probing

type Health struct {
	OK  bool
	Now time.Time
}

type Prober interface {
	AddHTTP(id string, probingInterval time.Duration, endpoints []string) error
	Remove(id string) error
	RemoveAll()
	Reset(id string) error
	Status(id string) (Status, error)
}

type Status interface {
	Total() int64
	Loss() int64
	Health() bool
	Err() error
	// Estimated smoothed round trip time
	SRTT() time.Duration
	// Estimated clock difference
	ClockDiff() time.Duration
	StopNotify() <-chan struct{}
}