Add an Eio backend

.github/workflows/main.yml

@@ -17,15 +17,21 @@ jobs:
           - 4.03.x
           - 4.08.x
           - 4.12.x
+          - 5.1.x
+        include:
+          - packages: [ {name: inotify, opam-file: inotify.opam} ]
+          - packages: [ {name: inotify, opam-file: inotify.opam}, { name: inotify-eio, opam-file: inotify.opam } ]
+            ocaml-compiler: 5.1.x
     runs-on: ${{ matrix.os }}
     steps:
     - uses: actions/checkout@v2
     - uses: ocaml/setup-ocaml@v2
       with:
         ocaml-compiler: ${{ matrix.ocaml-compiler }}
+        opam-local-packages: ${{ join(matrix.packages.*.opam-file, ' ') }}
     - run: opam pin -n .
-    - run: opam depext -yt inotify
-    - run: opam install -t . --deps-only
-    - run: opam exec -- dune build
+    - run: opam depext -yt ${{ join(matrix.packages.*.name, ' ') }}
+    - run: opam install -t ${{ join(matrix.packages.*.name, ' ') }} --deps-only
+    - run: opam exec -- dune build --only-packages ${{ join(matrix.packages.*.name, ',') }}
     - run: opam exec -- dune runtest
       if: ${{ matrix.os == 'ubuntu-latest'}}

CHANGES.md

@@ -1,4 +1,8 @@
 
+## Unreleased
+
+add an Eio backend in a new inotify-eio package
+
 ## 2.5
 
 add @since tags

README.md

@@ -15,8 +15,10 @@ The bindings are available via [OPAM](https://opam.ocaml.org):
 
 Alternatively, you can do it manually:
 
-    # If you want to lwt_inotify
+    # If you want to use lwt_inotify
     $ opam install lwt
+    # If you want to use eio_inotify
+    $ opam install eio
     $ opam install .
 
