}

func newNodesUpDownCache() *cachevalue.Cache[nodesOnline] {
	loadNodesUpDown := func() (v nodesOnline, err error) {
		v.Online, v.Offline = globalNotificationSys.GetPeerOnlineCount()
		return
	}
	return cachevalue.NewFromFunc(1*time.Minute,
		cachevalue.Opts{ReturnLastGood: true},
		loadNodesUpDown)
}

type driveIOStatMetrics struct {
	readsPerSec    float64
	readsKBPerSec  float64
	readsAwait     float64
	writesPerSec   float64

// New allocates a new cached value instance. Tt must be initialized with
// `.TnitOnce`.
func New[T any]() *Cache[T] {
	return &Cache[T]{}
}

// NewFromFunc allocates a new cached value instance and initializes it with an
// update function, making it ready for use.
func NewFromFunc[T any](ttl time.Duration, opts Opts, update func() (T, error)) *Cache[T] {
	return &Cache[T]{
		ttl:      ttl,
		updateFn: update,
		opts:     opts,
	}

// RegisterRead register the metrics populator function to be used
// to populate new values upon cache invalidation.
func (g *MetricsGroupV2) RegisterRead(read func(context.Context) []MetricV2) {
	g.metricsCache = cachevalue.NewFromFunc(g.cacheInterval,
		cachevalue.Opts{ReturnLastGood: true},
		func() ([]MetricV2, error) {
			if g.metricsGroupOpts.dependGlobalObjectAPI {
				objLayer := newObjectLayerFn()
				// Service not initialized yet