add test for fork_join

test/await/dune

@@ -1,6 +1,6 @@
 
 (tests
-  (names t_fib1 t_futs1 t_many)
+  (names t_fib1 t_futs1 t_many t_fork_join)
   (enabled_if (>= %{ocaml_version} 5.0))
   (libraries moonpool trace ;tracy-client.trace
              ))

test/await/t_fork_join.ml

@@ -0,0 +1,51 @@
+open Moonpool
+
+let rec fib_direct x =
+  if x <= 1 then
+    1
+  else
+    fib_direct (x - 1) + fib_direct (x - 2)
+
+let fib ~on x : int Fut.t =
+  let rec fib_rec x : int =
+    if x <= 18 then
+      fib_direct x
+    else (
+      let n1, n2 =
+        Fork_join.both (fun () -> fib_rec (x - 1)) (fun () -> fib_rec (x - 2))
+      in
+      n1 + n2
+    )
+  in
+  Fut.spawn ~on (fun () -> fib_rec x)
+
+(* NOTE: for tracy support
+   let () = Tracy_client_trace.setup ()
+*)
+let () = assert (List.init 10 fib_direct = [ 1; 1; 2; 3; 5; 8; 13; 21; 34; 55 ])
+
+let fib_40 : int =
+  let pool = Pool.create ~min:8 () in
+  fib ~on:pool 40 |> Fut.wait_block_exn
+
+let () = Printf.printf "fib 40 = %d\n%!" fib_40
+
+let run_test () =
+  let pool = Pool.create ~min:8 () in
+
+  assert (
+    List.init 10 (fib ~on:pool)
+    |> Fut.join_list |> Fut.wait_block_exn
+    = [ 1; 1; 2; 3; 5; 8; 13; 21; 34; 55 ]);
+
+  let fibs = Array.init 3 (fun _ -> fib ~on:pool 40) in
+
+  let res = Fut.join_array fibs |> Fut.wait_block in
+  Pool.shutdown pool;
+
+  assert (res = Ok (Array.make 3 fib_40))
+
+let () =
+  (* now make sure we can do this with multiple pools in parallel *)
+  let jobs = Array.init 2 (fun _ -> Thread.create run_test ()) in
+  Array.iter Thread.join jobs