 Usage
@@ -42,7 +44,18 @@ Lwt_main.run (
   (* watch=1 cookie=0 events=CREATE "file" *)
 ```
 
-Note that Lwt-style interface returns events one-by-one, but the Unix-style one returns
+Eio-style interface (findlib package `inotify-eio`):
+
+``` ocaml
+Eio_main.run @@ fun _env ->
+  let inotify = Eio_inotify.create () in
+  let _watch   = Eio_inotify.add_watch inotify "dir" [Inotify.S_Create] in
+  let event   = Eio_inotify.read inotify in
+  print_endline (Inotify.string_of_event event)
+  (* watch=1 cookie=0 events=CREATE "file" *)
+```
+
+Note that Lwt-style & Eio-style interfaces returns events one-by-one, but the Unix-style one returns
 them in small batches.
 
 Documentation

dune-project

@@ -1,4 +1,4 @@
-(lang dune 2.9)
+(lang dune 3.9)
 (generate_opam_files true)
 (version 2.5)
 
@@ -25,3 +25,18 @@
    (odoc :with-doc))
   (depopts
     lwt))
+
+(package
+  (name inotify-eio)
+  (synopsis "Inotify backend for eio")
+  (description "Inotify backend for eio")
+  (depends
+   base-unix
+   base-bytes
+   (fileutils (and :with-test (>= 0.4.4)))
+   (ounit2 (and :with-test (>= 2.0)))
+   (ocaml (>= 5.0))
+   (odoc :with-doc)
+   eio
+   (eio_main :with-test)
+   iomux))

inotify-eio.opam

@@ -0,0 +1,39 @@
+# This file is generated by dune, edit dune-project instead
+opam-version: "2.0"
+version: "2.5"
+synopsis: "Inotify backend for eio"
+description: "Inotify backend for eio"
+maintainer: ["whitequark <[email protected]>"]
+authors: ["whitequark <[email protected]>"]
+license: "LGPL-2.1-only WITH OCaml-LGPL-linking-exception"
+homepage: "https://github.com/whitequark/ocaml-inotify"
+doc: "https://whitequark.github.io/ocaml-inotify"
+bug-reports: "https://github.com/whitequark/ocaml-inotify/issues"
+depends: [
+  "dune" {>= "3.9"}
+  "base-unix"
+  "base-bytes"
+  "fileutils" {with-test & >= "0.4.4"}
+  "ounit2" {with-test & >= "2.0"}
+  "ocaml" {>= "5.0"}
+  "odoc" {with-doc}
+  "eio"
+  "eio_main" {with-test}
+  "iomux"
+]
+build: [
+  ["dune" "subst"] {dev}
+  [
+    "dune"
+    "build"
+    "-p"
+    name
+    "-j"
+    jobs
+    "@install"
+    "@runtest" {with-test}
+    "@doc" {with-doc}
+  ]
+]
+dev-repo: "git+https://github.com/whitequark/ocaml-inotify.git"
+available: os="linux"

inotify-eio.opam.template

@@ -0,0 +1 @@
+available: os="linux"

inotify.opam

@@ -10,7 +10,7 @@ homepage: "https://github.com/whitequark/ocaml-inotify"
 doc: "https://whitequark.github.io/ocaml-inotify"
 bug-reports: "https://github.com/whitequark/ocaml-inotify/issues"
 depends: [
-  "dune" {>= "2.9"}
+  "dune" {>= "3.9"}
   "base-unix"
   "base-bytes"
   "fileutils" {with-test & >= "0.4.4"}
@@ -29,12 +29,10 @@ build: [
     name
     "-j"
     jobs
-    "--promote-install-files=false"
     "@install"
     "@runtest" {with-test}
     "@doc" {with-doc}
   ]
-  ["dune" "install" "-p" name "--create-install-files" name]
 ]
 dev-repo: "git+https://github.com/whitequark/ocaml-inotify.git"
 available: os="linux"

lib/dune

@@ -12,3 +12,10 @@
   (flags (:standard -w -32-39))
   (libraries inotify lwt lwt.unix)
   (modules lwt_inotify))
+
+(library
+  (name eio_inotify)
+  (public_name inotify-eio)
+  (flags (:standard -w -32-39))
+  (libraries inotify eio.unix iomux)
+  (modules eio_inotify))

lib/eio_inotify.ml

@@ -0,0 +1,46 @@
+type t = {
+  queue   : Inotify.event Queue.t;
+  unix_fd : Unix.file_descr;
+  poll : Iomux.Poll.t
+}
+
+let create () =
+  try
+    let unix_fd = Inotify.create () in
+    let poll = Iomux.Poll.create () in
+    Iomux.Poll.set_index poll 0 unix_fd (Iomux.Poll.Flags.pollin);
+    {
+      queue   = Queue.create ();
+      unix_fd; 
+      poll
+      }
+  with exn ->
+    raise exn
+
+let add_watch inotify path selector =
+  Inotify.add_watch inotify.unix_fd path selector
+
+let rm_watch inotify wd =
