test: add a parallel quicksort

test/await/dune

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

test/await/t_sort.ml

@@ -0,0 +1,68 @@
+open Moonpool
+
+let rec select_sort arr i len =
+  if len >= 2 then (
+    let idx = ref i in
+    for j = i + 1 to i + len - 1 do
+      if arr.(j) < arr.(!idx) then idx := j
+    done;
+    let tmp = arr.(!idx) in
+    arr.(!idx) <- arr.(i);
+    arr.(i) <- tmp;
+    select_sort arr (i + 1) (len - 1)
+  )
+
+let sorted arr =
+  try
+    for i = 0 to Array.length arr - 2 do
+      if arr.(i) > arr.(i + 1) then (
+        Printf.printf "not sorted at %d\n%!" i;
+        raise Exit
+      )
+    done;
+    true
+  with Exit -> false
+
+let () =
+  let arr = [| 4; 2; 1; 5; 1; 10; 3 |] in
+  select_sort arr 0 (Array.length arr);
+  assert (sorted arr)
+
+let rec quicksort arr i len : unit =
+  if len <= 10 then
+    select_sort arr i len
+  else (
+    let pivot = arr.(i + (len / 2)) in
+    let low = ref (i - 1) in
+    let high = ref (i + len) in
+
+    while !low < !high do
+      incr low;
+      decr high;
+      while arr.(!low) < pivot do
+        incr low
+      done;
+      while arr.(!high) > pivot do
+        decr high
+      done;
+      if !low < !high then (
+        let tmp = arr.(!low) in
+        arr.(!low) <- arr.(!high);
+        arr.(!high) <- tmp
+      )
+    done;
+
+    Fork_join.both_ignore
+      (fun () -> quicksort arr i (!low - i))
+      (fun () -> quicksort arr !low (len - (!low - i)))
+  )
+
+let pool = Moonpool.Pool.create ~min:8 ()
+
+let () =
+  let arr = Array.init 400_000 (fun _ -> Random.int 300_000) in
+  Fut.spawn ~on:pool (fun () -> quicksort arr 0 (Array.length arr))
+  |> Fut.wait_block_exn;
+  (* Printf.printf "arr: [%s]\n%!" *)
+  (*   (String.concat ", " @@ List.map string_of_int @@ Array.to_list arr); *)
+  assert (sorted arr)