[RFC]: Convert to direct-style with Eio

.ocamlformat

@@ -1,4 +1,4 @@
-version = 0.26.2
+version = 0.27.0
 profile = conventional
 
 ocaml-version = 4.08.0

CHANGES.md

@@ -1,3 +1,9 @@
+## 4.0.0
+
+### Changed
+
+- Convert to direct-style with Eio (#2149, @patricoferris, @ElectreAAS, @clecat, @art-w)
+
 ## 3.11.0 (2025-06-19)
 
 ### Added

README.md

@@ -178,8 +178,6 @@ Git-based, filesystem-backed store.
 
 <!-- $MDX file=examples/readme.ml -->
 ```ocaml
-open Lwt.Syntax
-
 (* Irmin store with string contents *)
 module Store = Irmin_git_unix.FS.KV (Irmin.Contents.String)
 
@@ -192,25 +190,24 @@ let author = "Example <example@example.com>"
 (* Commit information *)
 let info fmt = Irmin_git_unix.info ~author fmt
 
-let main =
+let main () =
   (* Open the repo *)
-  let* repo = Store.Repo.v config in
+  let repo = Store.Repo.v config in
 
   (* Load the main branch *)
-  let* t = Store.main repo in
+  let t = Store.main repo in
 
   (* Set key "foo/bar" to "testing 123" *)
-  let* () =
-    Store.set_exn t ~info:(info "Updating foo/bar") [ "foo"; "bar" ]
-      "testing 123"
-  in
+  Store.set_exn t ~info:(info "Updating foo/bar") [ "foo"; "bar" ] "testing 123";
 
   (* Get key "foo/bar" and print it to stdout *)
-  let+ x = Store.get t [ "foo"; "bar" ] in
+  let x = Store.get t [ "foo"; "bar" ] in
   Printf.printf "foo/bar => '%s'\n" x
 
 (* Run the program *)
-let () = Lwt_main.run main
+let () =
+  Eio_main.run @@ fun env ->
+  Lwt_eio.with_event_loop ~clock:env#clock @@ fun _ -> main ()
 ```
 
 The example is contained in [examples/readme.ml](./examples/readme.ml) It can

bench.Dockerfile

@@ -0,0 +1,11 @@
+FROM ocaml/opam:debian-ocaml-5.1
+RUN sudo ln -sf /usr/bin/opam-2.1 /usr/bin/opam
+RUN mkdir bench-dir && chown opam:opam bench-dir
+WORKDIR bench-dir
+RUN sudo chown opam .
+COPY *.opam ./
+RUN opam remote add origin https://github.com/ocaml/opam-repository.git && opam update
+RUN opam pin -yn --with-version=dev .
+RUN opam install -y --deps-only --with-test .
+COPY . ./
+ENTRYPOINT opam exec -- make bench

bench/irmin-pack/bench_common.ml

@@ -14,7 +14,7 @@
  * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
  *)
 
-open Irmin.Export_for_backends
+module Mtime = Import.Mtime
 
 let c0 = Mtime_clock.counter ()
 let now_us () = Mtime.span_to_us (Mtime_clock.count c0)
@@ -78,7 +78,7 @@ let prepare_artefacts_dir path =
 
 let with_timer f =
   let t0 = Sys.time () in
-  let+ a = f () in
+  let a = f () in
   let t1 = Sys.time () -. t0 in
   (t1, a)
 
@@ -164,30 +164,30 @@ struct
   let add_chain_trees depth nb tree =
     let path = key 2 in
     let rec aux i tree =
-      if i >= nb then Lwt.return tree
+      if i >= nb then tree
       else
-        let* tree = chain_tree tree depth path in
+        let tree = chain_tree tree depth path in
         aux (i + 1) tree
     in
     aux 0 tree
 
   let large_tree path tree width =
     let rec aux i tree =
-      if i >= width then Lwt.return tree
+      if i >= width then tree
       else
         let k = path @ [ random_key () ] in
-        let* tree = Store.Tree.add tree k (random_blob ()) in
+        let tree = Store.Tree.add tree k (random_blob ()) in
         aux (i + 1) tree
     in
     aux 0 tree
 
   let add_large_trees width nb tree =
     let path = key 1 in
     let rec aux i tree =
-      if i >= nb then Lwt.return tree
+      if i >= nb then tree
       else
         let path = path @ [ random_key () ] in
-        let* tree = large_tree path tree width in
+        let tree = large_tree path tree width in
         aux (i + 1) tree
     in
     aux 0 tree

bench/irmin-pack/bench_common.mli

@@ -14,12 +14,14 @@
  * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
  *)
 
+module Mtime : module type of Import.Mtime
+
 val default_artefacts_dir : string
 val prepare_artefacts_dir : string -> unit
 val reporter : ?prefix:string -> unit -> Logs.reporter
 val setup_log : Fmt.style_renderer option -> Logs.level option -> unit
 val reset_stats : unit -> unit
-val with_timer : (unit -> 'a Lwt.t) -> (float * 'a) Lwt.t
+val with_timer : (unit -> 'a) -> float * 'a
 
 val with_progress_bar :
   message:string -> n:int -> unit:string -> ((int -> unit) -> 'a) -> 'a
@@ -40,11 +42,11 @@ end
 
 module Generate_trees
     (Store : Irmin.Generic_key.KV with type Schema.Contents.t = bytes) : sig
-  val add_chain_trees : int -> int -> Store.tree -> Store.tree Lwt.t
+  val add_chain_trees : int -> int -> Store.tree -> Store.tree
   (** [add_chain_trees depth nb tree] adds [nb] random contents to [tree],
       depthwise. *)
 
