feat fifo: expose private interface for the main runner threads

src/core/fifo_pool.ml

@@ -107,6 +107,17 @@ type ('a, 'b) create_args =
   ?name:string ->
   'a
 
+let default_around_task_ : around_task = AT_pair (ignore, fun _ _ -> ())
+
+let runner_of_state (pool : state) : t =
+  let run_async ~ls f = schedule_ pool @@ T_start { f; ls } in
+  Runner.For_runner_implementors.create
+    ~shutdown:(fun ~wait () -> shutdown_ pool ~wait)
+    ~run_async
+    ~size:(fun () -> size_ pool)
+    ~num_tasks:(fun () -> num_tasks_ pool)
+    ()
+
 let create ?(on_init_thread = default_thread_init_exit_)
     ?(on_exit_thread = default_thread_init_exit_) ?(on_exn = fun _ _ -> ())
     ?around_task ?num_threads ?name () : t =
@@ -114,7 +125,7 @@ let create ?(on_init_thread = default_thread_init_exit_)
   let around_task =
     match around_task with
     | Some (f, g) -> AT_pair (f, g)
-    | None -> AT_pair (ignore, fun _ _ -> ())
+    | None -> default_around_task_
   in
 
   let num_domains = Domain_pool_.n_domains () in
@@ -126,20 +137,11 @@ let create ?(on_init_thread = default_thread_init_exit_)
   let offset = Random.int num_domains in
 
   let pool =
-    let dummy = Thread.self () in
-    { threads = Array.make num_threads dummy; q = Bb_queue.create () }
+    let dummy_thread = Thread.self () in
+    { threads = Array.make num_threads dummy_thread; q = Bb_queue.create () }
   in
 
-  let run_async ~ls f = schedule_ pool @@ T_start { f; ls } in
-
-  let runner =
-    Runner.For_runner_implementors.create
-      ~shutdown:(fun ~wait () -> shutdown_ pool ~wait)
-      ~run_async
-      ~size:(fun () -> size_ pool)
-      ~num_tasks:(fun () -> num_tasks_ pool)
-      ()
-  in
+  let runner = runner_of_state pool in
 
   (* temporary queue used to obtain thread handles from domains
      on which the thread are started. *)
@@ -203,3 +205,13 @@ let with_ ?on_init_thread ?on_exit_thread ?on_exn ?around_task ?num_threads
   in
   let@ () = Fun.protect ~finally:(fun () -> shutdown pool) in
   f pool
+
+module Private_ = struct
+  type nonrec state = state
+
+  let create_state ~threads () : state = { threads; q = Bb_queue.create () }
+  let runner_of_state = runner_of_state
+
+  let run_thread (st : state) (self : t) ~on_exn : unit =
+    worker_thread_ st self ~on_exn ~around_task:default_around_task_
+end

src/core/fifo_pool.mli

@@ -44,3 +44,17 @@ val with_ : (unit -> (t -> 'a) -> 'a, _) create_args
     When [f pool] returns or fails, [pool] is shutdown and its resources
     are released.
     Most parameters are the same as in {!create}. *)
+
+(**/**)
+
+module Private_ : sig
+  type state
+
+  val create_state : threads:Thread.t array -> unit -> state
+  val runner_of_state : state -> Runner.t
+
+  val run_thread :
+    state -> t -> on_exn:(exn -> Printexc.raw_backtrace -> unit) -> unit
+end
+
+(**/**)