Stop scanning project file when a maximum limit is reached

To avoid excessive memory usage when opening in a directory with too many files.

Introduce the config variable config.max_project_files to choose the limit.

The mechanism introduced avoid using excessive memory but it fails to
let user access all the files in the directory. A better implementation
should not impose any limits but read each subdirectory on-demand, only
as they are expanded in the tree-view.

data/core/config.lua

@@ -16,5 +16,6 @@ config.line_height = 1.2
 config.indent_size = 2
 config.tab_type = "soft"
 config.line_limit = 80
+config.max_project_files = 2000
 
 return config

data/core/init.lua

@@ -34,6 +34,8 @@ local function project_scan_thread()
     local all = system.list_dir(path) or {}
     local dirs, files = {}, {}
 
+    local entries_count = 0
+    local max_entries = config.max_project_files
     for _, file in ipairs(all) do
       if not common.match_pattern(file, config.ignore_files) then
         local file = (path ~= "." and path .. PATHSEP or "") .. file
@@ -41,6 +43,8 @@ local function project_scan_thread()
         if info and info.size < size_limit then
           info.filename = file
           table.insert(info.type == "dir" and dirs or files, info)
+          entries_count = entries_count + 1
+          if entries_count > max_entries then break end
         end
       end
     end
@@ -48,7 +52,10 @@ local function project_scan_thread()
     table.sort(dirs, compare_file)
     for _, f in ipairs(dirs) do
       table.insert(t, f)
-      get_files(f.filename, t)
+      if entries_count <= max_entries then
+        local subdir_t, subdir_count = get_files(f.filename, t)
+        entries_count = entries_count + subdir_count
+      end
     end
 
     table.sort(files, compare_file)
@@ -56,14 +63,19 @@ local function project_scan_thread()
       table.insert(t, f)
     end
 
-    return t
+    return t, entries_count
   end
 
   while true do
     -- get project files and replace previous table if the new table is
     -- different
-    local t = get_files(".")
+    local t, entries_count = get_files(".")
     if diff_files(core.project_files, t) then
+      if entries_count > config.max_project_files then
+        core.status_view:show_message("!", style.accent,
+          "Too many files in project directory: stopping reading at "..
+          config.max_project_files.." files according to config.max_project_files.")
+      end
       core.project_files = t
       core.redraw = true
     end