Utils: add Lwt_pipe.pop_all_now

src/lib_stdlib_lwt/lwt_pipe.ml

@@ -162,14 +162,17 @@ let rec values_available q =
   else
     Lwt.return_unit
 
-let pop_all q =
-  let rec loop acc =
+let rec pop_all_loop q acc =
   match pop_now_exn q with
   | exception Empty -> List.rev acc
-    | e -> loop (e :: acc)
-  in
+  | e -> pop_all_loop q (e :: acc)
+
+let pop_all q =
   pop q >>= fun e ->
-  Lwt.return (loop [e])
+  Lwt.return (pop_all_loop q [e])
+
+let pop_all_now q =
+  pop_all_loop q []
 
 let close q =
   if not q.closed then begin

src/lib_stdlib_lwt/lwt_pipe.mli

@@ -34,6 +34,10 @@ val pop_all : 'a t -> 'a list Lwt.t
     removes and returns all the element in [q] (in the order they
     were inserted). *)
 
+val pop_all_now : 'a t -> 'a list
+(** [pop_all_now q] returns all the element in [q] (in the order they
+    were inserted), or [[]] if [q] is empty. *)
+
 val peek : 'a t -> 'a Lwt.t
 (** [peek] is like [pop] except it does not removes the first
     element. *)