func UnaryServerInterceptor()

in xray/grpc.go [68:133]
56 lines of code
10 McCabe index (conditional complexity)

func UnaryServerInterceptor(serverInterceptorOptions ...GrpcOption) grpc.UnaryServerInterceptor {
	var option grpcOption
	for _, options := range serverInterceptorOptions {
		options.apply(&option)
	}

	return func(ctx context.Context, req interface{}, info *grpc.UnaryServerInfo, handler grpc.UnaryHandler) (resp interface{}, err error) {
		md, ok := metadata.FromIncomingContext(ctx)

		var traceID string
		if ok && len(md.Get(TraceIDHeaderKey)) == 1 {
			traceID = md.Get(TraceIDHeaderKey)[0]
		}
		traceHeader := header.FromString(traceID)

		var host string

		if len(md.Get(":authority")) == 1 {
			host = md.Get(":authority")[0]
		}
		requestURL := url.URL{
			Scheme: "grpc",
			Host:   host,
			Path:   info.FullMethod,
		}

		var name string
		if option.segmentNamer == nil {
			name = inferServiceName(info.FullMethod)
		} else {
			name = option.segmentNamer.Name(host)
		}

		if option.config != nil {
			ctx = context.WithValue(ctx, RecorderContextKey{}, option.config)
		}

		var seg *Segment
		ctx, seg = NewSegmentFromHeader(ctx, name, &http.Request{
			Host:   host,
			URL:    &requestURL,
			Method: http.MethodPost,
		}, traceHeader)
		defer seg.Close(nil)

		seg.Lock()
		seg.GetHTTP().GetRequest().ClientIP, seg.GetHTTP().GetRequest().XForwardedFor = clientIPFromGrpcMetadata(md)
		seg.GetHTTP().GetRequest().URL = requestURL.String()
		seg.GetHTTP().GetRequest().Method = http.MethodPost
		if len(md.Get("user-agent")) == 1 {
			seg.GetHTTP().GetRequest().UserAgent = md.Get("user-agent")[0]
		}
		seg.Unlock()

		resp, err = handler(ctx, req)
		if err != nil {
			classifyErrorStatus(seg, err)
		}
		recordContentLength(seg, resp)
		if headerErr := addResponseTraceHeader(ctx, seg, traceHeader); headerErr != nil {
			logger.Debug("fail to set the grpc trace header")
		}

		return resp, err
	}
}