diff --git a/engine/api/cache/cache.go b/engine/api/cache/cache.go
index 19e5bf3ebb..d9b0bd32e6 100644
--- a/engine/api/cache/cache.go
+++ b/engine/api/cache/cache.go
@@ -121,6 +121,7 @@ func DequeueWithContext(c context.Context, queueName string, value interface{})
 	s.DequeueWithContext(c, queueName, value)
 }
 
+//QueueLen returns the length of a queue
 func QueueLen(queueName string) int {
 	if s == nil {
 		return 0