+  Inotify.rm_watch inotify.unix_fd wd
+
+let rec read inotify =
+  try
+    Queue.take inotify.queue
+  with Queue.Empty ->
+    Eio_unix.await_readable inotify.unix_fd;
+    let events = Inotify.read inotify.unix_fd in
+    List.iter (fun event -> Queue.push event inotify.queue) events;
+    read inotify
+
+let with_timeout d = Eio.Fiber.first (fun () -> Eio_unix.sleep d; Error `Timeout)
+
+let rec try_read inotify =
+  try
+    Some (Queue.take inotify.queue)
+  with Queue.Empty ->
+  match Iomux.Poll.ppoll_or_poll inotify.poll (Iomux.Util.fd_of_unix inotify.unix_fd) Nowait with
+    | r when r > 0 -> Some (read inotify)
+    | _ -> None
+
+let close inotify =
+  Unix.close inotify.unix_fd

lib/eio_inotify.mli

@@ -0,0 +1,24 @@
+(** An [Lwt] wrapper for {!Inotify} module *)
+
+(** Type of inotify descriptors. *)
+type t
+
+(** [create ()] returns a new inotify descriptor. *)
+val create    : unit -> t
+
+(** [add_watch desc path events] sets up [desc] to watch for [events] occuring
+    to [path], and returns a watch descriptor. *)
+val add_watch : t -> string -> Inotify.selector list -> Inotify.watch
+
+(** [rm_watch desc watch] stops [desc] from watching [watch]. *)
+val rm_watch  : t -> Inotify.watch -> unit
+
+(** [read desc] waits for an event to occur at [desc]. *)
+val read      : t -> Inotify.event
+
+(** [try_read desc] returns [Some event] if [desc] has queued events,
+    or [None] otherwise. *)
+val try_read  : t -> Inotify.event option
+
+(** [close desc] frees [desc]. *)
+val close     : t -> unit

lib_test/dune

@@ -1,9 +1,15 @@
 (test
-  (name test_inotify)
-  (libraries ounit2 inotify fileutils threads)
-  (modules test_inotify))
+ (name test_inotify)
+ (libraries ounit2 inotify fileutils threads)
+ (modules test_inotify))
 
 (test
-  (name test_inotify_lwt)
-  (libraries ounit2 inotify.lwt fileutils)
-  (modules test_inotify_lwt))
+ (name test_inotify_lwt)
+ (libraries ounit2 inotify.lwt fileutils)
+ (modules test_inotify_lwt))
+
+(test
+ (name test_inotify_eio)
+ (build_if %{lib-available:eio_main})
+ (libraries ounit2 inotify-eio eio_main fileutils)
+ (modules test_inotify_eio))

lib_test/test_inotify_eio.ml

@@ -0,0 +1,46 @@
+open OUnit2
+
+let test_read ctxt =
+  let tmpdir = bracket_tmpdir ctxt in
+  Eio_main.run @@ fun _env ->
+    let inotify = Eio_inotify.create () in
+    let watch = Eio_inotify.add_watch inotify tmpdir [Inotify.S_Create] in
+    FileUtil.touch (Printf.sprintf "%s/test" tmpdir);
+    let result = Eio_inotify.read inotify in
+    assert_equal (watch, [Inotify.Create], 0l, Some "test") result
+
+let test_try_read ctxt =
+  let tmpdir = bracket_tmpdir ctxt in
+  Eio_main.run @@ fun _env ->
+    let inotify = Eio_inotify.create () in
+    let watch = Eio_inotify.add_watch inotify tmpdir [Inotify.S_Create] in
+
+    let result = Eio_inotify.try_read inotify in
+    OUnit.assert_equal None result;
+
+    FileUtil.touch (Printf.sprintf "%s/test" tmpdir);
+    let result = Eio_inotify.try_read inotify in
+    assert_equal (Some (watch, [Inotify.Create], 0l, Some "test")) result;
+
+    let result = Eio_inotify.try_read inotify in
+    OUnit.assert_equal None result
+
+let test_error ctxt =
+  let tmpdir = bracket_tmpdir ctxt in
+  Eio_main.run @@ fun _env ->
+    let inotify = Eio_inotify.create () in
+    let tmpfile = Printf.sprintf "%s/nonexistent" tmpdir in
+    try
+      let _watch = Eio_inotify.add_watch inotify tmpfile [Inotify.S_Modify] in
+      assert_failure "must raise"
+    with
+      | ex -> assert_equal (Unix.Unix_error (Unix.ENOENT, "inotify_add_watch", tmpfile)) ex
+
+let suite = "Test Eio_inotify" >::: [
+    "Test read"           >:: test_read;
+    "Test try_read"       >:: test_try_read;
+    "Test error handling" >:: test_error;
+  ]
+
+let _ =
+  run_test_tt_main suite