Re: [PATCH] gitweb: Sort projects with undefined ages last

From: Junio C Hamano <gitster@pobox.com>
Date: Dec 10, 2012, 06:16 UTC
Message-ID: <7vip8actz3.fsf@alter.siamese.dyndns.org>
In-Reply-To: <1355114061-4652-1-git-send-email-mattjd@gmail.com>

Matthew Daley <mattjd@gmail.com> writes:

Show 14 quoted lines

> Sorting gitweb's project list by age ('Last Change') currently shows
> projects with undefined ages at the head of the list. This results in a
> less useful result when there are a number of projects that are missing
> or otherwise faulty and one is trying to see what projects have been
> updated recently.
>
> Fix by sorting these projects with undefined ages at the bottom of the
> list when sorting by age.
>
> Signed-off-by: Matthew Daley <mattjd@gmail.com>
> ---
> I realize this might be a bit bikesheddy, but it does improve the listing
> in the given use case. For an example of the problem, see ie.
> http://git.kernel.org/?o=age or http://repo.or.cz/w?a=project_list;o=age .

Yeah, it could be argued that in a very minor corner case showing new and empty ones at the top might attract more attention to them, but new and empty ones can stay inactive, so this change would be an overall improvement for these two sites. An alternative could be to give the mtime of the git directory to the age field if there is no commits in the repository, to sink the empty and inactive ones to the bottom quickly while showing newly created ones at the top, but it shouldn't make any practical difference.

Show 19 quoted lines

> I'm also not a Perl native, so any advice on making the patch good Perl is
> appreciated.
>
>  gitweb/gitweb.perl |    4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
>
> diff --git a/gitweb/gitweb.perl b/gitweb/gitweb.perl
> index 0f207f2..21da1b5 100755
> --- a/gitweb/gitweb.perl
> +++ b/gitweb/gitweb.perl
> @@ -5541,7 +5541,9 @@ sub sort_projects_list {
>  	if ($oi->{'type'} eq 'str') {
>  		@projects = sort {$a->{$oi->{'key'}} cmp $b->{$oi->{'key'}}} @$projlist;
>  	} else {
> -		@projects = sort {$a->{$oi->{'key'}} <=> $b->{$oi->{'key'}}} @$projlist;
> +		@projects = sort {$a->{$oi->{'key'}} <=> $b->{$oi->{'key'}}}
> +		            grep {defined $_->{$oi->{'key'}}} @$projlist;
> +		push @projects, grep {!defined $_->{$oi->{'key'}}} @$projlist;
>  	}

Two observations:

 * This iterates over the same @$projlist twice with grep, with one
   "defined" and the other "!defined", which may risk these two
   complementary grep conditions to go out of sync (it also may
   affect performance but that is a lessor issue).

   An alternative may be to change the expression used inside sort()
   to treat an undef as if it were a very large value, something
   like:

	sort {
        	defined $a->{$oi->{'key'}}
                ? (defined $b->{$oi->{'key'}}
                  ? ($a->{$oi->{'key'}} <=> $b->{$oi->{'key'}})
		  : -1)
                : (defined $b->{$oi->{'key'}} ? 1 : 0);
        }

 * This "sort undefs at the end is better than at the beginning" is
   good only for the "age" field, and we wouldn't know if we would
   add other keys for which it may be better to sort undef at the
   beginning.  The order_info{} currently has only one field of the
   'num' type, so this is not an immediate issue, but in order to
   future proof, it may make sense to rewrite the sort_projects_list
   function to map the order field name to a function given to sort,
   e.g.

	my %order_sort = (
		project => sub { $a->{'path'} cmp $b->{'path'} },
                descr => sub { $a->{'descr_long'} cmp $b->{'descr_long'} },
		owner => sub { $a->{'owner'} cmp $b->{'owner'} },
		age => sub { ... the num cmp with undef above ... },
	);
	if (!exists $order_sort{$order}) {
        	return @$projlist;
	}
	return sort $order_sort{$order} @$projlist;

I am not sure the second one is worth it, though.