Flatten sdk/metric/aggregation into sdk/metric (#4435)

* Deprecate the aggregation pkg

* Decouple the internal/aggregate from aggregation pkg

* Add Aggregation to the metric pkg

* Do not use sdk/metric/aggregation in stdoutmetric exporter

* Update all generated templates

* Update prom exporter

* Fix view example

* Add changes to changelog

* Update CHANGELOG.md

Co-authored-by: Robert Pająk <pellared@hotmail.com>

* Rename Sum to AggregationSum

* Fix comments

* Centralize validation of aggregation in pipeline

* Remove validation of agg in manual_reader selector opt

* Fix merge

---------

Co-authored-by: Robert Pająk <pellared@hotmail.com>

CHANGELOG.md

@@ -24,6 +24,7 @@ This project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.htm
 - Accept 201 to 299 HTTP status as success in `go.opentelemetry.io/otel/exporters/otlp/otlpmetric/otlpmetrichttp` and `go.opentelemetry.io/otel/exporters/otlp/otlptrace/otlptracehttp`. (#4365)
 - Document the `Temporality` and `Aggregation` methods of the `"go.opentelemetry.io/otel/sdk/metric".Exporter"` need to be concurrent safe. (#4381)
 - Expand the set of units supported by the prometheus exporter, and don't add unit suffixes if they are already present in `go.opentelemetry.op/otel/exporters/prometheus` (#4374)
+- Move the `Aggregation` interface and its implementations from `go.opentelemetry.io/otel/sdk/metric/aggregation` to `go.opentelemetry.io/otel/sdk/metric`. (#4435)
 - The exporters in `go.opentelemetry.io/otel/exporters/otlp/otlpmetric/otlpmetricgrpc` and `go.opentelemetry.io/otel/exporters/otlp/otlpmetric/otlpmetrichttp` support the `OTEL_EXPORTER_OTLP_METRICS_DEFAULT_HISTOGRAM_AGGREGATION` environment variable. (#4437)
 
 ### Changed
@@ -89,6 +90,8 @@ This project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.htm
 - The `go.opentelemetry.io/otel/exporters/otlp/otlptrace/internal/otlpconfig` package is deprecated. (#4425)
 - The `go.opentelemetry.io/otel/exporters/otlp/otlptrace/internal/otlptracetest` package is deprecated. (#4425)
 - The `go.opentelemetry.io/otel/exporters/otlp/otlptrace/internal/retry` package is deprecated. (#4425)
+- The `go.opentelemetry.io/otel/sdk/metric/aggregation` package is deprecated.
+  Use the aggregation types added to `go.opentelemetry.io/otel/sdk/metric` instead. (#4435)
 
 ## [1.16.0/0.39.0] 2023-05-18
 

example/view/main.go

@@ -29,7 +29,6 @@ import (
 	api "go.opentelemetry.io/otel/metric"
 	"go.opentelemetry.io/otel/sdk/instrumentation"
 	"go.opentelemetry.io/otel/sdk/metric"
-	"go.opentelemetry.io/otel/sdk/metric/aggregation"
 )
 
 const meterName = "github.com/open-telemetry/opentelemetry-go/example/view"
@@ -53,7 +52,7 @@ func main() {
 			},
 			metric.Stream{
 				Name: "bar",
-				Aggregation: aggregation.ExplicitBucketHistogram{
+				Aggregation: metric.AggregationExplicitBucketHistogram{
 					Boundaries: []float64{64, 128, 256, 512, 1024, 2048, 4096},
 				},
 			},

exporters/otlp/otlpmetric/internal/client.go

@@ -18,7 +18,6 @@ import (
 	"context"
 
 	"go.opentelemetry.io/otel/sdk/metric"
-	"go.opentelemetry.io/otel/sdk/metric/aggregation"
 	"go.opentelemetry.io/otel/sdk/metric/metricdata"
 	mpb "go.opentelemetry.io/proto/otlp/metrics/v1"
 )
@@ -29,7 +28,7 @@ type Client interface {
 	Temporality(metric.InstrumentKind) metricdata.Temporality
 
 	// Aggregation returns the Aggregation to use for an instrument kind.
-	Aggregation(metric.InstrumentKind) aggregation.Aggregation
+	Aggregation(metric.InstrumentKind) metric.Aggregation
 
 	// UploadMetrics transmits metric data to an OTLP receiver.
 	//

exporters/otlp/otlpmetric/internal/exporter.go

@@ -25,7 +25,6 @@ import (
 
 	"go.opentelemetry.io/otel/exporters/otlp/otlpmetric/internal/transform" // nolint: staticcheck  // Atomic deprecation.
 	"go.opentelemetry.io/otel/sdk/metric"
-	"go.opentelemetry.io/otel/sdk/metric/aggregation"
 	"go.opentelemetry.io/otel/sdk/metric/metricdata"
 	mpb "go.opentelemetry.io/proto/otlp/metrics/v1"
 )
@@ -47,7 +46,7 @@ func (e *Exporter) Temporality(k metric.InstrumentKind) metricdata.Temporality {
 }
 
 // Aggregation returns the Aggregation to use for an instrument kind.
-func (e *Exporter) Aggregation(k metric.InstrumentKind) aggregation.Aggregation {
+func (e *Exporter) Aggregation(k metric.InstrumentKind) metric.Aggregation {
 	e.clientMu.Lock()
 	defer e.clientMu.Unlock()
 	return e.client.Aggregation(k)
@@ -120,7 +119,7 @@ func (c shutdownClient) Temporality(k metric.InstrumentKind) metricdata.Temporal
 	return c.temporalitySelector(k)
 }
 
-func (c shutdownClient) Aggregation(k metric.InstrumentKind) aggregation.Aggregation {
+func (c shutdownClient) Aggregation(k metric.InstrumentKind) metric.Aggregation {
 	return c.aggregationSelector(k)
 }
 

exporters/otlp/otlpmetric/internal/exporter_test.go

@@ -22,7 +22,6 @@ import (
 	"github.com/stretchr/testify/assert"
 
 	"go.opentelemetry.io/otel/sdk/metric"
-	"go.opentelemetry.io/otel/sdk/metric/aggregation"
 	"go.opentelemetry.io/otel/sdk/metric/metricdata"
 	mpb "go.opentelemetry.io/proto/otlp/metrics/v1"
 )
@@ -37,7 +36,7 @@ func (c *client) Temporality(k metric.InstrumentKind) metricdata.Temporality {
 	return metric.DefaultTemporalitySelector(k)
 }
 
-func (c *client) Aggregation(k metric.InstrumentKind) aggregation.Aggregation {
+func (c *client) Aggregation(k metric.InstrumentKind) metric.Aggregation {
 	return metric.DefaultAggregationSelector(k)
 }
 

exporters/otlp/otlpmetric/internal/oconf/options.go

@@ -33,9 +33,7 @@ import (
 	"go.opentelemetry.io/otel/exporters/otlp/internal"                       // nolint: staticcheck  // Synchronous deprecation.
 	"go.opentelemetry.io/otel/exporters/otlp/internal/retry"                 // nolint: staticcheck  // Synchronous deprecation.
 	ominternal "go.opentelemetry.io/otel/exporters/otlp/otlpmetric/internal" // nolint: staticcheck  // Atomic deprecation.
-	"go.opentelemetry.io/otel/internal/global"
 	"go.opentelemetry.io/otel/sdk/metric"
-	"go.opentelemetry.io/otel/sdk/metric/aggregation"
 )
 
 const (
@@ -340,23 +338,8 @@ func WithTemporalitySelector(selector metric.TemporalitySelector) GenericOption
 }
 
 func WithAggregationSelector(selector metric.AggregationSelector) GenericOption {
-	// Deep copy and validate before using.
-	wrapped := func(ik metric.InstrumentKind) aggregation.Aggregation {
-		a := selector(ik)
-		cpA := a.Copy()
-		if err := cpA.Err(); err != nil {
-			cpA = metric.DefaultAggregationSelector(ik)
-			global.Error(
-				err, "using default aggregation instead",
-				"aggregation", a,
-				"replacement", cpA,
-			)
-		}
-		return cpA
-	}
-
 	return newGenericOption(func(cfg Config) Config {
-		cfg.Metrics.AggregationSelector = wrapped
+		cfg.Metrics.AggregationSelector = selector
 		return cfg
 	})
 }

exporters/otlp/otlpmetric/internal/oconf/options_test.go

@@ -24,7 +24,6 @@ import (
 	"go.opentelemetry.io/otel/exporters/otlp/internal/envconfig" // nolint: staticcheck  // Synchronous deprecation.
 	"go.opentelemetry.io/otel/exporters/otlp/otlpmetric/internal/oconf"
 	"go.opentelemetry.io/otel/sdk/metric"
-	"go.opentelemetry.io/otel/sdk/metric/aggregation"
 	"go.opentelemetry.io/otel/sdk/metric/metricdata"
 )
 
@@ -415,7 +414,7 @@ func TestConfigs(t *testing.T) {
 				// all" was set.
 				var undefinedKind metric.InstrumentKind
 				got := c.Metrics.AggregationSelector
-				assert.Equal(t, aggregation.Drop{}, got(undefinedKind))
+				assert.Equal(t, metric.AggregationDrop{}, got(undefinedKind))
 			},
 		},
 	}
@@ -441,8 +440,8 @@ func TestConfigs(t *testing.T) {
 	}
 }
 
-func dropSelector(metric.InstrumentKind) aggregation.Aggregation {
-	return aggregation.Drop{}
+func dropSelector(metric.InstrumentKind) metric.Aggregation {
+	return metric.AggregationDrop{}
 }
 
 func deltaSelector(metric.InstrumentKind) metricdata.Temporality {

exporters/otlp/otlpmetric/internal/otest/client_test.go

@@ -22,7 +22,6 @@ import (
 	"go.opentelemetry.io/otel/exporters/otlp/internal"                       // nolint: staticcheck  // Synchronous deprecation.
 	ominternal "go.opentelemetry.io/otel/exporters/otlp/otlpmetric/internal" // nolint: staticcheck  // Atomic deprecation.
 	"go.opentelemetry.io/otel/sdk/metric"
-	"go.opentelemetry.io/otel/sdk/metric/aggregation"
 	"go.opentelemetry.io/otel/sdk/metric/metricdata"
 	cpb "go.opentelemetry.io/proto/otlp/collector/metrics/v1"
 	mpb "go.opentelemetry.io/proto/otlp/metrics/v1"
@@ -37,7 +36,7 @@ func (c *client) Temporality(k metric.InstrumentKind) metricdata.Temporality {
 	return metric.DefaultTemporalitySelector(k)
 }
 
-func (c *client) Aggregation(k metric.InstrumentKind) aggregation.Aggregation {
+func (c *client) Aggregation(k metric.InstrumentKind) metric.Aggregation {
 	return metric.DefaultAggregationSelector(k)
 }
 

exporters/otlp/otlpmetric/otlpmetricgrpc/client_test.go

@@ -30,7 +30,6 @@ import (
 	"go.opentelemetry.io/otel/exporters/otlp/otlpmetric/otlpmetricgrpc/internal/oconf"
 	"go.opentelemetry.io/otel/exporters/otlp/otlpmetric/otlpmetricgrpc/internal/otest"
 	"go.opentelemetry.io/otel/sdk/metric"
-	"go.opentelemetry.io/otel/sdk/metric/aggregation"
 	"go.opentelemetry.io/otel/sdk/metric/metricdata"
 )
 
@@ -137,7 +136,7 @@ type clientShim struct {
 func (clientShim) Temporality(metric.InstrumentKind) metricdata.Temporality {
 	return metricdata.CumulativeTemporality
 }
-func (clientShim) Aggregation(metric.InstrumentKind) aggregation.Aggregation {
+func (clientShim) Aggregation(metric.InstrumentKind) metric.Aggregation {
 	return nil
 }
 func (clientShim) ForceFlush(ctx context.Context) error {

exporters/otlp/otlpmetric/otlpmetricgrpc/exporter.go

@@ -23,7 +23,6 @@ import (
 	"go.opentelemetry.io/otel/exporters/otlp/otlpmetric/otlpmetricgrpc/internal/transform"
 	"go.opentelemetry.io/otel/internal/global"
 	"go.opentelemetry.io/otel/sdk/metric"
-	"go.opentelemetry.io/otel/sdk/metric/aggregation"
 	"go.opentelemetry.io/otel/sdk/metric/metricdata"
 	metricpb "go.opentelemetry.io/proto/otlp/metrics/v1"
 )
@@ -70,7 +69,7 @@ func (e *Exporter) Temporality(k metric.InstrumentKind) metricdata.Temporality {
 }
 
