[RFC/PATCH (take 3)] gitweb: Add some mod_perl specific support

[Jakub Narebski <jnareb@gmail.com>]

Add $r variable which holds Apache2::RequestRec if script is run under
mod_perl (if $ENV{MOD_PERL} is defined). It is used as argument to
constructor of CGI object (needs CGI module version at least 2.93).
It is needed for further mod_perl support, for example adding
headers using Apache2::RequestRec methods instead of making Apache
to have to parse headers (to add it's own HTTP headers like Server:
header).

Following advice from CGI(3pm) man page, precompile all CGI routines
for mod_perl.

All this makes gitweb slightly faster under mod_perl (436 +/-  23.9 ms
for summary of git.git before, 429 +/- 12.0 ms after, according to
'ab -n 10 -k "http://localhost/perl/gitweb/gitweb.cgi?p=git.git"').

Signed-off-by: Jakub Narebski <jnareb@gmail.com>
---
The idea is to have gitweb run under CGI and under mod_perl 1.0 and 2.0
without modifications, but making use of mod_perl features which make script
faster, like for example adding headers via mod_perl API and not via parsing
headers by Apache.  In the future the plan is to be able to run gitweb under
not only current ModPerl::Registry (or Apache::Registry in mod_perl 1.0) but
also as a mod_perl handler, and as a FastCGI script using CGI::Fast.

Current portion of mod_perl cpecific additions is mod_perl version agnostic,
and avoids loading any mod_perl Perl modules.

I'd like to have it (and further mod_perl patches) reviewed by someone
better versed in mod_perl.

 gitweb/gitweb.perl |    9 ++++++++-
 1 files changed, 8 insertions(+), 1 deletions(-)

diff --git a/gitweb/gitweb.perl b/gitweb/gitweb.perl
index 902c514..f834c64 100755
--- a/gitweb/gitweb.perl
+++ b/gitweb/gitweb.perl
@@ -18,11 +18,18 @@ use File::Find qw();
 use File::Basename qw(basename);
 binmode STDOUT, ':utf8';
 
-our $cgi = new CGI;
+# mod_perl request
+my $r;
+$r = shift @_ if $ENV{MOD_PERL};
+
+our $cgi = new CGI($r);
 our $version = "++GIT_VERSION++";
 our $my_url = $cgi->url();
 our $my_uri = $cgi->url(-absolute => 1);
 
+# speeding up mod_perl and FastCGI (later)
+$cgi->compile() if $r;
+
 # core git executable to use
 # this can just be "git" if your webserver has a sensible PATH
 our $GIT = "++GIT_BINDIR++/git";
-- 
1.4.4.1