diff mbox series

[bug#51307,v2,3/3] scripts: hash: Add git serializer.

Message ID 20211118002023.3323307-4-zimon.toutoune@gmail.com
State Accepted
Headers show
Series scripts: hash: Several files and serializer. | expand

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Commit Message

Simon Tournier Nov. 18, 2021, 12:20 a.m. UTC 
* guix/scripts/hash.scm (git-hash): New procedure.
(%options): Use it.
* tests/guix-hash.sh: Test it.
* doc/guix.texi: Update.
---
 doc/guix.texi         |  4 +++-
 guix/scripts/hash.scm | 15 +++++++++++++++
 tests/guix-hash.sh    |  6 ++++++
 3 files changed, 24 insertions(+), 1 deletion(-)

Comments

Ludovic Courtès Dec. 21, 2021, 9:09 a.m. UTC | #1 
Hi,

zimoun <zimon.toutoune@gmail.com> skribis:

> On Mon, 20 Dec 2021 at 14:40, Ludovic Courtès <ludo@gnu.org> wrote:
>
>> > +  #:use-module ((disarchive git-hash) #:select (git-hash-file
>> > +                                                git-hash-directory))
>>
>> Use #:autoload (that makes Disarchive a soft dependency and also reduces
>> start-up time.)
>
> Thanks.  As I asked in the cover-letter, these are confusing for me.
> For instance, why not autoloading all the used modules?  And is it
> better to lazily load with something like:
>
>   (match (and=> (resolve-module '(disarchive) #:ensure #f)
>                 (lambda (disarchive)
>                   (cons (module-ref disarchive '%disarchive-log-port)
>                         (module-ref disarchive 'disarchive-assemble))))
>     (#f (format #t "could not load Disarchive~%")
>         #f)
>     ((%disarchive-log-port . disarchive-assemble)
>
> ?  From guix/build/download.scm, or any other "lazy reference" in the code code.
>
> What are the differences?  I have read the documentation but it is not
> clear for me the difference between '#:autoload' and 'module-ref'.

There are several reasons for autoloading: one is startup time/memory
footprint, and another one is having “soft dependencies” (you can still
build and use the thing when the dependency is missing; only that
specific feature is unavailable.)

Usually we’d use #:autoload, but in cases where we want full control
over the process, as in the Disarchive snippet you show above, we’d use
the programmatic interface.

There are also cases of “lazy references” where we use the programmatic
interface to load things at run time.  This is used for instance to keep
(guix …) modules independent of (gnu …) modules.

I hope this sheds some light!

>> I was wondering whether we should keep the deprecation warning for ‘-r’;
>> we might consider it a handy shorthand for ‘-S nar’?
>
> Ah, yes.  Deprecate '--recursive' but keep '-r' as shorthand for '-S
> nar'.  LGTM.

I’d treat ‘-r’ and ‘--recursive’ in the same way, no?  That is, keep
them both without a deprecation warning, but document them as aliases
for ‘-S nar’.  WDYT?

Thanks,
Ludo’.
diff mbox series

Patch

diff --git a/doc/guix.texi b/doc/guix.texi
index 20041c20b7..af2e99903b 100644
--- a/doc/guix.texi
+++ b/doc/guix.texi
@@ -11638,7 +11638,7 @@  legacy alias for @var{type} sets to @code{nar}.
 @itemx -S
 Compute the hash on @var{file} using @var{type} serialization.
 
-Supported types: @code{none} and @code{nar}.
+Supported types: @code{none}, @code{nar} and @code{git}.
 
 When using @code{nar}, the hash is computed on an archive containing
 @var{file}, including its children if it is a directory.  Some of the
@@ -11649,6 +11649,8 @@  impact on the hash (@pxref{Invoking guix archive}).
 @c FIXME: Replace xref above with xref to an ``Archive'' section when
 @c it exists.
 
