bug#32899: 27.0.50; wdired-do-renames: Speed up for long Emacs sessions

[Tino Calancha]

Severity: wishlist

In a long lived Emacs session with many buffers, we can
get a significant improvement with `wdired-do-renames' if we
drop an unnecessary step, i.e., if `dired-rename-file'
calls `dired-rename-subdir' iif FILE is a directory.

I observe gains as high as a factor 15.

--8<-----------------------------cut here---------------start------------->8---
commit 8e742e6c84bc2f992058a03274e60c294e29ee41
Author: Tino Calancha <tino.calancha@gmail.com>
Date:   Tue Oct 2 02:00:17 2018 +0900

    wdired-do-renames: Speed up for long Emacs sessions

    `dired-rename-file' calls unconditionally `dired-rename-subdir'.
    The second function performs performs a loop on all the Emacs
    buffers; this step is only needed if FILE is a directory.

    In a long lived Emacs session, this can make a difference
    when renaming a bunch of files with `wdired'.
    For instance, in my 40 days old Emacs session, with ~ 700 buffers,
    this patch increases the speed to rename 2000 files a factor ~ 15.

    * lisp/dired-aux.el (dired-rename-file): Call `dired-rename-subdir'
    iif FILE is a directory.  Add docstring.
    (dired-rename-subdir, dired-remove-entry)
    (dired-remove-file): Add docstring.

    (dired-remove-entry): Move definition into `dired.el'.

    * lisp/wdired.el (wdired-do-renames): Use a progress-reporter.

    * lisp/dired.el (dired-delete-entry):
    Use `dired-remove-entry'.  Add docstring.

    (dired-buffers-for-dir, dired-fun-in-all-buffers):
    Change comment into docstring.
    (dired-fun-in-all-buffers): Prefer `when' and `push' here.

diff --git a/lisp/dired-aux.el b/lisp/dired-aux.el
index 1f13204b7c..9ec97cf3ce 100644
--- a/lisp/dired-aux.el
+++ b/lisp/dired-aux.el
@@ -1485,17 +1485,13 @@ dired-after-subdir-garbage

 ;;;###autoload
 (defun dired-remove-file (file)
+  "Remove entry FILE on each dired buffer.
+Note this doesn't delete FILE in the file system.
+See `dired-delete-file' in case you wish that."
   (dired-fun-in-all-buffers
    (file-name-directory file) (file-name-nondirectory file)
    #'dired-remove-entry file))

-(defun dired-remove-entry (file)
-  (save-excursion
-    (and (dired-goto-file file)
-        (let (buffer-read-only)
-          (delete-region (progn (beginning-of-line) (point))
-                         (line-beginning-position 2))))))
-
 ;;;###autoload
 (defun dired-relist-file (file)
   "Create or update the line for FILE in all Dired buffers it would belong in."
@@ -1600,6 +1596,9 @@ dired-copy-file-recursive

 ;;;###autoload
 (defun dired-rename-file (file newname ok-if-already-exists)
+  "Rename FILE to NEWNAME.
+Signal a `file-already-exists' error if a file NEWNAME already exists
+unless OK-IF-ALREADY-EXISTS is non-nil."
   (dired-handle-overwrite newname)
   (dired-maybe-create-dirs (file-name-directory newname))
   (rename-file file newname ok-if-already-exists) ; error is caught
in -create-files
@@ -1609,9 +1608,12 @@ dired-rename-file
         (set-visited-file-name newname nil t)))
   (dired-remove-file file)
   ;; See if it's an inserted subdir, and rename that, too.
-  (dired-rename-subdir file newname))
+  (when (file-directory-p file)
+    (dired-rename-subdir file newname)))

 (defun dired-rename-subdir (from-dir to-dir)
+  "Rename subdir FROM-DIR to TO-DIR.
+This updates the name of all buffers visiting files under FROM-DIR."
   (setq from-dir (file-name-as-directory from-dir)
        to-dir (file-name-as-directory to-dir))
   (dired-fun-in-all-buffers from-dir nil
diff --git a/lisp/dired.el b/lisp/dired.el
index 5c7bb9599c..52399d2623 100644
--- a/lisp/dired.el
+++ b/lisp/dired.el
@@ -2607,12 +2607,12 @@ dired-copy-filename-as-kill
 ;; Keeping Dired buffers in sync with the filesystem and with each other

