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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.
This commit is contained in:
Ludovic Courtès 2013-01-27 17:58:46 +01:00
parent d9307267b3
commit 82fe08ed20
3 changed files with 36 additions and 33 deletions
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4
doc/guix.texi
View File

@ -514,6 +514,10 @@ installed packages, the profile is made to point to the @dfn{empty
profile}, also known as @dfn{profile zero}---i.e., it contains no files
apart from its own meta-data.
Installing, removing, or upgrading packages from a generation that has
been rolled back to overwrites previous future generations. Thus, the
history of a profile's generations is always linear.
@item --profile=@var{profile}
@itemx -p @var{profile}
Use @var{profile} instead of the user's default profile.

41
guix-package.in
View File

@ -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)))
(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

20
tests/guix-package.sh
View File

@ -90,22 +90,26 @@ then
test "`readlink_base "$profile"`" = "$profile-0-link"
done
# Reinstall after roll-back to generation 1.
# Reinstall after roll-back to the empty profile.
guix-package --bootstrap -p "$profile" -i "$boot_make"
test "`readlink_base "$profile"`" = "$profile-4-link"
test -x "$profile/bin/guile" && test -x "$profile/bin/make"
test "`readlink_base "$profile"`" = "$profile-1-link"
test -x "$profile/bin/guile" && ! test -x "$profile/bin/make"
# Roll-back to generation 3[*], and install---all at once.
# [*] FIXME: Eventually, this should roll-back to generation 1.
# Roll-back to generation 0, and install---all at once.
guix-package --bootstrap -p "$profile" --roll-back -i "$boot_guile"
test "`readlink_base "$profile"`" = "$profile-5-link"
test "`readlink_base "$profile"`" = "$profile-1-link"
test -x "$profile/bin/guile" && ! test -x "$profile/bin/make"
# Install Make.
guix-package --bootstrap -p "$profile" -i "$boot_make"
test "`readlink_base "$profile"`" = "$profile-2-link"
test -x "$profile/bin/guile" && test -x "$profile/bin/make"
# Make a "hole" in the list of generations, and make sure we can
# roll back "over" it.
rm "$profile-4-link"
rm "$profile-1-link"
guix-package --bootstrap -p "$profile" --roll-back
test "`readlink_base "$profile"`" = "$profile-3-link"
test "`readlink_base "$profile"`" = "$profile-0-link"
fi
# Make sure the `:' syntax works.