Add priority threads to keep editor busy

Fix a problem introduced when fixing the dirty pixel problem, commit
cb08c5c. The node, when determining the layout was rounding the size
of the fixed-size view. In turns this latter was calling move_towards
to the default_size it wanted. If default_size was non-integer the
value vas never archieved because it was rounded during layout and
move_towars was keeping the editor busy by setting the
core.need_redraw flag.

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
@@ -173,45 +173,10 @@ local function show_max_files_warning()
     )
 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
-    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()
-    end
-  else
-    dir.watch_id = system.watch_dir(dir.name, true)
-  end
-  dir.files = t
-  core.dir_rescan_add_job(dir, ".")
-end
 
-
-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)
-  local dir = {
-    name = path,
-    item = {filename = common.basename(path), type = "dir", topdir = true},
-    files_limit = false,
-    is_dirty = true,
-    shown_subdir = {},
-  }
-  table.insert(core.project_directories, dir)
-  scan_project_folder(#core.project_directories)
-  if path == core.project_dir then
-    core.project_files = dir.files
-  end
-  core.redraw = true
+local function watch_folder(dir)
+  local rec = dir.entries_count <= config.max_project_files or PLATFORM ~= "Linux"
+  dir.watch_id = system.watch_dir(dir.name, rec)
 end
 
 
@@ -304,12 +269,59 @@ local function rescan_project_subdir(dir, filename_rooted)
     local filename = strip_leading_path(filename_rooted)
     index, n = project_subdir_bounds(dir, filename)
   end
-
   if not files_list_match(dir.files, index, n, new_files) then
     files_list_replace(dir.files, index, n, new_files)
     dir.is_dirty = true
-    return true
   end
+  return #new_files - n
+end
+
+
+-- Populate a project folder top directory by scanning the filesystem.
+local function scan_project_folder(index)
+  local dir = core.project_directories[index]
+  dir.files, dir.entries_count = get_directory_files(dir, dir.name, "", {}, nil, 0)
+  local dirs_list = {}
+  for _, info in pairs(dir.files) do
+    if info.type == 'dir' then
+      dirs_list[#dirs_list + 1] = info
+    end
+  end
+  core.add_thread(function()
+    for _, info in pairs(dirs_list) do
+      local n = rescan_project_subdir(dir, PATHSEP .. info.filename)
+      dir.entries_count = dir.entries_count + n
+      if dir.entries_count > config.max_project_files then
+        dir.files_limit = true
+        show_max_files_warning()
+        break
+      end
+      coroutine.yield()
+    end
+    watch_folder(dir)
+    core.dir_rescan_add_job(dir, ".")
+  end, nil, true)
+end
+
+
+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_volume(path)
+  local dir = {
+    name = path,
+    item = {filename = common.basename(path), type = "dir", topdir = true},
+    files_limit = false,
+    is_dirty = true,
+    shown_subdir = {},
+  }
+  table.insert(core.project_directories, dir)
+  scan_project_folder(#core.project_directories)
+  if path == core.project_dir then
+    core.project_files = dir.files
+  end
+  core.redraw = true
 end
 
 
@@ -572,9 +584,9 @@ 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
@@ -919,10 +931,17 @@ function core.show_title_bar(show)
 end
 
 
-function core.add_thread(f, weak_ref)
+function core.has_priority_threads()
+  for _, t in ipairs(core.threads) do
+    if t.prio then return true end
+  end
+end
+
+
+function core.add_thread(f, weak_ref, priority)
   local key = weak_ref or #core.threads + 1
   local fn = function() return core.try(f) end
-  core.threads[key] = { cr = coroutine.create(fn), wake = 0 }
+  core.threads[key] = { cr = coroutine.create(fn), wake = 0, prio = priority }
   return key
 end
 
@@ -1066,12 +1085,6 @@ end
 
 local scheduled_rescan = {}
 
-function core.has_pending_rescan()
-  for _ in pairs(scheduled_rescan) do
-    return true
-  end
-end
-
 
 function core.dir_rescan_add_job(dir, filepath)
   local dirpath = filepath:match("^(.+)[/\\].+$")
@@ -1108,8 +1121,8 @@ function core.dir_rescan_add_job(dir, filepath)
       local rescan = scheduled_rescan[abs_dirpath]
       if not rescan then return end
       if system.get_time() > rescan.time_limit then
-        local has_changes = rescan_project_subdir(rescan.dir, rescan.path)
-        if has_changes then
+        local n_changes = rescan_project_subdir(rescan.dir, rescan.path)
+        if n_changes > 0 then
           core.redraw = true -- we run without an event, from a thread
           rescan.time_limit = new_time
         else
@@ -1119,7 +1132,7 @@ function core.dir_rescan_add_job(dir, filepath)
       end
       coroutine.yield(0.2)
     end
-  end)
+  end, nil, true)
 end
 
 
@@ -1286,7 +1299,7 @@ function core.run()
   while true do
     core.frame_start = system.get_time()
     local did_redraw = core.step()
-    local need_more_work = run_threads() or core.has_pending_rescan()
+    local need_more_work = run_threads() or core.has_priority_threads()
     if core.restart_request or core.quit_request then break end
     if not did_redraw and not need_more_work then
       idle_iterations = idle_iterations + 1

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