feat(lsp): replace fswatch with inotifywait

This patch replaces fswatch with inotifywait from inotify-toools:

https://github.com/inotify-tools/inotify-tools

fswatch takes ~1min to set up recursively for the Samba source code
directory. inotifywait needs less than a second to do the same thing.

emcrisostomo/fswatch#321

Also it fswatch seems to be unmaintained in the meantime.

Signed-off-by: Andreas Schneider <[email protected]>

runtime/doc/lua.txt

@@ -543,10 +543,10 @@ Example: File-change detection                                    *watch-file*
     vim.api.nvim_command(
       "command! -nargs=1 Watch call luaeval('watch_file(_A)', expand('<args>'))")
 <
-                                                         *fswatch-limitations*
-When on Linux and using fswatch, you may need to increase the maximum number
-of `inotify` watches and queued events as the default limit can be too low. To
-increase the limit, run: >sh
+                                                         *inotify-limitations*
+When on Linux and using inotifywait, you may need to increase the maximum
+number of `inotify` watches and queued events as the default limit can be too
+low. To increase the limit, run: >sh
     sysctl fs.inotify.max_user_watches=100000
     sysctl fs.inotify.max_queued_events=100000
 <

runtime/doc/news.txt

@@ -54,7 +54,9 @@ EVENTS
 
 LSP
 
-• TODO
+• The watchfunc backend was implemented with fswatch, but deactivated by
+  default. The fswatch backend was replaced with inotifywait from
+  inotify-tools. This is a much faster backend.
 
 LUA
 

runtime/lua/vim/_watch.lua

@@ -227,11 +227,12 @@ end
 --- @param data string
 --- @param opts vim._watch.Opts?
 --- @param callback vim._watch.Callback
-local function fswatch_output_handler(data, opts, callback)
+local function inotifywait_output_handler(data, opts, callback)
   local d = vim.split(data, '%s+')
 
   -- only consider the last reported event
-  local fullpath, event = d[1], d[#d]
+  local path, event, file = d[1], d[2], d[#d]
+  local fullpath = vim.fs.joinpath(path, file)
 
   if skip(fullpath, opts) then
     return
@@ -240,20 +241,16 @@ local function fswatch_output_handler(data, opts, callback)
   --- @type integer
   local change_type
 
-  if event == 'Created' then
+  if event == 'CREATE' then
     change_type = M.FileChangeType.Created
-  elseif event == 'Removed' then
+  elseif event == 'DELETE' then
     change_type = M.FileChangeType.Deleted
-  elseif event == 'Updated' then
+  elseif event == 'MODIFY' then
     change_type = M.FileChangeType.Changed
-  elseif event == 'Renamed' then
-    local _, staterr, staterrname = uv.fs_stat(fullpath)
-    if staterrname == 'ENOENT' then
-      change_type = M.FileChangeType.Deleted
-    else
-      assert(not staterr, staterr)
-      change_type = M.FileChangeType.Created
-    end
+  elseif event == 'MOVED_FROM' then
+    change_type = M.FileChangeType.Deleted
+  elseif event == 'MOVED_TO' then
+    change_type = M.FileChangeType.Created
   end
 
   if change_type then
@@ -265,24 +262,23 @@ end
 --- @param opts vim._watch.Opts?
 --- @param callback vim._watch.Callback Callback for new events
 --- @return fun() cancel Stops the watcher
-function M.fswatch(path, opts, callback)
-  -- debounce isn't the same as latency but close enough
-  local latency = 0.5 -- seconds
-  if opts and opts.debounce then
-    latency = opts.debounce / 1000
-  end
-
+function M.inotify(path, opts, callback)
+  -- FIXME Follwo symlinks, yes or no?
   local obj = vim.system({
-    'fswatch',
-    '--event=Created',
-    '--event=Removed',
-    '--event=Updated',
-    '--event=Renamed',
-    '--event-flags',
+    'inotifywait',
+    '--quiet', -- suppress startup messages
+    '--no-dereference', -- don't follow symlinks
+    '--monitor', -- keep listening for events forever
     '--recursive',
-    '--latency=' .. tostring(latency),
-    '--exclude',
-    '/.git/',
+    '--event',
+    'create',
+    '--event',
+    'delete',
+    '--event',
+    'modify',
+    '--event',
+    'move',
+    '@.git', -- ignore git directory
     path,
   }, {
     stderr = function(err, data)
@@ -292,11 +288,11 @@ function M.fswatch(path, opts, callback)
 
       if data and #vim.trim(data) > 0 then
         vim.schedule(function()
-          if vim.fn.has('linux') == 1 and vim.startswith(data, 'Event queue overflow') then
-            data = 'inotify(7) limit reached, see :h fswatch-limitations for more info.'
+          if vim.fn.has('linux') == 1 and vim.startswith(data, 'Failed to watch') then
+            data = 'inotify(7) limit reached, see :h inotify-limitations for more info.'
           end
 
