chore(watchers): refactor events and make debouncer safe

- fs poll -> fs events
- make debouncer safe and fix diagnostics events

lua/nvim-tree/watcher.lua

@@ -9,6 +9,13 @@ local M = {
 local Watcher = {}
 Watcher.__index = Watcher
 
+local FS_EVENT_FLAGS = {
+  -- inotify or equivalent will be used; fallback to stat has not yet been implemented
+  stat = false,
+  -- recursive is not functional in neovim's libuv implementation
+  recursive = false,
+}
+
 function Watcher.new(opts)
   for _, existing in ipairs(M._watchers) do
     if existing._opts.absolute_path == opts.absolute_path then
@@ -35,40 +42,47 @@ function Watcher:start()
 
   local rc, _, name
 
-  self._p, _, name = uv.new_fs_poll()
-  if not self._p then
-    self._p = nil
+  self._e, _, name = uv.new_fs_event()
+  if not self._e then
+    self._e = nil
     utils.warn(
-      string.format("Could not initialize an fs_poll watcher for path %s : %s", self._opts.absolute_path, name)
+      string.format("Could not initialize an fs_event watcher for path %s : %s", self._opts.absolute_path, name)
     )
     return nil
   end
 
-  local poll_cb = vim.schedule_wrap(function(err)
+  local event_cb = vim.schedule_wrap(function(err, filename, events)
     if err then
-      log.line("watcher", "poll_cb for %s fail : %s", self._opts.absolute_path, err)
+      log.line("watcher", "event_cb for %s fail : %s", self._opts.absolute_path, err)
     else
+      log.line("watcher", "event_cb '%s' '%s' %s", self._opts.absolute_path, filename, vim.inspect(events))
       self._opts.on_event(self._opts)
     end
   end)
 
-  rc, _, name = uv.fs_poll_start(self._p, self._opts.absolute_path, self._opts.interval, poll_cb)
+  rc, _, name = self._e:start(self._opts.absolute_path, FS_EVENT_FLAGS, event_cb)
   if rc ~= 0 then
-    utils.warn(string.format("Could not start the fs_poll watcher for path %s : %s", self._opts.absolute_path, name))
+    utils.warn(string.format("Could not start the fs_event watcher for path %s : %s", self._opts.absolute_path, name))
     return nil
   end
 
   return self
 end
 
-function Watcher:stop()
-  log.line("watcher", "Watcher:stop  '%s'", self._opts.absolute_path)
-  if self._p then
-    local rc, _, name = uv.fs_poll_stop(self._p)
+function Watcher:destroy()
+  log.line("watcher", "Watcher:destroy '%s'", self._opts.absolute_path)
+  if self._e then
+    local rc, _, name = self._e:stop()
     if rc ~= 0 then
-      utils.warn(string.format("Could not stop the fs_poll watcher for path %s : %s", self._opts.absolute_path, name))
+      utils.warn(string.format("Could not stop the fs_event watcher for path %s : %s", self._opts.absolute_path, name))
+    end
+    self._e = nil
+  end
+  for i, w in ipairs(M._watchers) do
+    if w == self then
+      table.remove(M._watchers, i)
+      break
     end
-    self._p = nil
   end
 end
 
@@ -76,7 +90,7 @@ M.Watcher = Watcher
 
 function M.purge_watchers()
   for _, watcher in pairs(M._watchers) do
-    watcher:stop()
+    watcher:destroy()
   end
   M._watchers = {}
 end