feat(utils): add time statistics tracker

cmd/xtrellis/utils/utils.go

@@ -30,3 +30,43 @@ func DebugLog(format string, args ...interface{}) {
 	s2 := fmt.Sprintf(format, args...)
 	log.Printf("%s %s", s1, s2)
 }
+
+// Time statistics tracker
+type TimeStats struct {
+	Avg   float64
+	Last  float64
+	Max   float64
+	Min   float64
+	Total float64
+
+	times []float64
+}
+
+func NewTimeStats() *TimeStats {
+	return &TimeStats{}
+}
+
+func (ts *TimeStats) RecordTime(time float64) {
+	init := len(ts.times) == 0
+
+	if init || time < ts.Min {
+		ts.Min = time
+	}
+
+	if init || time > ts.Max {
+		ts.Max = time
+	}
+
+	ts.Last = time
+
+	ts.Total += time
+
+	ts.times = append(ts.times, time)
+
+	ts.Avg = ts.Total / float64(len(ts.times))
+}
+
+func (ts *TimeStats) GetStatsString() string {
+	var ms float64 = 1000000
+	return fmt.Sprintf("last/min/avg/max = %.2f / %.2f / %.2f / %.2f ms", ts.Last/ms, ts.Min/ms, ts.Avg/ms, ts.Max/ms)
+}