cpu idle updaters

cpuidle.go

func (broker *Broker) updateCPUIdle() {
	select {
	case broker.cpuUpdateChannel <- true:
	default:
	}
}

func (broker *Broker) cpuIdleUpdater() {
	// Initial values required to get stats
	minPeriod := 20 * time.Millisecond
	idle, total := getCPUSample()
	broker.idleJiffies = idle
	broker.totalJiffies = total
	broker.updatedJiffies = time.Now()
	for {
		<-broker.cpuUpdateChannel
		now := time.Now()
		if broker.updatedJiffies.Add(minPeriod).After(now) {
			continue
		}
		idle, total := getCPUSample()
		if total == broker.totalJiffies {
			continue
		}
		alpha := math.Min(1, 0.5*float64(now.Sub(broker.updatedJiffies)/time.Millisecond)/1000)
		broker.CPUIdle = float64(idle-broker.idleJiffies) / float64(total-broker.totalJiffies)
		broker.CPUIdleAvg = (1-alpha)*broker.CPUIdleAvg + alpha*broker.CPUIdle
		broker.idleJiffies = idle
		broker.totalJiffies = total
		broker.updatedJiffies = now
		// Don't update CPU so frequently, waiting here make updateCPUIdle fails to write
		time.Sleep(minPeriod)
	}
}