Drop the registry package

This is to shrink the PR open-telemetry#100.

The only place where the registry.Variable type was used was metrics,
so just inline that type into its only user. The use of the
registry.Variable type in core.Key was limited to the Name field.

The stats package also used the registry.Variable type, but seems that
also only the Name field was used and the package is going to be
dropped anyway.

api/core/key.go

@@ -3,12 +3,10 @@ package core
 import (
 	"fmt"
 	"unsafe"
-
-	"go.opentelemetry.io/api/registry"
 )
 
 type Key struct {
-	Variable registry.Variable
+	Name string
 }
 
 type KeyValue struct {
@@ -148,7 +146,7 @@ func (k Key) Uint(v uint) KeyValue {
 }
 
 func (k Key) Defined() bool {
-	return k.Variable.Defined()
+	return len(k.Name) != 0
 }
 
 // TODO make this a lazy one-time conversion.

api/core/key_test.go

@@ -7,7 +7,6 @@ import (
 	"github.com/google/go-cmp/cmp"
 
 	"go.opentelemetry.io/api/core"
-	"go.opentelemetry.io/api/registry"
 )
 
 func TestBool(t *testing.T) {
@@ -306,15 +305,13 @@ func TestDefined(t *testing.T) {
 		{
 			name: "Key.Defined() returns true when len(v.Name) != 0",
 			k: core.Key{
-				registry.Variable{
-					Name: "foo",
-				},
+				Name: "foo",
 			},
 			want: true,
 		},
 		{
 			name: "Key.Defined() returns false when len(v.Name) == 0",
-			k:    core.Key{registry.Variable{}},
+			k:    core.Key{},
 			want: false,
 		},
 	} {

api/key/key.go

@@ -2,22 +2,10 @@ package key
 
 import (
 	"go.opentelemetry.io/api/core"
-	"go.opentelemetry.io/api/registry"
 )
 
-type AnyValue struct{}
-
-func (AnyValue) String() string {
-	return "AnyValue"
-}
-
-func New(name string, opts ...registry.Option) core.Key {
+func New(name string) core.Key {
 	return core.Key{
-		Variable: registry.Register(name, AnyValue{}, opts...),
+		Name: name,
 	}
 }
-
-var (
-	WithDescription = registry.WithDescription
-	WithUnit        = registry.WithUnit
-)

api/metric/api.go

@@ -18,7 +18,6 @@ import (
 	"context"
 
 	"go.opentelemetry.io/api/core"
-	"go.opentelemetry.io/api/registry"
 	"go.opentelemetry.io/api/unit"
 )
 
@@ -40,31 +39,33 @@ type Float64Gauge interface {
 }
 
 type Handle struct {
-	Variable registry.Variable
+	Name        string
+	Description string
+	Unit        unit.Unit
 
 	Type MetricType
 	Keys []core.Key
 }
 
-type Option func(*Handle, *[]registry.Option)
+type Option func(*Handle)
 
 // WithDescription applies provided description.
 func WithDescription(desc string) Option {
-	return func(_ *Handle, to *[]registry.Option) {
-		*to = append(*to, registry.WithDescription(desc))
+	return func(m *Handle) {
+		m.Description = desc
 	}
 }
 
 // WithUnit applies provided unit.
 func WithUnit(unit unit.Unit) Option {
-	return func(_ *Handle, to *[]registry.Option) {
-		*to = append(*to, registry.WithUnit(unit))
+	return func(m *Handle) {
+		m.Unit = unit
 	}
 }
 
 // WithKeys applies the provided dimension keys.
 func WithKeys(keys ...core.Key) Option {
-	return func(m *Handle, _ *[]registry.Option) {
+	return func(m *Handle) {
 		m.Keys = keys
 	}
 }

api/metric/common.go

@@ -14,17 +14,11 @@
 
 package metric
 
-import (
-	"go.opentelemetry.io/api/registry"
-)
-
 func registerMetric(name string, mtype MetricType, opts []Option, metric *Handle) {
-	var varOpts []registry.Option
-
 	for _, opt := range opts {
-		opt(metric, &varOpts)
+		opt(metric)
 	}
 
-	metric.Variable = registry.Register(name, mtype, varOpts...)
+	metric.Name = name
 	metric.Type = mtype
 }

api/stats/stats.go

@@ -19,15 +19,14 @@ import (
 	"sync/atomic"
 
 	"go.opentelemetry.io/api/core"
-	"go.opentelemetry.io/api/registry"
 )
 
 type MeasureHandle struct {
-	Variable registry.Variable
+	Name string
 }
 
 type Measure interface {
-	V() registry.Variable
+	N() string
 	M(value float64) Measurement
 }
 
@@ -71,20 +70,9 @@ func RecordSingle(ctx context.Context, m Measurement) {
 	GlobalRecorder().RecordSingle(ctx, m)
 }
 
-type AnyStatistic struct{}
-
-func (AnyStatistic) String() string {
-	return "AnyStatistic"
-}
-
-var (
-	WithDescription = registry.WithDescription
-	WithUnit        = registry.WithUnit
-)
-
-func NewMeasure(name string, opts ...registry.Option) *MeasureHandle {
+func NewMeasure(name string) *MeasureHandle {
 	return &MeasureHandle{
-		Variable: registry.Register(name, AnyStatistic{}, opts...),
+		Name: name,
 	}
 }
 
