func Handler()

in tracing/inbound_http.go [12:55]
33 lines of code
4 McCabe index (conditional complexity)

func Handler(h http.Handler, opts ...HandlerOption) http.Handler {
	config := applyHandlerOptions(opts)

	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		if isHealthCheck(r) {
			h.ServeHTTP(w, r)
			return
		}

		tracer := opentracing.GlobalTracer()
		if tracer == nil {
			h.ServeHTTP(w, r)
			return
		}

		wireContext, _ := tracer.Extract(
			opentracing.HTTPHeaders,
			opentracing.HTTPHeadersCarrier(r.Header))

		// Create the span referring to the RPC client if available.
		// If wireContext == nil, a root span will be created.
		additionalStartSpanOpts := []opentracing.StartSpanOption{
			ext.RPCServerOption(wireContext),
		}

		correlationID := correlation.ExtractFromContext(r.Context())
		if correlationID != "" {
			additionalStartSpanOpts = append(additionalStartSpanOpts, opentracing.Tag{Key: "correlation_id", Value: correlationID})
		}

		serverSpan := opentracing.StartSpan(
			config.getOperationName(r),
			additionalStartSpanOpts...,
		)
		serverSpan.SetTag("http.method", r.Method)
		serverSpan.SetTag("http.url", r.URL)

		defer serverSpan.Finish()

		ctx := opentracing.ContextWithSpan(r.Context(), serverSpan)

		h.ServeHTTP(w, r.WithContext(ctx))
	})
}