Move metric.Descriptor out of metric API into sdkapi

bridge/opencensus/exporter.go

@@ -147,7 +147,7 @@ func convertResource(res *ocresource.Resource) *resource.Resource {
 }
 
 // convertDescriptor converts an OpenCensus Descriptor to an OpenTelemetry Descriptor
-func convertDescriptor(ocDescriptor metricdata.Descriptor) (metric.Descriptor, error) {
+func convertDescriptor(ocDescriptor metricdata.Descriptor) (sdkapi.Descriptor, error) {
 	var (
 		nkind number.Kind
 		ikind sdkapi.InstrumentKind
@@ -167,7 +167,7 @@ func convertDescriptor(ocDescriptor metricdata.Descriptor) (metric.Descriptor, e
 		ikind = sdkapi.CounterObserverInstrumentKind
 	default:
 		// Includes TypeGaugeDistribution, TypeCumulativeDistribution, TypeSummary
-		return metric.Descriptor{}, fmt.Errorf("%w; descriptor type: %v", errConversion, ocDescriptor.Type)
+		return sdkapi.Descriptor{}, fmt.Errorf("%w; descriptor type: %v", errConversion, ocDescriptor.Type)
 	}
 	opts := []metric.InstrumentOption{
 		metric.WithDescription(ocDescriptor.Description),
@@ -181,5 +181,5 @@ func convertDescriptor(ocDescriptor metricdata.Descriptor) (metric.Descriptor, e
 		opts = append(opts, metric.WithUnit(unit.Milliseconds))
 	}
 	cfg := metric.NewInstrumentConfig(opts...)
-	return metric.NewDescriptor(ocDescriptor.Name, ikind, nkind, cfg.Description(), cfg.Unit()), nil
+	return sdkapi.NewDescriptor(ocDescriptor.Name, ikind, nkind, cfg.Description(), cfg.Unit()), nil
 }

bridge/opencensus/exporter_test.go

@@ -391,7 +391,7 @@ func TestConvertDescriptor(t *testing.T) {
 	for _, tc := range []struct {
 		desc        string
 		input       metricdata.Descriptor
-		expected    metric.Descriptor
+		expected    sdkapi.Descriptor
 		expectedErr error
 	}{
 		{

exporters/otlp/otlpmetric/exporter.go

@@ -20,7 +20,7 @@ import (
 	"sync"
 
 	"go.opentelemetry.io/otel/exporters/otlp/otlpmetric/internal/metrictransform"
-	"go.opentelemetry.io/otel/metric"
+	"go.opentelemetry.io/otel/metric/sdkapi"
 	metricsdk "go.opentelemetry.io/otel/sdk/export/metric"
 	"go.opentelemetry.io/otel/sdk/export/metric/aggregation"
 	"go.opentelemetry.io/otel/sdk/resource"
@@ -96,7 +96,7 @@ func (e *Exporter) Shutdown(ctx context.Context) error {
 	return err
 }
 
-func (e *Exporter) ExportKindFor(descriptor *metric.Descriptor, aggregatorKind aggregation.Kind) metricsdk.ExportKind {
+func (e *Exporter) ExportKindFor(descriptor *sdkapi.Descriptor, aggregatorKind aggregation.Kind) metricsdk.ExportKind {
 	return e.exportKindSelector.ExportKindFor(descriptor, aggregatorKind)
 }
 

exporters/otlp/otlpmetric/internal/metrictransform/metric_test.go

@@ -25,7 +25,6 @@ import (
 	"github.com/stretchr/testify/require"
 
 	"go.opentelemetry.io/otel/attribute"
-	"go.opentelemetry.io/otel/metric"
 	"go.opentelemetry.io/otel/metric/metrictest"
 	"go.opentelemetry.io/otel/metric/number"
 	"go.opentelemetry.io/otel/metric/sdkapi"
@@ -101,18 +100,18 @@ func TestStringKeyValues(t *testing.T) {
 }
 
 func TestMinMaxSumCountValue(t *testing.T) {
-	mmscs := minmaxsumcount.New(2, &metric.Descriptor{})
+	mmscs := minmaxsumcount.New(2, &sdkapi.Descriptor{})
 	mmsc, ckpt := &mmscs[0], &mmscs[1]
 
