From 6b3a4f7ef3297a4de3366d1bca376e21f699e773 Mon Sep 17 00:00:00 2001
From: Tyler Yahn <codingalias@gmail.com>
Date: Mon, 24 Jul 2023 11:20:50 -0700
Subject: [PATCH] Revert to having a valueMap

---
 sdk/metric/internal/aggregate/sum.go | 74 ++++++++++++++--------------
 1 file changed, 38 insertions(+), 36 deletions(-)

diff --git a/sdk/metric/internal/aggregate/sum.go b/sdk/metric/internal/aggregate/sum.go
index 2c1ee50e468..cbcaf6967ac 100644
--- a/sdk/metric/internal/aggregate/sum.go
+++ b/sdk/metric/internal/aggregate/sum.go
@@ -23,28 +23,37 @@ import (
 	"go.opentelemetry.io/otel/sdk/metric/metricdata"
 )
 
+// valueMap is the storage for sums.
+type valueMap[N int64 | float64] struct {
+	sync.Mutex
+	values map[attribute.Set]N
+}
+
+func newValueMap[N int64 | float64]() *valueMap[N] {
+	return &valueMap[N]{values: make(map[attribute.Set]N)}
+}
+
+func (s *valueMap[N]) measure(_ context.Context, value N, attr attribute.Set) {
+	s.Lock()
+	s.values[attr] += value
+	s.Unlock()
+}
+
 // newSum returns an aggregator that summarizes a set of measurements as their
 // arithmetic sum. Each sum is scoped by attributes and the aggregation cycle
 // the measurements were made in.
 func newSum[N int64 | float64]() *sum[N] {
 	return &sum[N]{
-		values: make(map[attribute.Set]N),
-		start:  now(),
+		valueMap: newValueMap[N](),
+		start:    now(),
 	}
 }
 
 // sum summarizes a set of measurements made as their arithmetic sum.
 type sum[N int64 | float64] struct {
-	sync.Mutex
+	*valueMap[N]
 
-	values map[attribute.Set]N
-	start  time.Time
-}
-
-func (s *sum[N]) measure(ctx context.Context, value N, attr attribute.Set) {
-	s.Lock()
-	s.values[attr] += value
-	s.Unlock()
+	start time.Time
 }
 
 func (s *sum[N]) delta(dest *[]metricdata.DataPoint[N]) {
@@ -57,11 +66,11 @@ func (s *sum[N]) delta(dest *[]metricdata.DataPoint[N]) {
 	*dest = reset(*dest, n, n)
 
 	var i int
-	for a, val := range s.values {
+	for a, value := range s.values {
 		(*dest)[i].Attributes = a
 		(*dest)[i].StartTime = s.start
 		(*dest)[i].Time = t
-		(*dest)[i].Value = val
+		(*dest)[i].Value = value
 		// Do not report stale values.
 		delete(s.values, a)
 		i++
@@ -80,11 +89,11 @@ func (s *sum[N]) cumulative(dest *[]metricdata.DataPoint[N]) {
 	*dest = reset(*dest, n, n)
 
 	var i int
-	for a, val := range s.values {
-		(*dest)[i].Attributes = a
+	for attr, value := range s.values {
+		(*dest)[i].Attributes = attr
 		(*dest)[i].StartTime = s.start
 		(*dest)[i].Time = t
-		(*dest)[i].Value = val
+		(*dest)[i].Value = value
 		// TODO (#3006): This will use an unbounded amount of memory if there
 		// are unbounded number of attribute sets being aggregated. Attribute
 		// sets that become "stale" need to be forgotten so this will not
@@ -98,26 +107,19 @@ func (s *sum[N]) cumulative(dest *[]metricdata.DataPoint[N]) {
 // the aggregation cycle the measurements were made in.
 func newPrecomputedSum[N int64 | float64]() *precomputedSum[N] {
 	return &precomputedSum[N]{
-		values: make(map[attribute.Set]N),
-		start:  now(),
+		valueMap: newValueMap[N](),
+		start:    now(),
 	}
 }
 
 // precomputedSum summarizes a set of observatrions as their arithmetic sum.
 type precomputedSum[N int64 | float64] struct {
-	sync.Mutex
+	*valueMap[N]
 
-	values   map[attribute.Set]N
 	reported map[attribute.Set]N
 	start    time.Time
 }
 
-func (s *precomputedSum[N]) measure(ctx context.Context, value N, attr attribute.Set) {
-	s.Lock()
-	s.values[attr] += value
-	s.Unlock()
-}
-
 func (s *precomputedSum[N]) delta(dest *[]metricdata.DataPoint[N]) {
 	t := now()
 	newReported := make(map[attribute.Set]N)
@@ -129,17 +131,17 @@ func (s *precomputedSum[N]) delta(dest *[]metricdata.DataPoint[N]) {
 	*dest = reset(*dest, n, n)
 
 	var i int
-	for a, val := range s.values {
-		delta := val - s.reported[a]
+	for attr, value := range s.values {
+		delta := value - s.reported[attr]
 
-		(*dest)[i].Attributes = a
+		(*dest)[i].Attributes = attr
 		(*dest)[i].StartTime = s.start
 		(*dest)[i].Time = t
 		(*dest)[i].Value = delta
 
-		newReported[a] = val
+		newReported[attr] = value
 		// Unused attribute sets do not report.
-		delete(s.values, a)
+		delete(s.values, attr)
 		i++
 	}
 	// Unused attribute sets are forgotten.
@@ -158,14 +160,14 @@ func (s *precomputedSum[N]) cumulative(dest *[]metricdata.DataPoint[N]) {
 	*dest = reset(*dest, n, n)
 
 	var i int
-	for a, val := range s.values {
-		(*dest)[i].Attributes = a
+	for attr, value := range s.values {
+		(*dest)[i].Attributes = attr
 		(*dest)[i].StartTime = s.start
 		(*dest)[i].Time = t
-		(*dest)[i].Value = val
-		s.values[a] = val
+		(*dest)[i].Value = value
+		s.values[attr] = value
 		// Unused attribute sets do not report.
-		delete(s.values, a)
+		delete(s.values, attr)
 		i++
 	}
 }