Update Histogram Extrema and Sum to be generic (#3870)

* Update Histogram Extrema and Sum to be generic

* Update metric SDK

* Update exporters

* Add changes to changelog

CHANGELOG.md

@@ -10,6 +10,7 @@ This project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.htm
 
 ### Changed
 
+- The `Extrema` in `go.opentelemetry.io/otel/sdk/metric/metricdata` is redefined with a generic argument of `[N int64 | float64]`. (#3870)
 - Move No-Op implementation from `go.opentelemetry.io/otel/metric` into its own package `go.opentelemetry.io/otel/metric/noop`. (#3941)
   - `metric.NewNoopMeterProvider` is replaced with `noop.NewMeterProvider`
 

exporters/otlp/otlpmetric/internal/transform/metricdata.go

@@ -175,7 +175,7 @@ func Histogram[N int64 | float64](h metricdata.Histogram[N]) (*mpb.Metric_Histog
 func HistogramDataPoints[N int64 | float64](dPts []metricdata.HistogramDataPoint[N]) []*mpb.HistogramDataPoint {
 	out := make([]*mpb.HistogramDataPoint, 0, len(dPts))
 	for _, dPt := range dPts {
-		sum := dPt.Sum
+		sum := float64(dPt.Sum)
 		hdp := &mpb.HistogramDataPoint{
 			Attributes:        AttrIter(dPt.Attributes.Iter()),
 			StartTimeUnixNano: uint64(dPt.StartTime.UnixNano()),
@@ -186,10 +186,12 @@ func HistogramDataPoints[N int64 | float64](dPts []metricdata.HistogramDataPoint
 			ExplicitBounds:    dPt.Bounds,
 		}
 		if v, ok := dPt.Min.Value(); ok {
-			hdp.Min = &v
+			vF64 := float64(v)
+			hdp.Min = &vF64
 		}
 		if v, ok := dPt.Max.Value(); ok {
-			hdp.Max = &v
+			vF64 := float64(v)
+			hdp.Max = &vF64
 		}
 		out = append(out, hdp)
 	}

exporters/otlp/otlpmetric/internal/transform/metricdata_test.go

@@ -59,19 +59,19 @@ var (
 		Count:        30,
 		Bounds:       []float64{1, 5},
 		BucketCounts: []uint64{0, 30, 0},
-		Min:          metricdata.NewExtrema(minA),
-		Max:          metricdata.NewExtrema(maxA),
-		Sum:          sumA,
+		Min:          metricdata.NewExtrema(int64(minA)),
+		Max:          metricdata.NewExtrema(int64(maxA)),
+		Sum:          int64(sumA),
 	}, {
 		Attributes:   bob,
 		StartTime:    start,
 		Time:         end,
 		Count:        3,
 		Bounds:       []float64{1, 5},
 		BucketCounts: []uint64{0, 1, 2},
-		Min:          metricdata.NewExtrema(minB),
-		Max:          metricdata.NewExtrema(maxB),
-		Sum:          sumB,
+		Min:          metricdata.NewExtrema(int64(minB)),
+		Max:          metricdata.NewExtrema(int64(maxB)),
+		Sum:          int64(sumB),
 	}}
 	otelHDPFloat64 = []metricdata.HistogramDataPoint[float64]{{
 		Attributes:   alice,

exporters/prometheus/exporter.go

@@ -193,7 +193,7 @@ func addHistogramMetric[N int64 | float64](ch chan<- prometheus.Metric, histogra
 			cumulativeCount += dp.BucketCounts[i]
 			buckets[bound] = cumulativeCount
 		}
-		m, err := prometheus.NewConstHistogram(desc, dp.Count, dp.Sum, buckets, values...)
+		m, err := prometheus.NewConstHistogram(desc, dp.Count, float64(dp.Sum), buckets, values...)
 		if err != nil {
 			otel.Handle(err)
 			continue

sdk/metric/internal/aggregator_test.go

@@ -38,9 +38,6 @@ var (
 	bob   = attribute.NewSet(attribute.String("user", "bob"), attribute.Bool("admin", false))
 	carol = attribute.NewSet(attribute.String("user", "carol"), attribute.Bool("admin", false))
 