 // Aggregation returns the Aggregation to use for an instrument kind.
-func (e *Exporter) Aggregation(k metric.InstrumentKind) aggregation.Aggregation {
+func (e *Exporter) Aggregation(k metric.InstrumentKind) metric.Aggregation {
 	return e.aggregationSelector(k)
 }
 

exporters/otlp/otlpmetric/otlpmetricgrpc/internal/oconf/envconfig.go

@@ -29,7 +29,6 @@ import (
 	"go.opentelemetry.io/otel/exporters/otlp/otlpmetric/otlpmetricgrpc/internal/envconfig"
 	"go.opentelemetry.io/otel/internal/global"
 	"go.opentelemetry.io/otel/sdk/metric"
-	"go.opentelemetry.io/otel/sdk/metric/aggregation"
 	"go.opentelemetry.io/otel/sdk/metric/metricdata"
 )
 
@@ -204,9 +203,9 @@ func withEnvAggPreference(n string, fn func(metric.AggregationSelector)) func(e
 			case "explicit_bucket_histogram":
 				fn(metric.DefaultAggregationSelector)
 			case "base2_exponential_bucket_histogram":
-				fn(func(kind metric.InstrumentKind) aggregation.Aggregation {
+				fn(func(kind metric.InstrumentKind) metric.Aggregation {
 					if kind == metric.InstrumentKindHistogram {
-						return aggregation.Base2ExponentialHistogram{
+						return metric.AggregationBase2ExponentialHistogram{
 							MaxSize:  160,
 							MaxScale: 20,
 							NoMinMax: false,

exporters/otlp/otlpmetric/otlpmetricgrpc/internal/oconf/envconfig_test.go

@@ -24,7 +24,6 @@ import (
 	"github.com/stretchr/testify/require"
 
 	"go.opentelemetry.io/otel/sdk/metric"
-	"go.opentelemetry.io/otel/sdk/metric/aggregation"
 	"go.opentelemetry.io/otel/sdk/metric/metricdata"
 )
 
@@ -111,7 +110,7 @@ func TestWithEnvAggPreference(t *testing.T) {
 	tests := []struct {
 		name     string
 		envValue string
-		want     map[metric.InstrumentKind]aggregation.Aggregation
+		want     map[metric.InstrumentKind]metric.Aggregation
 	}{
 		{
 			name:     "default do not set the selector",
@@ -124,7 +123,7 @@ func TestWithEnvAggPreference(t *testing.T) {
 		{
 			name:     "explicit_bucket_histogram",
 			envValue: "explicit_bucket_histogram",
-			want: map[metric.InstrumentKind]aggregation.Aggregation{
+			want: map[metric.InstrumentKind]metric.Aggregation{
 				metric.InstrumentKindCounter:                 metric.DefaultAggregationSelector(metric.InstrumentKindCounter),
 				metric.InstrumentKindHistogram:               metric.DefaultAggregationSelector(metric.InstrumentKindHistogram),
 				metric.InstrumentKindUpDownCounter:           metric.DefaultAggregationSelector(metric.InstrumentKindUpDownCounter),
@@ -136,9 +135,9 @@ func TestWithEnvAggPreference(t *testing.T) {
 		{
 			name:     "base2_exponential_bucket_histogram",
 			envValue: "base2_exponential_bucket_histogram",
-			want: map[metric.InstrumentKind]aggregation.Aggregation{
+			want: map[metric.InstrumentKind]metric.Aggregation{
 				metric.InstrumentKindCounter: metric.DefaultAggregationSelector(metric.InstrumentKindCounter),
-				metric.InstrumentKindHistogram: aggregation.Base2ExponentialHistogram{
+				metric.InstrumentKindHistogram: metric.AggregationBase2ExponentialHistogram{
 					MaxSize:  160,
 					MaxScale: 20,
 					NoMinMax: false,

exporters/otlp/otlpmetric/otlpmetricgrpc/internal/oconf/options.go

@@ -32,9 +32,7 @@ import (
 
 	"go.opentelemetry.io/otel/exporters/otlp/otlpmetric"
 	"go.opentelemetry.io/otel/exporters/otlp/otlpmetric/otlpmetricgrpc/internal/retry"
-	"go.opentelemetry.io/otel/internal/global"
 	"go.opentelemetry.io/otel/sdk/metric"
-	"go.opentelemetry.io/otel/sdk/metric/aggregation"
 )
 
 const (
@@ -354,23 +352,8 @@ func WithTemporalitySelector(selector metric.TemporalitySelector) GenericOption
 }
 
 func WithAggregationSelector(selector metric.AggregationSelector) GenericOption {
-	// Deep copy and validate before using.
-	wrapped := func(ik metric.InstrumentKind) aggregation.Aggregation {
-		a := selector(ik)
-		cpA := a.Copy()
-		if err := cpA.Err(); err != nil {
-			cpA = metric.DefaultAggregationSelector(ik)
-			global.Error(
-				err, "using default aggregation instead",
-				"aggregation", a,
-				"replacement", cpA,
-			)
-		}
-		return cpA
-	}
-
 	return newGenericOption(func(cfg Config) Config {
-		cfg.Metrics.AggregationSelector = wrapped
+		cfg.Metrics.AggregationSelector = selector
 		return cfg
 	})
 }

exporters/otlp/otlpmetric/otlpmetricgrpc/internal/oconf/options_test.go

@@ -26,7 +26,6 @@ import (
 
 	"go.opentelemetry.io/otel/exporters/otlp/otlpmetric/otlpmetricgrpc/internal/envconfig"
 	"go.opentelemetry.io/otel/sdk/metric"
-	"go.opentelemetry.io/otel/sdk/metric/aggregation"
 	"go.opentelemetry.io/otel/sdk/metric/metricdata"
 )
 
@@ -417,7 +416,7 @@ func TestConfigs(t *testing.T) {
 				// all" was set.
 				var undefinedKind metric.InstrumentKind
 				got := c.Metrics.AggregationSelector
-				assert.Equal(t, aggregation.Drop{}, got(undefinedKind))
+				assert.Equal(t, metric.AggregationDrop{}, got(undefinedKind))
 			},
 		},
 	}
@@ -443,8 +442,8 @@ func TestConfigs(t *testing.T) {
 	}
 }
 
-func dropSelector(metric.InstrumentKind) aggregation.Aggregation {
-	return aggregation.Drop{}
+func dropSelector(metric.InstrumentKind) metric.Aggregation {
+	return metric.AggregationDrop{}
 }
 
 func deltaSelector(metric.InstrumentKind) metricdata.Temporality {

exporters/otlp/otlpmetric/otlpmetricgrpc/internal/otest/client_test.go

@@ -24,7 +24,6 @@ import (
 	"go.opentelemetry.io/otel"
 	"go.opentelemetry.io/otel/exporters/otlp/otlpmetric/otlpmetricgrpc/internal"
 	"go.opentelemetry.io/otel/sdk/metric"
-	"go.opentelemetry.io/otel/sdk/metric/aggregation"
 	"go.opentelemetry.io/otel/sdk/metric/metricdata"
 	cpb "go.opentelemetry.io/proto/otlp/collector/metrics/v1"
 	mpb "go.opentelemetry.io/proto/otlp/metrics/v1"
@@ -39,7 +38,7 @@ func (c *client) Temporality(k metric.InstrumentKind) metricdata.Temporality {
 	return metric.DefaultTemporalitySelector(k)
 }
 
-func (c *client) Aggregation(k metric.InstrumentKind) aggregation.Aggregation {
+func (c *client) Aggregation(k metric.InstrumentKind) metric.Aggregation {
 	return metric.DefaultAggregationSelector(k)
 }
 

exporters/otlp/otlpmetric/otlpmetrichttp/client_test.go

@@ -30,7 +30,6 @@ import (
 	"go.opentelemetry.io/otel/exporters/otlp/otlpmetric/otlpmetrichttp/internal/oconf"
 	"go.opentelemetry.io/otel/exporters/otlp/otlpmetric/otlpmetrichttp/internal/otest"
 	"go.opentelemetry.io/otel/sdk/metric"
-	"go.opentelemetry.io/otel/sdk/metric/aggregation"
 	"go.opentelemetry.io/otel/sdk/metric/metricdata"
 )
 
@@ -41,7 +40,7 @@ type clientShim struct {
 func (clientShim) Temporality(metric.InstrumentKind) metricdata.Temporality {
 	return metricdata.CumulativeTemporality
 }
-func (clientShim) Aggregation(metric.InstrumentKind) aggregation.Aggregation {
+func (clientShim) Aggregation(metric.InstrumentKind) metric.Aggregation {
 	return nil
 }
 func (clientShim) ForceFlush(ctx context.Context) error {

exporters/otlp/otlpmetric/otlpmetrichttp/exporter.go

@@ -23,7 +23,6 @@ import (
 	"go.opentelemetry.io/otel/exporters/otlp/otlpmetric/otlpmetrichttp/internal/transform"
 	"go.opentelemetry.io/otel/internal/global"
 	"go.opentelemetry.io/otel/sdk/metric"
-	"go.opentelemetry.io/otel/sdk/metric/aggregation"
 	"go.opentelemetry.io/otel/sdk/metric/metricdata"
 	metricpb "go.opentelemetry.io/proto/otlp/metrics/v1"
 )
@@ -70,7 +69,7 @@ func (e *Exporter) Temporality(k metric.InstrumentKind) metricdata.Temporality {
 }
 
 // Aggregation returns the Aggregation to use for an instrument kind.
-func (e *Exporter) Aggregation(k metric.InstrumentKind) aggregation.Aggregation {
+func (e *Exporter) Aggregation(k metric.InstrumentKind) metric.Aggregation {
 	return e.aggregationSelector(k)
 }
 

exporters/otlp/otlpmetric/otlpmetrichttp/internal/oconf/envconfig.go

@@ -29,7 +29,6 @@ import (
 	"go.opentelemetry.io/otel/exporters/otlp/otlpmetric/otlpmetrichttp/internal/envconfig"
 	"go.opentelemetry.io/otel/internal/global"
 	"go.opentelemetry.io/otel/sdk/metric"
-	"go.opentelemetry.io/otel/sdk/metric/aggregation"
 	"go.opentelemetry.io/otel/sdk/metric/metricdata"
 )
 
@@ -204,9 +203,9 @@ func withEnvAggPreference(n string, fn func(metric.AggregationSelector)) func(e
 			case "explicit_bucket_histogram":
 				fn(metric.DefaultAggregationSelector)
 			case "base2_exponential_bucket_histogram":
-				fn(func(kind metric.InstrumentKind) aggregation.Aggregation {
+				fn(func(kind metric.InstrumentKind) metric.Aggregation {
 					if kind == metric.InstrumentKindHistogram {
-						return aggregation.Base2ExponentialHistogram{
+						return metric.AggregationBase2ExponentialHistogram{
 							MaxSize:  160,
 							MaxScale: 20,
 							NoMinMax: false,

exporters/otlp/otlpmetric/otlpmetrichttp/internal/oconf/envconfig_test.go

@@ -24,7 +24,6 @@ import (
 	"github.com/stretchr/testify/require"
 
 	"go.opentelemetry.io/otel/sdk/metric"
-	"go.opentelemetry.io/otel/sdk/metric/aggregation"
 	"go.opentelemetry.io/otel/sdk/metric/metricdata"
 )
 
@@ -111,7 +110,7 @@ func TestWithEnvAggPreference(t *testing.T) {
 	tests := []struct {
 		name     string
 		envValue string
-		want     map[metric.InstrumentKind]aggregation.Aggregation
+		want     map[metric.InstrumentKind]metric.Aggregation
 	}{
 		{
 			name:     "default do not set the selector",
@@ -124,7 +123,7 @@ func TestWithEnvAggPreference(t *testing.T) {
 		{
 			name:     "explicit_bucket_histogram",
 			envValue: "explicit_bucket_histogram",
-			want: map[metric.InstrumentKind]aggregation.Aggregation{
+			want: map[metric.InstrumentKind]metric.Aggregation{
 				metric.InstrumentKindCounter:                 metric.DefaultAggregationSelector(metric.InstrumentKindCounter),
 				metric.InstrumentKindHistogram:               metric.DefaultAggregationSelector(metric.InstrumentKindHistogram),
 				metric.InstrumentKindUpDownCounter:           metric.DefaultAggregationSelector(metric.InstrumentKindUpDownCounter),
@@ -136,9 +135,9 @@ func TestWithEnvAggPreference(t *testing.T) {
 		{
 			name:     "base2_exponential_bucket_histogram",
 			envValue: "base2_exponential_bucket_histogram",
-			want: map[metric.InstrumentKind]aggregation.Aggregation{
+			want: map[metric.InstrumentKind]metric.Aggregation{
 				metric.InstrumentKindCounter: metric.DefaultAggregationSelector(metric.InstrumentKindCounter),
-				metric.InstrumentKindHistogram: aggregation.Base2ExponentialHistogram{
+				metric.InstrumentKindHistogram: metric.AggregationBase2ExponentialHistogram{
 					MaxSize:  160,
 					MaxScale: 20,
 					NoMinMax: false,

exporters/otlp/otlpmetric/otlpmetrichttp/internal/oconf/options.go

@@ -32,9 +32,7 @@ import (
 
 	"go.opentelemetry.io/otel/exporters/otlp/otlpmetric"
 	"go.opentelemetry.io/otel/exporters/otlp/otlpmetric/otlpmetrichttp/internal/retry"
-	"go.opentelemetry.io/otel/internal/global"
 	"go.opentelemetry.io/otel/sdk/metric"
-	"go.opentelemetry.io/otel/sdk/metric/aggregation"
 )
 
 const (
@@ -354,23 +352,8 @@ func WithTemporalitySelector(selector metric.TemporalitySelector) GenericOption
 }
 
 func WithAggregationSelector(selector metric.AggregationSelector) GenericOption {
-	// Deep copy and validate before using.
-	wrapped := func(ik metric.InstrumentKind) aggregation.Aggregation {
-		a := selector(ik)
-		cpA := a.Copy()
-		if err := cpA.Err(); err != nil {
-			cpA = metric.DefaultAggregationSelector(ik)
-			global.Error(
-				err, "using default aggregation instead",
-				"aggregation", a,
-				"replacement", cpA,
-			)
-		}
-		return cpA
-	}
-
 	return newGenericOption(func(cfg Config) Config {
-		cfg.Metrics.AggregationSelector = wrapped
+		cfg.Metrics.AggregationSelector = selector
 		return cfg
 	})
 }

exporters/otlp/otlpmetric/otlpmetrichttp/internal/oconf/options_test.go

@@ -26,7 +26,6 @@ import (
 
 	"go.opentelemetry.io/otel/exporters/otlp/otlpmetric/otlpmetrichttp/internal/envconfig"
 	"go.opentelemetry.io/otel/sdk/metric"
-	"go.opentelemetry.io/otel/sdk/metric/aggregation"
 	"go.opentelemetry.io/otel/sdk/metric/metricdata"
 )
 
