func()

in tracing/outbound_http.go [19:74]

• 42 lines of code
• 5 McCabe index (conditional complexity)

func (c tracingRoundTripper) RoundTrip(req *http.Request) (res *http.Response, e error) {
	tracer := opentracing.GlobalTracer()
	if tracer == nil {
		return c.delegate.RoundTrip(req)
	}

	ctx := req.Context()

	var parentCtx opentracing.SpanContext

	parentSpan := opentracing.SpanFromContext(ctx)
	if parentSpan != nil {
		parentCtx = parentSpan.Context()
	}

	// start a new Span to wrap HTTP request
	span := opentracing.StartSpan(
		c.config.getOperationName(req),
		opentracing.ChildOf(parentCtx),
	)
	defer span.Finish()

	ctx = opentracing.ContextWithSpan(ctx, span)

	// attach ClientTrace to the Context, and Context to request
	trace := newClientTrace(span)
	ctx = httptrace.WithClientTrace(ctx, trace)
	req = req.WithContext(ctx)

	ext.SpanKindRPCClient.Set(span)
	ext.HTTPUrl.Set(span, req.URL.String())
	ext.HTTPMethod.Set(span, req.Method)

	carrier := opentracing.HTTPHeadersCarrier(req.Header)
	err := span.Tracer().Inject(span.Context(), opentracing.HTTPHeaders, carrier)

	if err != nil {
		logkit.ContextLogger(ctx).WithError(err).Error("tracing span injection failed")
	}

	response, err := c.delegate.RoundTrip(req)

	if err != nil {
		span.LogFields(
			otlog.String("event", "roundtrip error"),
			otlog.Object("error", err),
		)
	} else {
		span.LogFields(
			otlog.String("event", "roundtrip complete"),
			otlog.Int("status", response.StatusCode),
		)
	}

	return response, err
}