-	monoIncr    = setMap{alice: 1, bob: 10, carol: 2}
-	nonMonoIncr = setMap{alice: 1, bob: -1, carol: 2}
-
 	// Sat Jan 01 2000 00:00:00 GMT+0000.
 	staticTime    = time.Unix(946684800, 0)
 	staticNowFunc = func() time.Time { return staticTime }
@@ -52,8 +49,16 @@ var (
 	}
 )
 
+func monoIncr[N int64 | float64]() setMap[N] {
+	return setMap[N]{alice: 1, bob: 10, carol: 2}
+}
+
+func nonMonoIncr[N int64 | float64]() setMap[N] {
+	return setMap[N]{alice: 1, bob: -1, carol: 2}
+}
+
 // setMap maps attribute sets to a number.
-type setMap map[attribute.Set]int
+type setMap[N int64 | float64] map[attribute.Set]N
 
 // expectFunc is a function that returns an Aggregation of expected values for
 // a cycle that contains m measurements (total across all goroutines). Each
@@ -79,7 +84,7 @@ type aggregatorTester[N int64 | float64] struct {
 	CycleN int
 }
 
-func (at *aggregatorTester[N]) Run(a Aggregator[N], incr setMap, eFunc expectFunc) func(*testing.T) {
+func (at *aggregatorTester[N]) Run(a Aggregator[N], incr setMap[N], eFunc expectFunc) func(*testing.T) {
 	m := at.MeasurementN * at.GoroutineN
 	return func(t *testing.T) {
 		t.Run("Comparable", func(t *testing.T) {

sdk/metric/internal/histogram.go

@@ -24,19 +24,19 @@ import (
 	"go.opentelemetry.io/otel/sdk/metric/metricdata"
 )
 
-type buckets struct {
+type buckets[N int64 | float64] struct {
 	counts   []uint64
 	count    uint64
-	sum      float64
-	min, max float64
+	sum      N
+	min, max N
 }
 
 // newBuckets returns buckets with n bins.
-func newBuckets(n int) *buckets {
-	return &buckets{counts: make([]uint64, n)}
+func newBuckets[N int64 | float64](n int) *buckets[N] {
+	return &buckets[N]{counts: make([]uint64, n)}
 }
 
-func (b *buckets) bin(idx int, value float64) {
+func (b *buckets[N]) bin(idx int, value N) {
 	b.counts[idx]++
 	b.count++
 	b.sum += value
@@ -52,7 +52,7 @@ func (b *buckets) bin(idx int, value float64) {
 type histValues[N int64 | float64] struct {
 	bounds []float64
 
-	values   map[attribute.Set]*buckets
+	values   map[attribute.Set]*buckets[N]
 	valuesMu sync.Mutex
 }
 
@@ -66,24 +66,19 @@ func newHistValues[N int64 | float64](bounds []float64) *histValues[N] {
 	sort.Float64s(b)
 	return &histValues[N]{
 		bounds: b,
-		values: make(map[attribute.Set]*buckets),
+		values: make(map[attribute.Set]*buckets[N]),
 	}
 }
 
 // Aggregate records the measurement value, scoped by attr, and aggregates it
 // into a histogram.
 func (s *histValues[N]) Aggregate(value N, attr attribute.Set) {
-	// Accept all types to satisfy the Aggregator interface. However, since
-	// the Aggregation produced by this Aggregator is only float64, convert
-	// here to only use this type.
-	v := float64(value)
-
 	// This search will return an index in the range [0, len(s.bounds)], where
 	// it will return len(s.bounds) if value is greater than the last element
 	// of s.bounds. This aligns with the buckets in that the length of buckets
 	// is len(s.bounds)+1, with the last bucket representing:
 	// (s.bounds[len(s.bounds)-1], +∞).
-	idx := sort.SearchFloat64s(s.bounds, v)
+	idx := sort.SearchFloat64s(s.bounds, float64(value))
 