@@ -417,7 +416,7 @@ func TestConfigs(t *testing.T) {
 				// all" was set.
 				var undefinedKind metric.InstrumentKind
 				got := c.Metrics.AggregationSelector
-				assert.Equal(t, aggregation.Drop{}, got(undefinedKind))
+				assert.Equal(t, metric.AggregationDrop{}, got(undefinedKind))
 			},
 		},
 	}
@@ -443,8 +442,8 @@ func TestConfigs(t *testing.T) {
 	}
 }
 
-func dropSelector(metric.InstrumentKind) aggregation.Aggregation {
-	return aggregation.Drop{}
+func dropSelector(metric.InstrumentKind) metric.Aggregation {
+	return metric.AggregationDrop{}
 }
 
 func deltaSelector(metric.InstrumentKind) metricdata.Temporality {

exporters/otlp/otlpmetric/otlpmetrichttp/internal/otest/client_test.go

@@ -24,7 +24,6 @@ import (
 	"go.opentelemetry.io/otel"
 	"go.opentelemetry.io/otel/exporters/otlp/otlpmetric/otlpmetrichttp/internal"
 	"go.opentelemetry.io/otel/sdk/metric"
-	"go.opentelemetry.io/otel/sdk/metric/aggregation"
 	"go.opentelemetry.io/otel/sdk/metric/metricdata"
 	cpb "go.opentelemetry.io/proto/otlp/collector/metrics/v1"
 	mpb "go.opentelemetry.io/proto/otlp/metrics/v1"
@@ -39,7 +38,7 @@ func (c *client) Temporality(k metric.InstrumentKind) metricdata.Temporality {
 	return metric.DefaultTemporalitySelector(k)
 }
 
-func (c *client) Aggregation(k metric.InstrumentKind) aggregation.Aggregation {
+func (c *client) Aggregation(k metric.InstrumentKind) metric.Aggregation {
 	return metric.DefaultAggregationSelector(k)
 }
 

exporters/prometheus/config_test.go

@@ -21,13 +21,12 @@ import (
 	"github.com/stretchr/testify/assert"
 
 	"go.opentelemetry.io/otel/sdk/metric"
-	"go.opentelemetry.io/otel/sdk/metric/aggregation"
 )
 
 func TestNewConfig(t *testing.T) {
 	registry := prometheus.NewRegistry()
 
-	aggregationSelector := func(metric.InstrumentKind) aggregation.Aggregation { return nil }
+	aggregationSelector := func(metric.InstrumentKind) metric.Aggregation { return nil }
 
 	testCases := []struct {
 		name       string
@@ -142,7 +141,7 @@ func TestNewConfig(t *testing.T) {
 }
 
 func TestConfigManualReaderOptions(t *testing.T) {
-	aggregationSelector := func(metric.InstrumentKind) aggregation.Aggregation { return nil }
+	aggregationSelector := func(metric.InstrumentKind) metric.Aggregation { return nil }
 
 	testCases := []struct {
 		name            string

exporters/prometheus/exporter_test.go

@@ -28,7 +28,6 @@ import (
 	"go.opentelemetry.io/otel/attribute"
 	otelmetric "go.opentelemetry.io/otel/metric"
 	"go.opentelemetry.io/otel/sdk/metric"
-	"go.opentelemetry.io/otel/sdk/metric/aggregation"
 	"go.opentelemetry.io/otel/sdk/resource"
 	semconv "go.opentelemetry.io/otel/semconv/v1.21.0"
 )
@@ -397,7 +396,7 @@ func TestPrometheusExporter(t *testing.T) {
 				metric.WithReader(exporter),
 				metric.WithView(metric.NewView(
 					metric.Instrument{Name: "histogram_*"},
-					metric.Stream{Aggregation: aggregation.ExplicitBucketHistogram{
+					metric.Stream{Aggregation: metric.AggregationExplicitBucketHistogram{
 						Boundaries: []float64{0, 5, 10, 25, 50, 75, 100, 250, 500, 1000},
 					}},
 				)),

exporters/stdout/stdoutmetric/config.go

@@ -17,9 +17,7 @@ import (
 	"encoding/json"
 	"os"
 
-	"go.opentelemetry.io/otel/internal/global"
 	"go.opentelemetry.io/otel/sdk/metric"
-	"go.opentelemetry.io/otel/sdk/metric/aggregation"
 )
 
 // config contains options for the exporter.
@@ -100,22 +98,7 @@ func (t temporalitySelectorOption) apply(c config) config {
 // package or the aggregation explicitly passed for a view matching an
 // instrument.
 func WithAggregationSelector(selector metric.AggregationSelector) Option {
-	// Deep copy and validate before using.
-	wrapped := func(ik metric.InstrumentKind) aggregation.Aggregation {
-		a := selector(ik)
-		cpA := a.Copy()
-		if err := cpA.Err(); err != nil {
-			cpA = metric.DefaultAggregationSelector(ik)
-			global.Error(
-				err, "using default aggregation instead",
-				"aggregation", a,
-				"replacement", cpA,
-			)
-		}
-		return cpA
-	}
-
-	return aggregationSelectorOption{selector: wrapped}
+	return aggregationSelectorOption{selector: selector}
 }
 
 type aggregationSelectorOption struct {

exporters/stdout/stdoutmetric/exporter.go

@@ -23,7 +23,6 @@ import (
 
 	"go.opentelemetry.io/otel/internal/global"
 	"go.opentelemetry.io/otel/sdk/metric"
-	"go.opentelemetry.io/otel/sdk/metric/aggregation"
 	"go.opentelemetry.io/otel/sdk/metric/metricdata"
 )
 
@@ -58,7 +57,7 @@ func (e *exporter) Temporality(k metric.InstrumentKind) metricdata.Temporality {
 	return e.temporalitySelector(k)
 }
 
-func (e *exporter) Aggregation(k metric.InstrumentKind) aggregation.Aggregation {
+func (e *exporter) Aggregation(k metric.InstrumentKind) metric.Aggregation {
 	return e.aggregationSelector(k)
 }
 

exporters/stdout/stdoutmetric/exporter_test.go

@@ -26,7 +26,6 @@ import (
 
 	"go.opentelemetry.io/otel/exporters/stdout/stdoutmetric"
 	"go.opentelemetry.io/otel/sdk/metric"
-	"go.opentelemetry.io/otel/sdk/metric/aggregation"
 	"go.opentelemetry.io/otel/sdk/metric/metricdata"
 )
 
@@ -115,8 +114,8 @@ func TestTemporalitySelector(t *testing.T) {
 	assert.Equal(t, metricdata.DeltaTemporality, exp.Temporality(unknownKind))
 }
 
-func dropSelector(metric.InstrumentKind) aggregation.Aggregation {
-	return aggregation.Drop{}
+func dropSelector(metric.InstrumentKind) metric.Aggregation {
+	return metric.AggregationDrop{}
 }
 
 func TestAggregationSelector(t *testing.T) {
@@ -127,5 +126,5 @@ func TestAggregationSelector(t *testing.T) {
 	require.NoError(t, err)
 
 	var unknownKind metric.InstrumentKind
-	assert.Equal(t, aggregation.Drop{}, exp.Aggregation(unknownKind))
+	assert.Equal(t, metric.AggregationDrop{}, exp.Aggregation(unknownKind))
 }

internal/shared/otlp/otlpmetric/oconf/envconfig.go.tmpl

@@ -29,7 +29,6 @@ import (
 	"{{ .envconfigImportPath }}"
 	"go.opentelemetry.io/otel/internal/global"
 	"go.opentelemetry.io/otel/sdk/metric"
-	"go.opentelemetry.io/otel/sdk/metric/aggregation"
 	"go.opentelemetry.io/otel/sdk/metric/metricdata"
 )
 
@@ -204,9 +203,9 @@ func withEnvAggPreference(n string, fn func(metric.AggregationSelector)) func(e
 			case "explicit_bucket_histogram":
 				fn(metric.DefaultAggregationSelector)
 			case "base2_exponential_bucket_histogram":
-				fn(func(kind metric.InstrumentKind) aggregation.Aggregation {
+				fn(func(kind metric.InstrumentKind) metric.Aggregation {
 					if kind == metric.InstrumentKindHistogram {
-						return aggregation.Base2ExponentialHistogram{
+						return metric.AggregationBase2ExponentialHistogram{
 							MaxSize:  160,
 							MaxScale: 20,
 							NoMinMax: false,

internal/shared/otlp/otlpmetric/oconf/envconfig_test.go.tmpl

@@ -24,7 +24,6 @@ import (
 	"github.com/stretchr/testify/require"
 
 	"go.opentelemetry.io/otel/sdk/metric"
-	"go.opentelemetry.io/otel/sdk/metric/aggregation"
 	"go.opentelemetry.io/otel/sdk/metric/metricdata"
 )
 
@@ -111,7 +110,7 @@ func TestWithEnvAggPreference(t *testing.T) {
 	tests := []struct {
 		name     string
 		envValue string
-		want     map[metric.InstrumentKind]aggregation.Aggregation
+		want     map[metric.InstrumentKind]metric.Aggregation
 	}{
 		{
 			name:     "default do not set the selector",
@@ -124,7 +123,7 @@ func TestWithEnvAggPreference(t *testing.T) {
 		{
 			name:     "explicit_bucket_histogram",
 			envValue: "explicit_bucket_histogram",
-			want: map[metric.InstrumentKind]aggregation.Aggregation{
+			want: map[metric.InstrumentKind]metric.Aggregation{
 				metric.InstrumentKindCounter:                 metric.DefaultAggregationSelector(metric.InstrumentKindCounter),
 				metric.InstrumentKindHistogram:               metric.DefaultAggregationSelector(metric.InstrumentKindHistogram),
 				metric.InstrumentKindUpDownCounter:           metric.DefaultAggregationSelector(metric.InstrumentKindUpDownCounter),
@@ -136,9 +135,9 @@ func TestWithEnvAggPreference(t *testing.T) {
 		{
 			name:     "base2_exponential_bucket_histogram",
 			envValue: "base2_exponential_bucket_histogram",
-			want: map[metric.InstrumentKind]aggregation.Aggregation{
+			want: map[metric.InstrumentKind]metric.Aggregation{
 				metric.InstrumentKindCounter: metric.DefaultAggregationSelector(metric.InstrumentKindCounter),
-				metric.InstrumentKindHistogram: aggregation.Base2ExponentialHistogram{
+				metric.InstrumentKindHistogram: metric.AggregationBase2ExponentialHistogram{
 					MaxSize:  160,
 					MaxScale: 20,
 					NoMinMax: false,

internal/shared/otlp/otlpmetric/oconf/options.go.tmpl

@@ -32,9 +32,7 @@ import (
 
 	"go.opentelemetry.io/otel/exporters/otlp/otlpmetric"
 	"{{ .retryImportPath }}"
-	"go.opentelemetry.io/otel/internal/global"
 	"go.opentelemetry.io/otel/sdk/metric"
-	"go.opentelemetry.io/otel/sdk/metric/aggregation"
 )
 
 const (
@@ -354,23 +352,8 @@ func WithTemporalitySelector(selector metric.TemporalitySelector) GenericOption
 }
 
 func WithAggregationSelector(selector metric.AggregationSelector) GenericOption {
-	// Deep copy and validate before using.
-	wrapped := func(ik metric.InstrumentKind) aggregation.Aggregation {
-		a := selector(ik)
-		cpA := a.Copy()
-		if err := cpA.Err(); err != nil {
-			cpA = metric.DefaultAggregationSelector(ik)
-			global.Error(
-				err, "using default aggregation instead",
-				"aggregation", a,
-				"replacement", cpA,
-			)
-		}
-		return cpA
-	}
-
 	return newGenericOption(func(cfg Config) Config {
-		cfg.Metrics.AggregationSelector = wrapped
+		cfg.Metrics.AggregationSelector = selector
 		return cfg
 	})
 }

internal/shared/otlp/otlpmetric/oconf/options_test.go.tmpl

@@ -26,7 +26,6 @@ import (
 
 	"{{ .envconfigImportPath }}"
 	"go.opentelemetry.io/otel/sdk/metric"
-	"go.opentelemetry.io/otel/sdk/metric/aggregation"
 	"go.opentelemetry.io/otel/sdk/metric/metricdata"
 )
 
