add Pool.size

moonpool.opam

@@ -11,8 +11,8 @@ depends: [
   "ocaml" {>= "4.08"}
   "dune" {>= "3.0"}
   "either"
-  "mdx" {>= "1.9.0" & with-test}
   "odoc" {with-doc}
+  "mdx" {>= "1.9.0" & with-test}
 ]
 build: [
   ["dune" "subst"] {dev}

src/pool.ml

@@ -22,6 +22,7 @@ let add_global_thread_loop_wrapper f : unit =
   done
 
 let[@inline] run self f : unit = S_queue.push self.q f
+let size self = Array.length self.threads
 
 let worker_thread_ ~on_exn (active : bool A.t) (q : _ S_queue.t) : unit =
   while A.get active do

src/pool.mli

@@ -33,6 +33,9 @@ val create :
        to use for this pool's workers.
   *)
 
+val size : t -> int
+(** Number of threads *)
+
 val shutdown : t -> unit
 (** Shutdown the pool and wait for it to terminate. Idempotent. *)