tick method
void
tick()
Scans the registry once, reporting any timed-out nodes.
Implementation
void tick() {
final now = clock.now();
final expired = <RegisteredNode>[];
for (final node in registry.all) {
if (now.difference(node.lastSeen) > timeout) {
expired.add(node);
}
}
for (final node in expired) {
onTimeout(node);
}
}