@@ -95,8 +83,8 @@ func (m *MeasureHandle) M(value float64) Measurement {
 	}
 }
 
-func (m *MeasureHandle) V() registry.Variable {
-	return m.Variable
+func (m *MeasureHandle) N() string {
+	return m.Name
 }
 
 func (noopRecorder) Record(ctx context.Context, m ...Measurement) {
@@ -113,6 +101,6 @@ func (noopMeasure) M(float64) Measurement {
 	return Measurement{}
 }
 
-func (noopMeasure) V() registry.Variable {
-	return registry.Variable{}
+func (noopMeasure) N() string {
+	return ""
 }

api/tag/context.go

@@ -48,7 +48,7 @@ func Do(ctx context.Context, f func(ctx context.Context)) {
 	m := FromContext(ctx)
 	keyvals := make([]string, 0, 2*len(m.m))
 	for k, v := range m.m {
-		keyvals = append(keyvals, k.Variable.Name, v.value.Emit())
+		keyvals = append(keyvals, k.Name, v.value.Emit())
 	}
 	pprof.Do(ctx, pprof.Labels(keyvals...), f)
 }

example/basic/main.go

@@ -19,7 +19,6 @@ import (
 
 	"go.opentelemetry.io/api/key"
 	"go.opentelemetry.io/api/metric"
-	"go.opentelemetry.io/api/registry"
 	"go.opentelemetry.io/api/stats"
 	"go.opentelemetry.io/api/tag"
 	"go.opentelemetry.io/api/trace"
@@ -34,9 +33,9 @@ var (
 
 	meter = metric.GlobalMeter() // TODO: should share resources ^^^?
 
-	fooKey     = key.New("ex.com/foo", registry.WithDescription("A Foo var"))
-	barKey     = key.New("ex.com/bar", registry.WithDescription("A Bar var"))
-	lemonsKey  = key.New("ex.com/lemons", registry.WithDescription("A Lemons var"))
+	fooKey     = key.New("ex.com/foo")
+	barKey     = key.New("ex.com/bar")
+	lemonsKey  = key.New("ex.com/lemons")
 	anotherKey = key.New("ex.com/another")
 
 	oneMetric = metric.NewFloat64Gauge("ex.com/one",

experimental/streaming/exporter/reader/format/format.go

@@ -37,7 +37,7 @@ func AppendEvent(buf *strings.Builder, data reader.Event) {
 			if skipIf && data.Attributes.HasValue(kv.Key) {
 				return true
 			}
-			buf.WriteString(" " + kv.Key.Variable.Name + "=" + kv.Value.Emit())
+			buf.WriteString(" " + kv.Key.Name + "=" + kv.Value.Emit())
 			return true
 		}
 	}
@@ -74,7 +74,7 @@ func AppendEvent(buf *strings.Builder, data reader.Event) {
 		buf.WriteString(data.Message)
 		buf.WriteString(" (")
 		data.Attributes.Foreach(func(kv core.KeyValue) bool {
-			buf.WriteString(" " + kv.Key.Variable.Name + "=" + kv.Value.Emit())
+			buf.WriteString(" " + kv.Key.Name + "=" + kv.Value.Emit())
 			return true
 		})
 		buf.WriteString(")")
@@ -86,7 +86,7 @@ func AppendEvent(buf *strings.Builder, data reader.Event) {
 
 		for _, s := range data.Stats {
 			f(false)(core.Key{
-				Variable: s.Measure.V(),
+				Name: s.Measure.N(),
 			}.Float64(s.Value))
 
 			buf.WriteString(" {")
@@ -96,7 +96,7 @@ func AppendEvent(buf *strings.Builder, data reader.Event) {
 					buf.WriteString(",")
 				}
 				i++
-				buf.WriteString(kv.Key.Variable.Name)
+				buf.WriteString(kv.Key.Name)
 				buf.WriteString("=")
 				buf.WriteString(kv.Value.Emit())
 				return true

experimental/streaming/sdk/trace.go

@@ -37,9 +37,7 @@ var (
 	ErrorKey     = key.New("error")
 	SpanIDKey    = key.New("span_id")
 	TraceIDKey   = key.New("trace_id")
-	MessageKey   = key.New("message",
-		key.WithDescription("message text: info, error, etc"),
-	)
+	MessageKey   = key.New("message")
 )
 
 func New() trace.Tracer {

exporter/trace/jaeger/jaeger.go

@@ -187,7 +187,7 @@ func spanDataToThrift(data *trace.SpanData) *gen.Span {
 	for _, a := range data.MessageEvents {
 		fields := make([]*gen.Tag, 0, len(a.Attributes))
 		for _, kv := range a.Attributes {
-			tag := attributeToTag(kv.Key.Variable.Name, kv.Value.Emit())
+			tag := attributeToTag(kv.Key.Name, kv.Value.Emit())
 			if tag != nil {
 				fields = append(fields, tag)
 			}

plugin/httptrace/clienttrace.go

@@ -35,9 +35,7 @@ var (
 	HTTPHeaderMIME = key.New("http.mime")
 	HTTPRemoteAddr = key.New("http.remote")
 	HTTPLocalAddr  = key.New("http.local")
-	MessageKey     = key.New("message",
-		key.WithDescription("message text: info, error, etc"),
-	)
+	MessageKey     = key.New("message")
 )
 
 type clientTracer struct {

plugin/httptrace/httptrace.go

@@ -91,7 +91,7 @@ func (h hinjector) Inject(sc core.SpanContext, tags tag.Map) {
 		// TODO: implement MaxHops
 		tc.TraceState = append(tc.TraceState, tracestate.Member{
 			Vendor: Vendor,
-			Tenant: kv.Key.Variable.Name,
+			Tenant: kv.Key.Name,
 			Value:  kv.Value.Emit(),
 		})
 		return true