From: Jakub Narebski <jnareb@gmail.com>
Date: Wed, 20 Sep 2006 22:40:52 GMT
Subject: Re: [PATCH 2/2] gitweb: Make git_get_refs_list do work of git_get_references
Message-ID: <200609210040.52886.jnareb@gmail.com>
In-Reply-To: <7veju6h0et.fsf@assigned-by-dhcp.cox.net>

Junio C Hamano wrote:
> Jakub Narebski wrote:
>> +                     if (! $4) { # unpeeled, direct reference
>> +                             push @refs, { hash => $1, name => $3 }; # without type
>> +                     } elsif ($3 eq $refs[-1]{'name'}) {
>> +                             # most likely a tag is followed by its peeled
>> +                             # (deref) one, and when that happens we know the
>> +                             # previous one was of type 'tag'.
>> +                             $refs[-1]{'type'} = "tag";
>> +                     }
>>...
>> -     return \@reflist;
>> +     return (\@reflist, \%refs);
> 
> You are maintaining reflist (an array of hashrefs each element
> of which describes name, type, hash and other parse_ref()
> information for the ref) and refs (a hash that maps from name to
> hash) separatly.  I wonder if this really has the performance
> advantage over just compute and return reflist from here and
> have the callers who need the mapping to derive it from the list
> (i.e.
> 
>         my ($reflist) = git_get_refs_list();
>         my %refs = map { $_->{name} => $_->{hash} } @$reflist;
> ).

The %refs hash contain also map from peeled (dereferenced) object
to ref name. The information about derefs is not present in @reflist.
So the answer is that you can't derive %refs from @reflist. 
-- 
Jakub Narebski
ShadeHawk on #git
Poland