chore(watchers): Watcher shares single fs_event from Event, node watchers use unique path prefixed debounce context (#1453)

Author: alex-courtis

lua/nvim-tree/explorer/watch.lua

@@ -45,21 +45,23 @@ function M.create_watcher(absolute_path)
     return nil
   end
 
-  log.line("watcher", "node start '%s'", absolute_path)
-  return Watcher.new {
-    absolute_path = absolute_path,
-    on_event = function(opts)
-      log.line("watcher", "node event scheduled '%s'", opts.absolute_path)
-      utils.debounce("explorer:watch:" .. opts.absolute_path, M.debounce_delay, function()
-        refresh_path(opts.absolute_path)
-      end)
-    end,
-  }
+  local function callback(watcher)
+    log.line("watcher", "node event scheduled %s", watcher.context)
+    utils.debounce(watcher.context, M.debounce_delay, function()
+      refresh_path(watcher._path)
+    end)
+  end
+
+  M.uid = M.uid + 1
+  return Watcher:new(absolute_path, callback, {
+    context = "explorer:watch:" .. absolute_path .. ":" .. M.uid,
+  })
 end
 
 function M.setup(opts)
   M.enabled = opts.filesystem_watchers.enable
   M.debounce_delay = opts.filesystem_watchers.debounce_delay
+  M.uid = 0
 end
 
 return M

lua/nvim-tree/git/init.lua

@@ -143,16 +143,17 @@ function M.load_project_status(cwd)
   local watcher = nil
   if M.config.filesystem_watchers.enable then
     log.line("watcher", "git start")
-    watcher = Watcher.new {
-      absolute_path = utils.path_join { project_root, ".git" },
+
+    local callback = function(w)
+      log.line("watcher", "git event scheduled '%s'", w.project_root)
+      utils.debounce("git:watcher:" .. w.project_root, M.config.filesystem_watchers.debounce_delay, function()
+        reload_tree_at(w.project_root)
+      end)
+    end
+
+    watcher = Watcher:new(utils.path_join { project_root, ".git" }, callback, {
       project_root = project_root,
-      on_event = function(opts)
-        log.line("watcher", "git event scheduled '%s'", opts.project_root)
-        utils.debounce("git:watcher:" .. opts.project_root, M.config.filesystem_watchers.debounce_delay, function()
-          reload_tree_at(opts.project_root)
-        end)
-      end,
-    }
+    })
   end
 
   M.projects[project_root] = {

lua/nvim-tree/utils.lua

@@ -169,15 +169,17 @@ end
 ---Matching executable files in Windows.
 ---@param ext string
 ---@return boolean
-local PATHEXT = vim.env.PATHEXT or ""
-local wexe = vim.split(PATHEXT:gsub("%.", ""), ";")
-local pathexts = {}
-for _, v in pairs(wexe) do
-  pathexts[v] = true
-end
-
 function M.is_windows_exe(ext)
-  return pathexts[ext:upper()]
+  if not M.pathexts then
+    local PATHEXT = vim.env.PATHEXT or ""
+    local wexe = vim.split(PATHEXT:gsub("%.", ""), ";")
+    M.pathexts = {}
+    for _, v in pairs(wexe) do
+      M.pathexts[v] = true
+    end
+  end
+
+  return M.pathexts[ext:upper()]
 end
 
 function M.rename_loaded_buffers(old_path, new_path)
@@ -379,4 +381,23 @@ function M.clear_prompt()
   end
 end
 
+-- return a new table with values from array
+function M.array_shallow_clone(array)
+  local to = {}
+  for _, v in ipairs(array) do
+    table.insert(to, v)
+  end
+  return to
+end
+
+-- remove item from array if it exists
+function M.array_remove(array, item)
+  for i, v in ipairs(array) do
+    if v == item then
+      table.remove(array, i)
+      break
+    end
+  end
+end
+
 return M

lua/nvim-tree/watcher.lua

@@ -3,10 +3,16 @@ local uv = vim.loop
 local log = require "nvim-tree.log"
 local utils = require "nvim-tree.utils"
 
-local M = {
+local M = {}
+
+local Event = {
+  _events = {},
+}
+Event.__index = Event
+
+local Watcher = {
   _watchers = {},
 }
-local Watcher = {}
 Watcher.__index = Watcher
 
 local FS_EVENT_FLAGS = {
@@ -16,87 +22,129 @@ local FS_EVENT_FLAGS = {
   recursive = false,
 }
 
-function Watcher.new(opts)
-  for _, existing in ipairs(M._watchers) do
-    if existing._opts.absolute_path == opts.absolute_path then
-      log.line("watcher", "Watcher:new using existing '%s'", opts.absolute_path)
-      return existing
-    end
-  end
-
-  log.line("watcher", "Watcher:new '%s'", opts.absolute_path)
+function Event:new(path)
+  log.line("watcher", "Event:new '%s'", path)
 