-          vim.notify('fswatch: ' .. data, vim.log.levels.ERROR)
+          vim.notify('inotify: ' .. data, vim.log.levels.ERROR)
         end)
       end
     end,
@@ -306,7 +302,7 @@ function M.fswatch(path, opts, callback)
       end
 
       for line in vim.gsplit(data or '', '\n', { plain = true, trimempty = true }) do
-        fswatch_output_handler(line, opts, callback)
+        inotifywait_output_handler(line, opts, callback)
       end
     end,
     -- --latency is locale dependent but tostring() isn't and will always have '.' as decimal point.

runtime/lua/vim/lsp/_watchfiles.lua

@@ -9,8 +9,8 @@ local M = {}
 
 if vim.fn.has('win32') == 1 or vim.fn.has('mac') == 1 then
   M._watchfunc = watch.watch
-elseif vim.fn.executable('fswatch') == 1 then
-  M._watchfunc = watch.fswatch
+elseif vim.fn.executable('inotifywait') == 1 then
+  M._watchfunc = watch.inotify
 else
   M._watchfunc = watch.watchdirs
 end

runtime/lua/vim/lsp/health.lua

@@ -90,16 +90,16 @@ local function check_watcher()
     watchfunc_name = 'libuv-watch'
   elseif watchfunc == vim._watch.watchdirs then
     watchfunc_name = 'libuv-watchdirs'
-  elseif watchfunc == vim._watch.fswatch then
-    watchfunc_name = 'fswatch'
+  elseif watchfunc == vim._watch.inotifywait then
+    watchfunc_name = 'inotifywait'
   else
     local nm = debug.getinfo(watchfunc, 'S').source
     watchfunc_name = string.format('Custom (%s)', nm)
   end
 
   report_info('File watch backend: ' .. watchfunc_name)
   if watchfunc_name == 'libuv-watchdirs' then
-    report_warn('libuv-watchdirs has known performance issues. Consider installing fswatch.')
+    report_warn('libuv-watchdirs has known performance issues. Consider installing inotify-tools.')
   end
 end
 

test/functional/lua/watch_spec.lua

@@ -23,10 +23,11 @@ describe('vim._watch', function()
 
   local function run(watchfunc)
     it('detects file changes (watchfunc=' .. watchfunc .. '())', function()
-      if watchfunc == 'fswatch' then
+      if watchfunc == 'inotify' then
         skip(is_os('win'), 'not supported on windows')
         skip(is_os('mac'), 'flaky test on mac')
-        skip(not is_ci() and n.fn.executable('fswatch') == 0, 'fswatch not installed and not on CI')
+        skip(not is_ci() and n.fn.executable('inotifywait') == 0,
+             'inotify-tools not installed and not on CI')
       end
 
       if watchfunc == 'watch' then
@@ -123,5 +124,5 @@ describe('vim._watch', function()
 
   run('watch')
   run('watchdirs')
-  run('fswatch')
+  run('inotify')
 end)

test/functional/plugin/lsp_spec.lua

@@ -5048,12 +5048,12 @@ describe('LSP', function()
       it(
         string.format('sends notifications when files change (watchfunc=%s)', watchfunc),
         function()
-          if watchfunc == 'fswatch' then
+          if watchfunc == 'inotify' then
             skip(is_os('win'), 'not supported on windows')
             skip(is_os('mac'), 'flaky test on mac')
             skip(
-              not is_ci() and fn.executable('fswatch') == 0,
-              'fswatch not installed and not on CI'
+              not is_ci() and fn.executable('inotifywait') == 0,
+              'inotify-tools not installed and not on CI'
             )
           end
 
@@ -5185,7 +5185,7 @@ describe('LSP', function()
 
     test_filechanges('watch')
     test_filechanges('watchdirs')
-    test_filechanges('fswatch')
+    test_filechanges('inotify')
 
     it('correctly registers and unregisters', function()
       local root_dir = '/some_dir'