From f6f26d4ce4622660762a3d1fabb5000455adb7b5 Mon Sep 17 00:00:00 2001 From: Ihor Radchenko Date: Sun, 8 May 2022 12:32:40 +0800 Subject: [PATCH] org-babel-tangle: Do not overwrite when contents does not change * lisp/ob-tangle.el (org-babel-tangle): Do not overwrite existing tangled files if their contents is exactly the same as we are going to write during tangle process. This avoids unneeded disk writes and can speed up tangling significantly when many small files are tangled from a single .org source. An example of performance improvement when tangling an .org file into ~200 files: (benchmark-run 10 (org-babel-tangle)) Before the commit (on SSD): (76.33826743 8 11.551725374) After the commit: (43.628606052 4 5.751274237) --- lisp/ob-tangle.el | 23 ++++++++++++++++++----- 1 file changed, 18 insertions(+), 5 deletions(-) diff --git a/lisp/ob-tangle.el b/lisp/ob-tangle.el index 16d938afb..6685a1599 100644 --- a/lisp/ob-tangle.el +++ b/lisp/ob-tangle.el @@ -282,11 +282,24 @@ matching a regular expression." lspecs) (when make-dir (make-directory fnd 'parents)) - ;; erase previous file - (when (file-exists-p file-name) - (delete-file file-name)) - (write-region nil nil file-name) - (mapc (lambda (mode) (set-file-modes file-name mode)) modes) + (unless + (and (file-exists-p file-name) + (let ((tangle-buf (current-buffer))) + (with-temp-buffer + (insert-file-contents file-name) + (and + (equal (buffer-size) + (buffer-size tangle-buf)) + (= 0 + (let (case-fold-search) + (compare-buffer-substrings + nil nil nil + tangle-buf nil nil))))))) + ;; erase previous file + (when (file-exists-p file-name) + (delete-file file-name)) + (write-region nil nil file-name) + (mapc (lambda (mode) (set-file-modes file-name mode)) modes)) (push file-name path-collector)))))) (if (equal arg '(4)) (org-babel-tangle-single-block 1 t)