feat: refresh lualine on auto-command events again

The basic idea is that we don't process refresh events just as they come. We queue them and process them every certain time quantum (by default 60fps). Under this, previous timers as well as autocmds all become refresh events. The event queue should be empty 99% of the time, there's a quick check for that. So, although this check is being performed quite often performance impact shouldn't be negligible. This should hopefully let us have a snappy experience with fewer refreshes, without flicker.

Author: shadmansaleh

lua/lualine.lua

@@ -17,6 +17,7 @@ local timers = {
   stl_timer = vim.loop.new_timer(),
   tal_timer = vim.loop.new_timer(),
   wb_timer = vim.loop.new_timer(),
+  refresh_check_timer = vim.loop.new_timer(),
   halt_stl_refresh = false, -- mutex ?
   halt_tal_refresh = false,
   halt_wb_refresh = false,
@@ -333,6 +334,13 @@ local function should_ignore_focus(user_config, win)
   end
 end
 
+local refresh_event_queue = {
+  has_events = false,
+  statusline = {},
+  tabline = {},
+  winbar = {},
+}
+
 ---@alias LualineRefreshOptsKind
 ---| 'all'
 ---| 'tabpage'
@@ -344,7 +352,8 @@ end
 ---@class LualineRefreshOpts
 ---@field scope LualineRefreshOptsKind
 ---@field place LualineRefreshOptsPlace[]
----@field trigger 'timer' | 'init' |'unknown'
+---@field trigger 'timer' | 'init' | 'autocmd' |'unknown'
+---@field queued boolean
 --- Refresh contents of lualine
 ---@param opts LualineRefreshOpts
 local function refresh(opts)
@@ -357,6 +366,14 @@ local function refresh(opts)
     trigger = 'unknown',
   })
 
+  if not opts.queued then
+    for _, place in ipairs(opts.place) do
+      refresh_event_queue['has_events'] = true
+      refresh_event_queue[place] = vim.tbl_extend('force', opts, { place = { place }, queued = true })
+    end
+    return
+  end
+
   local wins = {}
   local old_actual_curwin = vim.g.actual_curwin
 
@@ -449,6 +466,7 @@ end
 local function set_tabline(hide)
   vim.loop.timer_stop(timers.tal_timer)
   timers.halt_tal_refresh = true
+  vim.cmd([[augroup lualine_tal_refresh | exe "autocmd!" | augroup END]])
   if not hide and next(config.tabline) ~= nil then
     vim.loop.timer_start(
       timers.tal_timer,
@@ -458,6 +476,13 @@ local function set_tabline(hide)
         refresh { scope = 'tabpage', place = { 'tabline' }, trigger = 'timer' }
       end, 3, 'lualine: Failed to refresh tabline')
     )
+    modules.utils.define_autocmd(
+      table.concat(config.options.refresh.events, ','),
+      '*',
+      "call v:lua.require'lualine'.refresh({'kind': 'tabpage', 'place': ['tabline'], 'trigger': 'autocmd'})",
+      'lualine_tal_refresh'
+    )
+
     modules.nvim_opts.set('showtabline', config.options.always_show_tabline and 2 or 1, { global = true })
     timers.halt_tal_refresh = false
     vim.schedule(function()
@@ -471,12 +496,43 @@ local function set_tabline(hide)
   end
 end
 
