add Lwt.waiter_of_wakener

Ignore-this: 6a3ab84651cfaef9677b9ce503d655ad

darcs-hash:20101208162521-c41ad-1bf846856ed489467fd1178ad924e37a97865a84

src/core/lwt.ml

@@ -321,6 +321,8 @@ let task () =
   } in
   (thread t, wakener t)
 
+let waiter_of_wakener wakener = thread (wakener_repr wakener)
+
 (* apply function, reifying explicit exceptions into the thread type
    apply: ('a -(exn)-> 'b t) -> ('a -(n)-> 'b t)
    semantically a natural transformation TE -> T, where T is the thread

src/core/lwt.mli

@@ -186,6 +186,9 @@ val wakeup_exn : 'a u -> exn -> unit
   (** [wakeup_exn t e] makes the sleeping thread [t] fail with the
       exception [e]. *)
 
+val waiter_of_wakener : 'a u -> 'a t
+  (** Returns the thread associated to a wakener. *)
+
 (** {6 Threads state} *)
 
 (** State of a thread *)