Fix duplicated tags in InfluxDB

vendor/github.com/go-kit/kit/metrics/timer.go

@@ -7,6 +7,7 @@ import "time"
 type Timer struct {
 	h Histogram
 	t time.Time
+	u time.Duration
 }
 
 // NewTimer wraps the given histogram and records the current time.
@@ -14,15 +15,22 @@ func NewTimer(h Histogram) *Timer {
 	return &Timer{
 		h: h,
 		t: time.Now(),
+		u: time.Second,
 	}
 }
 
 // ObserveDuration captures the number of seconds since the timer was
 // constructed, and forwards that observation to the histogram.
 func (t *Timer) ObserveDuration() {
-	d := time.Since(t.t).Seconds()
+	d := float64(time.Since(t.t).Nanoseconds()) / float64(t.u)
 	if d < 0 {
 		d = 0
 	}
 	t.h.Observe(d)
 }
+
+// Unit sets the unit of the float64 emitted by the timer.
+// By default, the timer emits seconds.
+func (t *Timer) Unit(u time.Duration) {
+	t.u = u
+}