前述のように競合状態です。「git pull --rebase」は、コミットを再生するときに同じファイルを複数回変更する場合があります。以下の場合はゲームオーバーです。
- gitはファイル「foo」を変更します
- 自動復帰が開始され、「foo」がリロードされます
- git は、同じ秒内にファイル「foo」を再度変更します
UNIX のファイル時刻には 2 番目の解像度があるため、emacs が 2 番目の変更が発生したことを通知する方法はありません。最近、その方法で多くの変更を失ったことに気付いたので、emacs で問題に対処することにしました。次のようにemacsコードにパッチを当てました。ファイルが変更された時刻が現在のシステム時刻と同じである場合、次の間隔まで自動復帰を延期します。
;;
;; Fix the auto-revert-handler so that if the system time is the
;; same as the new modified time for a file, skip it on this
;; iteration. This should fix race conditions when a file is changed
;; multiple times within the same second.
;;
(defun file-change-too-close-for-comfort ()
(let* ((file-time-raw (nth 5 (file-attributes (buffer-file-name))))
(file-time (+ (lsh (nth 0 file-time-raw) 16) (nth 1 file-time-raw)))
(current-time (+ (lsh (nth 0 (current-time)) 16) (nth 1 (current-time)))))
(and (eq current-time file-time)
(message "%s: postpone revert" (buffer-name))
t)))
(defun auto-revert-handler ()
"Revert current buffer, if appropriate.
This is an internal function used by Auto-Revert Mode."
(when (or auto-revert-tail-mode (not (buffer-modified-p)))
(let* ((buffer (current-buffer)) size
(revert
(or (and buffer-file-name
(file-readable-p buffer-file-name)
(if auto-revert-tail-mode
;; Tramp caches the file attributes. Setting
;; `tramp-cache-inhibit' forces Tramp to
;; reread the values.
(let ((tramp-cache-inhibit-cache t))
(/= auto-revert-tail-pos
(setq size
(nth 7 (file-attributes
buffer-file-name)))))
(and (not (file-remote-p buffer-file-name))
(not (verify-visited-file-modtime buffer))
(not (file-change-too-close-for-comfort)))))
(and (or auto-revert-mode
global-auto-revert-non-file-buffers)
revert-buffer-function
(boundp 'buffer-stale-function)
(functionp buffer-stale-function)
(funcall buffer-stale-function t))))
eob eoblist)
(when revert
(when (and auto-revert-verbose
(not (eq revert 'fast)))
(message "Reverting buffer `%s'." (buffer-name)))
;; If point (or a window point) is at the end of the buffer,
;; we want to keep it at the end after reverting. This allows
;; to tail a file.
(when buffer-file-name
(setq eob (eobp))
(walk-windows
#'(lambda (window)
(and (eq (window-buffer window) buffer)
(= (window-point window) (point-max))
(push window eoblist)))
'no-mini t))
(if auto-revert-tail-mode
(auto-revert-tail-handler size)
;; Bind buffer-read-only in case user has done C-x C-q,
;; so as not to forget that. This gives undesirable results
;; when the file's mode changes, but that is less common.
(let ((buffer-read-only buffer-read-only))
(revert-buffer 'ignore-auto 'dont-ask 'preserve-modes)))
(when buffer-file-name
(when eob (goto-char (point-max)))
(dolist (window eoblist)
(set-window-point window (point-max)))))
;; `preserve-modes' avoids changing the (minor) modes. But we
;; do want to reset the mode for VC, so we do it manually.
(when (or revert auto-revert-check-vc-info)
(vc-find-file-hook)))))