From: Giuseppe Bilotta <giuseppe.bilotta@gmail.com>
Date: Sat, 06 Feb 2010 09:02:21 GMT
Subject: Re: [PATCH 1/4] gitweb: notes feature
Message-ID: <cb7bb73a1002060102n5544f825x3d01860b1228cee@mail.gmail.com>
In-Reply-To: <201002060044.11225.jnareb@gmail.com>

2010/2/6 Jakub Narebski <jnareb@gmail.com>:
> On Thu, 4 Feb 2010, Giuseppe Bilotta wrote:
>
> BTW. shouldn't this series be marked as RFC?
>

[snip]

>
> Signoff?

Y'know, one would figure that, this not being my first contribution
and what, I'd have learned to do this properly 8-/.

>> +     # Notes support. When this feature is enabled, the presence of notes
>> +     # for any commit is signaled, and the note content is made available
>> +     # in a way appropriate for the current view.
>> +     # Set this to '*' to enable all notes namespace, or to a shell-glob
>> +     # specification to enable specific namespaces only.
>
> It is not obvious from this description that you can provide _list_ of
> notes namespaces (or list of shell-globs).

I'm starting to think it might make sense to not have a list here, but
rather a single value only. First of all, multiple refs can be
indicated à la shell with {ref1,ref2,ref3}. Or, we can also use the
intended command-line syntax ref1:ref2:ref3, which would help
consistency. It also makes things easier for project overrides, as per
your subsequent comment:

>> +
>> +     # To enable system wide have in $GITWEB_CONFIG
>> +     # $feature{'notes'}{'default'} = ['*'];
>> +     # To have project specific config enable override in $GITWEB_CONFIG
>> +     # $feature{'notes'}{'override'} = 1;
>> +     # and in project config gitweb.notes = namespace;
>
> How you can provide list of notes here?  Is overriding limited to single
> name or shell-glob?
>
> See feature_snapshot for example implementation.

As mentioned above, I'd rather use the same syntax deployed on the
command line, either shell-like or PATH-like multiple paths.

> Second, perhaps it is time to refactor all those similar feature_xxx
> subroutines (just a possible suggestion)?

feature_notes looks remarkably like feature_avatar, indeed.

>> +# return all refs matching refs/notes/<globspecs> where the globspecs
>> +# are taken from the notes feature content.
>> +sub get_note_refs {
>> +     my @globs = gitweb_get_feature('notes');
>> +     my @note_refs = ();
>> +     foreach my $glob (@globs) {
>> +             if (open my $fd, '-|', git_cmd(), 'for-each-ref',
>> +                 '--format=%(refname)', "refs/notes/$glob") {
>
>                open my $fd, '-|', git_cmd(), 'for-each-ref',
>                        '--format=%(refname)', "refs/notes/$glob"
>                        or return;
>
> would reduce indent level a bit.

Good idea, thanks.

>> +                     while (<$fd>) {
>> +                             chomp;
>> +                             push @note_refs, $_ if $_;
>> +                     }
>
> Why not simply
>
>                chomp(@note_refs = <$fd>);

Because I didn't know chomp worked on lists. Thanks for the idea.

>> +             my %notes = () ;
>> +             foreach my $note_ref (@note_refs) {
>> +                     my $obj = "$note_ref:$co{'id'}";
>> +                     if (open my $fd, '-|', git_cmd(), 'rev-parse',
>> +                             '--verify', '-q', $obj) {
>> +                             my $exists = <$fd>;
>> +                             close $fd;
>> +                             if (defined $exists) {
>> +                                     if (open $fd, '-|', git_cmd(), 'show', $obj) {
>> +                                             $notes{$note_ref} = scalar <$fd>;
>> +                                             close $fd;
>> +                                     }
>> +                             }
>> +                     }
>> +             }
>
> First, there are '--batch' and '--batch-check' options to git-cat-file.
> With these I think you can get all notes with just single git command,
> although using it is a bit complicated (requires open2 from IPC::Open2
> for bidi communication).

Hm. The IPC::Open2 doc makes it sound horribly scary, but still doable.

> Second, if not using 'git cat-file --batch', perhaps it would be easier
> to read each $note_ref tree using 'git ls-tree'/'git ls-tree -r', and
> parse its output to check for which commits/objects there are notes
> available, and only then call 'git show' (or reuse connection to
> 'git cat-file --batch').
>
> The second solution, with a bit more work, could work even in presence
> of fan-out schemes for notes, I think.

An interesting approach. Without fan-out, git ls-tree -r
refs/notes/whatever [hash ...] gives us the blobs we're interested in.
In case of fan-out schemes, the efficiency of this approach probably
depends on the kind of fan-out we have, and would require some
heavy-duty grepping. A git ls-notes plumbing with a similar syntax and
output would be a nice thing to have.

-- 
Giuseppe "Oblomov" Bilotta