Add a limit for very slow filesystems

When adding a directory in a project we check if the filesystem is too
slow. If it is too slow we act as if the projects was files-limited by
the number of files but we show a specific warning.

This solution is not perfect but for very low filesystem it can limit
the problem. Otherwise the application would be totally irresponsive.

data/core/common.lua

@@ -280,24 +280,61 @@ local function split_on_slash(s, sep_pattern)
 end
 
 
-function common.normalize_path(filename)
+-- The filename argument given to the function is supposed to
+-- come from system.absolute_path and as such should be an
+-- absolute path without . or .. elements.
+-- This function exists because on Windows the drive letter returned
+-- by system.absolute_path is sometimes with a lower case and sometimes
+-- with an upper case to we normalize to upper case.
+function common.normalize_volume(filename)
   if not filename then return end
+  if PATHSEP == '\\' then
+    local drive, rem = filename:match('^([a-zA-Z]:\\)(.*)')
+    if drive then
+      return drive:upper() .. rem
+    end
+  end
+  return filename
+end
+
+
+function common.normalize_path(filename)
+  if not filename then return end
+  local volume
   if PATHSEP == '\\' then
     filename = filename:gsub('[/\\]', '\\')
-    local drive, rem = filename:match('^([a-zA-Z])(:.*)')
-    filename = drive and drive:upper() .. rem or filename
+    local drive, rem = filename:match('^([a-zA-Z]:\\)(.*)')
+    if drive then
+      volume, filename = drive:upper(), rem
+    else
+      drive, rem = filename:match('^(\\\\[^\\]+\\[^\\]+\\)(.*)')
+      if drive then
+        volume, filename = drive, rem
+      end
+    end
+  else
+    local relpath = filename:match('^/(.+)')
+    if relpath then
+      volume, filename = "/", relpath
+    end
   end
   local parts = split_on_slash(filename, PATHSEP)
   local accu = {}
   for _, part in ipairs(parts) do
-    if part == '..' and #accu > 0 and accu[#accu] ~= ".." then
+    if part == '..' then
+      if #accu > 0 and accu[#accu] ~= ".." then
         table.remove(accu)
+      elseif volume then
+        error("invalid path " .. volume .. filename)
+      else
+        table.insert(accu, part)
+      end
     elseif part ~= '.' then
       table.insert(accu, part)
     end
   end
   local npath = table.concat(accu, PATHSEP)
-  return npath == "" and PATHSEP or npath
+  return (volume or "") .. (npath == "" and PATHSEP or npath)
 end
 
 

data/core/init.lua

@@ -36,7 +36,7 @@ end
 
 
 local function update_recents_project(action, dir_path_abs)
-  local dirname = common.normalize_path(dir_path_abs)
+  local dirname = common.normalize_volume(dir_path_abs)
   if not dirname then return end
   local recents = core.recent_projects
   local n = #recents
@@ -56,7 +56,7 @@ function core.set_project_dir(new_dir, change_project_fn)
   local chdir_ok = pcall(system.chdir, new_dir)
   if chdir_ok then
     if change_project_fn then change_project_fn() end
-    core.project_dir = common.normalize_path(new_dir)
+    core.project_dir = common.normalize_volume(new_dir)
     core.project_directories = {}
     core.add_project_directory(new_dir)
     return true
@@ -106,6 +106,15 @@ local function get_project_file_info(root, file)
 end
 
 
+-- Predicate function to inhibit directory recursion in get_directory_files
+-- based on a time limit and the number of files.
+local function timed_max_files_pred(dir, filename, entries_count, t_elapsed)
+  local n_limit = entries_count <= config.max_project_files
+  local t_limit = t_elapsed < 20 / config.fps
+  return n_limit and t_limit and core.project_subdir_is_shown(dir, filename)
+end
+
+
 -- "root" will by an absolute path without trailing '/'
 -- "path" will be a path starting with '/' and without trailing '/'
 --    or the empty string.
@@ -114,12 +123,13 @@ end
 -- When recursing "root" will always be the same, only "path" will change.
 -- Returns a list of file "items". In eash item the "filename" will be the
 -- complete file path relative to "root" *without* the trailing '/'.
-local function get_directory_files(dir, root, path, t, begin_hook, max_files)
+local function get_directory_files(dir, root, path, t, entries_count, recurse_pred, begin_hook)
   if begin_hook then begin_hook() end
+  local t0 = system.get_time()
   local all = system.list_dir(root .. path) or {}
+  local t_elapsed = system.get_time() - t0
   local dirs, files = {}, {}
 
-  local entries_count = 0
   for _, file in ipairs(all) do
     local info = get_project_file_info(root, path .. PATHSEP .. file)
     if info then
@@ -128,13 +138,16 @@ local function get_directory_files(dir, root, path, t, begin_hook, max_files)
     end
   end
 
+  local recurse_complete = true
   table.sort(dirs, compare_file)
   for _, f in ipairs(dirs) do
     table.insert(t, f)
-    if (not max_files or entries_count <= max_files) and core.project_subdir_is_shown(dir, f.filename) then
-      local sub_limit = max_files and max_files - entries_count
-      local _, n = get_directory_files(dir, root, PATHSEP .. f.filename, t, begin_hook, sub_limit)
-      entries_count = entries_count + n
+    if recurse_pred(dir, f.filename, entries_count, t_elapsed) then
+      local _, complete, n = get_directory_files(dir, root, PATHSEP .. f.filename, t, entries_count, recurse_pred, begin_hook)
+      recurse_complete = recurse_complete and complete
+      entries_count = n
+    else
+      recurse_complete = false
     end
   end
 