 	s.valuesMu.Lock()
 	defer s.valuesMu.Unlock()
@@ -97,12 +92,12 @@ func (s *histValues[N]) Aggregate(value N, attr attribute.Set) {
 		// Then,
 		//
 		//   buckets = (-∞, 0], (0, 5.0], (5.0, 10.0], (10.0, +∞)
-		b = newBuckets(len(s.bounds) + 1)
+		b = newBuckets[N](len(s.bounds) + 1)
 		// Ensure min and max are recorded values (not zero), for new buckets.
-		b.min, b.max = v, v
+		b.min, b.max = value, value
 		s.values[attr] = b
 	}
-	b.bin(idx, v)
+	b.bin(idx, value)
 }
 
 // NewDeltaHistogram returns an Aggregator that summarizes a set of

sdk/metric/internal/histogram_test.go

@@ -48,41 +48,41 @@ func testHistogram[N int64 | float64](t *testing.T) {
 		CycleN:       defaultCycles,
 	}
 
-	incr := monoIncr
+	incr := monoIncr[N]()
 	eFunc := deltaHistExpecter[N](incr)
 	t.Run("Delta", tester.Run(NewDeltaHistogram[N](histConf), incr, eFunc))
 	eFunc = cumuHistExpecter[N](incr)
 	t.Run("Cumulative", tester.Run(NewCumulativeHistogram[N](histConf), incr, eFunc))
 }
 
-func deltaHistExpecter[N int64 | float64](incr setMap) expectFunc {
+func deltaHistExpecter[N int64 | float64](incr setMap[N]) expectFunc {
 	h := metricdata.Histogram[N]{Temporality: metricdata.DeltaTemporality}
 	return func(m int) metricdata.Aggregation {
 		h.DataPoints = make([]metricdata.HistogramDataPoint[N], 0, len(incr))
 		for a, v := range incr {
-			h.DataPoints = append(h.DataPoints, hPoint[N](a, float64(v), uint64(m)))
+			h.DataPoints = append(h.DataPoints, hPoint[N](a, v, uint64(m)))
 		}
 		return h
 	}
 }
 
-func cumuHistExpecter[N int64 | float64](incr setMap) expectFunc {
+func cumuHistExpecter[N int64 | float64](incr setMap[N]) expectFunc {
 	var cycle int
 	h := metricdata.Histogram[N]{Temporality: metricdata.CumulativeTemporality}
 	return func(m int) metricdata.Aggregation {
 		cycle++
 		h.DataPoints = make([]metricdata.HistogramDataPoint[N], 0, len(incr))
 		for a, v := range incr {
-			h.DataPoints = append(h.DataPoints, hPoint[N](a, float64(v), uint64(cycle*m)))
+			h.DataPoints = append(h.DataPoints, hPoint[N](a, v, uint64(cycle*m)))
 		}
 		return h
 	}
 }
 
 // hPoint returns an HistogramDataPoint that started and ended now with multi
 // number of measurements values v. It includes a min and max (set to v).
-func hPoint[N int64 | float64](a attribute.Set, v float64, multi uint64) metricdata.HistogramDataPoint[N] {
-	idx := sort.SearchFloat64s(bounds, v)
+func hPoint[N int64 | float64](a attribute.Set, v N, multi uint64) metricdata.HistogramDataPoint[N] {
+	idx := sort.SearchFloat64s(bounds, float64(v))
 	counts := make([]uint64, len(bounds)+1)
 	counts[idx] += multi
 	return metricdata.HistogramDataPoint[N]{
@@ -94,25 +94,32 @@ func hPoint[N int64 | float64](a attribute.Set, v float64, multi uint64) metricd
 		BucketCounts: counts,
 		Min:          metricdata.NewExtrema(v),
 		Max:          metricdata.NewExtrema(v),
-		Sum:          v * float64(multi),
+		Sum:          v * N(multi),
 	}
 }
 
