Split GetSpanDetails function

tracing/opencensus/endpoint.go

@@ -31,12 +31,8 @@ func TraceEndpoint(name string, options ...EndpointOption) endpoint.Middleware {
 
 	return func(next endpoint.Endpoint) endpoint.Endpoint {
 		return func(ctx context.Context, request interface{}) (response interface{}, err error) {
-			var attributes []trace.Attribute
-
-			if cfg.GetSpanDetails != nil {
-				var newName string
-
-				newName, attributes = cfg.GetSpanDetails(ctx, name)
+			if cfg.GetName != nil {
+				newName := cfg.GetName(ctx, name)
 
 				if newName != "" {
 					name = newName
@@ -47,11 +43,15 @@ func TraceEndpoint(name string, options ...EndpointOption) endpoint.Middleware {
 			if len(cfg.Attributes) > 0 {
 				span.AddAttributes(cfg.Attributes...)
 			}
-			if len(attributes) > 0 {
-				span.AddAttributes(attributes...)
-			}
 			defer span.End()
 
+			if cfg.GetAttributes != nil {
+				attributes := cfg.GetAttributes(ctx)
+				if len(attributes) > 0 {
+					span.AddAttributes(attributes...)
+				}
+			}
+
 			defer func() {
 				if err != nil {
 					if lberr, ok := err.(lb.RetryError); ok {

tracing/opencensus/endpoint_options.go

@@ -16,12 +16,15 @@ type EndpointOptions struct {
 	// creation by our Endpoint middleware.
 	Attributes []trace.Attribute
 
-	// GetSpanDetails holds the function to use for generating the span name
+	// GetName holds the function used for generating the span name
 	// based on the current name and from the information found in the incoming Request.
-	// It can also return additional attributes for the span.
 	//
-	// A returned empty name defaults to the name that the middleware was initialized with.
-	GetSpanDetails func(ctx context.Context, name string) (string, []trace.Attribute)
+	// If the returned name is empty, the existing name for the endpoint is kept.
+	GetName func(ctx context.Context, name string) string
+
+	// GetAttributes holds the function used for extracting additional attributes
+	// from the information found in the incoming Request.
+	GetAttributes func(ctx context.Context) []trace.Attribute
 }
 
 // EndpointOption allows for functional options to our OpenCensus endpoint
@@ -52,9 +55,16 @@ func WithIgnoreBusinessError(val bool) EndpointOption {
 	}
 }
 
-// WithSpanDetails extracts details from the request context (like span name and additional attributes).
-func WithSpanDetails(fn func(ctx context.Context, name string) (string, []trace.Attribute)) EndpointOption {
+// WithSpanName extracts additional attributes from the request context.
+func WithSpanName(fn func(ctx context.Context, name string) string) EndpointOption {
+	return func(o *EndpointOptions) {
+		o.GetName = fn
+	}
+}
+
+// WithSpanAttributes extracts additional attributes from the request context.
+func WithSpanAttributes(fn func(ctx context.Context) []trace.Attribute) EndpointOption {
 	return func(o *EndpointOptions) {
-		o.GetSpanDetails = fn
+		o.GetAttributes = fn
 	}
 }

tracing/opencensus/endpoint_test.go

@@ -88,8 +88,11 @@ func TestTraceEndpoint(t *testing.T) {
 	}
 	mw = opencensus.TraceEndpoint(
 		"",
-		opencensus.WithSpanDetails(func(ctx context.Context, name string) (string, []trace.Attribute) {
-			return span6, span6Attrs
+		opencensus.WithSpanName(func(ctx context.Context, name string) string {
+			return span6
+		}),
+		opencensus.WithSpanAttributes(func(ctx context.Context) []trace.Attribute {
+			return span6Attrs
 		}),
 	)
 	mw(endpoint.Nop)(ctx, nil)