@@ -417,7 +416,7 @@ func TestConfigs(t *testing.T) {
 				// all" was set.
 				var undefinedKind metric.InstrumentKind
 				got := c.Metrics.AggregationSelector
-				assert.Equal(t, aggregation.Drop{}, got(undefinedKind))
+				assert.Equal(t, metric.AggregationDrop{}, got(undefinedKind))
 			},
 		},
 	}
@@ -443,8 +442,8 @@ func TestConfigs(t *testing.T) {
 	}
 }
 
-func dropSelector(metric.InstrumentKind) aggregation.Aggregation {
-	return aggregation.Drop{}
+func dropSelector(metric.InstrumentKind) metric.Aggregation {
+	return metric.AggregationDrop{}
 }
 
 func deltaSelector(metric.InstrumentKind) metricdata.Temporality {

internal/shared/otlp/otlpmetric/otest/client_test.go.tmpl

@@ -24,7 +24,6 @@ import (
 	"go.opentelemetry.io/otel"
 	"{{ .internalImportPath }}"
 	"go.opentelemetry.io/otel/sdk/metric"
-	"go.opentelemetry.io/otel/sdk/metric/aggregation"
 	"go.opentelemetry.io/otel/sdk/metric/metricdata"
 	cpb "go.opentelemetry.io/proto/otlp/collector/metrics/v1"
 	mpb "go.opentelemetry.io/proto/otlp/metrics/v1"
@@ -39,7 +38,7 @@ func (c *client) Temporality(k metric.InstrumentKind) metricdata.Temporality {
 	return metric.DefaultTemporalitySelector(k)
 }
 
-func (c *client) Aggregation(k metric.InstrumentKind) aggregation.Aggregation {
+func (c *client) Aggregation(k metric.InstrumentKind) metric.Aggregation {
 	return metric.DefaultAggregationSelector(k)
 }
 

sdk/metric/aggregation.go

@@ -0,0 +1,201 @@
+// Copyright The OpenTelemetry Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package metric // import "go.opentelemetry.io/otel/sdk/metric"
+
+import (
+	"errors"
+	"fmt"
+)
+
+// errAgg is wrapped by misconfigured aggregations.
+var errAgg = errors.New("aggregation")
+
+// Aggregation is the aggregation used to summarize recorded measurements.
+type Aggregation interface {
+	// copy returns a deep copy of the Aggregation.
+	copy() Aggregation
+
+	// err returns an error for any misconfigured Aggregation.
+	err() error
+}
+
+// AggregationDrop is an Aggregation that drops all recorded data.
+type AggregationDrop struct{} // AggregationDrop has no parameters.
+
+var _ Aggregation = AggregationDrop{}
+
+// copy returns a deep copy of d.
+func (d AggregationDrop) copy() Aggregation { return d }
+
+// err returns an error for any misconfiguration. A drop aggregation has no
+// parameters and cannot be misconfigured, therefore this always returns nil.
+func (AggregationDrop) err() error { return nil }
+
+// AggregationDefault is an Aggregation that uses the default instrument kind selection
+// mapping to select another Aggregation. A metric reader can be configured to
+// make an aggregation selection based on instrument kind that differs from
+// the default. This Aggregation ensures the default is used.
+//
+// See the "go.opentelemetry.io/otel/sdk/metric".DefaultAggregationSelector
+// for information about the default instrument kind selection mapping.
+type AggregationDefault struct{} // AggregationDefault has no parameters.
+
+var _ Aggregation = AggregationDefault{}
+
+// copy returns a deep copy of d.
+func (d AggregationDefault) copy() Aggregation { return d }
+
+// err returns an error for any misconfiguration. A default aggregation has no
+// parameters and cannot be misconfigured, therefore this always returns nil.
+func (AggregationDefault) err() error { return nil }
+
+// AggregationSum is an Aggregation that summarizes a set of measurements as their
+// arithmetic sum.
+type AggregationSum struct{} // AggregationSum has no parameters.
+
+var _ Aggregation = AggregationSum{}
+
+// copy returns a deep copy of s.
+func (s AggregationSum) copy() Aggregation { return s }
+
+// err returns an error for any misconfiguration. A sum aggregation has no
+// parameters and cannot be misconfigured, therefore this always returns nil.
+func (AggregationSum) err() error { return nil }
+
+// AggregationLastValue is an Aggregation that summarizes a set of measurements as the
+// last one made.
+type AggregationLastValue struct{} // AggregationLastValue has no parameters.
+
+var _ Aggregation = AggregationLastValue{}
+
+// copy returns a deep copy of l.
+func (l AggregationLastValue) copy() Aggregation { return l }
+
+// err returns an error for any misconfiguration. A last-value aggregation has
+// no parameters and cannot be misconfigured, therefore this always returns
+// nil.
+func (AggregationLastValue) err() error { return nil }
+
+// AggregationExplicitBucketHistogram is an Aggregation that summarizes a set of
+// measurements as an histogram with explicitly defined buckets.
+type AggregationExplicitBucketHistogram struct {
+	// Boundaries are the increasing bucket boundary values. Boundary values
+	// define bucket upper bounds. Buckets are exclusive of their lower
+	// boundary and inclusive of their upper bound (except at positive
+	// infinity). A measurement is defined to fall into the greatest-numbered
+	// bucket with a boundary that is greater than or equal to the
+	// measurement. As an example, boundaries defined as:
+	//
+	// []float64{0, 5, 10, 25, 50, 75, 100, 250, 500, 1000}
+	//
+	// Will define these buckets:
+	//
+	// (-∞, 0], (0, 5.0], (5.0, 10.0], (10.0, 25.0], (25.0, 50.0],
+	// (50.0, 75.0], (75.0, 100.0], (100.0, 250.0], (250.0, 500.0],
+	// (500.0, 1000.0], (1000.0, +∞)
+	Boundaries []float64
+	// NoMinMax indicates whether to not record the min and max of the
+	// distribution. By default, these extrema are recorded.
+	//
+	// Recording these extrema for cumulative data is expected to have little
+	// value, they will represent the entire life of the instrument instead of
+	// just the current collection cycle. It is recommended to set this to true
+	// for that type of data to avoid computing the low-value extrema.
+	NoMinMax bool
+}
+
+var _ Aggregation = AggregationExplicitBucketHistogram{}
+
+// errHist is returned by misconfigured ExplicitBucketHistograms.
+var errHist = fmt.Errorf("%w: explicit bucket histogram", errAgg)
+
+// err returns an error for any misconfiguration.
+func (h AggregationExplicitBucketHistogram) err() error {
+	if len(h.Boundaries) <= 1 {
+		return nil
+	}
+
+	// Check boundaries are monotonic.
+	i := h.Boundaries[0]
+	for _, j := range h.Boundaries[1:] {
+		if i >= j {
+			return fmt.Errorf("%w: non-monotonic boundaries: %v", errHist, h.Boundaries)
+		}
+		i = j
+	}
+
+	return nil
+}
+
+// copy returns a deep copy of h.
+func (h AggregationExplicitBucketHistogram) copy() Aggregation {
+	b := make([]float64, len(h.Boundaries))
+	copy(b, h.Boundaries)
+	return AggregationExplicitBucketHistogram{
+		Boundaries: b,
+		NoMinMax:   h.NoMinMax,
+	}
+}
+
+// AggregationBase2ExponentialHistogram is an Aggregation that summarizes a set of
+// measurements as an histogram with bucket widths that grow exponentially.
+type AggregationBase2ExponentialHistogram struct {
+	// MaxSize is the maximum number of buckets to use for the histogram.
+	MaxSize int32
+	// MaxScale is the maximum resolution scale to use for the histogram.
+	//
+	// MaxScale has a maximum value of 20. Using a value of 20 means the
+	// maximum number of buckets that can fit within the range of a
+	// signed 32-bit integer index could be used.
+	//
+	// MaxScale has a minimum value of -10. Using a value of -10 means only
+	// two buckets will be use.
+	MaxScale int32
+
+	// NoMinMax indicates whether to not record the min and max of the
+	// distribution. By default, these extrema are recorded.
+	//
+	// Recording these extrema for cumulative data is expected to have little
+	// value, they will represent the entire life of the instrument instead of
+	// just the current collection cycle. It is recommended to set this to true
+	// for that type of data to avoid computing the low-value extrema.
+	NoMinMax bool
+}
+
+var _ Aggregation = AggregationBase2ExponentialHistogram{}
+
+// copy returns a deep copy of the Aggregation.
+func (e AggregationBase2ExponentialHistogram) copy() Aggregation {
+	return e
+}
+
+const (
+	expoMaxScale = 20
+	expoMinScale = -10
+)
+
+// errExpoHist is returned by misconfigured Base2ExponentialBucketHistograms.
+var errExpoHist = fmt.Errorf("%w: exponential histogram", errAgg)
+
+// err returns an error for any misconfigured Aggregation.
+func (e AggregationBase2ExponentialHistogram) err() error {
+	if e.MaxScale > expoMaxScale {
+		return fmt.Errorf("%w: max size %d is greater than maximum scale %d", errExpoHist, e.MaxSize, expoMaxScale)
+	}
+	if e.MaxSize <= 0 {
+		return fmt.Errorf("%w: max size %d is less than or equal to zero", errExpoHist, e.MaxSize)
+	}
+	return nil
+}

sdk/metric/aggregation/aggregation.go

@@ -14,6 +14,9 @@
 
 // Package aggregation contains configuration types that define the
 // aggregation operation used to summarizes recorded measurements.
+//
+// Deprecated: Use the aggregation types in go.opentelemetry.io/otel/sdk/metric
+// instead.
 package aggregation // import "go.opentelemetry.io/otel/sdk/metric/aggregation"
 
 import (

sdk/metric/aggregation_test.go

@@ -0,0 +1,95 @@
+// Copyright The OpenTelemetry Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package metric
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestAggregationErr(t *testing.T) {
+	t.Run("DropOperation", func(t *testing.T) {
+		assert.NoError(t, AggregationDrop{}.err())
+	})
+
+	t.Run("SumOperation", func(t *testing.T) {
+		assert.NoError(t, AggregationSum{}.err())
+	})
+
+	t.Run("LastValueOperation", func(t *testing.T) {
+		assert.NoError(t, AggregationLastValue{}.err())
+	})
+
+	t.Run("ExplicitBucketHistogramOperation", func(t *testing.T) {
+		assert.NoError(t, AggregationExplicitBucketHistogram{}.err())
+
+		assert.NoError(t, AggregationExplicitBucketHistogram{
+			Boundaries: []float64{0},
+			NoMinMax:   true,
+		}.err())
+
+		assert.NoError(t, AggregationExplicitBucketHistogram{
+			Boundaries: []float64{0, 5, 10, 25, 50, 75, 100, 250, 500, 1000},
+		}.err())
+	})
+
+	t.Run("NonmonotonicHistogramBoundaries", func(t *testing.T) {
+		assert.ErrorIs(t, AggregationExplicitBucketHistogram{
+			Boundaries: []float64{2, 1},
+		}.err(), errAgg)
+
+		assert.ErrorIs(t, AggregationExplicitBucketHistogram{
+			Boundaries: []float64{0, 1, 2, 1, 3, 4},
+		}.err(), errAgg)
+	})
+
+	t.Run("ExponentialHistogramOperation", func(t *testing.T) {
+		assert.NoError(t, AggregationBase2ExponentialHistogram{
+			MaxSize:  160,
+			MaxScale: 20,
+		}.err())
+
+		assert.NoError(t, AggregationBase2ExponentialHistogram{
+			MaxSize:  1,
+			NoMinMax: true,
+		}.err())
+
+		assert.NoError(t, AggregationBase2ExponentialHistogram{
+			MaxSize:  1024,
+			MaxScale: -3,
+		}.err())
+	})
+
+	t.Run("InvalidExponentialHistogramOperation", func(t *testing.T) {
+		// MazSize must be greater than 0
+		assert.ErrorIs(t, AggregationBase2ExponentialHistogram{}.err(), errAgg)
+
+		// MaxScale Must be <=20
+		assert.ErrorIs(t, AggregationBase2ExponentialHistogram{
+			MaxSize:  1,
+			MaxScale: 30,
+		}.err(), errAgg)
+	})
+}
+
+func TestExplicitBucketHistogramDeepCopy(t *testing.T) {
+	const orig = 0.0
+	b := []float64{orig}
+	h := AggregationExplicitBucketHistogram{Boundaries: b}
+	cpH := h.copy().(AggregationExplicitBucketHistogram)
+	b[0] = orig + 1
+	assert.Equal(t, orig, cpH.Boundaries[0], "changing the underlying slice data should not affect the copy")
+}

sdk/metric/benchmark_test.go

@@ -23,7 +23,6 @@ import (
 
 	"go.opentelemetry.io/otel/attribute"
 	"go.opentelemetry.io/otel/metric"
-	"go.opentelemetry.io/otel/sdk/metric/aggregation"
 	"go.opentelemetry.io/otel/sdk/metric/metricdata"
 )
 
