ddtrace/tracer: review patch

- Change UserTagOption to UserMonitoringOption
- Options now return a closure that sets the tag directly
- Improve comments
- SetUser new sets the tags even if span type assertion fails

ddtrace/tracer/option.go

@@ -830,41 +830,40 @@ func StackFrames(n, skip uint) FinishOption {
 	}
 }
 
-// UserTagOption represents a function that can be provided as a parameter to SetUser.
-// This is used to normalize user tags key/value pairs.
-type UserTagOption func() (key string, val interface{})
+// UserMonitoringOption represents a function that can be provided as a parameter to SetUser.
+type UserMonitoringOption func(Span)
 
-// WithUserEmailTag emits the normalized key/value UserTagOption holding user email information.
-func WithUserEmailTag(email string) UserTagOption {
-	return func() (key string, val interface{}) {
-		return "usr.email", email
+// WithUserEmail returns the option setting the email of the authenticated user.
+func WithUserEmail(email string) UserMonitoringOption {
+	return func(s Span) {
+		s.SetTag("usr.email", email)
 	}
 }
 
-// WithUserNameTag emits the normalized key/value UserTagOption holding user name information.
-func WithUserNameTag(name string) UserTagOption {
-	return func() (key string, val interface{}) {
-		return "usr.name", name
+// WithUserName returns the option setting the name of the authenticated user.
+func WithUserName(name string) UserMonitoringOption {
+	return func(s Span) {
+		s.SetTag("usr.name", name)
 	}
 }
 
-// WithUserSessionIDTag emits the normalized key/value UserTagOption holding user session id information.
-func WithUserSessionIDTag(sessionID string) UserTagOption {
-	return func() (key string, val interface{}) {
-		return "usr.session_id", sessionID
+// WithUserSessionID returns the option setting the session ID of the authenticated user.
+func WithUserSessionID(sessionID string) UserMonitoringOption {
+	return func(s Span) {
+		s.SetTag("usr.session_id", sessionID)
 	}
 }
 
-// WithUserRoleTag emits the normalized key/value UserTagOption holding user role information.
-func WithUserRoleTag(role string) UserTagOption {
-	return func() (key string, val interface{}) {
-		return "usr.role", role
+// WithUserRole returns the option setting the role of the authenticated user.
+func WithUserRole(role string) UserMonitoringOption {
+	return func(s Span) {
+		s.SetTag("usr.role", role)
 	}
 }
 
-// WithUserScopeTag emits the normalized key/value UserTagOption holding user scope information.
-func WithUserScopeTag(scope string) UserTagOption {
-	return func() (key string, val interface{}) {
-		return "usr.scope", scope
+// WithUserScope returns the option setting the scope (authorizations) of the authenticated user
+func WithUserScope(scope string) UserMonitoringOption {
+	return func(s Span) {
+		s.SetTag("usr.scope", scope)
 	}
 }

ddtrace/tracer/tracer.go

@@ -153,21 +153,20 @@ func Inject(ctx ddtrace.SpanContext, carrier interface{}) error {
 	return internal.GetGlobalTracer().Inject(ctx, carrier)
 }
 
-// SetUser tags the root span of s with the provided user id as well as the
-// optional tags provided as userTagOption parameters. This allows user identification
-// across all spans of a trace.
-func SetUser(s Span, id string, opts ...UserTagOption) {
+// SetUser associates user information to the current trace which the
+// provided span belongs to. The options can be used to tune which user
+// bit of information gets monitored.
+func SetUser(s Span, id string, opts ...UserMonitoringOption) {
 	if s == nil {
 		return
 	}
-	if span, ok := s.(*span); ok {
-		if span.context != nil {
-			span = span.context.trace.root
-		}
-		span.SetTag("usr.id", id)
-		for _, fn := range opts {
-			span.SetTag(fn())
-		}
+	if span, ok := s.(*span); ok && span.context != nil {
+		span = span.context.trace.root
+		s = span
+	}
+	s.SetTag("usr.id", id)
+	for _, fn := range opts {
+		fn(s)
 	}
 }