-	assert.NoError(t, mmsc.Update(context.Background(), 1, &metric.Descriptor{}))
-	assert.NoError(t, mmsc.Update(context.Background(), 10, &metric.Descriptor{}))
+	assert.NoError(t, mmsc.Update(context.Background(), 1, &sdkapi.Descriptor{}))
+	assert.NoError(t, mmsc.Update(context.Background(), 10, &sdkapi.Descriptor{}))
 
 	// Prior to checkpointing ErrNoData should be returned.
 	_, _, _, _, err := minMaxSumCountValues(ckpt)
 	assert.EqualError(t, err, aggregation.ErrNoData.Error())
 
 	// Checkpoint to set non-zero values
-	require.NoError(t, mmsc.SynchronizedMove(ckpt, &metric.Descriptor{}))
+	require.NoError(t, mmsc.SynchronizedMove(ckpt, &sdkapi.Descriptor{}))
 	min, max, sum, count, err := minMaxSumCountValues(ckpt)
 	if assert.NoError(t, err) {
 		assert.Equal(t, min, number.NewInt64Number(1))
@@ -125,7 +124,7 @@ func TestMinMaxSumCountValue(t *testing.T) {
 func TestMinMaxSumCountDatapoints(t *testing.T) {
 	desc := metrictest.NewDescriptor("", sdkapi.HistogramInstrumentKind, number.Int64Kind)
 	labels := attribute.NewSet(attribute.String("one", "1"))
-	mmscs := minmaxsumcount.New(2, &metric.Descriptor{})
+	mmscs := minmaxsumcount.New(2, &sdkapi.Descriptor{})
 	mmsc, ckpt := &mmscs[0], &mmscs[1]
 
 	assert.NoError(t, mmsc.Update(context.Background(), 1, &desc))
@@ -172,7 +171,7 @@ func TestMinMaxSumCountPropagatesErrors(t *testing.T) {
 	// ErrNoData should be returned by both the Min and Max values of
 	// a MinMaxSumCount Aggregator. Use this fact to check the error is
 	// correctly returned.
-	mmsc := &minmaxsumcount.New(1, &metric.Descriptor{})[0]
+	mmsc := &minmaxsumcount.New(1, &sdkapi.Descriptor{})[0]
 	_, _, _, _, err := minMaxSumCountValues(mmsc)
 	assert.Error(t, err)
 	assert.Equal(t, aggregation.ErrNoData, err)
@@ -390,13 +389,13 @@ func (t *testAgg) Aggregation() aggregation.Aggregation {
 
 // None of these three are used:
 
-func (t *testAgg) Update(ctx context.Context, number number.Number, descriptor *metric.Descriptor) error {
+func (t *testAgg) Update(ctx context.Context, number number.Number, descriptor *sdkapi.Descriptor) error {
 	return nil
 }
-func (t *testAgg) SynchronizedMove(destination export.Aggregator, descriptor *metric.Descriptor) error {
+func (t *testAgg) SynchronizedMove(destination export.Aggregator, descriptor *sdkapi.Descriptor) error {
 	return nil
 }
-func (t *testAgg) Merge(aggregator export.Aggregator, descriptor *metric.Descriptor) error {
+func (t *testAgg) Merge(aggregator export.Aggregator, descriptor *sdkapi.Descriptor) error {
 	return nil
 }
 

exporters/prometheus/prometheus.go

@@ -30,6 +30,7 @@ import (
 	"go.opentelemetry.io/otel/attribute"
 	"go.opentelemetry.io/otel/metric"
 	"go.opentelemetry.io/otel/metric/number"
+	"go.opentelemetry.io/otel/metric/sdkapi"
 	export "go.opentelemetry.io/otel/sdk/export/metric"
 	"go.opentelemetry.io/otel/sdk/export/metric/aggregation"
 	"go.opentelemetry.io/otel/sdk/instrumentation"
@@ -132,7 +133,7 @@ func (e *Exporter) Controller() *controller.Controller {
 }
 