-  local watcher = setmetatable({
-    _opts = opts,
-  }, Watcher)
+  local e = setmetatable({
+    _path = path,
+    _fs_event = nil,
+    _listeners = {},
+  }, Event)
 
-  watcher = watcher:start()
-
-  table.insert(M._watchers, watcher)
-
-  return watcher
+  if e:start() then
+    Event._events[path] = e
+    return e
+  else
+    return nil
+  end
 end
 
-function Watcher:start()
-  log.line("watcher", "Watcher:start '%s'", self._opts.absolute_path)
+function Event:start()
+  log.line("watcher", "Event:start '%s'", self._path)
 
   local rc, _, name
 
-  self._e, _, name = uv.new_fs_event()
-  if not self._e then
-    self._e = nil
-    utils.notify.warn(
-      string.format("Could not initialize an fs_event watcher for path %s : %s", self._opts.absolute_path, name)
-    )
-    return nil
+  self._fs_event, _, name = uv.new_fs_event()
+  if not self._fs_event then
+    self._fs_event = nil
+    utils.notify.warn(string.format("Could not initialize an fs_event watcher for path %s : %s", self._path, name))
+    return false
   end
 
-  local event_cb = vim.schedule_wrap(function(err, filename, events)
+  local event_cb = vim.schedule_wrap(function(err, filename)
     if err then
-      log.line("watcher", "event_cb for %s fail : %s", self._opts.absolute_path, err)
+      log.line("watcher", "event_cb for %s fail : %s", self._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)
+      log.line("watcher", "event_cb '%s' '%s'", self._path, filename)
+      for _, listener in ipairs(self._listeners) do
+        listener()
+      end
     end
   end)
 
-  rc, _, name = self._e:start(self._opts.absolute_path, FS_EVENT_FLAGS, event_cb)
+  rc, _, name = self._fs_event:start(self._path, FS_EVENT_FLAGS, event_cb)
   if rc ~= 0 then
-    utils.notify.warn(
-      string.format("Could not start the fs_event watcher for path %s : %s", self._opts.absolute_path, name)
-    )
-    return nil
+    utils.notify.warn(string.format("Could not start the fs_event watcher for path %s : %s", self._path, name))
+    return false
   end
 
-  return self
+  return true
 end
 
-function Watcher:destroy()
-  log.line("watcher", "Watcher:destroy '%s'", self._opts.absolute_path)
-  if self._e then
-    local rc, _, name = self._e:stop()
+function Event:add(listener)
+  table.insert(self._listeners, listener)
+end
+
+function Event:remove(listener)
+  utils.array_remove(self._listeners, listener)
+  if #self._listeners == 0 then
+    self:destroy()
+  end
+end
+
+function Event:destroy()
+  log.line("watcher", "Event:destroy '%s'", self._path)
+
+  if self._fs_event then
+    local rc, _, name = self._fs_event:stop()
     if rc ~= 0 then
-      utils.notify.warn(
-        string.format("Could not stop the fs_event watcher for path %s : %s", self._opts.absolute_path, name)
-      )
+      utils.notify.warn(string.format("Could not stop the fs_event watcher for path %s : %s", self._path, name))
     end
-    self._e = nil
+    self._fs_event = nil
   end
-  for i, w in ipairs(M._watchers) do
-    if w == self then
-      table.remove(M._watchers, i)
-      break
-    end
+
+  Event._events[self._path] = nil
+end
+
+function Watcher:new(path, callback, data)
+  log.line("watcher", "Watcher:new '%s'", path)
+
+  local w = setmetatable(data, Watcher)
+
+  w._event = Event._events[path] or Event:new(path)
+  w._listener = nil
+  w._path = path
+  w._callback = callback
+
+  if not w._event then
+    return nil
+  end
+
+  w:start()
+
+  table.insert(Watcher._watchers, w)
+
+  return w
+end
+
+function Watcher:start()
+  self._listener = function()
+    self._callback(self)
   end
+
+  self._event:add(self._listener)
+end
+
+function Watcher:destroy()
+  log.line("watcher", "Watcher:destroy '%s'", self._path)
+
+  self._event:remove(self._listener)
+
+  utils.array_remove(Watcher._watchers, self)
 end
 
 M.Watcher = Watcher
 
 function M.purge_watchers()
-  for _, watcher in pairs(M._watchers) do
-    watcher:destroy()
+  log.line("watcher", "purge_watchers")
+
+  for _, w in ipairs(utils.array_shallow_clone(Watcher._watchers)) do
+    w:destroy()
+  end
+
+  for _, e in pairs(Event._events) do
+    e:destroy()
   end
-  M._watchers = {}
 end
 
 return M