+Using @code{git} serializes the file or directory as a Git tree.
+
 @item --exclude-vcs
 @itemx -x
 When combined with @option{--recursive}, exclude version control system
diff --git a/guix/scripts/hash.scm b/guix/scripts/hash.scm
index d05ecb80ba..80581f2340 100644
--- a/guix/scripts/hash.scm
+++ b/guix/scripts/hash.scm
@@ -35,6 +35,8 @@  (define-module (guix scripts hash)
   #:use-module (srfi srfi-11)
   #:use-module (srfi srfi-26)
   #:use-module (srfi srfi-37)
+  #:use-module ((disarchive git-hash) #:select (git-hash-file
+                                                git-hash-directory))
   #:export (guix-hash))
 
 
@@ -60,6 +62,17 @@  (define* (default-hash file #:optional
      (call-with-input-file file
        (cute port-hash algorithm <>)))))
 
+(define* (git-hash file #:optional
+                       (algorithm (assoc-ref %default-options 'hash-algorithm))
+                       select?)
+  (define directory?
+    (case (stat:type (stat file))
+      ((directory) #t)
+      (else #f)))
+  (if directory?
+      (git-hash-directory file algorithm)
+      (git-hash-file file algorithm)))
+
 
 ;;;
 ;;; Command-line options.
@@ -138,6 +151,8 @@  (define serializer-proc
                        default-hash)
                       ("nar"
                        nar-hash)
+                      ("git"
+                       git-hash)
                       (x
                        (leave (G_ "unsupported serializer type: ~a~%")
                               arg))))
diff --git a/tests/guix-hash.sh b/tests/guix-hash.sh
index cdcfac19bc..bb3973771f 100644
--- a/tests/guix-hash.sh
+++ b/tests/guix-hash.sh
@@ -34,6 +34,9 @@  test `guix hash -f base32 /dev/null` = 4oymiquy7qobjgx36tejs35zeqt24qpemsnzgtfes
 test `guix hash -H sha512 -f hex /dev/null` = cf83e1357eefb8bdf1542850d66d8007d620e4050b5715dc83f4a921d36ce9ce47d0d13c5d85f2b0ff8318d2877eec2f63b931bd47417a81a538327af927da3e
 test `guix hash -H sha1 -f base64 /dev/null` = "2jmj7l5rSw0yVb/vlWAYkK/YBwk="
 
+# idem as `cat /dev/null | git hash-object --stdin`
+test `guix hash -S git -H sha1 -f hex  /dev/null` = e69de29bb2d1d6434b8b29ae775ad8c2e48c5391
+
 ! guix hash -H abcd1234 /dev/null
 
 mkdir "$tmpdir"
@@ -44,6 +47,7 @@  mkdir "$tmpdir/subdir"
 
 test `guix hash -S nar "$tmpdir"` = 10k1lw41wyrjf9mxydi0is5nkpynlsvgslinics4ppir13g7d74p
 test `guix hash -S nar "$tmpdir" -H sha512` = 301ra58c2vahczzxiyfin41mpyb0ljh4dh9zn3ijvwviaw1j40sfzw5skh9x945da88n3785ggifzig7acd6k72h0mpsc20m1f66m9n
+test `guix hash -S git "$tmpdir" -H sha512` = 158b10d1bsdk4pm8ym9cg9ckfak1b0cgpw7365cl6s341ir380mh2f4ylicyh8khyrfnwq5cn9766d7m8fbfwwl94ndkv456v6a8knr
 
 # Deprecated --recursive option
 test `guix hash -r "$tmpdir" 2>/dev/null` = 10k1lw41wyrjf9mxydi0is5nkpynlsvgslinics4ppir13g7d74p
@@ -62,9 +66,11 @@  touch "$tmpdir/.git/foo"
 
 # ...changes the hash
 test `guix hash -S nar $tmpdir` = 0a50z04zyzf7pidwxv0nwbj82pgzbrhdy9562kncnvkcfvb48m59
+test `guix hash -S git $tmpdir` = 0ghlpca9xaswa1ay1g55dknwd9q899mi3ahfr43pq083v8wisjc7
 
 # ...but remains the same when using `-x'
 test `guix hash -S nar $tmpdir -x` = 10k1lw41wyrjf9mxydi0is5nkpynlsvgslinics4ppir13g7d74p
+test `guix hash -S git $tmpdir -x` = 0ghlpca9xaswa1ay1g55dknwd9q899mi3ahfr43pq083v8wisjc7
 
 # Without '-r', this should fail.
 ! guix hash "$tmpdir"