package Apache::Profiler;

use strict;
use vars qw($VERSION);
$VERSION = 0.01;

use Apache::Log;
use Time::HiRes qw(gettimeofday);

sub handler {
    my $r = shift;
    $r->pnotes(ap_start_time => scalar gettimeofday());
    $r->register_cleanup(\&compute);
}

sub compute {
    my $r = shift;
    my $now = gettimeofday();
    my $diff = $now - $r->pnotes('ap_start_time');

    my $threshold = $r->dir_config('ProfileLongerThan') || 0;
    if ($diff >= $threshold) {
	my $uri = $r->uri;
	my $query = $r->query_string;
	if ($query) { $uri .= "?$query" }
	$r->log->notice("uri: $uri takes $diff seconds");
    }
}

1;
__END__

=head1 NAME

Apache::Profiler - profiles time seconds needed for every request

=head1 SYNOPSIS

  <Location /cgi-bin>
  PerlInitHandler Apache::Profiler
  </Location>

=head1 DESCRIPTION

Apache::Profiler is a mod_perl init (and cleanup) handler to profile
time taken to process one request. Profiled data is reported to the
Apache Log file. It'd be useful to profile some heavy application
taking a long time to proceed.

It uses L<Time::HiRes> to take milliseconds, and outputs profiled data
as Apache log C<notice> level like:

  [Tue Oct  7 20:52:53 2003] [notice] [client 127.0.0.1] uri: /test.html takes 0.0648910999298096 seconds

=head1 CONFIGURATION

=over 4

=item ProfileLongerThan

  PerlSetVar ProfileLongerThan 0.5

specifies lower limit of request time taken to profile. This example
only logs requests which takes longer than 0.5 seconds. This value is
set to 0 by default, which means it logs all requests.

=back

=head1 TODO

=over 4

=item *

customizable log format (exportable to some profiling tools)

=item *

profiles CPU time rather than C<gettimeofday>

=back

patches are always welcome!

=head1 AUTHOR

Tatsuhiko Miyagawa E<lt>miyagawa@bulknews.netE<gt>

This library is free software; you can redistribute it and/or modify
it under the same terms as Perl itself.

=head1 SEE ALSO

L<Apache::Log>, L<Time::HiRes>

=cut