avoid duplicate tags

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

opentracing.go

@@ -94,6 +94,7 @@ type otSpan struct {
 	opts      tracer.SpanOptions
 	status    tracer.SpanStatus
 	statusMsg string
+	labels    []interface{}
 }
 
 func (os *otSpan) TraceID() string {
@@ -118,23 +119,29 @@ func (os *otSpan) Tracer() tracer.Tracer {
 }
 
 func (os *otSpan) Finish(opts ...tracer.SpanOption) {
-	if len(os.opts.Labels)%2 != 0 {
-		os.opts.Labels = os.opts.Labels[:len(os.opts.Labels)-1]
+	options := os.opts
+	for _, o := range opts {
+		o(&options)
 	}
-	os.opts.Labels = tracer.UniqLabels(os.opts.Labels)
-	for idx := 0; idx < len(os.opts.Labels); idx += 2 {
-		k, ok := os.opts.Labels[idx].(string)
-		if !ok {
-			continue
+
+	l := len(options.Labels)
+	for idx := 0; idx < l; idx++ {
+		switch lt := options.Labels[idx].(type) {
+		case attribute.KeyValue:
+			os.span.SetTag(string(lt.Key), lt.Value.AsInterface())
+		case string:
+			if l > idx+1 {
+				os.span.SetTag(lt, options.Labels[idx+1])
+				idx++
+			}
 		}
-		v := os.opts.Labels[idx+1]
-		os.span.SetTag(k, v)
 	}
+
 	if os.status == tracer.SpanStatusError {
 		os.span.SetTag("error", true)
 		os.span.LogKV("error", os.statusMsg)
 	}
-	os.span.SetTag("span.kind", os.opts.Kind)
+	os.span.SetTag("span.kind", options.Kind)
 	os.span.Finish()
 }
 
@@ -163,18 +170,7 @@ func (os *otSpan) Kind() tracer.SpanKind {
 }
 
 func (os *otSpan) AddLabels(labels ...interface{}) {
-	l := len(labels)
-	for idx := 0; idx < len(labels); idx++ {
-		switch lt := labels[idx].(type) {
-		case attribute.KeyValue:
-			os.span.SetTag(string(lt.Key), lt.Value.AsInterface())
-		case string:
-			if l < idx+1 {
-				os.span.SetTag(lt, labels[idx+1])
-				idx++
-			}
-		}
-	}
+	os.labels = append(os.labels, labels...)
 }
 
 func NewTracer(opts ...tracer.Option) *otTracer {

opentracing_test.go

@@ -30,3 +30,24 @@ func TestTraceID(t *testing.T) {
 		t.Fatalf("invalid span span id %#+v", v)
 	}
 }
+
+func TestTraceTags(t *testing.T) {
+	md := metadata.New(1)
+	ctx, cancel := context.WithCancel(context.Background())
+	defer cancel()
+	ctx = metadata.NewIncomingContext(ctx, md)
+
+	mtr := mocktracer.New()
+	tr := NewTracer(Tracer(mtr))
+	if err := tr.Init(); err != nil {
+		t.Fatal(err)
+	}
+
+	var sp tracer.Span
+
+	ctx, sp = tr.Start(ctx, "test", tracer.WithSpanLabels("key", "val", "odd"))
+	sp.Finish()
+
+	msp := mtr.FinishedSpans()[0]
+	t.Logf("mock span %#+v", msp.Tags())
+}