if len(peerClients) == 0 {
		return nil
	}
	idx := xxhash.Sum64String(s) % uint64(len(peerClients))
	return peerClients[idx]
}

// GetPeerOnlineCount gets the count of online and offline nodes.
func (sys *NotificationSys) GetPeerOnlineCount() (nodesOnline, nodesOffline int) {
	nodesOnline = 1 // Self is always online.
	nodesOffline = 0
	nodesOnlineIndex := make([]bool, len(sys.peerClients))

		metricsGroupOpts: opts,
	}
	mg.RegisterRead(func(_ context.Context) (metrics []MetricV2) {
		metrics = make([]MetricV2, 0, 16)
		nodesUp, nodesDown := globalNotificationSys.GetPeerOnlineCount()
		metrics = append(metrics, MetricV2{
			Description: getNodeOnlineTotalMD(),
			Value:       float64(nodesUp),
		})
		metrics = append(metrics, MetricV2{
			Description: getNodeOfflineTotalMD(),