Merge pull request #27347 from lewis6991/fswatch

feat(lsp): add fswatch watchfunc backend

runtime/lua/vim/lsp/_watchfiles.lua

@@ -7,7 +7,13 @@ local lpeg = vim.lpeg
 
 local M = {}
 
-M._watchfunc = (vim.fn.has('win32') == 1 or vim.fn.has('mac') == 1) and watch.watch or watch.poll
+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
+else
+  M._watchfunc = watch.watchdirs
+end
 
 ---@type table<integer, table<string, function[]>> client id -> registration id -> cancel function
 local cancels = vim.defaulttable()
@@ -163,4 +169,13 @@ function M.unregister(unreg, ctx)
   end
 end
 
+--- @param client_id integer
+function M.cancel(client_id)
+  for _, reg_cancels in pairs(cancels[client_id]) do
+    for _, cancel in pairs(reg_cancels) do
+      cancel()
+    end
+  end
+end
+
 return M

runtime/lua/vim/lsp/client.lua

@@ -815,6 +815,7 @@ function Client:_stop(force)
       rpc.terminate()
       self._graceful_shutdown_failed = true
     end
+    vim.lsp._watchfiles.cancel(self.id)
   end)
 end
 

runtime/lua/vim/lsp/health.lua

@@ -1,10 +1,9 @@
 local M = {}
 
---- Performs a healthcheck for LSP
-function M.check()
-  local report_info = vim.health.info
-  local report_warn = vim.health.warn
+local report_info = vim.health.info
+local report_warn = vim.health.warn
 
+local function check_log()
   local log = vim.lsp.log
   local current_log_level = log.get_level()
   local log_level_string = log.levels[current_log_level] ---@type string
@@ -27,9 +26,11 @@ function M.check()
 
   local report_fn = (log_size / 1000000 > 100 and report_warn or report_info)
   report_fn(string.format('Log size: %d KB', log_size / 1000))
+end
 
-  local clients = vim.lsp.get_clients()
+local function check_active_clients()
   vim.health.start('vim.lsp: Active Clients')
+  local clients = vim.lsp.get_clients()
   if next(clients) then
     for _, client in pairs(clients) do
       local attached_to = table.concat(vim.tbl_keys(client.attached_buffers or {}), ',')
@@ -48,4 +49,33 @@ function M.check()
   end
 end
 
+local function check_watcher()
+  vim.health.start('vim.lsp: File watcher')
+  local watchfunc = vim.lsp._watchfiles._watchfunc
+  assert(watchfunc)
+  local watchfunc_name --- @type string
+  if watchfunc == vim._watch.watch then
+    watchfunc_name = 'libuv-watch'
+  elseif watchfunc == vim._watch.watchdirs then
+    watchfunc_name = 'libuv-watchdirs'
+  elseif watchfunc == vim._watch.fswatch then
+    watchfunc_name = 'fswatch'
+  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.')
+  end
+end
+
+--- Performs a healthcheck for LSP
+function M.check()
+  check_log()
+  check_active_clients()
+  check_watcher()
+end
+
 return M