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authorLudovic Courtès <ludo@gnu.org>2013-01-27 17:58:46 +0100
committerLudovic Courtès <ludo@gnu.org>2013-01-27 17:58:46 +0100
commit82fe08ed207a17c51370dc90e965c15ee9db9235 (patch)
treef9a06dfc729e5ce0af5013fa1370b875b7e3014f /guix-package.in
parentd9307267b3b4a87391e33daacef162745f057c3d (diff)
guix-package: Always use the next number for new generations.
Suggested by Andreas Enge <andreas@enge.fr> at <http://lists.gnu.org/archive/html/bug-guix/2013-01/msg00325.html>. * guix-package.in (latest-profile-number): Remove. (switch-symlinks): New procedure. (roll-back)[switch-link]: Use it. (guix-package)[process-actions]: Always choose NUMBER + 1 for the new profile. Use `switch-symlinks' instead of `symlink'. Remove code to delete PROFILE when it exists since `switch-symlinks' has the same effect. * tests/guix-package.sh: Adjust existing `--roll-back' tests. * doc/guix.texi (Invoking guix-package): Document this `--roll-back' behavior.
Diffstat (limited to 'guix-package.in')
-rw-r--r--guix-package.in45
1 files changed, 20 insertions, 25 deletions
diff --git a/guix-package.in b/guix-package.in
index caddae1392..46d8d66d2e 100644
--- a/guix-package.in
+++ b/guix-package.in
@@ -144,16 +144,6 @@ former profiles were found."
(cute regexp-exec (profile-regexp profile) <>))
profiles))))
-(define (latest-profile-number profile)
- "Return the identifying number of the latest generation of PROFILE.
-PROFILE is the name of the symlink to the current generation."
- (fold (lambda (number highest)
- (if (> number highest)
- number
- highest))
- 0
- (profile-numbers profile)))
-
(define (previous-profile-number profile number)
"Return the number of the generation before generation NUMBER of
PROFILE, or 0 if none exists. It could be NUMBER - 1, but it's not the
@@ -203,9 +193,15 @@ all of PACKAGES, a list of name/version/output/path tuples."
(compose string->number (cut match:substring <> 1)))
0))
+(define (switch-symlinks link target)
+ "Atomically switch LINK, a symbolic link, to point to TARGET. Works
+both when LINK already exists and when it does not."
+ (let ((pivot (string-append link ".new")))
+ (symlink target pivot)
+ (rename-file pivot link)))
+
(define (roll-back profile)
"Roll back to the previous generation of PROFILE."
- ;; XXX: Get the previous generation number from the manifest?
(let* ((number (profile-number profile))
(previous-number (previous-profile-number profile number))
(previous-profile (format #f "~a-~a-link"
@@ -214,11 +210,9 @@ all of PACKAGES, a list of name/version/output/path tuples."
(define (switch-link)
;; Atomically switch PROFILE to the previous profile.
- (let ((pivot (string-append previous-profile ".new")))
- (format #t (_ "switching from generation ~a to ~a~%")
- number previous-number)
- (symlink previous-profile pivot)
- (rename-file pivot profile)))
+ (format #t (_ "switching from generation ~a to ~a~%")
+ number previous-number)
+ (switch-symlinks profile previous-profile))
(cond ((not (file-exists? profile)) ; invalid profile
(format (current-error-port)
@@ -237,7 +231,7 @@ all of PACKAGES, a list of name/version/output/path tuples."
(when (not (build-derivations (%store) (list drv-path)))
(leave (_ "failed to build the empty profile~%")))
- (symlink prof previous-profile)
+ (switch-symlinks previous-profile prof)
(switch-link)))
(else (switch-link))))) ; anything else
@@ -499,10 +493,13 @@ Install, remove, or upgrade PACKAGES in a single transaction.\n"))
(%store) (manifest-packages
(profile-manifest profile))))
(old-prof (derivation-path->output-path old-drv))
- (number (latest-profile-number profile))
- (name (format #f "~a/~a-~a-link"
- (dirname profile)
- (basename profile) (+ 1 number))))
+ (number (profile-number profile))
+
+ ;; Always use NUMBER + 1 for the new profile,
+ ;; possibly overwriting a "previous future
+ ;; generation".
+ (name (format #f "~a-~a-link"
+ profile (+ 1 number))))
(if (string=? old-prof prof)
(when (or (pair? install) (pair? remove))
(format (current-error-port)
@@ -515,10 +512,8 @@ Install, remove, or upgrade PACKAGES in a single transaction.\n"))
(%make-void-port "w"))))
(build-derivations (%store) (list prof-drv)))
(begin
- (symlink prof name)
- (when (file-exists? profile)
- (delete-file profile))
- (symlink name profile))))))))))
+ (switch-symlinks name prof)
+ (switch-symlinks profile name))))))))))
(define (process-query opts)
;; Process any query specified by OPTS. Return #t when a query was