Rename the sdk/export/metric package name (#432)

Rename the package from "export" to "metric". Note that all the existing
imports of this package use an explicit name of `export` and, therefore,
no import declaration changes are included.

Rename the `MetricKind` to `Kind` to not stutter in the type usage. Note
this does not include a method name change for the `Descriptor` method
`MetricKind`.

sdk/export/metric/aggregator/aggregator_test.go

@@ -77,7 +77,7 @@ func testRangeNegative(t *testing.T, alt bool, desc *export.Descriptor) {
 func TestRangeTest(t *testing.T) {
 	for _, nkind := range []core.NumberKind{core.Float64NumberKind, core.Int64NumberKind} {
 		t.Run(nkind.String(), func(t *testing.T) {
-			for _, mkind := range []export.MetricKind{
+			for _, mkind := range []export.Kind{
 				export.CounterKind,
 				export.GaugeKind,
 				export.MeasureKind,

sdk/export/metric/kind_string.go

@@ -0,0 +1,25 @@
+// Code generated by "stringer -type=Kind"; DO NOT EDIT.
+
+package metric
+
+import "strconv"
+
+func _() {
+	// An "invalid array index" compiler error signifies that the constant values have changed.
+	// Re-run the stringer command to generate them again.
+	var x [1]struct{}
+	_ = x[CounterKind-0]
+	_ = x[GaugeKind-1]
+	_ = x[MeasureKind-2]
+}
+
+const _Kind_name = "CounterKindGaugeKindMeasureKind"
+
+var _Kind_index = [...]uint8{0, 11, 20, 31}
+
+func (i Kind) String() string {
+	if i < 0 || i >= Kind(len(_Kind_index)-1) {
+		return "Kind(" + strconv.FormatInt(int64(i), 10) + ")"
+	}
+	return _Kind_name[_Kind_index[i]:_Kind_index[i+1]]
+}

sdk/export/metric/metric.go

@@ -12,9 +12,9 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-package export
+package metric
 
-//go:generate stringer -type=MetricKind
+//go:generate stringer -type=Kind
 
 import (
 	"context"
@@ -283,12 +283,12 @@ func (r Record) Labels() Labels {
 	return r.labels
 }
 
-// MetricKind describes the kind of instrument.
-type MetricKind int8
+// Kind describes the kind of instrument.
+type Kind int8
 
 const (
 	// Counter kind indicates a counter instrument.
-	CounterKind MetricKind = iota
+	CounterKind Kind = iota
 
 	// Gauge kind indicates a gauge instrument.
 	GaugeKind
@@ -304,7 +304,7 @@ const (
 // exporter.
 type Descriptor struct {
 	name        string
-	metricKind  MetricKind
+	metricKind  Kind
 	keys        []core.Key
 	description string
 	unit        unit.Unit
@@ -320,7 +320,7 @@ type Descriptor struct {
 // exporter.
 func NewDescriptor(
 	name string,
-	metricKind MetricKind,
+	metricKind Kind,
 	keys []core.Key,
 	description string,
 	unit unit.Unit,
@@ -345,7 +345,7 @@ func (d *Descriptor) Name() string {
 
 // MetricKind returns the kind of instrument: counter, gauge, or
 // measure.
-func (d *Descriptor) MetricKind() MetricKind {
+func (d *Descriptor) MetricKind() Kind {
 	return d.metricKind
 }
 

sdk/export/metric/metrickind_string.go

@@ -1,25 +0,0 @@
-// Code generated by "stringer -type=MetricKind"; DO NOT EDIT.
-
-package export
-
-import "strconv"
-
-func _() {
-	// An "invalid array index" compiler error signifies that the constant values have changed.
-	// Re-run the stringer command to generate them again.
-	var x [1]struct{}
-	_ = x[CounterKind-0]
-	_ = x[GaugeKind-1]
-	_ = x[MeasureKind-2]
-}
-
-const _MetricKind_name = "CounterKindGaugeKindMeasureKind"
-
-var _MetricKind_index = [...]uint8{0, 11, 20, 31}
-
-func (i MetricKind) String() string {
-	if i < 0 || i >= MetricKind(len(_MetricKind_index)-1) {
-		return "MetricKind(" + strconv.FormatInt(int64(i), 10) + ")"
-	}
-	return _MetricKind_name[_MetricKind_index[i]:_MetricKind_index[i+1]]
-}

sdk/metric/aggregator/test/test.go

@@ -53,7 +53,7 @@ func newProfiles() []Profile {
 	}
 }
 
-func NewAggregatorTest(mkind export.MetricKind, nkind core.NumberKind, alternate bool) *export.Descriptor {
+func NewAggregatorTest(mkind export.Kind, nkind core.NumberKind, alternate bool) *export.Descriptor {
 	desc := export.NewDescriptor("test.name", mkind, nil, "", "", nkind, alternate)
 	return desc
 }

sdk/metric/sdk.go

@@ -298,7 +298,7 @@ func (m *SDK) labsFor(ls api.LabelSet) *labels {
 	return &m.empty
 }
 
-func (m *SDK) newInstrument(name string, metricKind export.MetricKind, numberKind core.NumberKind, opts *api.Options) *instrument {
+func (m *SDK) newInstrument(name string, metricKind export.Kind, numberKind core.NumberKind, opts *api.Options) *instrument {
 	descriptor := export.NewDescriptor(
 		name,
 		metricKind,