User-configured watch exclusions

CHANGES.md

@@ -26,6 +26,8 @@ Unreleased
 - Speed up rule generation for libraries and executables with many modules
   (#7187, @jchavarri)
 
+- Add `--watch-exclusions` to Dune build options (#7216, @jonahbeckford)
+
 - Do not re-render UI on every frame if the UI doesn't change (#7186, fix
   #7184, @rgrinberg)
 

bench/bench.ml

@@ -130,6 +130,7 @@ let () =
     ; stats = None
     ; insignificant_changes = `React
     ; signal_watcher = `No
+    ; watch_exclusions = []
     }
   in
   let clean, zero =

bench/micro/dune_bench/scheduler_bench.ml

@@ -10,6 +10,7 @@ let config =
   ; stats = None
   ; insignificant_changes = `React
   ; signal_watcher = `No
+  ; watch_exclusions = []
   }
 
 let setup =

bin/common.ml

@@ -530,6 +530,7 @@ module Builder = struct
     ; separate_error_messages : bool
     ; require_dune_project_file : bool
     ; insignificant_changes : [ `React | `Ignore ]
+    ; watch_exclusions : string list
     ; build_dir : string
     ; store_digest_preimage : bool
     ; root : string option
@@ -538,6 +539,20 @@ module Builder = struct
 
   let set_root t root = { t with root = Some root }
 
+  (** Cmdliner documentation markup language
+      (https://erratique.ch/software/cmdliner/doc/tool_man.html#doclang)
+      requires that dollar signs (ex. $(tname)) and backslashes are escaped. *)
+  let docmarkup_escape s =
+    let b = Buffer.create (2 * String.length s) in
+    for i = 0 to String.length s - 1 do
+      match s.[i] with
+      | ('$' | '\\') as c ->
+        Buffer.add_char b '\\';
+        Buffer.add_char b c
+      | c -> Buffer.add_char b c
+    done;
+    Buffer.contents b
+
   let term =
     let docs = copts_sect in
     let+ config_from_command_line = shared_with_config_file
@@ -765,6 +780,28 @@ module Builder = struct
                ])
             Automatic
         & info [ "file-watcher" ] ~doc)
+    and+ watch_exclusions =
+      let std_exclusions = Dune_config.standard_watch_exclusions in
+      let doc =
+        let escaped_std_exclusions =
+          List.map ~f:docmarkup_escape std_exclusions
+        in
+        "Adds a POSIX regular expression that will exclude matching \
+         directories from $(b,`dune build --watch`). The option $(opt) can be \
+         repeated to add multiple exclusions. Semicolons can be also used as a \
+         separator. If no exclusions are provided, then a standard set of \
+         exclusions is used; however, if $(i,one or more) $(opt) are used, \
+         $(b,none) of the standard exclusions are used. The standard \
+         exclusions are: "
+        ^ String.concat ~sep:" " escaped_std_exclusions
+      in
+      let arg =
+        Arg.(
+          value
+          & opt_all (list ~sep:';' string) [ std_exclusions ]
+          & info [ "watch-exclusions" ] ~docs ~docv:"REGEX" ~doc)
+      in
+      Term.(const List.flatten $ arg)
     and+ wait_for_filesystem_clock =
       Arg.(
         value & flag
@@ -853,6 +890,7 @@ module Builder = struct
     ; require_dune_project_file
     ; insignificant_changes =
         (if react_to_insignificant_changes then `React else `Ignore)
+    ; watch_exclusions
     ; build_dir = Option.value ~default:default_build_dir build_dir
     ; store_digest_preimage
     ; root
@@ -905,6 +943,8 @@ let signal_watcher t =
     (* if we aren't building anything, then we don't mind interrupting dune immediately *)
     `No
 
+let watch_exclusions t = t.builder.watch_exclusions
+
 let stats t = t.stats
 
 let insignificant_changes t = t.builder.insignificant_changes

bin/common.mli

@@ -19,6 +19,8 @@ val forbid_builds : t -> t
 
 val signal_watcher : t -> [ `Yes | `No ]
 