 // ExportKindFor implements ExportKindSelector.
-func (e *Exporter) ExportKindFor(desc *metric.Descriptor, kind aggregation.Kind) export.ExportKind {
+func (e *Exporter) ExportKindFor(desc *sdkapi.Descriptor, kind aggregation.Kind) export.ExportKind {
 	return export.CumulativeExportKindSelector().ExportKindFor(desc, kind)
 }
 

exporters/stdout/stdoutmetric/metric.go

@@ -22,7 +22,7 @@ import (
 	"time"
 
 	"go.opentelemetry.io/otel/attribute"
-	"go.opentelemetry.io/otel/metric"
+	"go.opentelemetry.io/otel/metric/sdkapi"
 	exportmetric "go.opentelemetry.io/otel/sdk/export/metric"
 	"go.opentelemetry.io/otel/sdk/export/metric/aggregation"
 	"go.opentelemetry.io/otel/sdk/instrumentation"
@@ -47,7 +47,7 @@ type line struct {
 	Timestamp *time.Time `json:"Timestamp,omitempty"`
 }
 
-func (e *metricExporter) ExportKindFor(desc *metric.Descriptor, kind aggregation.Kind) exportmetric.ExportKind {
+func (e *metricExporter) ExportKindFor(desc *sdkapi.Descriptor, kind aggregation.Kind) exportmetric.ExportKind {
 	return exportmetric.StatelessExportKindSelector().ExportKindFor(desc, kind)
 }
 

internal/metric/global/meter.go

@@ -24,6 +24,7 @@ import (
 	"go.opentelemetry.io/otel/internal/metric/registry"
 	"go.opentelemetry.io/otel/metric"
 	"go.opentelemetry.io/otel/metric/number"
+	"go.opentelemetry.io/otel/metric/sdkapi"
 )
 
 // This file contains the forwarding implementation of MeterProvider used as
@@ -78,7 +79,7 @@ type meterEntry struct {
 }
 
 type instrument struct {
-	descriptor metric.Descriptor
+	descriptor sdkapi.Descriptor
 }
 
 type syncImpl struct {
@@ -122,7 +123,7 @@ var _ metric.InstrumentImpl = &syncImpl{}
 var _ metric.BoundSyncImpl = &syncHandle{}
 var _ metric.AsyncImpl = &asyncImpl{}
 
-func (inst *instrument) Descriptor() metric.Descriptor {
+func (inst *instrument) Descriptor() sdkapi.Descriptor {
 	return inst.descriptor
 }
 
@@ -197,7 +198,7 @@ func (m *meterImpl) setDelegate(key meterKey, provider metric.MeterProvider) {
 	m.asyncInsts = nil
 }
 
-func (m *meterImpl) NewSyncInstrument(desc metric.Descriptor) (metric.SyncImpl, error) {
+func (m *meterImpl) NewSyncInstrument(desc sdkapi.Descriptor) (metric.SyncImpl, error) {
 	m.lock.Lock()
 	defer m.lock.Unlock()
 
@@ -265,7 +266,7 @@ func (bound *syncHandle) Unbind() {
 // Async delegation
 
 func (m *meterImpl) NewAsyncInstrument(
-	desc metric.Descriptor,
+	desc sdkapi.Descriptor,
 	runner metric.AsyncRunner,
 ) (metric.AsyncImpl, error) {
 

internal/metric/global/meter_test.go

@@ -27,6 +27,7 @@ import (
 	metricglobal "go.opentelemetry.io/otel/metric/global"
 	"go.opentelemetry.io/otel/metric/metrictest"
 	"go.opentelemetry.io/otel/metric/number"
+	"go.opentelemetry.io/otel/metric/sdkapi"
 )
 
 var Must = metric.Must
@@ -239,7 +240,7 @@ func (m *meterProviderWithConstructorError) Meter(iName string, opts ...metric.M
 	return metric.WrapMeterImpl(&meterWithConstructorError{m.MeterProvider.Meter(iName, opts...).MeterImpl()})
 }
 