-  val add_large_trees : int -> int -> Store.tree -> Store.tree Lwt.t
+  val add_large_trees : int -> int -> Store.tree -> Store.tree
   (** [add_large_trees width nb tree] adds [nb] random contents to [tree],
       breadthwise. *)
 end

bench/irmin-pack/dune

@@ -8,7 +8,6 @@
  (libraries
   irmin-pack
   irmin-test.bench
-  lwt
   unix
   cmdliner
   logs
@@ -21,7 +20,7 @@
 (library
  (name bench_common)
  (public_name irmin-bench.common)
- (modules bench_common)
+ (modules bench_common import)
  (libraries irmin-pack irmin-pack.unix irmin-tezos unix progress uuidm)
  (preprocess
   (pps ppx_irmin.internal))
@@ -42,15 +41,13 @@
   trace_replay
   trace_replay_intf
   tezos_history_metrics
-  trace_stat_summary_cb
-  import)
+  trace_stat_summary_cb)
  (preprocess
   (pps ppx_irmin.internal ppx_repr ppx_deriving.enum))
  (libraries
   irmin
   irmin-pack
   unix
-  lwt
   repr
   ppx_repr
   bentov
@@ -71,7 +68,6 @@
   irmin-pack
   irmin-pack.mem
   irmin-test.bench
-  lwt
   unix
   cmdliner
   logs

bench/irmin-pack/import.ml

@@ -15,3 +15,14 @@
  *)
 
 include Irmin.Export_for_backends
+
+module Mtime = struct
+  include Mtime
+
+  module Span = struct
+    include Mtime.Span
+
+    let to_s span = Mtime.Span.to_float_ns span *. 1e-9
+    let to_us span = Mtime.Span.to_float_ns span *. 1e-3
+  end
+end

bench/irmin-pack/tezos_history_metrics.ml

@@ -22,7 +22,8 @@
 
     Computed using:
 
-    https://api.tzstats.com/series/block.json?collapse=1w&columns=n_tx,n_ops,count *)
+    https://api.tzstats.com/series/block.json?collapse=1w&columns=n_tx,n_ops,count
+*)
 let weekly_stats =
   [
     (1529884800000, 497, 16396, 1814);

bench/irmin-pack/trace_collection.ml

@@ -21,8 +21,7 @@
 
     A module [Make_replayable] has yet to be implemented. *)
 
-open Lwt.Syntax
-module Mtime = Import.Mtime
+module Mtime = Bench_common.Mtime
 
 (** Make state trace collector. *)
 module Make_stat (Store : Irmin.Generic_key.KV) = struct
@@ -201,8 +200,7 @@ module Make_stat (Store : Irmin.Generic_key.KV) = struct
 
   let short_op_end { t0; writer; _ } short_op =
     let duration =
-      Mtime_clock.count t0 |> fun span ->
-      Mtime.span_to_s span |> Int32.bits_of_float
+      Mtime_clock.count t0 |> Mtime.span_to_s |> Int32.bits_of_float
     in
     let op =
       match short_op with
@@ -217,34 +215,34 @@ module Make_stat (Store : Irmin.Generic_key.KV) = struct
     Def.append_row writer op
 
   let create_store_before tree =
-    let+ Store.Tree.{ nodes; leafs; skips; depth; width } =
+    let Store.Tree.{ nodes; leafs; skips; depth; width } =
       Store.Tree.stats ~force:false tree
     in
     Def.{ nodes; leafs; skips; depth; width }
 
   let create_store_after tree =
-    let* watched_nodes_length =
-      Lwt_list.map_s
+    let watched_nodes_length =
+      List.map
         (fun (_, steps) -> Store.Tree.length tree steps)
         Def.step_list_per_watched_node
     in
-    Lwt.return Def.{ watched_nodes_length }
+    Def.{ watched_nodes_length }
 
   let commit_begin t tree =
     short_op_begin t;
     let stats_before =
       Bag_of_stats.create t.store_path t.prev_merge_durations
     in
     t.prev_merge_durations <- Index.Stats.((get ()).merge_durations);
-    let+ store_before = create_store_before tree in
+    let store_before = create_store_before tree in
     t.commit_before <- (stats_before, store_before)
 
   let commit_end t tree =
     let duration = Mtime_clock.count t.t0 |> Mtime.span_to_s in
     let duration = duration |> Int32.bits_of_float in
     let stats_after = Bag_of_stats.create t.store_path t.prev_merge_durations in
     t.prev_merge_durations <- Index.Stats.((get ()).merge_durations);
-    let+ store_after = create_store_after tree in
+    let store_after = create_store_after tree in
     let op =
       `Commit
         Def.

bench/irmin-pack/trace_definitions.ml

@@ -226,7 +226,8 @@ module Stat_trace = struct
       store_pack : int64;
     }
     [@@deriving repr]
-    (** Stats extracted from filesystem. Requires the path to the irmin store. *)
+    (** Stats extracted from filesystem. Requires the path to the irmin store.
+    *)
 
     type 'pack_stats bag_of_stats_base = {
       pack : 'pack_stats;