Add stats for GC pauses

histogram.go

@@ -1,9 +1,15 @@
 package main
 
+import (
+	"math"
+)
+
 type Histogram struct {
 	Bins    []Bin
 	Maxbins int
 	Total   uint64
+
+	min, max uint64
 }
 
 type Bin struct {
@@ -16,15 +22,24 @@ type Bin struct {
 // should be sufficient.
 func NewHistogram(n int) *Histogram {
 	return &Histogram{
-		Bins:    make([]Bin, 0),
+		Bins:    make([]Bin, 0, n),
 		Maxbins: n,
-		Total:   0,
+
+		min: math.MaxUint64,
 	}
 }
 
 func (h *Histogram) Add(n uint64) {
-	defer h.trim()
 	h.Total++
+
+	if n > h.max {
+		h.max = n
+	}
+	if n < h.min {
+		h.min = n
+	}
+
+	defer h.trim()
 	for i := range h.Bins {
 		if h.Bins[i].Value == n {
 			h.Bins[i].Count++
@@ -45,17 +60,17 @@ func (h *Histogram) Add(n uint64) {
 	h.Bins = append(h.Bins, Bin{Count: 1, Value: n})
 }
 
-func (h *Histogram) Quantile(q uint64) int64 {
-	count := q * h.Total
+func (h *Histogram) Quantile(q float64) int64 {
+	count := q * float64(h.Total)
 	for i := range h.Bins {
-		count -= h.Bins[i].Count
+		count -= float64(h.Bins[i].Count)
 
 		if count <= 0 {
 			return int64(h.Bins[i].Value)
 		}
 	}
 
-	return -1
+	return 0
 }
 
 // CDF returns the value of the cumulative distribution function
@@ -86,6 +101,24 @@ func (h *Histogram) Mean() float64 {
 	return sum / float64(h.Total)
 }
 
+// Min returns the minimal recorder value.
+func (h *Histogram) Min() uint64 {
+	if h.Total == 0 {
+		return 0
+	}
+
+	return h.min
+}
+
+// Max returns the maximum recorder value.
+func (h *Histogram) Max() uint64 {
+	if h.Total == 0 {
+		return 0
+	}
+
+	return h.max
+}
+
 // Variance returns the variance of the distribution
 func (h *Histogram) Variance() float64 {
 	if h.Total == 0 {

ui_single.go

@@ -15,6 +15,7 @@ type TermUISingle struct {
 	Sparkline  *termui.Sparklines
 	Pars       []*termui.Par
 	BarChart   *termui.BarChart
+	GCStats    *termui.Par
 	BarChart2  *termui.BarChart
 
 	bins int // histograms' bins count
@@ -85,6 +86,14 @@ func (t *TermUISingle) Init(data UIData) error {
 			bc.NumColor = termui.ColorBlack
 			return bc
 		}()
+		t.GCStats = func() *termui.Par {
+			p := termui.NewPar("")
+			p.Height = 4
+			p.Width = len("Max: 123ms") // example
+			p.HasBorder = false
+			p.TextFgColor = termui.ColorGreen
+			return p
+		}()
 	}
 
 	if data.HasGCIntervals {
@@ -150,13 +159,19 @@ func (t *TermUISingle) Update(data UIData) {
 		labels := make([]string, 0, len(counts))
 		for i := 0; i < len(counts); i++ {
 			vals = append(vals, int(counts[i]))
-			d := roundDuration(time.Duration(values[i]))
+			d := round(time.Duration(values[i]))
 			labels = append(labels, d.String())
 		}
 		t.BarChart.Data = vals
 		t.BarChart.DataLabels = labels
 		t.BarChart.Border.Label = "GC Pauses (last 256)"
 
+		t.GCStats.Text = fmt.Sprintf("Min: %v\nAvg: %v\n95p: %v\nMax: %v",
+			round(time.Duration(hist.Min())),
+			round(time.Duration(hist.Mean())),
+			round(time.Duration(hist.Quantile(0.95))),
+			round(time.Duration(hist.Max())),
+		)
 	}
 
 	if data.HasGCIntervals {
@@ -173,7 +188,7 @@ func (t *TermUISingle) Update(data UIData) {
 		labels := make([]string, 0, len(counts))
 		for i := 0; i < len(counts); i++ {
 			vals = append(vals, int(counts[i]))
-			d := roundDuration(time.Duration(values[i]))
+			d := round(time.Duration(values[i]))
 			labels = append(labels, d.String())
 		}
 		t.BarChart2.Data = vals
@@ -186,7 +201,7 @@ func (t *TermUISingle) Update(data UIData) {
 	var widgets []termui.Bufferer
 	widgets = append(widgets, t.Title, t.Status, t.Sparkline)
 	if data.HasGCPauses {
-		widgets = append(widgets, t.BarChart)
+		widgets = append(widgets, t.BarChart, t.GCStats)
 	}
 	if data.HasGCIntervals {
 		widgets = append(widgets, t.BarChart2)
@@ -263,6 +278,9 @@ func (t *TermUISingle) Relayout() {
 			t.BarChart.Height = h - calcHeight
 			t.BarChart.Y = th - t.BarChart.Height
 			t.BarChart.BarWidth = binWidth
+
+			t.GCStats.X = barchartWidth - t.GCStats.Width - 1
+			t.GCStats.Y = t.BarChart.Y + 1
 		}
 
 		if t.BarChart2 != nil {

var.go

@@ -129,7 +129,7 @@ type Duration struct {
 
 func (v *Duration) Kind() VarKind { return KindDuration }
 func (v *Duration) String() string {
-	return fmt.Sprintf("%s", roundDuration(time.Duration(v.dur)))
+	return fmt.Sprintf("%s", round(time.Duration(v.dur)))
 }
 
 func (v *Duration) Set(j *jason.Value) {
@@ -331,8 +331,8 @@ func (v VarName) Kind() VarKind {
 	return KindDefault
 }
 
-// roundDuration removes unneeded precision from the String() output for time.Duration.
-func roundDuration(d time.Duration) time.Duration {
+// round removes unneeded precision from the String() output for time.Duration.
+func round(d time.Duration) time.Duration {
 	r := time.Second
 	if d < time.Second {
 		r = time.Millisecond