#!/usr/bin/perl -w
# This script runs under mod_perl

use strict;
use CGI qw(:standard);

my %data = Cache::cache('info',\&do_it,200);

print header('text/html');
print start_html();
print p([$data{data},$data{source},$data{'time'},"Process: $$"]);
print end_html();

sub do_it {
	# do something that takes a long time 
	my $text = `ls -lR /`;
	return length($text);
	}

package Cache;

sub cache {
	our (%time, %asdf);
	my ($key, $sub, $time) = @_;
	if((not defined $asdf{$key}) or (not defined $time{$key}) or ($time{$key} < time - $time)){
		$time{$key} = time;
		$asdf{$key} = &$sub;
		my %out = (data => $asdf{$key}, 'time' => $time{$key}, source => 'db_query');
		return %out;
		}
	else{
		my %out = (data => $asdf{$key}, 'time' => $time{$key}, source => 'cache_query');
		return %out;
		}
	}