feat(instrumentation): lots of refactoring to support tag based backend, #4696

pkg/metrics/timer.go

@@ -3,21 +3,33 @@ package metrics
 //import "sync/atomic"
 
 type Timer interface {
+	Metric
+
 	AddTiming(int64)
-	Clear()
 	Avg() int64
 	Min() int64
 	Max() int64
-	Total() int64
+	Count() int64
 }
 
-func NewTimer() Timer {
+type StandardTimer struct {
+	*MetricMeta
+
+	total int64
+	count int64
+	avg   int64
+	min   int64
+	max   int64
+}
+
+func NewTimer(meta *MetricMeta) Timer {
 	return &StandardTimer{
-		avg:   0,
-		min:   0,
-		max:   0,
-		total: 0,
-		count: 0,
+		MetricMeta: meta,
+		avg:        0,
+		min:        0,
+		max:        0,
+		total:      0,
+		count:      0,
 	}
 }
 
@@ -56,14 +68,17 @@ func (this *StandardTimer) Max() int64 {
 	return this.max
 }
 
-func (this *StandardTimer) Total() int64 {
-	return this.total
+func (this *StandardTimer) Count() int64 {
+	return this.count
 }
 
-type StandardTimer struct {
-	total int64
-	count int64
-	avg   int64
-	min   int64
-	max   int64
+func (this *StandardTimer) Snapshot() Metric {
+	return &StandardTimer{
+		MetricMeta: this.MetricMeta,
+		avg:        this.avg,
+		min:        this.min,
+		max:        this.max,
+		total:      this.total,
+		count:      this.count,
+	}
 }