tracer: update wrapper

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

tracer/options.go

@@ -91,7 +91,9 @@ type SpanOptions struct {
 }
 
 // EventOptions contains event options
-type EventOptions struct{}
+type EventOptions struct {
+	Labels []interface{}
+}
 
 func WithSpanLabels(ls ...interface{}) options.Option {
 	return func(src interface{}) error {
@@ -110,6 +112,26 @@ func WithSpanLabels(ls ...interface{}) options.Option {
 	}
 }
 
+// EventOption func signature
+type EventOption func(o *EventOptions)
+
+func WithEventLabels(ls ...interface{}) options.Option {
+	return func(src interface{}) error {
+		v, err := options.Get(src, ".Labels")
+		if err != nil {
+			return err
+		} else if rutil.IsZero(v) {
+			v = reflect.MakeSlice(reflect.TypeOf(v), 0, len(ls)).Interface()
+		}
+		cv := reflect.ValueOf(v)
+		for _, l := range ls {
+			reflect.Append(cv, reflect.ValueOf(l))
+		}
+		err = options.Set(src, cv, ".Labels")
+		return err
+	}
+}
+
 func WithSpanKind(k SpanKind) options.Option {
 	return func(src interface{}) error {
 		return options.Set(src, k, ".Kind")