
with all its addresses. Expiries and TTLs are kept inline. Records are
serialised with Protobuf.
Housekeeping is performed on retrieve, and via a periodic GC routine.
The architecture mimics a write-through cache, although not strictly.
