getKeys method
Streams the keys, optionally filtered by regex. The returned
Future completes once the backend has accepted the request —
setup failures (store not open, invalid regex) reject the
Future eagerly rather than surfacing mid-stream; the Stream
then yields the matching keys.
Implementation
@override
Future<Stream<String>> getKeys({String? regex}) async {
// Eager validation: a bad regex rejects the Future, not the Stream.
final re = RegExp(regex ?? '.*');
final now = _nowMillis();
final rows = _db.raw.select(
'SELECT atkey FROM at_data WHERE (available_at IS NULL OR available_at <= ?) '
'AND (expires_at IS NULL OR expires_at > ?);',
[now, now]);
final matched =
rows.map((r) => r['atkey'] as String).where(re.hasMatch).toList();
return Stream.fromIterable(matched);
}