requestinfohandler: Make Prometheus reporting a receiver function

Convert the function that reports Prometheus metrics a receiver function
of the `requestInfo`. This makes the logic more self-contained as we
have to pass less variables into it and can readily reuse what we store
inside of the struct already anyway.

2 files changed, 38 insertions, 29 deletions

diff --git a/internal/grpc/middleware/requestinfohandler/requestinfohandler.go b/internal/grpc/middleware/requestinfohandler/requestinfohandler.go
index 843508bf3..7e59b6ce1 100644
--- a/internal/grpc/middleware/requestinfohandler/requestinfohandler.go
+++ b/internal/grpc/middleware/requestinfohandler/requestinfohandler.go
@@ -35,6 +35,7 @@ var requests = promauto.NewCounterVec(
 )
 
 type requestInfo struct {
+	fullMethod      string
 	clientName      string
 	callSite        string
 	authVersion     string
@@ -91,6 +92,7 @@ func getFromMD(md metadata.MD, header string) string {
 // using `unknown` if a value is not set
 func newRequestInfo(ctx context.Context, fullMethod, grpcMethodType string) requestInfo {
 	info := requestInfo{
+		fullMethod:      fullMethod,
 		clientName:      unknownValue,
 		callSite:        unknownValue,
 		authVersion:     unknownValue,
@@ -196,40 +198,31 @@ func newRequestInfo(ctx context.Context, fullMethod, grpcMethodType string) requ
 	return info
 }
 
-func extractServiceAndMethodName(fullMethodName string) (string, string) {
-	fullMethodName = strings.TrimPrefix(fullMethodName, "/") // remove leading slash
-	service, method, ok := strings.Cut(fullMethodName, "/")
-	if !ok {
-		return unknownValue, unknownValue
-	}
-	return service, method
-}
-
-func streamRPCType(info *grpc.StreamServerInfo) string {
-	if info.IsClientStream && !info.IsServerStream {
-		return "client_stream"
-	} else if !info.IsClientStream && info.IsServerStream {
-		return "server_stream"
-	}
-	return "bidi_stream"
-}
-
-func reportWithPrometheusLabels(info requestInfo, fullMethod string, err error) {
+func (i requestInfo) reportPrometheusMetrics(err error) {
 	grpcCode := structerr.GRPCCode(err)
-	serviceName, methodName := extractServiceAndMethodName(fullMethod)
+	serviceName, methodName := extractServiceAndMethodName(i.fullMethod)
 
 	requests.WithLabelValues(
-		info.clientName,   // client_name
+		i.clientName,      // client_name
 		serviceName,       // grpc_service
 		methodName,        // grpc_method
-		info.callSite,     // call_site
-		info.authVersion,  // auth_version
+		i.callSite,        // call_site
+		i.authVersion,     // auth_version
 		grpcCode.String(), // grpc_code
-		info.deadlineType, // deadline_type
-		info.methodOperation,
-		info.methodScope,
+		i.deadlineType,    // deadline_type
+		i.methodOperation,
+		i.methodScope,
 	).Inc()
-	grpcprometheus.WithConstLabels(prometheus.Labels{"deadline_type": info.deadlineType})
+	grpcprometheus.WithConstLabels(prometheus.Labels{"deadline_type": i.deadlineType})
+}
+
+func extractServiceAndMethodName(fullMethodName string) (string, string) {
+	fullMethodName = strings.TrimPrefix(fullMethodName, "/") // remove leading slash
+	service, method, ok := strings.Cut(fullMethodName, "/")
+	if !ok {
+		return unknownValue, unknownValue
+	}
+	return service, method
 }
 
 // UnaryInterceptor returns a Unary Interceptor
@@ -238,7 +231,7 @@ func UnaryInterceptor(ctx context.Context, req interface{}, serverInfo *grpc.Una
 
 	res, err := handler(ctx, req)
 