-func (m *meterWithConstructorError) NewSyncInstrument(_ metric.Descriptor) (metric.SyncImpl, error) {
+func (m *meterWithConstructorError) NewSyncInstrument(_ sdkapi.Descriptor) (metric.SyncImpl, error) {
 	return metric.NoopSync{}, errors.New("constructor error")
 }
 

internal/metric/registry/registry.go

@@ -21,6 +21,7 @@ import (
 
 	"go.opentelemetry.io/otel/attribute"
 	"go.opentelemetry.io/otel/metric"
+	"go.opentelemetry.io/otel/metric/sdkapi"
 )
 
 // UniqueInstrumentMeterImpl implements the metric.MeterImpl interface, adding
@@ -60,17 +61,17 @@ func (u *UniqueInstrumentMeterImpl) RecordBatch(ctx context.Context, labels []at
 
 // NewMetricKindMismatchError formats an error that describes a
 // mismatched metric instrument definition.
-func NewMetricKindMismatchError(desc metric.Descriptor) error {
+func NewMetricKindMismatchError(desc sdkapi.Descriptor) error {
 	return fmt.Errorf("metric %s registered as %s %s: %w",
 		desc.Name(),
 		desc.NumberKind(),
 		desc.InstrumentKind(),
 		ErrMetricKindMismatch)
 }
 
-// Compatible determines whether two metric.Descriptors are considered
+// Compatible determines whether two sdkapi.Descriptors are considered
 // the same for the purpose of uniqueness checking.
-func Compatible(candidate, existing metric.Descriptor) bool {
+func Compatible(candidate, existing sdkapi.Descriptor) bool {
 	return candidate.InstrumentKind() == existing.InstrumentKind() &&
 		candidate.NumberKind() == existing.NumberKind()
 }
@@ -80,7 +81,7 @@ func Compatible(candidate, existing metric.Descriptor) bool {
 // `descriptor` argument.  If there is an existing compatible
 // registration, this returns the already-registered instrument.  If
 // there is no conflict and no prior registration, returns (nil, nil).
-func (u *UniqueInstrumentMeterImpl) checkUniqueness(descriptor metric.Descriptor) (metric.InstrumentImpl, error) {
+func (u *UniqueInstrumentMeterImpl) checkUniqueness(descriptor sdkapi.Descriptor) (metric.InstrumentImpl, error) {
 	impl, ok := u.state[descriptor.Name()]
 	if !ok {
 		return nil, nil
@@ -94,7 +95,7 @@ func (u *UniqueInstrumentMeterImpl) checkUniqueness(descriptor metric.Descriptor
 }
 
 // NewSyncInstrument implements metric.MeterImpl.
-func (u *UniqueInstrumentMeterImpl) NewSyncInstrument(descriptor metric.Descriptor) (metric.SyncImpl, error) {
+func (u *UniqueInstrumentMeterImpl) NewSyncInstrument(descriptor sdkapi.Descriptor) (metric.SyncImpl, error) {
 	u.lock.Lock()
 	defer u.lock.Unlock()
 
@@ -116,7 +117,7 @@ func (u *UniqueInstrumentMeterImpl) NewSyncInstrument(descriptor metric.Descript
 
 // NewAsyncInstrument implements metric.MeterImpl.
 func (u *UniqueInstrumentMeterImpl) NewAsyncInstrument(
-	descriptor metric.Descriptor,
+	descriptor sdkapi.Descriptor,
 	runner metric.AsyncRunner,
 ) (metric.AsyncImpl, error) {
 	u.lock.Lock()

metric/metric.go

@@ -20,7 +20,6 @@ import (
 	"go.opentelemetry.io/otel/attribute"
 	"go.opentelemetry.io/otel/metric/number"
 	"go.opentelemetry.io/otel/metric/sdkapi"
-	"go.opentelemetry.io/otel/metric/unit"
 )
 
