rename Simple_pool into Fifo_pool, update doc

Makefile

@@ -24,7 +24,7 @@ DUNE_OPTS_BENCH?=--profile=release
 N?=40
 NITER?=2
 BENCH_PSIZE?=1,4,8,20
-BENCH_KIND?=simple,pool
+BENCH_KIND?=fifo,pool
 BENCH_CUTOFF?=20
 bench-fib:
 	@echo running for N=$(N)
@@ -34,7 +34,7 @@ bench-fib:
 
 PI_NSTEPS?=100_000_000
 PI_MODES?=seq,par1,forkjoin
-PI_KIND?=simple,pool
+PI_KIND?=fifo,pool
 bench-pi:
 	@echo running for N=$(PI_NSTEPS)
 	dune build $(DUNE_OPTS_BENCH) benchs/pi.exe

benchs/fib_rec.ml

@@ -20,7 +20,7 @@ let () = assert (List.init 10 fib_direct = [ 1; 1; 2; 3; 5; 8; 13; 21; 34; 55 ])
 
 let create_pool ~psize ~kind () =
   match kind with
-  | "simple" -> Simple_pool.create ~min:psize ()
+  | "fifo" -> Fifo_pool.create ~min:psize ()
   | "pool" -> Pool.create ~min:psize ()
   | _ -> assert false
 
@@ -54,7 +54,7 @@ let () =
       "-niter", Arg.Set_int niter, " number of iterations";
       "-cutoff", Arg.Set_int cutoff, " cutoff for sequential computation";
       ( "-kind",
-        Arg.Symbol ([ "pool"; "simple" ], ( := ) kind),
+        Arg.Symbol ([ "pool"; "fifo" ], ( := ) kind),
         " pick pool implementation" );
     ]
     |> Arg.align

benchs/pi.ml

@@ -24,11 +24,11 @@ let with_pool ~kind f =
       Pool.with_ ~per_domain:1 f
     else
       Pool.with_ ~min:!j f
-  | "simple" ->
+  | "fifo" ->
     if !j = 0 then
-      Simple_pool.with_ ~per_domain:1 f
+      Fifo_pool.with_ ~per_domain:1 f
     else
-      Simple_pool.with_ ~min:!j f
+      Fifo_pool.with_ ~min:!j f
   | _ -> assert false
 
 (** Run in parallel using {!Fut.for_} *)
@@ -120,7 +120,7 @@ let () =
       "-j", Arg.Set_int j, " number of threads";
       "-t", Arg.Set time, " printing timing";
       ( "-kind",
-        Arg.Symbol ([ "pool"; "simple" ], ( := ) kind),
+        Arg.Symbol ([ "pool"; "fifo" ], ( := ) kind),
         " pick pool implementation" );
     ]
     |> Arg.align

src/fifo_pool.mli

@@ -1,8 +1,16 @@
-(** A simple thread pool.
+(** A simple thread pool in FIFO order.
 
-    This uses a single blocking queue to manage tasks, it's very
-    simple and reliable. Like {!Pool} it distributes a fixed number
-    of workers over several domains.
+    FIFO: first-in, first-out. Basically tasks are put into a queue,
+    and worker threads pull them out of the queue at the other end.
+
+    Since this uses a single blocking queue to manage tasks, it's very
+    simple and reliable. The number of worker threads is fixed, but
+    they are spread over several domains to enable parallelism.
+
+    This can be useful for latency-sensitive applications (e.g. as a
+    pool of workers for network servers). Work-stealing pools might
+    have higher throughput but they're very unfair to some tasks; by
+    contrast, here, older tasks have priority over younger tasks.
 
     @since NEXT_RELEASE *)
 

src/moonpool.ml

@@ -11,7 +11,7 @@ module Fut = Fut
 module Lock = Lock
 module Pool = Pool
 module Runner = Runner
-module Simple_pool = Simple_pool
+module Fifo_pool = Fifo_pool
 
 module Private = struct
   module Ws_deque_ = Ws_deque_

src/moonpool.mli

@@ -5,7 +5,7 @@
 *)
 
 module Pool = Pool
-module Simple_pool = Simple_pool
+module Fifo_pool = Fifo_pool
 module Runner = Runner
 
 val start_thread_on_some_domain : ('a -> unit) -> 'a -> Thread.t

test/t_fib.ml

@@ -4,7 +4,7 @@ let ( let@ ) = ( @@ )
 
 let with_pool ~kind () f =
   match kind with
-  | `Simple_pool -> Simple_pool.with_ ~min:4 () f
+  | `Fifo_pool -> Fifo_pool.with_ ~min:4 () f
   | `Pool -> Pool.with_ ~min:4 () f
 
 let rec fib x =
@@ -75,4 +75,4 @@ let run ~kind () =
 
 let () =
   run ~kind:`Pool ();
-  run ~kind:`Simple_pool ()
+  run ~kind:`Fifo_pool ()

test/t_props.ml

@@ -7,7 +7,7 @@ let add_test t = tests := t :: !tests
 
 let with_pool ~kind () f =
   match kind with
-  | `Simple_pool -> Simple_pool.with_ ~min:4 ~per_domain:1 () f
+  | `Fifo_pool -> Fifo_pool.with_ ~min:4 ~per_domain:1 () f
   | `Pool -> Pool.with_ ~min:4 ~per_domain:1 () f
 
 let () =
@@ -48,7 +48,7 @@ let () =
 
 let () =
   let tests =
-    List.map (fun t -> [ t ~kind:`Simple_pool; t ~kind:`Pool ]) !tests
+    List.map (fun t -> [ t ~kind:`Fifo_pool; t ~kind:`Pool ]) !tests
     |> List.flatten
   in
   QCheck_base_runner.run_tests_main tests

test/t_resource.ml

@@ -4,7 +4,7 @@ let ( let@ ) = ( @@ )
 
 let with_pool ~kind () f =
   match kind with
-  | `Simple_pool -> Simple_pool.with_ ~min:4 ~per_domain:1 () f
+  | `Fifo_pool -> Fifo_pool.with_ ~min:4 ~per_domain:1 () f
   | `Pool -> Pool.with_ ~min:4 ~per_domain:1 () f
 
 (* test proper resource handling *)
@@ -24,4 +24,4 @@ let run ~kind () =
 
 let () =
   run ~kind:`Pool ();
-  run ~kind:`Simple_pool ()
+  run ~kind:`Fifo_pool ()

test/t_tree_futs.ml

@@ -4,7 +4,7 @@ let ( let@ ) = ( @@ )
 
 let with_pool ~kind ~j () f =
   match kind with
-  | `Simple_pool -> Simple_pool.with_ ~min:j () f
+  | `Fifo_pool -> Fifo_pool.with_ ~min:j () f
   | `Pool -> Pool.with_ ~min:j () f
 
 type 'a tree =
@@ -89,4 +89,4 @@ let () =
   Tracy_client_trace.setup ();
    *)
   run_main ~kind:`Pool ();
-  run_main ~kind:`Simple_pool ()
+  run_main ~kind:`Fifo_pool ()

test/t_unfair.ml

@@ -20,7 +20,7 @@ let run ~kind () =
     in
 
     match kind with
-    | `Simple -> Simple_pool.create ~min:3 ~on_init_thread ~around_task ()
+    | `Simple -> Fifo_pool.create ~min:3 ~on_init_thread ~around_task ()
     | `Pool -> Pool.create ~min:3 ~on_init_thread ~around_task ()
   in