feat(lsp): drop fswatch, use inotifywait (#29374)

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.

https://github.com/emcrisostomo/fswatch/issues/321

Also it fswatch seems to be unmaintained in the meantime.

Signed-off-by: Andreas Schneider <asn@cryptomilk.org>

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 on_inotifywait_output(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 +262,22 @@ 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)
   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 +287,11 @@ 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 +301,7 @@ 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)
+        on_inotifywait_output(line, opts, callback)
       end
     end,
     -- --latency is locale dependent but tostring() isn't and will always have '.' as decimal point.