@@ -36,7 +35,7 @@ var viewBenchmarks = []struct {
 		"DropView",
 		[]View{NewView(
 			Instrument{Name: "*"},
-			Stream{Aggregation: aggregation.Drop{}},
+			Stream{Aggregation: AggregationDrop{}},
 		)},
 	},
 	{

sdk/metric/config_test.go

@@ -22,7 +22,6 @@ import (
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
 
-	"go.opentelemetry.io/otel/sdk/metric/aggregation"
 	"go.opentelemetry.io/otel/sdk/metric/metricdata"
 	"go.opentelemetry.io/otel/sdk/resource"
 )
@@ -39,7 +38,7 @@ type reader struct {
 
 var _ Reader = (*reader)(nil)
 
-func (r *reader) aggregation(kind InstrumentKind) aggregation.Aggregation { // nolint:revive  // import-shadow for method scoped by type.
+func (r *reader) aggregation(kind InstrumentKind) Aggregation { // nolint:revive  // import-shadow for method scoped by type.
 	return r.aggregationFunc(kind)
 }
 

sdk/metric/exporter.go

@@ -18,7 +18,6 @@ import (
 	"context"
 	"fmt"
 
-	"go.opentelemetry.io/otel/sdk/metric/aggregation"
 	"go.opentelemetry.io/otel/sdk/metric/metricdata"
 )
 
@@ -39,7 +38,7 @@ type Exporter interface {
 	//
 	// This method needs to be concurrent safe with itself and all the other
 	// Exporter methods.
-	Aggregation(InstrumentKind) aggregation.Aggregation
+	Aggregation(InstrumentKind) Aggregation
 
 	// Export serializes and transmits metric data to a receiver.
 	//

sdk/metric/instrument.go

@@ -26,7 +26,6 @@ import (
 	"go.opentelemetry.io/otel/metric"
 	"go.opentelemetry.io/otel/metric/embedded"
 	"go.opentelemetry.io/otel/sdk/instrumentation"
-	"go.opentelemetry.io/otel/sdk/metric/aggregation"
 	"go.opentelemetry.io/otel/sdk/metric/internal/aggregate"
 )
 
@@ -146,7 +145,7 @@ type Stream struct {
 	// Unit is the unit of measurement recorded.
 	Unit string
 	// Aggregation the stream uses for an instrument.
-	Aggregation aggregation.Aggregation
+	Aggregation Aggregation
 	// AllowAttributeKeys are an allow-list of attribute keys that will be
 	// preserved for the stream. Any attribute recorded for the stream with a
 	// key not in this slice will be dropped.

sdk/metric/internal/aggregate/aggregate.go

@@ -19,7 +19,6 @@ import (
 	"time"
 
 	"go.opentelemetry.io/otel/attribute"
-	"go.opentelemetry.io/otel/sdk/metric/aggregation"
 	"go.opentelemetry.io/otel/sdk/metric/metricdata"
 )
 
@@ -102,8 +101,8 @@ func (b Builder[N]) Sum(monotonic bool) (Measure[N], ComputeAggregation) {
 
 // ExplicitBucketHistogram returns a histogram aggregate function input and
 // output.
-func (b Builder[N]) ExplicitBucketHistogram(cfg aggregation.ExplicitBucketHistogram, noSum bool) (Measure[N], ComputeAggregation) {
-	h := newHistogram[N](cfg, noSum)
+func (b Builder[N]) ExplicitBucketHistogram(boundaries []float64, noMinMax, noSum bool) (Measure[N], ComputeAggregation) {
+	h := newHistogram[N](boundaries, noMinMax, noSum)
 	switch b.Temporality {
 	case metricdata.DeltaTemporality:
 		return b.filter(h.measure), h.delta
@@ -114,8 +113,8 @@ func (b Builder[N]) ExplicitBucketHistogram(cfg aggregation.ExplicitBucketHistog
 
 // ExponentialBucketHistogram returns a histogram aggregate function input and
 // output.
-func (b Builder[N]) ExponentialBucketHistogram(cfg aggregation.Base2ExponentialHistogram, noSum bool) (Measure[N], ComputeAggregation) {
-	h := newExponentialHistogram[N](cfg, noSum)
+func (b Builder[N]) ExponentialBucketHistogram(maxSize, maxScale int32, noMinMax, noSum bool) (Measure[N], ComputeAggregation) {
+	h := newExponentialHistogram[N](maxSize, maxScale, noMinMax, noSum)
 	switch b.Temporality {
 	case metricdata.DeltaTemporality:
 		return b.filter(h.measure), h.delta

sdk/metric/internal/aggregate/exponential_histogram.go

@@ -23,7 +23,6 @@ import (
 
 	"go.opentelemetry.io/otel"
 	"go.opentelemetry.io/otel/attribute"
-	"go.opentelemetry.io/otel/sdk/metric/aggregation"
 	"go.opentelemetry.io/otel/sdk/metric/metricdata"
 )
 
@@ -326,12 +325,12 @@ func (b *expoBuckets) downscale(delta int) {
 // newExponentialHistogram returns an Aggregator that summarizes a set of
 // measurements as an exponential histogram. Each histogram is scoped by attributes
 // and the aggregation cycle the measurements were made in.
-func newExponentialHistogram[N int64 | float64](cfg aggregation.Base2ExponentialHistogram, noSum bool) *expoHistogram[N] {
+func newExponentialHistogram[N int64 | float64](maxSize, maxScale int32, noMinMax, noSum bool) *expoHistogram[N] {
 	return &expoHistogram[N]{
 		expoHistogramValues: newExpoHistValues[N](
-			int(cfg.MaxSize),
-			int(cfg.MaxScale),
-			cfg.NoMinMax,
+			int(maxSize),
+			int(maxScale),
+			noMinMax,
 			noSum,
 		),
 		start: now(),

sdk/metric/internal/aggregate/exponential_histogram_test.go

@@ -25,7 +25,6 @@ import (
 
 	"go.opentelemetry.io/otel/attribute"
 	"go.opentelemetry.io/otel/internal/global"
-	"go.opentelemetry.io/otel/sdk/metric/aggregation"
 	"go.opentelemetry.io/otel/sdk/metric/metricdata"
 	"go.opentelemetry.io/otel/sdk/metric/metricdata/metricdatatest"
 )
@@ -645,31 +644,33 @@ func BenchmarkAppend(b *testing.B) {
 	}
 }
 
-var expoHistConf = aggregation.Base2ExponentialHistogram{
-	MaxSize:  160,
-	MaxScale: 20,
-}
-
 func BenchmarkExponentialHistogram(b *testing.B) {
+	const (
+		maxSize  = 160
+		maxScale = 20
+		noMinMax = false
+		noSum    = false
+	)
+
 	b.Run("Int64/Cumulative", benchmarkAggregate(func() (Measure[int64], ComputeAggregation) {
 		return Builder[int64]{
 			Temporality: metricdata.CumulativeTemporality,
-		}.ExponentialBucketHistogram(expoHistConf, false)
+		}.ExponentialBucketHistogram(maxSize, maxScale, noMinMax, noSum)
 	}))
 	b.Run("Int64/Delta", benchmarkAggregate(func() (Measure[int64], ComputeAggregation) {
 		return Builder[int64]{
 			Temporality: metricdata.DeltaTemporality,
-		}.ExponentialBucketHistogram(expoHistConf, false)
+		}.ExponentialBucketHistogram(maxSize, maxScale, noMinMax, noSum)
 	}))
 	b.Run("Float64/Cumulative", benchmarkAggregate(func() (Measure[float64], ComputeAggregation) {
 		return Builder[float64]{
 			Temporality: metricdata.CumulativeTemporality,
-		}.ExponentialBucketHistogram(expoHistConf, false)
+		}.ExponentialBucketHistogram(maxSize, maxScale, noMinMax, noSum)
 	}))
 	b.Run("Float64/Delta", benchmarkAggregate(func() (Measure[float64], ComputeAggregation) {
 		return Builder[float64]{
 			Temporality: metricdata.DeltaTemporality,
-		}.ExponentialBucketHistogram(expoHistConf, false)
+		}.ExponentialBucketHistogram(maxSize, maxScale, noMinMax, noSum)
 	}))
 }
 
@@ -711,10 +712,12 @@ type exponentialHistogramAggregationTestCase[N int64 | float64] struct {
 }
 
 func testExponentialHistogramAggregation[N int64 | float64](t *testing.T) {
-	cfg := aggregation.Base2ExponentialHistogram{
-		MaxSize:  4,
-		MaxScale: 20,
-	}
+	const (
+		maxSize  = 4
+		maxScale = 20
+		noMinMax = false
+		noSum    = false
+	)
 
 	tests := []exponentialHistogramAggregationTestCase[N]{
 		{
@@ -722,7 +725,7 @@ func testExponentialHistogramAggregation[N int64 | float64](t *testing.T) {
 			build: func() (Measure[N], ComputeAggregation) {
 				return Builder[N]{
 					Temporality: metricdata.DeltaTemporality,
-				}.ExponentialBucketHistogram(cfg, false)
+				}.ExponentialBucketHistogram(maxSize, maxScale, noMinMax, noSum)
 			},
 			input: [][]N{
 				{4, 4, 4, 2, 16, 1},
@@ -750,7 +753,7 @@ func testExponentialHistogramAggregation[N int64 | float64](t *testing.T) {
 			build: func() (Measure[N], ComputeAggregation) {
 				return Builder[N]{
 					Temporality: metricdata.CumulativeTemporality,
-				}.ExponentialBucketHistogram(cfg, false)
+				}.ExponentialBucketHistogram(maxSize, maxScale, noMinMax, noSum)
 			},
 			input: [][]N{
 				{4, 4, 4, 2, 16, 1},
@@ -778,7 +781,7 @@ func testExponentialHistogramAggregation[N int64 | float64](t *testing.T) {
 			build: func() (Measure[N], ComputeAggregation) {
 				return Builder[N]{
 					Temporality: metricdata.DeltaTemporality,
-				}.ExponentialBucketHistogram(cfg, false)
+				}.ExponentialBucketHistogram(maxSize, maxScale, noMinMax, noSum)
 			},
 			input: [][]N{
 				{2, 3, 8},
@@ -807,7 +810,7 @@ func testExponentialHistogramAggregation[N int64 | float64](t *testing.T) {
 			build: func() (Measure[N], ComputeAggregation) {
 				return Builder[N]{
 					Temporality: metricdata.CumulativeTemporality,
-				}.ExponentialBucketHistogram(cfg, false)
+				}.ExponentialBucketHistogram(maxSize, maxScale, noMinMax, noSum)
 			},
 			input: [][]N{
 				{2, 3, 8},

sdk/metric/internal/aggregate/histogram.go

@@ -21,7 +21,6 @@ import (
 	"time"
 
 	"go.opentelemetry.io/otel/attribute"
-	"go.opentelemetry.io/otel/sdk/metric/aggregation"
 	"go.opentelemetry.io/otel/sdk/metric/metricdata"
 )
 
@@ -109,10 +108,10 @@ func (s *histValues[N]) measure(_ context.Context, value N, attr attribute.Set)
 
 // newHistogram returns an Aggregator that summarizes a set of measurements as
 // an histogram.
-func newHistogram[N int64 | float64](cfg aggregation.ExplicitBucketHistogram, noSum bool) *histogram[N] {
+func newHistogram[N int64 | float64](boundaries []float64, noMinMax, noSum bool) *histogram[N] {
 	return &histogram[N]{
-		histValues: newHistValues[N](cfg.Boundaries, noSum),
-		noMinMax:   cfg.NoMinMax,
+		histValues: newHistValues[N](boundaries, noSum),
+		noMinMax:   noMinMax,
 		start:      now(),
 	}
 }

sdk/metric/internal/aggregate/histogram_test.go

@@ -23,17 +23,13 @@ import (
 	"github.com/stretchr/testify/require"
 
