revalidate method
Refetches every watched, settled query that is not already in flight,
and returns how many it started. With onlyStale true (the default) only
queries that aged past their staleTime are refetched. Driven by the
freshness installers.
Implementation
int revalidate({bool onlyStale = true}) {
var started = 0;
for (final record in _records.values.toList()) {
if (record.listeners.isEmpty || !record.settled) continue;
if (record.inflight != null) continue;
if (onlyStale && !_expired(record)) continue;
_detach(_start(record));
started++;
}
return started;
}