 func TestBucketsBin(t *testing.T) {
-	b := newBuckets(3)
-	assertB := func(counts []uint64, count uint64, sum, min, max float64) {
-		assert.Equal(t, counts, b.counts)
-		assert.Equal(t, count, b.count)
-		assert.Equal(t, sum, b.sum)
-		assert.Equal(t, min, b.min)
-		assert.Equal(t, max, b.max)
-	}
+	t.Run("Int64", testBucketsBin[int64]())
+	t.Run("Float64", testBucketsBin[float64]())
+}
+
+func testBucketsBin[N int64 | float64]() func(t *testing.T) {
+	return func(t *testing.T) {
+		b := newBuckets[N](3)
+		assertB := func(counts []uint64, count uint64, sum, min, max N) {
+			assert.Equal(t, counts, b.counts)
+			assert.Equal(t, count, b.count)
+			assert.Equal(t, sum, b.sum)
+			assert.Equal(t, min, b.min)
+			assert.Equal(t, max, b.max)
+		}
 
-	assertB([]uint64{0, 0, 0}, 0, 0, 0, 0)
-	b.bin(1, 2)
-	assertB([]uint64{0, 1, 0}, 1, 2, 0, 2)
-	b.bin(0, -1)
-	assertB([]uint64{1, 1, 0}, 2, 1, -1, 2)
+		assertB([]uint64{0, 0, 0}, 0, 0, 0, 0)
+		b.bin(1, 2)
+		assertB([]uint64{0, 1, 0}, 1, 2, 0, 2)
+		b.bin(0, -1)
+		assertB([]uint64{1, 1, 0}, 2, 1, -1, 2)
+	}
 }
 
 func testHistImmutableBounds[N int64 | float64](newA func(aggregation.ExplicitBucketHistogram) Aggregator[N], getBounds func(Aggregator[N]) []float64) func(t *testing.T) {

sdk/metric/internal/lastvalue_test.go

@@ -37,7 +37,7 @@ func testLastValue[N int64 | float64]() func(*testing.T) {
 		CycleN:       defaultCycles,
 	}
 
-	eFunc := func(increments setMap) expectFunc {
+	eFunc := func(increments setMap[N]) expectFunc {
 		data := make([]metricdata.DataPoint[N], 0, len(increments))
 		for a, v := range increments {
 			point := metricdata.DataPoint[N]{Attributes: a, Time: now(), Value: N(v)}
@@ -46,7 +46,7 @@ func testLastValue[N int64 | float64]() func(*testing.T) {
 		gauge := metricdata.Gauge[N]{DataPoints: data}
 		return func(int) metricdata.Aggregation { return gauge }
 	}
-	incr := monoIncr
+	incr := monoIncr[N]()
 	return tester.Run(NewLastValue[N](), incr, eFunc(incr))
 }
 

sdk/metric/internal/sum_test.go

@@ -39,71 +39,71 @@ func testSum[N int64 | float64](t *testing.T) {
 	}
 
 	t.Run("Delta", func(t *testing.T) {
-		incr, mono := monoIncr, true
+		incr, mono := monoIncr[N](), true
 		eFunc := deltaExpecter[N](incr, mono)
 		t.Run("Monotonic", tester.Run(NewDeltaSum[N](mono), incr, eFunc))
 
-		incr, mono = nonMonoIncr, false
+		incr, mono = nonMonoIncr[N](), false
 		eFunc = deltaExpecter[N](incr, mono)
 		t.Run("NonMonotonic", tester.Run(NewDeltaSum[N](mono), incr, eFunc))
 	})
 
 	t.Run("Cumulative", func(t *testing.T) {
-		incr, mono := monoIncr, true
+		incr, mono := monoIncr[N](), true
 		eFunc := cumuExpecter[N](incr, mono)
 		t.Run("Monotonic", tester.Run(NewCumulativeSum[N](mono), incr, eFunc))
 
