Update gopsutil code

Latest gosutil includes two backward incompatible changes:

First, it removed unused Stolen field in
shirou/gopsutil@cae8efc#diff-d9747e2da342bdb995f6389533ad1a3d
.

Second, it updated the Windows cpu stats calculation to be inline with
other platforms, where it returns absolate stats rather than
percentages.  See shirou/gopsutil#611.

client/stats/cpu.go

@@ -1,61 +1,34 @@
 package stats
 
 import (
-	"runtime"
-	"time"
-
 	shelpers "github.com/hashicorp/nomad/helper/stats"
+	"github.com/shirou/gopsutil/cpu"
 )
 
-// CpuStats calculates cpu usage percentage
-type CpuStats struct {
-	prevCpuTime float64
-	prevTime    time.Time
-
-	totalCpus int
-}
-
-// NewCpuStats returns a cpu stats calculator
-func NewCpuStats() *CpuStats {
-	numCpus := runtime.NumCPU()
-	cpuStats := &CpuStats{
-		totalCpus: numCpus,
-	}
-	return cpuStats
-}
-
-// Percent calculates the cpu usage percentage based on the current cpu usage
-// and the previous cpu usage where usage is given as time in nanoseconds spend
-// in the cpu
-func (c *CpuStats) Percent(cpuTime float64) float64 {
-	now := time.Now()
+func (h *HostStatsCollector) collectCPUStats() (cpus []*CPUStats, totalTicks float64, err error) {
 
-	if c.prevCpuTime == 0.0 {
-		// invoked first time
-		c.prevCpuTime = cpuTime
-		c.prevTime = now
-		return 0.0
+	ticksConsumed := 0.0
+	cpuStats, err := cpu.Times(true)
+	if err != nil {
+		return nil, 0.0, err
 	}
-
-	timeDelta := now.Sub(c.prevTime).Nanoseconds()
-	ret := c.calculatePercent(c.prevCpuTime, cpuTime, timeDelta)
-	c.prevCpuTime = cpuTime
-	c.prevTime = now
-	return ret
-}
-
-// TicksConsumed calculates the total ticks consumes by the process across all
-// cpu cores
-func (c *CpuStats) TicksConsumed(percent float64) float64 {
-	return (percent / 100) * shelpers.TotalTicksAvailable() / float64(c.totalCpus)
-}
-
-func (c *CpuStats) calculatePercent(t1, t2 float64, timeDelta int64) float64 {
-	vDelta := t2 - t1
-	if timeDelta <= 0 || vDelta <= 0.0 {
-		return 0.0
+	cs := make([]*CPUStats, len(cpuStats))
+	for idx, cpuStat := range cpuStats {
+		percentCalculator, ok := h.statsCalculator[cpuStat.CPU]
+		if !ok {
+			percentCalculator = NewHostCpuStatsCalculator()
+			h.statsCalculator[cpuStat.CPU] = percentCalculator
+		}
+		idle, user, system, total := percentCalculator.Calculate(cpuStat)
+		cs[idx] = &CPUStats{
+			CPU:    cpuStat.CPU,
+			User:   user,
+			System: system,
+			Idle:   idle,
+			Total:  total,
+		}
+		ticksConsumed += (total / 100.0) * (shelpers.TotalTicksAvailable() / float64(len(cpuStats)))
 	}
 
-	overall_percent := (vDelta / float64(timeDelta)) * 100.0
-	return overall_percent
+	return cs, ticksConsumed, nil
 }

client/stats/host.go

@@ -275,7 +275,7 @@ func (h *HostCpuStatsCalculator) Calculate(times cpu.TimesStat) (idle float64, u
 	currentSystem := times.System
 	currentTotal := times.Total()
 	currentBusy := times.User + times.System + times.Nice + times.Iowait + times.Irq +
-		times.Softirq + times.Steal + times.Guest + times.GuestNice + times.Stolen
+		times.Softirq + times.Steal + times.Guest + times.GuestNice
 
 	deltaTotal := currentTotal - h.prevTotal
 	idle = ((currentIdle - h.prevIdle) / deltaTotal) * 100