-	reportWithPrometheusLabels(info, serverInfo.FullMethod, err)
+	info.reportPrometheusMetrics(err)
 
 	return res, err
 }
@@ -250,7 +243,16 @@ func StreamInterceptor(srv interface{}, stream grpc.ServerStream, serverInfo *gr
 
 	err := handler(srv, stream)
 
-	reportWithPrometheusLabels(info, serverInfo.FullMethod, err)
+	info.reportPrometheusMetrics(err)
 
 	return err
 }
+
+func streamRPCType(info *grpc.StreamServerInfo) string {
+	if info.IsClientStream && !info.IsServerStream {
+		return "client_stream"
+	} else if !info.IsClientStream && info.IsServerStream {
+		return "server_stream"
+	}
+	return "bidi_stream"
+}
diff --git a/internal/grpc/middleware/requestinfohandler/requestinfohandler_test.go b/internal/grpc/middleware/requestinfohandler/requestinfohandler_test.go
index c9c9946d7..bad0e39ee 100644
--- a/internal/grpc/middleware/requestinfohandler/requestinfohandler_test.go
+++ b/internal/grpc/middleware/requestinfohandler/requestinfohandler_test.go
@@ -113,6 +113,7 @@ func TestNewRequestInfo(t *testing.T) {
 			metadata:   metadata.Pairs(),
 			deadline:   false,
 			expectedInfo: requestInfo{
+				fullMethod:      "/gitaly.RepositoryService/UnknownMethod",
 				clientName:      unknownValue,
 				callSite:        unknownValue,
 				authVersion:     unknownValue,
@@ -127,6 +128,7 @@ func TestNewRequestInfo(t *testing.T) {
 			metadata:   metadata.Pairs(),
 			deadline:   false,
 			expectedInfo: requestInfo{
+				fullMethod:      "/gitaly.RepositoryService/ObjectFormat",
 				clientName:      unknownValue,
 				callSite:        unknownValue,
 				authVersion:     unknownValue,
@@ -141,6 +143,7 @@ func TestNewRequestInfo(t *testing.T) {
 			metadata:   metadata.Pairs(),
 			deadline:   false,
 			expectedInfo: requestInfo{
+				fullMethod:      "/gitaly.RepositoryService/CreateRepository",
 				clientName:      unknownValue,
 				callSite:        unknownValue,
 				authVersion:     unknownValue,
@@ -155,6 +158,7 @@ func TestNewRequestInfo(t *testing.T) {
 			metadata:   metadata.Pairs(),
 			deadline:   false,
 			expectedInfo: requestInfo{
+				fullMethod:      "/gitaly.RepositoryService/OptimizeRepository",
 				clientName:      unknownValue,
 				callSite:        unknownValue,
 				authVersion:     unknownValue,
@@ -169,6 +173,7 @@ func TestNewRequestInfo(t *testing.T) {
 			metadata:   metadata.Pairs(),
 			deadline:   false,
 			expectedInfo: requestInfo{
+				fullMethod:      "/gitaly.RepositoryService/OptimizeRepository",
 				clientName:      unknownValue,
 				callSite:        unknownValue,
 				authVersion:     unknownValue,
@@ -183,6 +188,7 @@ func TestNewRequestInfo(t *testing.T) {
 			metadata:   metadata.Pairs(),
 			deadline:   false,
 			expectedInfo: requestInfo{
+				fullMethod:      "/gitaly.RemoteService/FindRemoteRepository",
 				clientName:      unknownValue,
 				callSite:        unknownValue,
 				authVersion:     unknownValue,
@@ -231,6 +237,7 @@ func TestGRPCTags(t *testing.T) {
 		info := newRequestInfo(ctx, "/gitaly.RepositoryService/OptimizeRepository", "unary")
 
 		require.Equal(t, requestInfo{
+			fullMethod:      "/gitaly.RepositoryService/OptimizeRepository",
 			clientName:      clientName,
 			callSite:        "unknown",
 			authVersion:     "unknown",