 	"go.opentelemetry.io/otel/attribute"
-	"go.opentelemetry.io/otel/sdk/metric/aggregation"
 	"go.opentelemetry.io/otel/sdk/metric/metricdata"
 	"go.opentelemetry.io/otel/sdk/metric/metricdata/metricdatatest"
 )
 
 var (
 	bounds   = []float64{1, 5}
-	histConf = aggregation.ExplicitBucketHistogram{
-		Boundaries: bounds,
-		NoMinMax:   false,
-	}
+	noMinMax = false
 )
 
 func TestHistogram(t *testing.T) {
@@ -59,7 +55,7 @@ func testDeltaHist[N int64 | float64](c conf[N]) func(t *testing.T) {
 	in, out := Builder[N]{
 		Temporality: metricdata.DeltaTemporality,
 		Filter:      attrFltr,
-	}.ExplicitBucketHistogram(histConf, c.noSum)
+	}.ExplicitBucketHistogram(bounds, noMinMax, c.noSum)
 	ctx := context.Background()
 	return test[N](in, out, []teststep[N]{
 		{
@@ -125,7 +121,7 @@ func testCumulativeHist[N int64 | float64](c conf[N]) func(t *testing.T) {
 	in, out := Builder[N]{
 		Temporality: metricdata.CumulativeTemporality,
 		Filter:      attrFltr,
-	}.ExplicitBucketHistogram(histConf, c.noSum)
+	}.ExplicitBucketHistogram(bounds, noMinMax, c.noSum)
 	ctx := context.Background()
 	return test[N](in, out, []teststep[N]{
 		{
@@ -277,7 +273,7 @@ func TestHistogramImmutableBounds(t *testing.T) {
 	cpB := make([]float64, len(b))
 	copy(cpB, b)
 
-	h := newHistogram[int64](aggregation.ExplicitBucketHistogram{Boundaries: b}, false)
+	h := newHistogram[int64](b, false, false)
 	require.Equal(t, cpB, h.bounds)
 
 	b[0] = 10
@@ -293,7 +289,7 @@ func TestHistogramImmutableBounds(t *testing.T) {
 }
 
 func TestCumulativeHistogramImutableCounts(t *testing.T) {
-	h := newHistogram[int64](histConf, false)
+	h := newHistogram[int64](bounds, noMinMax, false)
 	h.measure(context.Background(), 5, alice)
 
 	var data metricdata.Aggregation = metricdata.Histogram[int64]{}
@@ -311,7 +307,7 @@ func TestCumulativeHistogramImutableCounts(t *testing.T) {
 func TestDeltaHistogramReset(t *testing.T) {
 	t.Cleanup(mockTime(now))
 
-	h := newHistogram[int64](histConf, false)
+	h := newHistogram[int64](bounds, noMinMax, false)
 
 	var data metricdata.Aggregation = metricdata.Histogram[int64]{}
 	require.Equal(t, 0, h.delta(&data))
@@ -340,21 +336,21 @@ func BenchmarkHistogram(b *testing.B) {
 	b.Run("Int64/Cumulative", benchmarkAggregate(func() (Measure[int64], ComputeAggregation) {
 		return Builder[int64]{
 			Temporality: metricdata.CumulativeTemporality,
-		}.ExplicitBucketHistogram(histConf, false)
+		}.ExplicitBucketHistogram(bounds, noMinMax, false)
 	}))
 	b.Run("Int64/Delta", benchmarkAggregate(func() (Measure[int64], ComputeAggregation) {
 		return Builder[int64]{
 			Temporality: metricdata.DeltaTemporality,
-		}.ExplicitBucketHistogram(histConf, false)
+		}.ExplicitBucketHistogram(bounds, noMinMax, false)
 	}))
 	b.Run("Float64/Cumulative", benchmarkAggregate(func() (Measure[float64], ComputeAggregation) {
 		return Builder[float64]{
 			Temporality: metricdata.CumulativeTemporality,
-		}.ExplicitBucketHistogram(histConf, false)
+		}.ExplicitBucketHistogram(bounds, noMinMax, false)
 	}))
 	b.Run("Float64/Delta", benchmarkAggregate(func() (Measure[float64], ComputeAggregation) {
 		return Builder[float64]{
 			Temporality: metricdata.DeltaTemporality,
-		}.ExplicitBucketHistogram(histConf, false)
+		}.ExplicitBucketHistogram(bounds, noMinMax, false)
 	}))
 }

sdk/metric/manual_reader.go

@@ -22,7 +22,6 @@ import (
 	"sync/atomic"
 
 	"go.opentelemetry.io/otel/internal/global"
-	"go.opentelemetry.io/otel/sdk/metric/aggregation"
 	"go.opentelemetry.io/otel/sdk/metric/metricdata"
 )
 
@@ -70,7 +69,7 @@ func (mr *ManualReader) temporality(kind InstrumentKind) metricdata.Temporality
 }
 
 // aggregation returns what Aggregation to use for kind.
-func (mr *ManualReader) aggregation(kind InstrumentKind) aggregation.Aggregation { // nolint:revive  // import-shadow for method scoped by type.
+func (mr *ManualReader) aggregation(kind InstrumentKind) Aggregation { // nolint:revive  // import-shadow for method scoped by type.
 	return mr.aggregationSelector(kind)
 }
 
@@ -201,25 +200,7 @@ func (t temporalitySelectorOption) applyManual(mrc manualReaderConfig) manualRea
 // this option is not used, the reader will use the DefaultAggregationSelector
 // or the aggregation explicitly passed for a view matching an instrument.
 func WithAggregationSelector(selector AggregationSelector) ManualReaderOption {
-	// Deep copy and validate before using.
-	wrapped := func(ik InstrumentKind) aggregation.Aggregation {
-		a := selector(ik)
-		if a == nil {
-			return nil
-		}
-		cpA := a.Copy()
-		if err := cpA.Err(); err != nil {
-			cpA = DefaultAggregationSelector(ik)
-			global.Error(
-				err, "using default aggregation instead",
-				"aggregation", a,
-				"replacement", cpA,
-			)
-		}
-		return cpA
-	}
-
-	return aggregationSelectorOption{selector: wrapped}
+	return aggregationSelectorOption{selector: selector}
 }
 
 type aggregationSelectorOption struct {

sdk/metric/meter_test.go

@@ -31,7 +31,6 @@ import (
 	"go.opentelemetry.io/otel/internal/global"
 	"go.opentelemetry.io/otel/metric"
 	"go.opentelemetry.io/otel/sdk/instrumentation"
-	"go.opentelemetry.io/otel/sdk/metric/aggregation"
 	"go.opentelemetry.io/otel/sdk/metric/metricdata"
 	"go.opentelemetry.io/otel/sdk/metric/metricdata/metricdatatest"
 	"go.opentelemetry.io/otel/sdk/resource"
@@ -1137,8 +1136,8 @@ func TestUnregisterUnregisters(t *testing.T) {
 }
 
 func TestRegisterCallbackDropAggregations(t *testing.T) {
-	aggFn := func(InstrumentKind) aggregation.Aggregation {
-		return aggregation.Drop{}
+	aggFn := func(InstrumentKind) Aggregation {
+		return AggregationDrop{}
 	}
 	r := NewManualReader(WithAggregationSelector(aggFn))
 	mp := NewMeterProvider(WithReader(r))
@@ -1818,11 +1817,11 @@ func BenchmarkInstrumentCreation(b *testing.B) {
 	}
 }
 
-func testNilAggregationSelector(InstrumentKind) aggregation.Aggregation {
+func testNilAggregationSelector(InstrumentKind) Aggregation {
 	return nil
 }
-func testDefaultAggregationSelector(InstrumentKind) aggregation.Aggregation {
-	return aggregation.Default{}
+func testDefaultAggregationSelector(InstrumentKind) Aggregation {
+	return AggregationDefault{}
 }
 func testUndefinedTemporalitySelector(InstrumentKind) metricdata.Temporality {
 	return metricdata.Temporality(0)

sdk/metric/periodic_reader.go

@@ -24,7 +24,6 @@ import (
 
 	"go.opentelemetry.io/otel"
 	"go.opentelemetry.io/otel/internal/global"
-	"go.opentelemetry.io/otel/sdk/metric/aggregation"
 	"go.opentelemetry.io/otel/sdk/metric/metricdata"
 )
 
@@ -204,7 +203,7 @@ func (r *PeriodicReader) temporality(kind InstrumentKind) metricdata.Temporality
 }
 
 // aggregation returns what Aggregation to use for kind.
-func (r *PeriodicReader) aggregation(kind InstrumentKind) aggregation.Aggregation { // nolint:revive  // import-shadow for method scoped by type.
+func (r *PeriodicReader) aggregation(kind InstrumentKind) Aggregation { // nolint:revive  // import-shadow for method scoped by type.
 	return r.exporter.Aggregation(kind)
 }
 

sdk/metric/periodic_reader_test.go

@@ -25,7 +25,6 @@ import (
 
 	"go.opentelemetry.io/otel"
 	"go.opentelemetry.io/otel/metric"
-	"go.opentelemetry.io/otel/sdk/metric/aggregation"
 	"go.opentelemetry.io/otel/sdk/metric/metricdata"
 )
 
@@ -168,7 +167,7 @@ func (e *fnExporter) Temporality(k InstrumentKind) metricdata.Temporality {
 	return DefaultTemporalitySelector(k)
 }
 
-func (e *fnExporter) Aggregation(k InstrumentKind) aggregation.Aggregation {
+func (e *fnExporter) Aggregation(k InstrumentKind) Aggregation {
 	if e.aggregationFunc != nil {
 		return e.aggregationFunc(k)
 	}

sdk/metric/pipeline.go

@@ -27,7 +27,6 @@ import (
 	"go.opentelemetry.io/otel/metric"
 	"go.opentelemetry.io/otel/metric/embedded"
 	"go.opentelemetry.io/otel/sdk/instrumentation"
-	"go.opentelemetry.io/otel/sdk/metric/aggregation"
 	"go.opentelemetry.io/otel/sdk/metric/internal"
 	"go.opentelemetry.io/otel/sdk/metric/internal/aggregate"
 	"go.opentelemetry.io/otel/sdk/metric/metricdata"
@@ -308,14 +307,28 @@ type aggVal[N int64 | float64] struct {
 // is returned.
 func (i *inserter[N]) cachedAggregator(scope instrumentation.Scope, kind InstrumentKind, stream Stream) (meas aggregate.Measure[N], aggID uint64, err error) {
 	switch stream.Aggregation.(type) {
-	case nil, aggregation.Default:
+	case nil:
 		// Undefined, nil, means to use the default from the reader.
 		stream.Aggregation = i.pipeline.reader.aggregation(kind)
 		switch stream.Aggregation.(type) {
-		case nil, aggregation.Default:
+		case nil, AggregationDefault:
 			// If the reader returns default or nil use the default selector.
 			stream.Aggregation = DefaultAggregationSelector(kind)
+		default:
+			// Deep copy and validate before using.
+			stream.Aggregation = stream.Aggregation.copy()
+			if err := stream.Aggregation.err(); err != nil {
+				orig := stream.Aggregation
+				stream.Aggregation = DefaultAggregationSelector(kind)
+				global.Error(
+					err, "using default aggregation instead",
+					"aggregation", orig,
+					"replacement", stream.Aggregation,
+				)
+			}
 		}
+	case AggregationDefault:
+		stream.Aggregation = DefaultAggregationSelector(kind)
 	}
 
 	if err := isAggregatorCompatible(kind, stream.Aggregation); err != nil {
@@ -423,15 +436,15 @@ func (i *inserter[N]) instID(kind InstrumentKind, stream Stream) instID {
 // aggregateFunc returns new aggregate functions matching agg, kind, and
 // monotonic. If the agg is unknown or temporality is invalid, an error is
 // returned.
-func (i *inserter[N]) aggregateFunc(b aggregate.Builder[N], agg aggregation.Aggregation, kind InstrumentKind) (meas aggregate.Measure[N], comp aggregate.ComputeAggregation, err error) {
+func (i *inserter[N]) aggregateFunc(b aggregate.Builder[N], agg Aggregation, kind InstrumentKind) (meas aggregate.Measure[N], comp aggregate.ComputeAggregation, err error) {
 	switch a := agg.(type) {
-	case aggregation.Default:
+	case AggregationDefault:
 		return i.aggregateFunc(b, DefaultAggregationSelector(kind), kind)
-	case aggregation.Drop:
+	case AggregationDrop:
 		// Return nil in and out to signify the drop aggregator.
-	case aggregation.LastValue:
+	case AggregationLastValue:
 		meas, comp = b.LastValue()
-	case aggregation.Sum:
+	case AggregationSum:
 		switch kind {
 		case InstrumentKindObservableCounter:
 			meas, comp = b.PrecomputedSum(true)
@@ -444,7 +457,7 @@ func (i *inserter[N]) aggregateFunc(b aggregate.Builder[N], agg aggregation.Aggr
 			// instrumentKindUndefined or other invalid instrument kinds.
 			meas, comp = b.Sum(false)
 		}
-	case aggregation.ExplicitBucketHistogram:
+	case AggregationExplicitBucketHistogram:
 		var noSum bool
 		switch kind {
 		case InstrumentKindUpDownCounter, InstrumentKindObservableUpDownCounter, InstrumentKindObservableGauge:
@@ -453,8 +466,8 @@ func (i *inserter[N]) aggregateFunc(b aggregate.Builder[N], agg aggregation.Aggr
 			// https://github.com/open-telemetry/opentelemetry-specification/blob/v1.21.0/specification/metrics/sdk.md#histogram-aggregations
 			noSum = true
 		}
-		meas, comp = b.ExplicitBucketHistogram(a, noSum)
-	case aggregation.Base2ExponentialHistogram:
+		meas, comp = b.ExplicitBucketHistogram(a.Boundaries, a.NoMinMax, noSum)
+	case AggregationBase2ExponentialHistogram:
 		var noSum bool
 		switch kind {
 		case InstrumentKindUpDownCounter, InstrumentKindObservableUpDownCounter, InstrumentKindObservableGauge:
@@ -463,7 +476,7 @@ func (i *inserter[N]) aggregateFunc(b aggregate.Builder[N], agg aggregation.Aggr
 			// https://github.com/open-telemetry/opentelemetry-specification/blob/v1.21.0/specification/metrics/sdk.md#histogram-aggregations
 			noSum = true
 		}
-		meas, comp = b.ExponentialBucketHistogram(a, noSum)
+		meas, comp = b.ExponentialBucketHistogram(a.MaxSize, a.MaxScale, a.NoMinMax, noSum)
 
