Merge pull request #8078 from the-mikedavis/code-server-where-is-file

Use code_server path cache in code:where_is_file/1

OTP-19194

lib/kernel/src/code.erl

@@ -1751,7 +1751,8 @@ file containing object code for `Module` and returns the absolute filename.
 which(Module) when is_atom(Module) ->
     case is_loaded(Module) of
 	false ->
-            which(Module, get_path());
+            File = atom_to_list(Module) ++ objfile_extension(),
+            where_is_file(File);
 	{file, File} ->
 	    File
     end.
@@ -1773,8 +1774,7 @@ locate application resource files.
       Filename :: file:filename(),
       Absname :: file:filename().
 where_is_file(File) when is_list(File) ->
-    Path = get_path(),
-    where_is_file(Path, File).
+    call({where_is_file, File}).
 
 %% To avoid unnecessary work when looking at many modules, this also
 %% accepts pairs of directories and pre-fetched contents in the path

lib/kernel/src/code_server.erl

@@ -302,6 +302,11 @@ handle_call({replace_path,Name,Dir,Control}, _From,
 handle_call(get_path, _From, S) ->
     {reply,[P || {P, _Cache} <- S#state.path],S};
 
+handle_call({where_is_file,File}, _From,
+            #state{path=Path,path_cache=Cache0}=S) ->
+    {Resp,Cache} = where_is_file(Path, File, Cache0),
+    {reply,Resp,S#state{path_cache=Cache}};
+
 handle_call(clear_cache, _From, S) ->
     {reply,ok,S#state{path_cache=#{}}};
 
@@ -1485,3 +1490,22 @@ archive_extension() ->
 
 to_list(X) when is_list(X) -> X;
 to_list(X) when is_atom(X) -> atom_to_list(X).
+
+where_is_file([], _File, Cache) ->
+    {non_existing, Cache};
+where_is_file([{Dir, nocache} | Tail], File, Cache) ->
+    Full = filename:append(Dir, File),
+    case erl_prim_loader:read_file_info(Full) of
+        {ok,_} ->
+            {Full, Cache};
+        _Error ->
+            where_is_file(Tail, File, Cache)
+    end;
+where_is_file([{Dir, CacheKey} | Tail], File, Cache) when is_integer(CacheKey) ->
+    case with_cache(CacheKey, Dir, File, Cache) of
+        {true, Cache1} ->
+            Full = filename:append(Dir, File),
+            {Full, Cache1};
+        {false, Cache1} ->
+            where_is_file(Tail, File, Cache1)
+    end.