branch: elpa/elfeed
commit 92050986b3e2e28703058648ae884a789036732e
Author: Daniel Mendler <[email protected]>
Commit: Daniel Mendler <[email protected]>
elfeed-db-pack: Write the new files first, then rename
The two renaming operations are not atomic, but still a little safer. Note
that
you should keep backups in any case.
We should use a separate data directory and rename it atomically in the
end, see
---
elfeed-db.el | 21 +++++++++++++++------
1 file changed, 15 insertions(+), 6 deletions(-)
diff --git a/elfeed-db.el b/elfeed-db.el
index 7527c8cc99..016a4809ad 100644
--- a/elfeed-db.el
+++ b/elfeed-db.el
@@ -271,7 +271,7 @@ The FEED-OR-ID may be a feed struct or a feed ID (url)."
(mkdir elfeed-db-directory t)
(let* ((coding-system-for-write 'utf-8)
(dest (expand-file-name "index" elfeed-db-directory))
- (temp (concat dest "-tmp"))
+ (temp (concat dest ".tmp"))
(write-region-inhibit-fsync nil))
;; We write to a temporary file and rename to avoid corrupting the database
;; on crash. `file-precious-flag' is insufficient as it only works for
@@ -600,11 +600,16 @@ If STATS-P is true, return the space cleared in bytes."
(defun elfeed-db-pack ()
"Pack all content into a single archive for efficient storage."
- (let ((coding-system-for-write 'utf-8)
- (next-archive (make-hash-table :test 'equal))
- (packed ()))
+ (let* ((content-dest (elfeed-ref-archive-filename ".gz"))
+ (content-temp (file-name-with-extension content-dest ".tmp.gz"))
+ (index-dest (elfeed-ref-archive-filename ".index"))
+ (index-temp (file-name-with-extension index-dest ".tmp.index"))
+ (next-archive (make-hash-table :test 'equal))
+ (coding-system-for-write 'utf-8)
+ (write-region-inhibit-fsync nil)
+ (packed ()))
(make-directory (expand-file-name "data" elfeed-db-directory) t)
- (with-temp-file (elfeed-ref-archive-filename ".gz")
+ (with-temp-file content-temp
(with-elfeed-db-visit (entry _)
(let ((ref (elfeed-entry-content entry))
(start (1- (point))))
@@ -614,12 +619,16 @@ If STATS-P is true, return the space cleared in bytes."
(insert content)
(setf (gethash (elfeed-ref-id ref) next-archive)
(cons start (1- (point)))))))))
- (with-temp-file (elfeed-ref-archive-filename ".index")
+ (with-temp-file index-temp
(let ((standard-output (current-buffer))
(print-level nil)
(print-length nil)
(print-circle nil))
(prin1 next-archive)))
+ ;; Rename two files, non-atomically! Instead use separate temporary data
+ ;; directory, see https://github.com/emacs-elfeed/elfeed/pull/569.
+ (rename-file content-temp content-dest t)
+ (rename-file index-temp index-dest t)
(setf elfeed-ref-cache nil)
(setf elfeed-ref-archive next-archive)
(mapc #'elfeed-ref-delete packed)
