// lockAndSyncTime acquires the lock and updates the virtual time.
// Doing them together avoids the mistake of modifying some queue state
// before calling syncTimeLocked.
func (qs *queueSet) lockAndSyncTime(ctx context.Context) {
	qs.lock.Lock()
	qs.syncTimeLocked(ctx)
}

// syncTimeLocked updates the virtual time based on the assumption
// that the current state of the queues has been in effect since