 (defun dired-buffers-for-dir (dir &optional file)
-;; Return a list of buffers for DIR (top level or in-situ subdir).
-;; If FILE is non-nil, include only those whose wildcard pattern (if any)
-;; matches FILE.
-;; The list is in reverse order of buffer creation, most recent last.
-;; As a side effect, killed dired buffers for DIR are removed from
-;; dired-buffers.
+  "Return a list of buffers for DIR (top level or in-situ subdir).
+If FILE is non-nil, include only those whose wildcard pattern (if any)
+matches FILE.
+The list is in reverse order of buffer creation, most recent last.
+As a side effect, killed dired buffers for DIR are removed from
+dired-buffers."
   (setq dir (file-name-as-directory dir))
   (let (result buf)
     (dolist (elt dired-buffers)
@@ -3149,26 +3149,36 @@ dired-internal-do-deletions
   (dired-move-to-filename))

 (defun dired-fun-in-all-buffers (directory file fun &rest args)
-  ;; In all buffers dired'ing DIRECTORY, run FUN with ARGS.
-  ;; If the buffer has a wildcard pattern, check that it matches FILE.
-  ;; (FILE does not include a directory component.)
-  ;; FILE may be nil, in which case ignore it.
-  ;; Return list of buffers where FUN succeeded (i.e., returned non-nil).
+  "In all buffers dired'ing DIRECTORY, run FUN with ARGS.
+If the buffer has a wildcard pattern, check that it matches FILE.
+\(FILE does not include a directory component).
+FILE may be nil, in which case ignore it.
+Return list of buffers where FUN succeeded (i.e., returned non-nil)."
   (let (success-list)
     (dolist (buf (dired-buffers-for-dir (expand-file-name directory)
                                        file))
       (with-current-buffer buf
-       (if (apply fun args)
-           (setq success-list (cons (buffer-name buf) success-list)))))
+       (when (apply fun args)
+         (push (buffer-name buf) success-list))))
     success-list))

 ;; Delete the entry for FILE from
-(defun dired-delete-entry (file)
+(defun dired-remove-entry (file)
+  "Remove entry FILE in the current dired buffer.
+Note this doesn't delete FILE in the file system.
+See `dired-delete-file' in case you wish that."
   (save-excursion
     (and (dired-goto-file file)
-        (let ((inhibit-read-only t))
+        (let (buffer-read-only)
           (delete-region (progn (beginning-of-line) (point))
-                         (save-excursion (forward-line 1) (point))))))
+                         (line-beginning-position 2))))))
+
+(defun dired-delete-entry (file)
+  "Remove entry FILE in the current dired buffer.
+Like `dired-remove-entry' followed by `dired-clean-up-after-deletion'.
+Note this doesn't delete FILE in the file system.
+See `dired-delete-file' in case you wish that."
+  (dired-remove-entry file)
   (dired-clean-up-after-deletion file))

 (defvar dired-clean-up-buffers-too)
diff --git a/lisp/wdired.el b/lisp/wdired.el
index 3157e887d7..8852806dd6 100644
--- a/lisp/wdired.el
+++ b/lisp/wdired.el
@@ -459,10 +459,12 @@ wdired-finish-edit

 (defun wdired-do-renames (renames)
   "Perform RENAMES in parallel."
-  (let ((residue ())
-        (progress nil)
-        (errors 0)
-        (overwrite (or (not wdired-confirm-overwrite) 1)))
+  (let* ((residue ())
+         (progress nil)
+         (errors 0)
+         (total (1- (length renames)))
+         (prep (make-progress-reporter "Renaming" 0 total))
+         (overwrite (or (not wdired-confirm-overwrite) 1)))
     (while (or renames
                ;; We've done one round through the renames, we have found
                ;; some residue, but we also made some progress, so maybe
@@ -470,6 +472,7 @@ wdired-do-renames
                (prog1 (setq renames residue)
                  (setq progress nil)
                  (setq residue nil)))
+      (progress-reporter-update prep (- total (length renames)))
       (let* ((rename (pop renames))
              (file-new (cdr rename)))
         (cond
@@ -517,6 +520,7 @@ wdired-do-renames
                  (dired-log "Rename `%s' to `%s' failed:\n%s\n"
                             file-ori file-new
                             err)))))))))
+    (progress-reporter-done prep)
     errors))

 (defun wdired-create-parentdirs (file-new)

--8<-----------------------------cut here---------------end--------------->8---
In GNU Emacs 27.0.50 (build 1, x86_64-pc-linux-gnu, GTK+ Version 3.22.11)
Repository revision: 6217746dd64b43a2a2b3b66ab50cfbbfc984f36c