Update aggregation.go/aggregator.go

sdk/export/metric/aggregation/aggregation.go

@@ -12,21 +12,25 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-package aggregator // import "go.opentelemetry.io/otel/sdk/export/metric/aggregator"
+package aggregation // import "go.opentelemetry.io/otel/sdk/export/metric/aggregation"
 
 import (
 	"fmt"
-	"math"
 	"time"
 
 	"go.opentelemetry.io/otel/api/metric"
-	export "go.opentelemetry.io/otel/sdk/export/metric"
 )
 
 // These interfaces describe the various ways to access state from an
-// Aggregator.
+// Aggregation.
 
 type (
+	// Aggregation is one of the interfaces below.
+	Aggregation interface {
+		// Kind returns the kind of aggregation used.
+		Kind() Kind
+	}
+
 	// Sum returns an aggregated sum.
 	Sum interface {
 		Sum() (metric.Number, error)
@@ -100,11 +104,25 @@ type (
 	}
 )
 
+type (
+	Kind string
+)
+
+const (
+	SumKind            Kind = "sum"
+	MinMaxSumCountKind Kind = "minmaxsumcount"
+	HistogramKind      Kind = "histogram"
+	LastValueKind      Kind = "lastvalue"
+	SketchKind         Kind = "sketch"
+	ExactKind          Kind = "exact"
+)
+
 var (
 	ErrInvalidQuantile  = fmt.Errorf("the requested quantile is out of range")
 	ErrNegativeInput    = fmt.Errorf("negative value is out of range for this instrument")
 	ErrNaNInput         = fmt.Errorf("NaN value is an invalid input")
 	ErrInconsistentType = fmt.Errorf("inconsistent aggregator types")
+	ErrNoSubtraction    = fmt.Errorf("aggregator does not subtract")
 
 	// ErrNoData is returned when (due to a race with collection)
 	// the Aggregator is check-pointed before the first value is set.
@@ -112,29 +130,7 @@ var (
 	ErrNoData = fmt.Errorf("no data collected by this aggregator")
 )
 
-// NewInconsistentMergeError formats an error describing an attempt to
-// merge different-type aggregators.  The result can be unwrapped as
-// an ErrInconsistentType.
-func NewInconsistentMergeError(a1, a2 export.Aggregator) error {
-	return fmt.Errorf("cannot merge %T with %T: %w", a1, a2, ErrInconsistentType)
-}
-
-// RangeTest is a commmon routine for testing for valid input values.
-// This rejects NaN values.  This rejects negative values when the
-// metric instrument does not support negative values, including
-// monotonic counter metrics and absolute ValueRecorder metrics.
-func RangeTest(number metric.Number, descriptor *metric.Descriptor) error {
-	numberKind := descriptor.NumberKind()
-
-	if numberKind == metric.Float64NumberKind && math.IsNaN(number.AsFloat64()) {
-		return ErrNaNInput
-	}
-
-	switch descriptor.MetricKind() {
-	case metric.CounterKind, metric.SumObserverKind:
-		if number.IsNegative(numberKind) {
-			return ErrNegativeInput
-		}
-	}
-	return nil
+// String returns a string representation of the aggregation kind.
+func (k Kind) String() string {
+	return string(k)
 }

sdk/metric/aggregator/aggregator.go

@@ -0,0 +1,51 @@
+// 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 aggregator // import "go.opentelemetry.io/otel/sdk/metric/aggregator"
+
+import (
+	"fmt"
+	"math"
+
+	"go.opentelemetry.io/otel/api/metric"
+	export "go.opentelemetry.io/otel/sdk/export/metric"
+	"go.opentelemetry.io/otel/sdk/export/metric/aggregation"
+)
+
+// NewInconsistentMergeError formats an error describing an attempt to
+// merge different-type aggregators.  The result can be unwrapped as
+// an ErrInconsistentType.
+func NewInconsistentMergeError(a1, a2 export.Aggregator) error {
+	return fmt.Errorf("cannot merge %T with %T: %w", a1, a2, aggregation.ErrInconsistentType)
+}
+
+// RangeTest is a commmon routine for testing for valid input values.
+// This rejects NaN values.  This rejects negative values when the
+// metric instrument does not support negative values, including
+// monotonic counter metrics and absolute ValueRecorder metrics.
+func RangeTest(number metric.Number, descriptor *metric.Descriptor) error {
+	numberKind := descriptor.NumberKind()
+
+	if numberKind == metric.Float64NumberKind && math.IsNaN(number.AsFloat64()) {
+		return aggregation.ErrNaNInput
+	}
+
+	switch descriptor.MetricKind() {
+	case metric.CounterKind, metric.SumObserverKind:
+		if number.IsNegative(numberKind) {
+			return aggregation.ErrNegativeInput
+		}
+	}
+	return nil
+}

sdk/metric/aggregator/aggregator_test.go

@@ -12,7 +12,7 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-package aggregator_test // import "go.opentelemetry.io/otel/sdk/export/metric/aggregator"
+package aggregator_test // import "go.opentelemetry.io/otel/sdk/metric/aggregator"
 
 import (
 	"errors"
@@ -22,7 +22,8 @@ import (
 	"github.com/stretchr/testify/require"
 
 	"go.opentelemetry.io/otel/api/metric"
-	"go.opentelemetry.io/otel/sdk/export/metric/aggregator"
+	"go.opentelemetry.io/otel/sdk/export/metric/aggregation"
+	"go.opentelemetry.io/otel/sdk/metric/aggregator"
 	"go.opentelemetry.io/otel/sdk/metric/aggregator/lastvalue"
 	"go.opentelemetry.io/otel/sdk/metric/aggregator/sum"
 )
@@ -34,7 +35,7 @@ func TestInconsistentMergeErr(t *testing.T) {
 		"cannot merge *sum.Aggregator with *lastvalue.Aggregator: inconsistent aggregator types",
 		err.Error(),
 	)
-	require.True(t, errors.Is(err, aggregator.ErrInconsistentType))
+	require.True(t, errors.Is(err, aggregation.ErrInconsistentType))
 }
 
 func testRangeNaN(t *testing.T, desc *metric.Descriptor) {
@@ -43,7 +44,7 @@ func testRangeNaN(t *testing.T, desc *metric.Descriptor) {
 	err := aggregator.RangeTest(nan, desc)
 
 	if desc.NumberKind() == metric.Float64NumberKind {
-		require.Equal(t, aggregator.ErrNaNInput, err)
+		require.Equal(t, aggregation.ErrNaNInput, err)
 	} else {
 		require.Nil(t, err)
 	}
@@ -64,7 +65,7 @@ func testRangeNegative(t *testing.T, desc *metric.Descriptor) {
 	negErr := aggregator.RangeTest(neg, desc)
 
 	require.Nil(t, posErr)
-	require.Equal(t, negErr, aggregator.ErrNegativeInput)
+	require.Equal(t, negErr, aggregation.ErrNegativeInput)
 }
 
 func TestRangeTest(t *testing.T) {