Add internal package structure for aggregation

.github/workflows/ci.yml

@@ -8,7 +8,7 @@ env:
   # Path to where test results will be saved.
   TEST_RESULTS: /tmp/test-results
   # Default minimum version of Go to support.
-  DEFAULT_GO_VERSION: 1.17
+  DEFAULT_GO_VERSION: 1.18
 jobs:
   lint:
     runs-on: ubuntu-latest

sdk/metric/config.go

@@ -12,8 +12,8 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-//go:build go1.17
-// +build go1.17
+//go:build go1.18
+// +build go1.18
 
 package metric // import "go.opentelemetry.io/otel/sdk/metric"
 

sdk/metric/config_test.go

@@ -12,8 +12,8 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-//go:build go1.17
-// +build go1.17
+//go:build go1.18
+// +build go1.18
 
 package metric
 

sdk/metric/export/data.go

@@ -12,8 +12,8 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-//go:build go1.17
-// +build go1.17
+//go:build go1.18
+// +build go1.18
 
 // TODO: NOTE this is a temporary space, it may be moved following the
 // discussion of #2813, or #2841

sdk/metric/exporter.go

@@ -12,8 +12,8 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-//go:build go1.17
-// +build go1.17
+//go:build go1.18
+// +build go1.18
 
 package metric // import "go.opentelemetry.io/otel/sdk/metric"
 

sdk/metric/go.mod

@@ -1,6 +1,6 @@
 module go.opentelemetry.io/otel/sdk/metric
 
-go 1.17
+go 1.18
 
 require (
 	github.com/go-logr/logr v1.2.3

sdk/metric/go.sum

@@ -6,7 +6,6 @@ github.com/go-logr/logr v1.2.3/go.mod h1:jdQByPbusPIv2/zmleS9BjJVeZ6kBagPoEUsqbV
 github.com/go-logr/stdr v1.2.2 h1:hSWxHoqTgW2S2qGc0LTAI563KZ5YKYRhT3MFKZMbjag=
 github.com/go-logr/stdr v1.2.2/go.mod h1:mMo/vtBO5dYbehREoey6XUKy/eSumjCCveDpRre4VKE=
 github.com/google/go-cmp v0.5.8 h1:e6P7q2lk1O+qJJb4BtCQXlK8vWEO8V1ZeuEdJNOqZyg=
-github.com/google/go-cmp v0.5.8/go.mod h1:17dUlkBOakJ0+DkrSSNjCkIjxS6bF9zb3elmeNGIjoY=
 github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
 github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
 github.com/stretchr/objx v0.1.0/go.mod h1:HFkY916IF+rwdDfMAkV7OtwuqBVzrE8GR6GFx+wExME=

sdk/metric/instrumentkind.go

@@ -12,8 +12,8 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-//go:build go1.17
-// +build go1.17
+//go:build go1.18
+// +build go1.18
 
 package metric // import "go.opentelemetry.io/otel/sdk/metric"
 

sdk/metric/internal/aggtor/aggregation.go

@@ -0,0 +1,106 @@
+// 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.
+
+//go:build go1.18
+// +build go1.18
+
+package aggtor // import "go.opentelemetry.io/otel/sdk/metric/internal/aggtor"
+
+import (
+	"errors"
+	"fmt"
+)
+
+// Aggregation is a single data point in a timeseries that summarizes
+// measurements made during a time span.
+type Aggregation struct {
+	// Timestamp defines the time the last measurement was made. If zero, no
+	// measurements were made for this time span. The time is represented as a
+	// unix timestamp with nanosecond precision.
+	Timestamp uint64
+
+	// Value is the summarization of the measurements made.
+	Value value
+}
+
+var errIncompatible = errors.New("incompatible aggregation")
+
+// Fold combines other into a.
+func (a Aggregation) Fold(other Aggregation) error {
+	if other.Timestamp > a.Timestamp {
+		a.Timestamp = other.Timestamp
+	}
+	return a.Value.fold(other.Value)
+}
+
+type value interface {
+	// fold combines other into the value. It will return an errIncompatible
+	// if other is not a compatible type with value.
+	fold(other value) error
+}
+
+// SingleValue summarizes a set of measurements as a single numeric value.
+type SingleValue[N int64 | float64] struct {
+	Value N
+}
+
+func (v SingleValue[N]) fold(other value) error {
+	o, ok := other.(SingleValue[N])
+	if !ok {
+		return fmt.Errorf("%w: value types %T and %T", errIncompatible, v, other)
+	}
+	v.Value += o.Value
+	return nil
+}
+
+// HistogramValue summarizes a set of measurements as a histogram.
+type HistogramValue struct {
+	Bounds   []float64
+	Counts   []uint64
+	Sum      float64
+	Min, Max float64
+}
+
+func (v HistogramValue) fold(other value) error {
+	o, ok := other.(HistogramValue)
+	if !ok {
+		return fmt.Errorf("%w: value types %T and %T", errIncompatible, v, other)
+	}
+	if !sliceEqual[float64](v.Bounds, o.Bounds) || len(o.Counts) != len(v.Counts) {
+		return fmt.Errorf("%w: different histogram binning", errIncompatible)
+	}
+	v.Sum += o.Sum
+	for i, c := range o.Counts {
+		v.Counts[i] += c
+	}
+	if o.Min < v.Min {
+		v.Min = o.Min
+	}
+	if o.Max > v.Max {
+		v.Max = o.Max
+	}
+	return nil
+}
+
+func sliceEqual[T comparable](a, b []T) bool {
+	if len(a) != len(b) {
+		return false
+	}
+	for i, v := range a {
+		if v != b[i] {
+			return false
+		}
+	}
+	return true
+}

