Retrieve lost code due to merge

bridge/opentracing/bridge.go

@@ -711,3 +711,104 @@ func (t *BridgeTracer) getPropagator() propagation.TextMapPropagator {
 	}
 	return otel.GetTextMapPropagator()
 }
+
+// textMapWrapper Provides opentracing.TextMapWriter and opentracing.TextMapReader to
+// propagation.TextMapCarrier compatibility.
+// Usually, Inject method will only use the write-related interface.
+// Extract method will only use the reade-related interface.
+// To avoid panic,
+// when the carrier implements only one of the interfaces,
+// it provides a default implementation of the other interface (textMapWriter and textMapReader).
+type textMapWrapper struct {
+	opentracing.TextMapWriter
+	opentracing.TextMapReader
+	readerMap map[string]string
+}
+
+func (t *textMapWrapper) Get(key string) string {
+	if t.readerMap == nil {
+		t.loadMap()
+	}
+
+	return t.readerMap[key]
+}
+
+func (t *textMapWrapper) Set(key string, value string) {
+	t.TextMapWriter.Set(key, value)
+}
+
+func (t *textMapWrapper) Keys() []string {
+	if t.readerMap == nil {
+		t.loadMap()
+	}
+
+	str := make([]string, 0, len(t.readerMap))
+	for key := range t.readerMap {
+		str = append(str, key)
+	}
+
+	return str
+}
+
+func (t *textMapWrapper) loadMap() {
+	t.readerMap = make(map[string]string)
+
+	_ = t.ForeachKey(func(key, val string) error {
+		t.readerMap[key] = val
+		return nil
+	})
+}
+
+func newTextMapWrapperForExtract(carrier interface{}) (*textMapWrapper, error) {
+	t := &textMapWrapper{}
+
+	reader, ok := carrier.(opentracing.TextMapReader)
+	if !ok {
+		return nil, ot.ErrInvalidCarrier
+	}
+
+	t.TextMapReader = reader
+
+	writer, ok := carrier.(opentracing.TextMapWriter)
+	if ok {
+		t.TextMapWriter = writer
+	} else {
+		t.TextMapWriter = &textMapWriter{}
+	}
+
+	return t, nil
+}
+
+func newTextMapWrapperForInject(carrier interface{}) (*textMapWrapper, error) {
+	t := &textMapWrapper{}
+
+	writer, ok := carrier.(opentracing.TextMapWriter)
+	if !ok {
+		return nil, ot.ErrInvalidCarrier
+	}
+
+	t.TextMapWriter = writer
+
+	reader, ok := carrier.(opentracing.TextMapReader)
+	if ok {
+		t.TextMapReader = reader
+	} else {
+		t.TextMapReader = &textMapReader{}
+	}
+
+	return t, nil
+}
+
+type textMapWriter struct {
+}
+
+func (t *textMapWriter) Set(key string, value string) {
+	return // maybe print a warning log
+}
+
+type textMapReader struct {
+}
+
+func (t *textMapReader) ForeachKey(handler func(key, val string) error) error {
+	return nil // maybe print a warning log
+}