From c202a150ba25e45788b89d087d65910841a29b61 Mon Sep 17 00:00:00 2001
From: Rudi Grinberg <rudi.grinberg@gmail.com>
Date: Thu, 11 Apr 2019 11:55:28 +0700
Subject: [PATCH] Remove caching of scopes

It does not seem to buy us anything performance wise

Signed-off-by: Rudi Grinberg <rudi.grinberg@gmail.com>
---
 src/scope.ml           | 32 +++++++++++++++-----------------
 src/stdune/map.ml      |  5 +++++
 src/stdune/map_intf.ml |  4 ++++
 3 files changed, 24 insertions(+), 17 deletions(-)

diff --git a/src/scope.ml b/src/scope.ml
index ea902d98ba5..95dfd8efad8 100644
--- a/src/scope.ml
+++ b/src/scope.ml
@@ -16,31 +16,29 @@ module DB = struct
   type scope = t
 
   type t =
-    { by_dir  : (Path.t, scope) Hashtbl.t
-    ; by_name : scope Dune_project.Name.Map.t
+    { by_name : scope Dune_project.Name.Map.t
+    ; by_dir : scope Path.Map.t
     ; context : string
     }
 
   let find_by_dir t dir =
     let rec loop d =
-      match Hashtbl.find t.by_dir d with
-      | Some scope -> scope
+      if Path.is_root d || not (Path.is_managed d) then
+        Exn.code_error "Scope.DB.find_by_dir got an invalid path"
+          [ "dir"    , Path.to_sexp dir
+          ; "context", Sexp.Encoder.string t.context
+          ];
+      match Path.Map.find t.by_dir d with
+      | Some s -> s
       | None ->
-        if Path.is_root d || not (Path.is_managed d) then
-          Exn.code_error "Scope.DB.find_by_dir got an invalid path"
-            [ "dir"    , Path.to_sexp dir
-            ; "context", Sexp.Encoder.string t.context
-            ];
-        match Path.parent d with
+        begin match Path.parent d with
         | None ->
           Exn.code_error "find_by_dir: invalid directory"
             [ "d", Path.to_sexp d
             ; "dir", Path.to_sexp dir
             ]
-        | Some d ->
-          let scope = loop d in
-          Hashtbl.add t.by_dir d scope;
-          scope
+        | Some d -> loop d
+        end
     in
     loop dir
 
@@ -142,9 +140,9 @@ module DB = struct
     let by_name =
       sccopes_by_name ~context ~projects ~lib_config ~public_libs internal_libs
     in
-    let by_dir = Hashtbl.create 1024 in
-    Dune_project.Name.Map.iter by_name ~f:(fun scope ->
-      Hashtbl.add by_dir scope.root scope);
+    let by_dir =
+      Dune_project.Name.Map.values by_name
+      |> Path.Map.of_list_map_exn ~f:(fun scope -> (scope.root, scope)) in
     Fdecl.set t { by_name ; by_dir ; context};
     (Fdecl.get t, public_libs)
 end
diff --git a/src/stdune/map.ml b/src/stdune/map.ml
index 5413e535939..dff8ce176ff 100644
--- a/src/stdune/map.ml
+++ b/src/stdune/map.ml
@@ -108,6 +108,11 @@ module Make(Key : Comparable.S) : S with type key = Key.t = struct
         | x :: y :: _ -> Error (k, x, y)
         | _ -> assert false
 
+  let of_list_map_exn t ~f =
+    match of_list_map t ~f with
+    | Ok x -> x
+    | Error _ -> Exn.code_error "Map.of_list_map_exn" []
+
   let of_list_exn l =
     match of_list l with
     | Ok    x -> x
diff --git a/src/stdune/map_intf.ml b/src/stdune/map_intf.ml
index ce289bac5e4..112a36d985b 100644
--- a/src/stdune/map_intf.ml
+++ b/src/stdune/map_intf.ml
@@ -58,6 +58,10 @@ module type S = sig
     :  'a list
     -> f:('a -> key * 'b)
     -> ('b t, key * 'a * 'a) Result.t
+  val of_list_map_exn
+    :  'a list
+    -> f:('a -> key * 'b)
+    -> 'b t
   val of_list_exn : (key * 'a) list -> 'a t
 
   val of_list_multi  : (key * 'a) list -> 'a list t