[bug#50359] [PATCH] import: Add 'generic-git' updater.

[Ludovic Courtès]

Hello,

This looks very cool!

Xinglu Chen <public@yoctocell.xyz> skribis:

> From f924dbb835425f6b9a5796918125592870391405 Mon Sep 17 00:00:00 2001
> Message-Id: 
> <f924dbb835425f6b9a5796918125592870391405.1631125652.git.public@yoctocell.xyz>
> From: Xinglu Chen <public@yoctocell.xyz>
> Date: Fri, 3 Sep 2021 17:50:56 +0200
> Subject: [PATCH] import: Add 'generic-git' updater.
>
> * guix/import/git.scm: New file.
> * doc/guix.texi (Invoking guix refresh): Document it.
> * Makefile.am (MODULES): Register it.
> * guix/git.scm (ls-remote-refs): New procedure.
>
> Co-authored-by: Sarah Morgensen <iskarian@mgsn.dev>

Overall LGTM; comments below.

> diff --git a/doc/guix.texi b/doc/guix.texi
> index 36a0c7f5ec..26afb1607a 100644
> --- a/doc/guix.texi
> +++ b/doc/guix.texi
> @@ -11920,6 +11920,33 @@ the updater for @uref{https://launchpad.net, 
> Launchpad} packages.
>  @item generic-html
>  a generic updater that crawls the HTML page where the source tarball of
>  the package is hosted, when applicable.
> +@item generic-git

Please add a newline above.

> +@lisp
> +(package
> +  (name "foo")
> +  ;; ...
> +  (properties
> +    '((tag-prefix . "^release0-")
> +      (tag-suffix . "[a-z]?$")
> +      (tag-version-delimiter . ":"))))
> +@end lisp      

Very nice.  Perhaps s/tag-/release-tag-/ for clarity?

> +(define* (ls-remote-refs url #:key tags?)
> +  "Return the list of references advertised at Git repository URL.  If TAGS?
> +is true, limit to only refs/tags."

To remain consistent with existing naming conventions, I’d call it
‘remote-refs’.

> +  (with-libgit2
> +   (call-with-temporary-directory
> +    (lambda (cache-directory)
> +      (let* ((repository (repository-init cache-directory))
> +             ;; Create an in-memory remote so we don't touch disk.
> +             (remote (remote-create-anonymous repository url)))

Too bad we need to create an empty repo; hopefully it costs next to
nothing though.

> +        (remote-connect remote)
> +        (remote-disconnect remote)
> +        (repository-close! repository)
> +
> +        (filter include? (map remote-head-name (remote-ls remote))))))))

Use ‘filter-map’.

> +(define* (get-version-mapping tags #:key prefix suffix delim pre-releases?)

Please add a docstring and remove ‘get-’ from the name.  :-)

> +  (define (guess-delim)
> +    (let ((total (length tags))
> +          (dots (reduce + 0 (map (cut string-count <> #\.) tags)))
> +          (dashes (reduce + 0 (map (cut string-count <> #\-) tags)))
> +          (underscores (reduce + 0 (map (cut string-count <> #\_) tags))))
> +      (display (format #t "total: ~d, dots: ~d, dashes ~d, underscores ~d~%"
> +              total dots dashes underscores))

Leftover?  (Also display + format.)

Please spell out ‘delimiter’ (info "(guix) Formatting Code").

> +      (cond
> +       ((>= dots (* total 0.35)) ".")
> +       ((>= dashes (* total 0.8)) "-")
> +       ((>= underscores (* total 0.8)) "_")
> +       (else ""))))

That’s a fancy heuristic.  :-)

> +  (let ((mapping (fold alist-cons '() (map get-version tags) tags)))
> +    (stable-sort! (filter car mapping) entry<?)))

It’s perhaps clearer written like this:

  (stable-sort (filter-map (lambda (tag)
                             (let ((version (get-version tag)))
                               (and version (cons version tag))))
                            tags)
               entry<?)

> +(define* (get-latest-tag url #:key prefix suffix delim pre-releases?)
> +  "Return the latest tag available from the Git repository at URL."

Maybe “the tag corresponding to the latest version”.

s/get-latest-tag/latest-tag/

> +  (define (pre-release? tag)
> +    (any (lambda (rx) (regexp-exec (make-regexp rx regexp/icase) tag))
> +              %pre-release-words))

Better call ‘make-regexp’ only once; so you could change
‘%pre-release-words’ to be a list of regexp objects instead of a list of
strings.

> +(define (latest-git-tag-version package tag-prefix tag-suffix
> +                                tag-version-delimiter refresh-pre-releases?)
> +  "Given a PACKAGE, the TAG-PREFIX, TAG-SUFFIX, TAG-VERSION-DELIMITER, and
> +REFRESH-PRE-RELEASES?  properties of PACKAGE, returns the latest version of
> +PACKAGE."

Maybe s/refresh-pre-releases?/accept-pre-preleases?/

Since this procedure takes a package, it probably doesn’t need the other
arguments: it can extract them from the package properties, rather than
doing it at the call site.

> +(define (latest-git-release package)
> +  "Return the latest release of PACKAGE."
> +  (let* ((name (package-name package))
> +         (properties (package-properties package))
> +         (tag-prefix (assq-ref properties 'tag-prefix))
> +         (tag-suffix (assq-ref properties 'tag-suffix))
> +         (tag-version-delimiter (assq-ref properties 'tag-version-delimiter))
> +         (refresh-pre-releases? (assq-ref properties 'refresh-pre-releases?))
> +         (old-version (package-version package))
> +         (url (git-reference-url (origin-uri (package-source package))))
> +         (new-version (latest-git-tag-version package
> +                                              tag-prefix
> +                                              tag-suffix
> +                                              tag-version-delimiter
> +                                              refresh-pre-releases?)))
> +
> +    (if new-version
> +        (upstream-source
> +         (package name)
> +         (version new-version)
> +         (urls (list url)))
> +        ;; No new release or no tags available.
> +        #f)))

Simply: (and new-version (upstream-source …)).

It would have been nice to have tests.  I think testing
‘latest-git-release’ should be feasible without too much hassle using
the (guix tests git) infrastructure, as is done in tests/git.scm, with a
package referring to a locally-created repo using a git-reference with a
file:// URL.

Could you send an updated patch?

Thanks,
Ludo’.