 	default:
 		err = errUnknownAggregation
@@ -483,11 +496,11 @@ func (i *inserter[N]) aggregateFunc(b aggregate.Builder[N], agg aggregation.Aggr
 // | Observable Counter       | ✓    |           | ✓   | ✓         | ✓                     |
 // | Observable UpDownCounter | ✓    |           | ✓   | ✓         | ✓                     |
 // | Observable Gauge         | ✓    | ✓         |     | ✓         | ✓                     |.
-func isAggregatorCompatible(kind InstrumentKind, agg aggregation.Aggregation) error {
+func isAggregatorCompatible(kind InstrumentKind, agg Aggregation) error {
 	switch agg.(type) {
-	case aggregation.Default:
+	case AggregationDefault:
 		return nil
-	case aggregation.ExplicitBucketHistogram, aggregation.Base2ExponentialHistogram:
+	case AggregationExplicitBucketHistogram, AggregationBase2ExponentialHistogram:
 		switch kind {
 		case InstrumentKindCounter,
 			InstrumentKindUpDownCounter,
@@ -499,7 +512,7 @@ func isAggregatorCompatible(kind InstrumentKind, agg aggregation.Aggregation) er
 		default:
 			return errIncompatibleAggregation
 		}
-	case aggregation.Sum:
+	case AggregationSum:
 		switch kind {
 		case InstrumentKindObservableCounter, InstrumentKindObservableUpDownCounter, InstrumentKindCounter, InstrumentKindHistogram, InstrumentKindUpDownCounter:
 			return nil
@@ -508,14 +521,14 @@ func isAggregatorCompatible(kind InstrumentKind, agg aggregation.Aggregation) er
 			// https://github.com/open-telemetry/opentelemetry-specification/issues/2710
 			return errIncompatibleAggregation
 		}
-	case aggregation.LastValue:
+	case AggregationLastValue:
 		if kind == InstrumentKindObservableGauge {
 			return nil
 		}
 		// TODO: review need for aggregation check after
 		// https://github.com/open-telemetry/opentelemetry-specification/issues/2710
 		return errIncompatibleAggregation
-	case aggregation.Drop:
+	case AggregationDrop:
 		return nil
 	default:
 		// This is used passed checking for default, it should be an error at this point.

sdk/metric/pipeline_registry_test.go

@@ -26,7 +26,6 @@ import (
 
 	"go.opentelemetry.io/otel"
 	"go.opentelemetry.io/otel/attribute"
-	"go.opentelemetry.io/otel/sdk/metric/aggregation"
 	"go.opentelemetry.io/otel/sdk/metric/internal/aggregate"
 	"go.opentelemetry.io/otel/sdk/metric/metricdata"
 	"go.opentelemetry.io/otel/sdk/metric/metricdata/metricdatatest"
@@ -35,14 +34,12 @@ import (
 
 var defaultView = NewView(Instrument{Name: "*"}, Stream{})
 
-type invalidAggregation struct {
-	aggregation.Aggregation
-}
+type invalidAggregation struct{}
 
-func (invalidAggregation) Copy() aggregation.Aggregation {
+func (invalidAggregation) copy() Aggregation {
 	return invalidAggregation{}
 }
-func (invalidAggregation) Err() error {
+func (invalidAggregation) err() error {
 	return nil
 }
 
@@ -146,7 +143,7 @@ func assertLastValue[N int64 | float64](t *testing.T, meas []aggregate.Measure[N
 func testCreateAggregators[N int64 | float64](t *testing.T) {
 	changeAggView := NewView(
 		Instrument{Name: "foo"},
-		Stream{Aggregation: aggregation.ExplicitBucketHistogram{
+		Stream{Aggregation: AggregationExplicitBucketHistogram{
 			Boundaries: []float64{0, 100},
 			NoMinMax:   true,
 		}},
@@ -176,7 +173,7 @@ func testCreateAggregators[N int64 | float64](t *testing.T) {
 	}{
 		{
 			name:   "Default/Drop",
-			reader: NewManualReader(WithAggregationSelector(func(ik InstrumentKind) aggregation.Aggregation { return aggregation.Drop{} })),
+			reader: NewManualReader(WithAggregationSelector(func(ik InstrumentKind) Aggregation { return AggregationDrop{} })),
 			inst:   instruments[InstrumentKindCounter],
 			validate: func(t *testing.T, meas []aggregate.Measure[N], comps []aggregate.ComputeAggregation, err error) {
 				t.Helper()
@@ -304,37 +301,37 @@ func testCreateAggregators[N int64 | float64](t *testing.T) {
 		},
 		{
 			name:     "Reader/Default/Cumulative/Sum/Monotonic",
-			reader:   NewManualReader(WithAggregationSelector(func(ik InstrumentKind) aggregation.Aggregation { return aggregation.Default{} })),
+			reader:   NewManualReader(WithAggregationSelector(func(ik InstrumentKind) Aggregation { return AggregationDefault{} })),
 			inst:     instruments[InstrumentKindCounter],
 			validate: assertSum[N](1, metricdata.CumulativeTemporality, true, [2]N{1, 4}),
 		},
 		{
 			name:     "Reader/Default/Cumulative/Sum/NonMonotonic",
-			reader:   NewManualReader(WithAggregationSelector(func(ik InstrumentKind) aggregation.Aggregation { return aggregation.Default{} })),
+			reader:   NewManualReader(WithAggregationSelector(func(ik InstrumentKind) Aggregation { return AggregationDefault{} })),
 			inst:     instruments[InstrumentKindUpDownCounter],
 			validate: assertSum[N](1, metricdata.CumulativeTemporality, false, [2]N{1, 4}),
 		},
 		{
 			name:     "Reader/Default/Cumulative/ExplicitBucketHistogram",
-			reader:   NewManualReader(WithAggregationSelector(func(ik InstrumentKind) aggregation.Aggregation { return aggregation.Default{} })),
+			reader:   NewManualReader(WithAggregationSelector(func(ik InstrumentKind) Aggregation { return AggregationDefault{} })),
 			inst:     instruments[InstrumentKindHistogram],
 			validate: assertHist[N](metricdata.CumulativeTemporality),
 		},
 		{
 			name:     "Reader/Default/Cumulative/PrecomputedSum/Monotonic",
-			reader:   NewManualReader(WithAggregationSelector(func(ik InstrumentKind) aggregation.Aggregation { return aggregation.Default{} })),
+			reader:   NewManualReader(WithAggregationSelector(func(ik InstrumentKind) Aggregation { return AggregationDefault{} })),
 			inst:     instruments[InstrumentKindObservableCounter],
 			validate: assertSum[N](1, metricdata.CumulativeTemporality, true, [2]N{1, 3}),
 		},
 		{
 			name:     "Reader/Default/Cumulative/PrecomputedSum/NonMonotonic",
-			reader:   NewManualReader(WithAggregationSelector(func(ik InstrumentKind) aggregation.Aggregation { return aggregation.Default{} })),
+			reader:   NewManualReader(WithAggregationSelector(func(ik InstrumentKind) Aggregation { return AggregationDefault{} })),
 			inst:     instruments[InstrumentKindObservableUpDownCounter],
 			validate: assertSum[N](1, metricdata.CumulativeTemporality, false, [2]N{1, 3}),
 		},
 		{
 			name:     "Reader/Default/Gauge",
-			reader:   NewManualReader(WithAggregationSelector(func(ik InstrumentKind) aggregation.Aggregation { return aggregation.Default{} })),
+			reader:   NewManualReader(WithAggregationSelector(func(ik InstrumentKind) Aggregation { return AggregationDefault{} })),
 			inst:     instruments[InstrumentKindObservableGauge],
 			validate: assertLastValue[N],
 		},
@@ -409,7 +406,7 @@ func TestPipelinesAggregatorForEachReader(t *testing.T) {
 func TestPipelineRegistryCreateAggregators(t *testing.T) {
 	renameView := NewView(Instrument{Name: "foo"}, Stream{Name: "bar"})
 	testRdr := NewManualReader()
-	testRdrHistogram := NewManualReader(WithAggregationSelector(func(ik InstrumentKind) aggregation.Aggregation { return aggregation.ExplicitBucketHistogram{} }))
+	testRdrHistogram := NewManualReader(WithAggregationSelector(func(ik InstrumentKind) Aggregation { return AggregationExplicitBucketHistogram{} }))
 
 	testCases := []struct {
 		name      string
@@ -498,7 +495,7 @@ func TestPipelineRegistryResource(t *testing.T) {
 }
 
 func TestPipelineRegistryCreateAggregatorsIncompatibleInstrument(t *testing.T) {
-	testRdrHistogram := NewManualReader(WithAggregationSelector(func(ik InstrumentKind) aggregation.Aggregation { return aggregation.Sum{} }))
+	testRdrHistogram := NewManualReader(WithAggregationSelector(func(ik InstrumentKind) Aggregation { return AggregationSum{} }))
 
