feat: move watchers to repo objects

lua/gitsigns/attach.lua

@@ -11,6 +11,7 @@ local config = require('gitsigns.config').config
 local dprint = log.dprint
 local dprintf = log.dprintf
 local throttle_by_id = require('gitsigns.debounce').throttle_by_id
+local debounce_trailing = require('gitsigns.debounce').debounce_trailing
 
 local api = vim.api
 local uv = vim.loop
@@ -216,6 +217,105 @@ local function get_buf_context(bufnr)
   }
 end
 
+--- @param bufnr integer
+--- @param old_relpath string
+local function handle_moved(bufnr, old_relpath)
+  local bcache = assert(cache[bufnr])
+  local git_obj = bcache.git_obj
+
+  local new_name = git_obj:has_moved()
+  if new_name then
+    dprintf('File moved to %s', new_name)
+    git_obj.relpath = new_name
+    if not git_obj.orig_relpath then
+      git_obj.orig_relpath = old_relpath
+    end
+  elseif git_obj.orig_relpath then
+    local orig_file = git_obj.repo.toplevel .. util.path_sep .. git_obj.orig_relpath
+    if not git_obj:file_info(orig_file).relpath then
+      return
+    end
+    --- File was moved in the index, but then reset
+    dprintf('Moved file reset')
+    git_obj.relpath = git_obj.orig_relpath
+    git_obj.orig_relpath = nil
+  else
+    -- File removed from index, do nothing
+    return
+  end
+
+  git_obj.file = git_obj.repo.toplevel .. util.path_sep .. git_obj.relpath
+  bcache.file = git_obj.file
+  git_obj:update()
+  if not manager.schedule(bufnr) then
+    return
+  end
+
+  local bufexists = util.bufexists(bcache.file)
+  local old_name = api.nvim_buf_get_name(bufnr)
+
+  if not bufexists then
+    -- Do not trigger BufFilePre/Post
+    -- TODO(lewis6991): figure out how to avoid reattaching without
+    -- disabling all autocommands.
+    util.noautocmd({ 'BufFilePre', 'BufFilePost' }, function()
+      util.buf_rename(bufnr, bcache.file)
+    end)
+  end
+
+  local msg = bufexists and 'Cannot rename' or 'Renamed'
+  dprintf('%s buffer %d from %s to %s', msg, bufnr, old_name, bcache.file)
+end
+
+--- @async
+--- @param bufnr integer
+local function watcher_handler0(bufnr)
+  local __FUNC__ = 'watcher_handler'
+
+  -- Avoid cache hit for detached buffer
+  -- ref: https://github.com/lewis6991/gitsigns.nvim/issues/956
+  if not manager.schedule(bufnr) then
+    dprint('buffer invalid (1)')
+    return
+  end
+
+  local git_obj = cache[bufnr].git_obj
+
+  Status:update(bufnr, { head = git_obj.repo.abbrev_head })
+
+  local was_tracked = git_obj.object_name ~= nil
+  local old_relpath = git_obj.relpath
+
+  git_obj:update()
+  if not manager.schedule(bufnr) then
+    dprint('buffer invalid (3)')
+    return
+  end
+
+  if config.watch_gitdir.follow_files and was_tracked and not git_obj.object_name then
+    -- File was tracked but is no longer tracked. Must of been removed or
+    -- moved. Check if it was moved and switch to it.
+    handle_moved(bufnr, old_relpath)
+    if not manager.schedule(bufnr) then
+      dprint('buffer invalid (4)')
+      return
+    end
+  end
+
+  cache[bufnr]:invalidate(true)
+
+  require('gitsigns.manager').update(bufnr)
+end
+
+--- Debounce to:
+--- - wait for all changes to the gitdir to complete.
+--- Throttle to:
+--- - ensure handler is only triggered once per git operation.
+--- - prevent updates to the same buffer from interleaving as the handler is
+---   async.
+local watcher_handler =
+  debounce_trailing(200, async.create(1, throttle_by_id(watcher_handler0, true)), 1)
+
 --- Ensure attaches cannot be interleaved for the same buffer.
 --- Since attaches are asynchronous we need to make sure an attach isn't
 --- performed whilst another one is in progress.
@@ -325,8 +425,9 @@ local attach_throttled = throttle_by_id(function(cbuf, ctx, aucmd)
   })
 
   if config.watch_gitdir.enable then
-    local watcher = require('gitsigns.watcher')
-    cache[cbuf].gitdir_watcher = watcher.watch_gitdir(cbuf, git_obj.repo.gitdir)
+    cache[cbuf].deregister_watcher = git_obj.repo:register_callback(function()
+      watcher_handler(cbuf)
+    end)
   end
 
   if not api.nvim_buf_is_loaded(cbuf) then

lua/gitsigns/cache.lua

@@ -17,7 +17,7 @@ local M = {
 --- @field hunks_staged?      Gitsigns.Hunk.Hunk[]
 ---
 --- @field staged_diffs?      Gitsigns.Hunk.Hunk[]
---- @field gitdir_watcher?    uv.uv_fs_event_t
+--- @field deregister_watcher? fun()
 --- @field git_obj            Gitsigns.GitObj
 --- @field blame?             table<integer,Gitsigns.BlameInfo?>
 local CacheEntry = M.CacheEntry
@@ -127,9 +127,8 @@ function CacheEntry:get_blame(lnum, opts)
 end
 
 function CacheEntry:destroy()
-  local w = self.gitdir_watcher
-  if w and not w:is_closing() then
-    w:close()
+  if self.deregister_watcher then
+    self.deregister_watcher()
   end
   self.git_obj.repo:unref()
 end

lua/gitsigns/git/repo.lua

@@ -22,6 +22,7 @@ local uv = vim.uv or vim.loop
 --- Username configured for the repo.
 --- Needed for to determine "You" in current line blame.
 --- @field username string
+--- @field watcher_callbacks table<fun(), true>
 local M = {}
 
 --- Run git command the with the objects gitdir and toplevel
@@ -96,6 +97,48 @@ function M:update_abbrev_head()
   self.abbrev_head = info.abbrev_head
 end
 
+--- vim.inspect but on one line
+--- @param x any
+--- @return string
+local function inspect(x)
+  return vim.inspect(x, { indent = '', newline = ' ' })
+end
+
+function M:_watcher_cb(err, filename, events)
+  if err then
+    log.dprintf('Git dir update error: %s', err)
+    return
+  end
+
+  -- The luv docs say filename is passed as a string but it has been observed
+  -- to sometimes be nil.
+  --    https://github.com/lewis6991/gitsigns.nvim/issues/848
+  if not filename then
+    log.eprint('No filename')
+    return
+  end
+
+  log.dprintf("Git dir update: '%s' %s", filename, inspect(events))
+
+  async.run(function()
+    self:update_abbrev_head()
+
+    for cb in pairs(self.watcher_callbacks) do
+      cb()
+    end
+  end)
+end
+
+--- @param cb fun()
+--- @return fun() deregister
+function M:register_callback(cb)
+  self.watcher_callbacks[cb] = true
+
+  return function()
+    self.watcher_callbacks[cb] = nil
+  end
+end
+
 --- @async
 --- @private
 --- @param info Gitsigns.RepoInfo
@@ -110,6 +153,12 @@ local function new(info)
   end
 
   self.username = self:command({ 'config', 'user.name' }, { ignore_error = true })[1]
+  self.watcher_callbacks = {}
+
+  local w = assert(uv.new_fs_event())
+  w:start(self.gitdir, {}, function(err, filename, events)
+    self:_watcher_cb(err, filename, events)
+  end)
 
   return self
 end