@@ -143,7 +156,7 @@ local function get_directory_files(dir, root, path, t, begin_hook, max_files)
     table.insert(t, f)
   end
 
-  return t, entries_count
+  return t, recurse_complete, entries_count
 end
 
 
@@ -165,26 +178,28 @@ function core.project_subdir_is_shown(dir, filename)
 end
 
 
-local function show_max_files_warning()
-  core.status_view:show_message("!", style.accent,
+local function show_max_files_warning(dir)
+  local message = dir.slow_filesystem and
+    "Filesystem is too slow: project files will not be indexed." or
     "Too many files in project directory: stopped reading at "..
     config.max_project_files.." files. For more information see "..
     "usage.md at github.com/franko/lite-xl."
-    )
+  core.status_view:show_message("!", style.accent, message)
 end
 
 -- Populate a project folder top directory by scanning the filesystem.
 local function scan_project_folder(index)
   local dir = core.project_directories[index]
-  local t, entries_count = get_directory_files(dir, dir.name, "", {}, nil, config.max_project_files)
-  if entries_count > config.max_project_files then
+  local t, complete, entries_count = get_directory_files(dir, dir.name, "", {}, 0, timed_max_files_pred)
+  if not complete then
+    dir.slow_filesystem = not complete and (entries_count <= config.max_project_files)
     dir.files_limit = true
     -- Watch non-recursively on Linux only.
     -- The reason is recursively watching with dmon on linux
     -- doesn't work on very large directories.
     dir.watch_id = system.watch_dir(dir.name, PLATFORM ~= "Linux")
     if core.status_view then -- May be not yet initialized.
-      show_max_files_warning()
+      show_max_files_warning(dir)
     end
   else
     dir.watch_id = system.watch_dir(dir.name, true)
@@ -198,7 +213,7 @@ function core.add_project_directory(path)
   -- top directories has a file-like "item" but the item.filename
   -- will be simply the name of the directory, without its path.
   -- The field item.topdir will identify it as a top level directory.
-  path = common.normalize_path(path)
+  path = common.normalize_volume(path)
   local dir = {
     name = path,
     item = {filename = common.basename(path), type = "dir", topdir = true},
@@ -298,7 +313,7 @@ local function project_subdir_bounds(dir, filename)
 end
 
 local function rescan_project_subdir(dir, filename_rooted)
-  local new_files = get_directory_files(dir, dir.name, filename_rooted, {}, coroutine.yield)
+  local new_files = get_directory_files(dir, dir.name, filename_rooted, {}, 0, core.project_subdir_is_shown, coroutine.yield)
   local index, n = 0, #dir.files
   if filename_rooted ~= "" then
     local filename = strip_leading_path(filename_rooted)
@@ -316,7 +331,7 @@ end
 function core.update_project_subdir(dir, filename, expanded)
   local index, n, file = project_subdir_bounds(dir, filename)
   if index then
-    local new_files = expanded and get_directory_files(dir, dir.name, PATHSEP .. filename, {}) or {}
+    local new_files = expanded and get_directory_files(dir, dir.name, PATHSEP .. filename, {}, 0, core.project_subdir_is_shown) or {}
     files_list_replace(dir.files, index, n, new_files)
     dir.is_dirty = true
     return true
@@ -572,9 +587,9 @@ function core.init()
   Doc = require "core.doc"
 
   if PATHSEP == '\\' then
-    USERDIR = common.normalize_path(USERDIR)
-    DATADIR = common.normalize_path(DATADIR)
-    EXEDIR  = common.normalize_path(EXEDIR)
+    USERDIR = common.normalize_volume(USERDIR)
+    DATADIR = common.normalize_volume(DATADIR)
+    EXEDIR  = common.normalize_volume(EXEDIR)
   end
 
   do
@@ -673,7 +688,7 @@ function core.init()
   -- We assume we have just a single project directory here. Now that StatusView
   -- is there show max files warning if needed.
   if core.project_directories[1].files_limit then
-    show_max_files_warning()
+    show_max_files_warning(core.project_directories[1])
   end
 
   for _, filename in ipairs(files) do

data/core/rootview.lua

@@ -412,7 +412,7 @@ end
 -- axis are swapped; this function lets us use the same code for both
 local function calc_split_sizes(self, x, y, x1, x2, y1, y2)
   local ds = ((x1 and x1 < 1) or (x2 and x2 < 1)) and 0 or style.divider_size
-  local n = math.floor(x1 and x1 + ds or (x2 and self.size[x] - x2 or self.size[x] * self.divider))
+  local n = x1 and x1 + ds or (x2 and self.size[x] - x2 or math.floor(self.size[x] * self.divider))
   self.a.position[x] = self.position[x]
   self.a.position[y] = self.position[y]
   self.a.size[x] = n - ds
@@ -675,6 +675,10 @@ end
 
 
 function Node:resize(axis, value)
+  -- the application works fine with non-integer values but to have pixel-perfect
+  -- placements of view elements, like the scrollbar, we round the value to be
+  -- an integer.
+  value = math.floor(value)
   if self.type == 'leaf' then
     -- If it is not locked we don't accept the
     -- resize operation here because for proportional panes the resize is