sdk/metric/internal/aggtor/aggregator.go

@@ -0,0 +1,27 @@
+// 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.
+
+//go:build go1.18
+// +build go1.18
+
+package aggtor // import "go.opentelemetry.io/otel/sdk/metric/internal/aggtor"
+
+// Aggregator forms an aggregation from a collection of recorded measurements.
+type Aggregator[N int64 | float64] interface {
+	// Record includes value in the aggregation.
+	Record(value N)
+
+	// Aggregate returns an aggregation of all recorded values.
+	Aggregate() Aggregation
+}

sdk/metric/internal/aggtor/doc.go

@@ -0,0 +1,20 @@
+// 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.
+
+//go:build go1.18
+// +build go1.18
+
+// Package aggtor provides types and functionality to accumulate and aggregate
+// measurements.
+package aggtor // import "go.opentelemetry.io/otel/sdk/metric/internal/aggtor"

sdk/metric/internal/aggtor/drop.go

@@ -0,0 +1,29 @@
+// 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.
+
+//go:build go1.18
+// +build go1.18
+
+package aggtor // import "go.opentelemetry.io/otel/sdk/metric/internal/aggtor"
+
+// dropAgg drops all recorded data and returns an empty Aggregation.
+type dropAgg[N int64 | float64] struct{}
+
+// NewDrop returns an Aggregator that drops all recorded data and returns an
+// empty Aggregation.
+func NewDrop[N int64 | float64]() Aggregator[N] { return &dropAgg[N]{} }
+
+func (s *dropAgg[N]) Record(value N) {}
+
+func (s *dropAgg[N]) Aggregate() Aggregation { return Aggregation{} }

sdk/metric/internal/aggtor/histogram.go

@@ -0,0 +1,40 @@
+// 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.
+
+//go:build go1.18
+// +build go1.18
+
+package aggtor // import "go.opentelemetry.io/otel/sdk/metric/internal/aggtor"
+
+// histogramAgg summarizes a set of measurements as an histogram with
+// explicitly defined buckets.
+type histogramAgg[N int64 | float64] struct {
+	// TODO: implement.
+}
+
+// NewHistogram returns an Aggregator that summarizes a set of measurements as
+// an histogram. The zero value will be used as the start value for all the
+// buckets of new Aggregations.
+func NewHistogram[N int64 | float64](zero Number[N], bounds []float64, recordMinMax bool) Aggregator[N] {
+	return &histogramAgg[N]{}
+}
+
+func (s *histogramAgg[N]) Record(value N) {
+	// TODO: implement.
+}
+
+func (s *histogramAgg[N]) Aggregate() Aggregation {
+	// TODO: implement.
+	return Aggregation{Value: HistogramValue{ /* TODO: calculate. */ }}
+}

sdk/metric/internal/aggtor/lastvalue.go

@@ -0,0 +1,39 @@
+// 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.
+
+//go:build go1.18
+// +build go1.18
+
+package aggtor // import "go.opentelemetry.io/otel/sdk/metric/internal/aggtor"
+
+// lastValueAgg summarizes a set of measurements as the last one made.
+type lastValueAgg[N int64 | float64] struct {
+	// TODO: implement.
+}
+
+// NewLastValue returns an Aggregator that summarizes a set of measurements as
+// the last one made. The zero value will be used as the start value for all
+// new Aggregations.
+func NewLastValue[N int64 | float64](zero Number[N]) Aggregator[N] {
+	return &lastValueAgg[N]{}
+}
+
+func (s *lastValueAgg[N]) Record(value N) {
+	// TODO: implement.
+}
+
+func (s *lastValueAgg[N]) Aggregate() Aggregation {
+	// TODO: implement.
+	return Aggregation{Value: SingleValue[N]{ /* TODO: calculate */ }}
+}