 // MeterProvider supports named Meter instances.
@@ -285,7 +284,7 @@ func (m Meter) newAsync(
 		return NoopAsync{}, nil
 	}
 	cfg := NewInstrumentConfig(opts...)
-	desc := NewDescriptor(name, mkind, nkind, cfg.description, cfg.unit)
+	desc := sdkapi.NewDescriptor(name, mkind, nkind, cfg.description, cfg.unit)
 	return m.impl.NewAsyncInstrument(desc, runner)
 }
 
@@ -303,7 +302,7 @@ func (m Meter) newSync(
 		return NoopSync{}, nil
 	}
 	cfg := NewInstrumentConfig(opts...)
-	desc := NewDescriptor(name, metricKind, numberKind, cfg.description, cfg.unit)
+	desc := sdkapi.NewDescriptor(name, metricKind, numberKind, cfg.description, cfg.unit)
 	return m.impl.NewSyncInstrument(desc)
 }
 
@@ -513,53 +512,3 @@ func (bm BatchObserverMust) NewFloat64UpDownCounterObserver(name string, oos ...
 		return inst
 	}
 }
-
-// Descriptor contains all the settings that describe an instrument,
-// including its name, metric kind, number kind, and the configurable
-// options.
-type Descriptor struct {
-	name           string
-	instrumentKind sdkapi.InstrumentKind
-	numberKind     number.Kind
-	description    string
-	unit           unit.Unit
-}
-
-// NewDescriptor returns a Descriptor with the given contents.
-func NewDescriptor(name string, ikind sdkapi.InstrumentKind, nkind number.Kind, description string, unit unit.Unit) Descriptor {
-	return Descriptor{
-		name:           name,
-		instrumentKind: ikind,
-		numberKind:     nkind,
-		description:    description,
-		unit:           unit,
-	}
-}
-
-// Name returns the metric instrument's name.
-func (d Descriptor) Name() string {
-	return d.name
-}
-
-// InstrumentKind returns the specific kind of instrument.
-func (d Descriptor) InstrumentKind() sdkapi.InstrumentKind {
-	return d.instrumentKind
-}
-
-// Description provides a human-readable description of the metric
-// instrument.
-func (d Descriptor) Description() string {
-	return d.description
-}
-
-// Unit describes the units of the metric instrument.  Unitless
-// metrics return the empty string.
-func (d Descriptor) Unit() unit.Unit {
-	return d.unit
-}
-
-// NumberKind returns whether this instrument is declared over int64,
-// float64, or uint64 values.
-func (d Descriptor) NumberKind() number.Kind {
-	return d.numberKind
-}

metric/metric_sdkapi.go

@@ -19,6 +19,7 @@ import (
 
 	"go.opentelemetry.io/otel/attribute"
 	"go.opentelemetry.io/otel/metric/number"
+	"go.opentelemetry.io/otel/metric/sdkapi"
 )
 
 // MeterImpl is the interface an SDK must implement to supply a Meter
@@ -30,13 +31,13 @@ type MeterImpl interface {
 	// NewSyncInstrument returns a newly constructed
 	// synchronous instrument implementation or an error, should
 	// one occur.
-	NewSyncInstrument(descriptor Descriptor) (SyncImpl, error)
+	NewSyncInstrument(descriptor sdkapi.Descriptor) (SyncImpl, error)
 
 	// NewAsyncInstrument returns a newly constructed
 	// asynchronous instrument implementation or an error, should
 	// one occur.
 	NewAsyncInstrument(
-		descriptor Descriptor,
+		descriptor sdkapi.Descriptor,
 		runner AsyncRunner,
 	) (AsyncImpl, error)
 }
@@ -50,7 +51,7 @@ type InstrumentImpl interface {
 	Implementation() interface{}
 
 	// Descriptor returns a copy of the instrument's Descriptor.
-	Descriptor() Descriptor
+	Descriptor() sdkapi.Descriptor
 }
 
 // SyncImpl is the implementation-level interface to a generic