-		incr, mono = nonMonoIncr, false
+		incr, mono = nonMonoIncr[N](), false
 		eFunc = cumuExpecter[N](incr, mono)
 		t.Run("NonMonotonic", tester.Run(NewCumulativeSum[N](mono), incr, eFunc))
 	})
 
 	t.Run("PreComputedDelta", func(t *testing.T) {
-		incr, mono := monoIncr, true
+		incr, mono := monoIncr[N](), true
 		eFunc := preDeltaExpecter[N](incr, mono)
 		t.Run("Monotonic", tester.Run(NewPrecomputedDeltaSum[N](mono), incr, eFunc))
 
-		incr, mono = nonMonoIncr, false
+		incr, mono = nonMonoIncr[N](), false
 		eFunc = preDeltaExpecter[N](incr, mono)
 		t.Run("NonMonotonic", tester.Run(NewPrecomputedDeltaSum[N](mono), incr, eFunc))
 	})
 
 	t.Run("PreComputedCumulative", func(t *testing.T) {
-		incr, mono := monoIncr, true
+		incr, mono := monoIncr[N](), true
 		eFunc := preCumuExpecter[N](incr, mono)
 		t.Run("Monotonic", tester.Run(NewPrecomputedCumulativeSum[N](mono), incr, eFunc))
 
-		incr, mono = nonMonoIncr, false
+		incr, mono = nonMonoIncr[N](), false
 		eFunc = preCumuExpecter[N](incr, mono)
 		t.Run("NonMonotonic", tester.Run(NewPrecomputedCumulativeSum[N](mono), incr, eFunc))
 	})
 }
 
-func deltaExpecter[N int64 | float64](incr setMap, mono bool) expectFunc {
+func deltaExpecter[N int64 | float64](incr setMap[N], mono bool) expectFunc {
 	sum := metricdata.Sum[N]{Temporality: metricdata.DeltaTemporality, IsMonotonic: mono}
 	return func(m int) metricdata.Aggregation {
 		sum.DataPoints = make([]metricdata.DataPoint[N], 0, len(incr))
 		for a, v := range incr {
-			sum.DataPoints = append(sum.DataPoints, point(a, N(v*m)))
+			sum.DataPoints = append(sum.DataPoints, point(a, v*N(m)))
 		}
 		return sum
 	}
 }
 
-func cumuExpecter[N int64 | float64](incr setMap, mono bool) expectFunc {
-	var cycle int
+func cumuExpecter[N int64 | float64](incr setMap[N], mono bool) expectFunc {
+	var cycle N
 	sum := metricdata.Sum[N]{Temporality: metricdata.CumulativeTemporality, IsMonotonic: mono}
 	return func(m int) metricdata.Aggregation {
 		cycle++
 		sum.DataPoints = make([]metricdata.DataPoint[N], 0, len(incr))
 		for a, v := range incr {
-			sum.DataPoints = append(sum.DataPoints, point(a, N(v*cycle*m)))
+			sum.DataPoints = append(sum.DataPoints, point(a, v*cycle*N(m)))
 		}
 		return sum
 	}
 }
 
-func preDeltaExpecter[N int64 | float64](incr setMap, mono bool) expectFunc {
+func preDeltaExpecter[N int64 | float64](incr setMap[N], mono bool) expectFunc {
 	sum := metricdata.Sum[N]{Temporality: metricdata.DeltaTemporality, IsMonotonic: mono}
 	last := make(map[attribute.Set]N)
 	return func(int) metricdata.Aggregation {
@@ -117,7 +117,7 @@ func preDeltaExpecter[N int64 | float64](incr setMap, mono bool) expectFunc {
 	}
 }
 
-func preCumuExpecter[N int64 | float64](incr setMap, mono bool) expectFunc {
+func preCumuExpecter[N int64 | float64](incr setMap[N], mono bool) expectFunc {
 	sum := metricdata.Sum[N]{Temporality: metricdata.CumulativeTemporality, IsMonotonic: mono}
 	return func(int) metricdata.Aggregation {
 		sum.DataPoints = make([]metricdata.DataPoint[N], 0, len(incr))