+local function check_refresh()
+  if not refresh_event_queue.has_events then
+    return
+  end
+  refresh_event_queue.has_events = nil
+
+  for place, refresh_cmd in pairs(refresh_event_queue) do
+    if type(refresh_cmd) == 'table' and refresh_cmd.queued == true then
+      refresh(refresh_cmd)
+      refresh_event_queue[place] = {}
+    end
+  end
+end
+
+local function set_refresh_checker()
+  vim.loop.timer_stop(timers.refresh_check_timer)
+  vim.loop.timer_start(
+    timers.refresh_check_timer,
+    0,
+    config.options.refresh.check,
+    modules.utils.timer_call(
+      timers.refresh_check_timer,
+      'lualine_refresh_check',
+      check_refresh,
+      3,
+      'lualine: Failed to refresh statusline'
+    )
+  )
+end
+
 --- Sets &statusline option to lualine
 --- adds auto command to redraw lualine on VimResized event
 ---@param hide boolean|nil if should hide statusline
 local function set_statusline(hide)
   vim.loop.timer_stop(timers.stl_timer)
   timers.halt_stl_refresh = true
+  vim.cmd([[augroup lualine_stl_refresh | exe "autocmd!" | augroup END]])
   if not hide and (next(config.sections) ~= nil or next(config.inactive_sections) ~= nil) then
     modules.nvim_opts.set('statusline', '%#lualine_transparent#', { global = true })
     if config.options.globalstatus then
@@ -489,6 +545,12 @@ local function set_statusline(hide)
           refresh { scope = 'window', place = { 'statusline' }, trigger = 'timer' }
         end, 3, 'lualine: Failed to refresh statusline')
       )
+      modules.utils.define_autocmd(
+        table.concat(config.options.refresh.events, ','),
+        '*',
+        "call v:lua.require'lualine'.refresh({'kind': 'window', 'place': ['statusline'], 'trigger': 'autocmd'})",
+        'lualine_stl_refresh'
+      )
     else
       modules.nvim_opts.set('laststatus', 2, { global = true })
       vim.loop.timer_start(
@@ -499,6 +561,13 @@ local function set_statusline(hide)
           refresh { scope = 'tabpage', place = { 'statusline' }, trigger = 'timer' }
         end, 3, 'lualine: Failed to refresh statusline')
       )
+
+      modules.utils.define_autocmd(
+        table.concat(config.options.refresh.events, ','),
+        '*',
+        "call v:lua.require'lualine'.refresh({'kind': 'tabpage', 'place': ['statusline'], 'trigger': 'autocmd'})",
+        'lualine_stl_refresh'
+      )
     end
     timers.halt_stl_refresh = false
     vim.schedule(function()
@@ -524,6 +593,7 @@ end
 local function set_winbar(hide)
   vim.loop.timer_stop(timers.wb_timer)
   timers.halt_wb_refresh = true
+  vim.cmd([[augroup lualine_wb_refresh | exe "autocmd!" | augroup END]])
   if not hide and (next(config.winbar) ~= nil or next(config.inactive_winbar) ~= nil) then
     vim.loop.timer_start(
       timers.wb_timer,
@@ -533,6 +603,13 @@ local function set_winbar(hide)
         refresh { scope = 'tabpage', place = { 'winbar' }, trigger = 'timer' }
       end, 3, 'lualine: Failed to refresh winbar')
     )
+    modules.utils.define_autocmd(
+      table.concat(config.options.refresh.events, ','),
+      '*',
+      "call v:lua.require'lualine'.refresh({'kind': 'tabpage', 'place': ['winbar'], 'trigger': 'autocmd'})",
+      'lualine_wb_refresh'
+    )
+
     timers.halt_wb_refresh = false
     vim.schedule(function()
       -- imediately refresh upon load.
@@ -613,6 +690,7 @@ local function setup(user_config)
     set_statusline()
     set_tabline()
     set_winbar()
+    set_refresh_checker()
   end
   if package.loaded['lualine.utils.notices'] then
     modules.utils_notices.notice_message_startup()

lua/lualine/config.lua

@@ -21,9 +21,22 @@ local config = {
     always_show_tabline = true,
     globalstatus = vim.go.laststatus == 3,
     refresh = {
-      statusline = 100,
-      tabline = 100,
-      winbar = 100,
+      statusline = 1000,
+      tabline = 1000,
+      winbar = 1000,
+      check = 16, -- ~60fps
+      events = {
+        'WinEnter',
+        'BufEnter',
+        'BufWritePost',
+        'SessionLoadPost',
+        'FileChangedShellPost',
+        'VimResized',
+        'Filetype',
+        'CursorMoved',
+        'CursorMovedI',
+        'ModeChanged',
+      },
     },
   },
   sections = {

tests/spec/lualine_spec.lua

@@ -24,9 +24,22 @@ describe('Lualine', function()
         always_show_tabline = true,
         globalstatus = false,
         refresh = {
-          statusline = 100,
-          tabline = 100,
-          winbar = 100,
+          statusline = 1000,
+          tabline = 1000,
+          winbar = 1000,
+          check = 16,
+          events = {
+            'WinEnter',
+            'BufEnter',
+            'BufWritePost',
+            'SessionLoadPost',
+            'FileChangedShellPost',
+            'VimResized',
+            'Filetype',
+            'CursorMoved',
+            'CursorMovedI',
+            'ModeChanged',
+          },
         },
       },
       sections = {