 	readers := []Reader{testRdrHistogram}
 	views := []View{defaultView}
@@ -599,187 +596,187 @@ func TestIsAggregatorCompatible(t *testing.T) {
 	testCases := []struct {
 		name string
 		kind InstrumentKind
-		agg  aggregation.Aggregation
+		agg  Aggregation
 		want error
 	}{
 		{
 			name: "SyncCounter and Drop",
 			kind: InstrumentKindCounter,
-			agg:  aggregation.Drop{},
+			agg:  AggregationDrop{},
 		},
 		{
 			name: "SyncCounter and LastValue",
 			kind: InstrumentKindCounter,
-			agg:  aggregation.LastValue{},
+			agg:  AggregationLastValue{},
 			want: errIncompatibleAggregation,
 		},
 		{
 			name: "SyncCounter and Sum",
 			kind: InstrumentKindCounter,
-			agg:  aggregation.Sum{},
+			agg:  AggregationSum{},
 		},
 		{
 			name: "SyncCounter and ExplicitBucketHistogram",
 			kind: InstrumentKindCounter,
-			agg:  aggregation.ExplicitBucketHistogram{},
+			agg:  AggregationExplicitBucketHistogram{},
 		},
 		{
 			name: "SyncCounter and ExponentialHistogram",
 			kind: InstrumentKindCounter,
-			agg:  aggregation.Base2ExponentialHistogram{},
+			agg:  AggregationBase2ExponentialHistogram{},
 		},
 		{
 			name: "SyncUpDownCounter and Drop",
 			kind: InstrumentKindUpDownCounter,
-			agg:  aggregation.Drop{},
+			agg:  AggregationDrop{},
 		},
 		{
 			name: "SyncUpDownCounter and LastValue",
 			kind: InstrumentKindUpDownCounter,
-			agg:  aggregation.LastValue{},
+			agg:  AggregationLastValue{},
 			want: errIncompatibleAggregation,
 		},
 		{
 			name: "SyncUpDownCounter and Sum",
 			kind: InstrumentKindUpDownCounter,
-			agg:  aggregation.Sum{},
+			agg:  AggregationSum{},
 		},
 		{
 			name: "SyncUpDownCounter and ExplicitBucketHistogram",
 			kind: InstrumentKindUpDownCounter,
-			agg:  aggregation.ExplicitBucketHistogram{},
+			agg:  AggregationExplicitBucketHistogram{},
 		},
 		{
 			name: "SyncUpDownCounter and ExponentialHistogram",
 			kind: InstrumentKindUpDownCounter,
-			agg:  aggregation.Base2ExponentialHistogram{},
+			agg:  AggregationBase2ExponentialHistogram{},
 		},
 		{
 			name: "SyncHistogram and Drop",
 			kind: InstrumentKindHistogram,
-			agg:  aggregation.Drop{},
+			agg:  AggregationDrop{},
 		},
 		{
 			name: "SyncHistogram and LastValue",
 			kind: InstrumentKindHistogram,
-			agg:  aggregation.LastValue{},
+			agg:  AggregationLastValue{},
 			want: errIncompatibleAggregation,
 		},
 		{
 			name: "SyncHistogram and Sum",
 			kind: InstrumentKindHistogram,
-			agg:  aggregation.Sum{},
+			agg:  AggregationSum{},
 		},
 		{
 			name: "SyncHistogram and ExplicitBucketHistogram",
 			kind: InstrumentKindHistogram,
-			agg:  aggregation.ExplicitBucketHistogram{},
+			agg:  AggregationExplicitBucketHistogram{},
 		},
 		{
 			name: "SyncHistogram and ExponentialHistogram",
 			kind: InstrumentKindHistogram,
-			agg:  aggregation.Base2ExponentialHistogram{},
+			agg:  AggregationBase2ExponentialHistogram{},
 		},
 		{
 			name: "ObservableCounter and Drop",
 			kind: InstrumentKindObservableCounter,
-			agg:  aggregation.Drop{},
+			agg:  AggregationDrop{},
 		},
 		{
 			name: "ObservableCounter and LastValue",
 			kind: InstrumentKindObservableCounter,
-			agg:  aggregation.LastValue{},
+			agg:  AggregationLastValue{},
 			want: errIncompatibleAggregation,
 		},
 		{
 			name: "ObservableCounter and Sum",
 			kind: InstrumentKindObservableCounter,
-			agg:  aggregation.Sum{},
+			agg:  AggregationSum{},
 		},
 		{
 			name: "ObservableCounter and ExplicitBucketHistogram",
 			kind: InstrumentKindObservableCounter,
-			agg:  aggregation.ExplicitBucketHistogram{},
+			agg:  AggregationExplicitBucketHistogram{},
 		},
 		{
 			name: "ObservableCounter and ExponentialHistogram",
 			kind: InstrumentKindObservableCounter,
-			agg:  aggregation.Base2ExponentialHistogram{},
+			agg:  AggregationBase2ExponentialHistogram{},
 		},
 		{
 			name: "ObservableUpDownCounter and Drop",
 			kind: InstrumentKindObservableUpDownCounter,
-			agg:  aggregation.Drop{},
+			agg:  AggregationDrop{},
 		},
 		{
 			name: "ObservableUpDownCounter and LastValue",
 			kind: InstrumentKindObservableUpDownCounter,
-			agg:  aggregation.LastValue{},
+			agg:  AggregationLastValue{},
 			want: errIncompatibleAggregation,
 		},
 		{
 			name: "ObservableUpDownCounter and Sum",
 			kind: InstrumentKindObservableUpDownCounter,
-			agg:  aggregation.Sum{},
+			agg:  AggregationSum{},
 		},
 		{
 			name: "ObservableUpDownCounter and ExplicitBucketHistogram",
 			kind: InstrumentKindObservableUpDownCounter,
-			agg:  aggregation.ExplicitBucketHistogram{},
+			agg:  AggregationExplicitBucketHistogram{},
 		},
 		{
 			name: "ObservableUpDownCounter and ExponentialHistogram",
 			kind: InstrumentKindObservableUpDownCounter,
-			agg:  aggregation.Base2ExponentialHistogram{},
+			agg:  AggregationBase2ExponentialHistogram{},
 		},
 		{
 			name: "ObservableGauge and Drop",
 			kind: InstrumentKindObservableGauge,
-			agg:  aggregation.Drop{},
+			agg:  AggregationDrop{},
 		},
 		{
-			name: "ObservableGauge and aggregation.LastValue{}",
+			name: "ObservableGauge and LastValue{}",
 			kind: InstrumentKindObservableGauge,
-			agg:  aggregation.LastValue{},
+			agg:  AggregationLastValue{},
 		},
 		{
 			name: "ObservableGauge and Sum",
 			kind: InstrumentKindObservableGauge,
-			agg:  aggregation.Sum{},
+			agg:  AggregationSum{},
 			want: errIncompatibleAggregation,
 		},
 		{
 			name: "ObservableGauge and ExplicitBucketHistogram",
 			kind: InstrumentKindObservableGauge,
-			agg:  aggregation.ExplicitBucketHistogram{},
+			agg:  AggregationExplicitBucketHistogram{},
 		},
 		{
 			name: "ObservableGauge and ExponentialHistogram",
 			kind: InstrumentKindObservableGauge,
-			agg:  aggregation.Base2ExponentialHistogram{},
+			agg:  AggregationBase2ExponentialHistogram{},
 		},
 		{
 			name: "unknown kind with Sum should error",
 			kind: undefinedInstrument,
-			agg:  aggregation.Sum{},
+			agg:  AggregationSum{},
 			want: errIncompatibleAggregation,
 		},
 		{
 			name: "unknown kind with LastValue should error",
 			kind: undefinedInstrument,
-			agg:  aggregation.LastValue{},
+			agg:  AggregationLastValue{},
 			want: errIncompatibleAggregation,
 		},
 		{
 			name: "unknown kind with Histogram should error",
 			kind: undefinedInstrument,
-			agg:  aggregation.ExplicitBucketHistogram{},
+			agg:  AggregationExplicitBucketHistogram{},
 			want: errIncompatibleAggregation,
 		},
 		{
 			name: "unknown kind with Histogram should error",
 			kind: undefinedInstrument,
-			agg:  aggregation.Base2ExponentialHistogram{},
+			agg:  AggregationBase2ExponentialHistogram{},
 			want: errIncompatibleAggregation,
 		},
 	}

sdk/metric/pipeline_test.go

@@ -32,7 +32,6 @@ import (
 	"go.opentelemetry.io/otel"
 	"go.opentelemetry.io/otel/attribute"
 	"go.opentelemetry.io/otel/sdk/instrumentation"
-	"go.opentelemetry.io/otel/sdk/metric/aggregation"
 	"go.opentelemetry.io/otel/sdk/metric/metricdata"
 	"go.opentelemetry.io/otel/sdk/metric/metricdata/metricdatatest"
 	"go.opentelemetry.io/otel/sdk/resource"
@@ -366,7 +365,7 @@ func TestInserterCachedAggregatorNameConflict(t *testing.T) {
 	kind := InstrumentKindCounter
 	stream := Stream{
 		Name:        name,
-		Aggregation: aggregation.Sum{},
+		Aggregation: AggregationSum{},
 	}
 
 	var vc cache[string, instID]

sdk/metric/reader.go

@@ -18,7 +18,6 @@ import (
 	"context"
 	"fmt"
 
-	"go.opentelemetry.io/otel/sdk/metric/aggregation"
 	"go.opentelemetry.io/otel/sdk/metric/metricdata"
 )
 
@@ -67,7 +66,7 @@ type Reader interface {
 	//
 	// This method needs to be concurrent safe with itself and all the other
 	// Reader methods.
-	aggregation(InstrumentKind) aggregation.Aggregation // nolint:revive  // import-shadow for method scoped by type.
+	aggregation(InstrumentKind) Aggregation // nolint:revive  // import-shadow for method scoped by type.
 
 	// Collect gathers and returns all metric data related to the Reader from
 	// the SDK and stores it in out. An error is returned if this is called
@@ -137,7 +136,7 @@ func DefaultTemporalitySelector(InstrumentKind) metricdata.Temporality {
 //
 // If the Aggregation returned is nil or DefaultAggregation, the selection from
 // DefaultAggregationSelector will be used.
-type AggregationSelector func(InstrumentKind) aggregation.Aggregation
+type AggregationSelector func(InstrumentKind) Aggregation
 
 // DefaultAggregationSelector returns the default aggregation and parameters
 // that will be used to summarize measurement made from an instrument of
@@ -145,14 +144,14 @@ type AggregationSelector func(InstrumentKind) aggregation.Aggregation
 // mapping: Counter ⇨ Sum, Observable Counter ⇨ Sum, UpDownCounter ⇨ Sum,
 // Observable UpDownCounter ⇨ Sum, Observable Gauge ⇨ LastValue,
 // Histogram ⇨ ExplicitBucketHistogram.
-func DefaultAggregationSelector(ik InstrumentKind) aggregation.Aggregation {
+func DefaultAggregationSelector(ik InstrumentKind) Aggregation {
 	switch ik {
 	case InstrumentKindCounter, InstrumentKindUpDownCounter, InstrumentKindObservableCounter, InstrumentKindObservableUpDownCounter:
-		return aggregation.Sum{}
+		return AggregationSum{}
 	case InstrumentKindObservableGauge:
-		return aggregation.LastValue{}
+		return AggregationLastValue{}
 	case InstrumentKindHistogram:
-		return aggregation.ExplicitBucketHistogram{
+		return AggregationExplicitBucketHistogram{
 			Boundaries: []float64{0, 5, 10, 25, 50, 75, 100, 250, 500, 750, 1000, 2500, 5000, 7500, 10000},
 			NoMinMax:   false,
 		}

sdk/metric/reader_test.go

@@ -316,7 +316,7 @@ func TestDefaultAggregationSelector(t *testing.T) {
 	}
 
 	for _, ik := range iKinds {
-		assert.NoError(t, DefaultAggregationSelector(ik).Err(), ik)
+		assert.NoError(t, DefaultAggregationSelector(ik).err(), ik)
 	}
 }
 

sdk/metric/view.go

@@ -20,7 +20,6 @@ import (
 	"strings"
 
 	"go.opentelemetry.io/otel/internal/global"
-	"go.opentelemetry.io/otel/sdk/metric/aggregation"
 )
 
 var (
@@ -92,10 +91,10 @@ func NewView(criteria Instrument, mask Stream) View {
 		matchFunc = criteria.matches
 	}
 
-	var agg aggregation.Aggregation
+	var agg Aggregation
 	if mask.Aggregation != nil {
-		agg = mask.Aggregation.Copy()
-		if err := agg.Err(); err != nil {
+		agg = mask.Aggregation.copy()
+		if err := agg.err(); err != nil {
 			global.Error(
 				err, "not using aggregation with view",
 				"criteria", criteria,

sdk/metric/view_test.go

@@ -28,7 +28,6 @@ import (
 	"go.opentelemetry.io/otel"
 	"go.opentelemetry.io/otel/attribute"
 	"go.opentelemetry.io/otel/sdk/instrumentation"
-	"go.opentelemetry.io/otel/sdk/metric/aggregation"
 )
 
 var (
@@ -395,13 +394,13 @@ func TestNewViewReplace(t *testing.T) {
 		},
 		{
 			name: "Aggregation",
-			mask: Stream{Aggregation: aggregation.LastValue{}},
+			mask: Stream{Aggregation: AggregationLastValue{}},
 			want: func(i Instrument) Stream {
 				return Stream{
 					Name:        i.Name,
 					Description: i.Description,
 					Unit:        i.Unit,
-					Aggregation: aggregation.LastValue{},
+					Aggregation: AggregationLastValue{},
 				}
 			},
 		},
@@ -423,14 +422,14 @@ func TestNewViewReplace(t *testing.T) {
 				Name:        alt,
 				Description: alt,
 				Unit:        "1",
-				Aggregation: aggregation.LastValue{},
+				Aggregation: AggregationLastValue{},
 			},
 			want: func(i Instrument) Stream {
 				return Stream{
 					Name:        alt,
 					Description: alt,
 					Unit:        "1",
-					Aggregation: aggregation.LastValue{},
+					Aggregation: AggregationLastValue{},
 				}
 			},
 		},
@@ -446,20 +445,19 @@ func TestNewViewReplace(t *testing.T) {
 }
 
 type badAgg struct {
-	aggregation.Aggregation
-	err error
+	e error
 }
 
-func (a badAgg) Copy() aggregation.Aggregation { return a }
+func (a badAgg) copy() Aggregation { return a }
 
-func (a badAgg) Err() error { return a.err }
+func (a badAgg) err() error { return a.e }
 
 func TestNewViewAggregationErrorLogged(t *testing.T) {
 	tLog := testr.NewWithOptions(t, testr.Options{Verbosity: 6})
 	l := &logCounter{LogSink: tLog.GetSink()}
 	otel.SetLogger(logr.New(l))
 
-	agg := badAgg{err: assert.AnError}
+	agg := badAgg{e: assert.AnError}
 	mask := Stream{Aggregation: agg}
 	got, match := NewView(completeIP, mask)(completeIP)
 	require.True(t, match, "view did not match exact criteria")
@@ -532,7 +530,7 @@ func ExampleNewView_drop() {
 	// library.
 	view := NewView(
 		Instrument{Scope: instrumentation.Scope{Name: "db"}},
-		Stream{Aggregation: aggregation.Drop{}},
+		Stream{Aggregation: AggregationDrop{}},
 	)
 
 	// The created view can then be registered with the OpenTelemetry metric
@@ -548,7 +546,7 @@ func ExampleNewView_drop() {
 	fmt.Printf("aggregation: %#v", stream.Aggregation)
 	// Output:
 	// name: queries
-	// aggregation: aggregation.Drop{}
+	// aggregation: metric.AggregationDrop{}
 }
 
 func ExampleNewView_wildcard() {