+val watch_exclusions : t -> string list
+
 val stats : t -> Dune_stats.t option
 
 val print_metrics : t -> bool

bin/import.ml

@@ -151,8 +151,9 @@ module Scheduler = struct
     let config =
       let insignificant_changes = Common.insignificant_changes common in
       let signal_watcher = Common.signal_watcher common in
+      let watch_exclusions = Common.watch_exclusions common in
       Dune_config.for_scheduler dune_config stats ~insignificant_changes
-        ~signal_watcher
+        ~signal_watcher ~watch_exclusions
     in
     let f =
       match Common.rpc common with
@@ -174,8 +175,9 @@ module Scheduler = struct
     let config =
       let signal_watcher = Common.signal_watcher common in
       let insignificant_changes = Common.insignificant_changes common in
+      let watch_exclusions = Common.watch_exclusions common in
       Dune_config.for_scheduler dune_config stats ~insignificant_changes
-        ~signal_watcher
+        ~signal_watcher ~watch_exclusions
     in
     let file_watcher = Common.file_watcher common in
     let run () =

bin/subst.ml

@@ -437,8 +437,8 @@ let term =
   Log.init_disabled ();
   Dune_engine.Scheduler.Run.go
     ~on_event:(fun _ _ -> ())
-    (Dune_config.for_scheduler config None ~insignificant_changes:`React
-       ~signal_watcher:`No)
+    (Dune_config.for_scheduler config ~watch_exclusions:[] None
+       ~insignificant_changes:`React ~signal_watcher:`No)
     subst
 
 let command = Cmd.v info term

src/dune_config_file/dune_config_file.ml

@@ -267,6 +267,23 @@ module Dune_config = struct
         let field f = f
       end)
 
+  let standard_watch_exclusions =
+    [ {|^_opam|}
+    ; {|/_opam|}
+    ; {|^_esy|}
+    ; {|/_esy|}
+    ; {|^\.#.*|} (* Such files can be created by Emacs and also Dune itself. *)
+    ; {|/\.#.*|}
+    ; {|~$|}
+    ; {|^#[^#]*#$|}
+    ; {|/#[^#]*#$|}
+    ; {|^4913$|} (* https://github.com/neovim/neovim/issues/3460 *)
+    ; {|/4913$|}
+    ; {|/.git|}
+    ; {|/.hg|}
+    ; {|:/windows|}
+    ]
+
   let hash = Poly.hash
 
   let equal a b = Poly.equal a b
@@ -460,7 +477,8 @@ module Dune_config = struct
         in
         loop commands)
 
-  let for_scheduler (t : t) stats ~insignificant_changes ~signal_watcher =
+  let for_scheduler (t : t) ~watch_exclusions stats ~insignificant_changes
+      ~signal_watcher =
     let concurrency =
       match t.concurrency with
       | Fixed i -> i
@@ -477,5 +495,6 @@ module Dune_config = struct
     ; stats
     ; insignificant_changes
     ; signal_watcher
+    ; watch_exclusions
     }
 end

src/dune_config_file/dune_config_file.mli

@@ -88,6 +88,9 @@ module Dune_config : sig
     val to_dyn : t -> Dyn.t
   end
 
+  (** A standard list of watch exclusions *)
+  val standard_watch_exclusions : string list
+
   val decode : Partial.t Dune_lang.Decoder.t
 
   (** Decode the same fields as the one accepted in the configuration file, but
@@ -122,8 +125,13 @@ module Dune_config : sig
 
   val equal : t -> t -> bool
 
+  (** [for_scheduler config ?watch_exclusions stats_opt ~insignificant_changes
+      ~signal_watcher]
+      creates a configuration for a scheduler from the user-visible Dune
+      [config]. *)
   val for_scheduler :
        t
+    -> watch_exclusions:string list
     -> Dune_stats.t option
     -> insignificant_changes:[ `React | `Ignore ]
     -> signal_watcher:[ `Yes | `No ]

src/dune_engine/scheduler.ml

@@ -10,6 +10,7 @@ module Config = struct
     ; stats : Dune_stats.t option
     ; insignificant_changes : [ `Ignore | `React ]
     ; signal_watcher : [ `Yes | `No ]
+    ; watch_exclusions : string list
     }
 end
 
@@ -1234,7 +1235,7 @@ module Run = struct
                ; thread_safe_send_emit_events_job =
                    (fun job -> Event_queue.send_file_watcher_task events job)
                }
-             ())
+             ~watch_exclusions:config.watch_exclusions ())
     in
     let t = prepare ~file_watcher in
     let initial_invalidation = Fs_memo.init ~dune_file_watcher:file_watcher in

src/dune_engine/scheduler.mli

@@ -8,6 +8,7 @@ module Config : sig
     ; stats : Dune_stats.t option
     ; insignificant_changes : [ `Ignore | `React ]
     ; signal_watcher : [ `Yes | `No ]
+    ; watch_exclusions : string list
     }
 end