tracer: dont return noop from context

Signed-off-by: Vasiliy Tolstov <v.tolstov@unistack.org>

tracer/context.go

@@ -8,14 +8,14 @@ import (
 type tracerKey struct{}
 
 // FromContext returns a tracer from context
-func FromContext(ctx context.Context) Tracer {
+func FromContext(ctx context.Context) (Tracer, bool) {
 	if ctx == nil {
-		return DefaultTracer
+		return nil, false
 	}
 	if tracer, ok := ctx.Value(tracerKey{}).(Tracer); ok {
-		return tracer
+		return tracer, true
 	}
-	return DefaultTracer
+	return nil, false
 }
 
 // NewContext saves the tracer in the context
@@ -29,14 +29,14 @@ func NewContext(ctx context.Context, tracer Tracer) context.Context {
 type spanKey struct{}
 
 // SpanFromContext returns a span from context
-func SpanFromContext(ctx context.Context) Span {
+func SpanFromContext(ctx context.Context) (Span, bool) {
 	if ctx == nil {
-		return &noopSpan{}
+		return nil, false
 	}
 	if span, ok := ctx.Value(spanKey{}).(Span); ok {
-		return span
+		return span, true
 	}
-	return &noopSpan{}
+	return nil, false
 }
 
 // NewSpanContext saves the span in the context

tracer/noop.go

@@ -35,6 +35,7 @@ type noopSpan struct {
 	ctx    context.Context
 	tracer Tracer
 	name   string
+	labels []Label
 }
 
 func (s *noopSpan) Finish(opts ...SpanOption) {
@@ -56,6 +57,7 @@ func (s *noopSpan) SetName(name string) {
 }
 
 func (s *noopSpan) SetLabels(labels ...Label) {
+	s.labels = labels
 }
 
 // NewTracer returns new memory tracer

tracer/tracer.go

@@ -38,26 +38,26 @@ type Label struct {
 	key string
 }
 
-func Any(k string, v interface{}) Label {
+func LabelAny(k string, v interface{}) Label {
 	return Label{key: k, val: v}
 }
 
-func String(k string, v string) Label {
+func LabelString(k string, v string) Label {
 	return Label{key: k, val: v}
 }
 
-func Int(k string, v int) Label {
+func LabelInt(k string, v int) Label {
 	return Label{key: k, val: v}
 }
 
-func Int64(k string, v int64) Label {
+func LabelInt64(k string, v int64) Label {
 	return Label{key: k, val: v}
 }
 
-func Float64(k string, v float64) Label {
+func LabelFloat64(k string, v float64) Label {
 	return Label{key: k, val: v}
 }
 
-func Bool(k string, v bool) Label {
+func LabelBool(k string, v bool) Label {
 	return Label{key: k, val: v}
 }