Hacking CodeIgniter for Persistent Timestamped Cache with Memcache

_cache.php

<?php

$ch_cache = empty($_COOKIE['URB-CC']) || (!empty($_COOKIE['URB-CC']) && $_COOKIE['URB-CC'] !== 'SUPERtWAKU');
if($ch_cache)
	setcookie('URB-CC', 'mtLJQdHqpef4nlwhA7hv', $_SERVER['REQUEST_TIME'] + 60*60*24*7, '/', '.urbanesia.com');

// Check for cached pages
function is_logged_in() {
	$check1 = !empty($_COOKIE['URB-CC']) && $_COOKIE['URB-CC'] === 'SUPERtWAKU';
	return $check1;
}

if(!is_logged_in() && class_exists('Memcache')) {
	$_start = microtime(TRUE);
	
	$url = $_SERVER['HTTP_HOST'];
	$url .= $_SERVER['REQUEST_URI'];
	
	$tmp = explode('/',$url);
	$blacklist = array(
	    'img', 
	    'auth',
	    'ajax'
	);
	if(!empty($tmp[1]) && in_array($tmp[1], $blacklist))
		return;

	$hs_host = '127.0.0.1';
	$hs_port = 11211;
	
	try {
		$hs = new Memcache;
		$hs->addServer('127.0.0.1', '11211', 1);
	} catch(Exception $e) {
		$hs = NULL;
	}
	
	$ns = "outputcachememc#".$_SERVER['HTTP_HOST'] . $_SERVER['REQUEST_URI'];
	$q = $hs->get($ns);

	$check1 = !empty($q);
	if($check1) {
		$q = _defalsify($q);
		$q .= '<!-- SERVED FROM HSOCK CACHE -->';

		$_end = microtime(TRUE);
		$ts = round($_end - $_start, 6);
		$q = str_replace('{elapsed_time_cc}', $ts, $q);

		header('Content-Type: text/html');
		echo $q; exit;
	} else {
		unset($hs);
		unset($url);
		unset($q);
		unset($hs_host);
		unset($hs_port);
	}
}

function _defalsify($value = '') {
	if($value == '<-FALSE_ARRAY->') {
		return array();
	} else if($value == '<-FALSE_OBJECT->') {
		return new stdclass;
	} else if($value == '<-FALSE_BOOLEAN->') {
		return false;
	} else if($value == '<-FALSE_NULL->') {
		return null;
	} else if($value == '<-FALSE_INTEGER->') {
		return 0;
	} else {
		return $value;
	}
}

index.php

<?php

// Check for cached pages
require_once '_cache.php';

/*
|---------------------------------------------------------------
| PHP ERROR REPORTING LEVEL
|---------------------------------------------------------------
|
| By default CI runs with error reporting set to ALL.  For security
| reasons you are encouraged to change this when your site goes live.
| For more info visit:  http://www.php.net/error_reporting
|
*/
	error_reporting(E_ALL);

/*
|---------------------------------------------------------------
| SYSTEM FOLDER NAME
|---------------------------------------------------------------
|
| This variable must contain the name of your "system" folder.
| Include the path if the folder is not in the same  directory
| as this file.
|
| NO TRAILING SLASH!
|
*/
	$system_folder = "../system";

/*
|---------------------------------------------------------------
| APPLICATION FOLDER NAME
|---------------------------------------------------------------
|
| If you want this front controller to use a different "application"
| folder then the default one you can set its name here. The folder 
| can also be renamed or relocated anywhere on your server.
| For more info please see the user guide:
| http://codeigniter.com/user_guide/general/managing_apps.html
|
|
| NO TRAILING SLASH!
|
*/
	$application_folder = "application";

/*
|===============================================================
| END OF USER CONFIGURABLE SETTINGS
|===============================================================
*/


/*
|---------------------------------------------------------------
| SET THE SERVER PATH
|---------------------------------------------------------------
|
| Let's attempt to determine the full-server path to the "system"
| folder in order to reduce the possibility of path problems.
| Note: We only attempt this if the user hasn't specified a 
| full server path.
|
*/
if (strpos($system_folder, '/') === FALSE)
{
	if (function_exists('realpath') AND @realpath(dirname(__FILE__)) !== FALSE)
	{
		$system_folder = realpath(dirname(__FILE__)).'/'.$system_folder;
	}
}
else
{
	// Swap directory separators to Unix style for consistency
	$system_folder = str_replace("\\", "/", $system_folder); 
}

/*
|---------------------------------------------------------------
| DEFINE APPLICATION CONSTANTS
|---------------------------------------------------------------
|
| EXT		- The file extension.  Typically ".php"
| SELF		- The name of THIS file (typically "index.php")
| FCPATH	- The full server path to THIS file
| BASEPATH	- The full server path to the "system" folder
| APPPATH	- The full server path to the "application" folder
|
*/
define('EXT', '.php');
define('SELF', pathinfo(__FILE__, PATHINFO_BASENAME));
define('FCPATH', str_replace(SELF, '', __FILE__));
define('BASEPATH', $system_folder.'/');

if (is_dir($application_folder))
{
	define('APPPATH', $application_folder.'/');
}
else
{
	if ($application_folder == '')
	{
		$application_folder = 'application';
	}

	define('APPPATH', BASEPATH.$application_folder.'/');
}

/*
|---------------------------------------------------------------
| LOAD THE FRONT CONTROLLER
|---------------------------------------------------------------
|
| And away we go...
|
*/
require_once BASEPATH.'codeigniter/CodeIgniter'.EXT;

/* End of file index.php */
/* Location: ./index.php */

MY_Output.php

<?php  if ( ! defined('BASEPATH')) exit('No direct script access allowed');

class MY_Output extends CI_Output {

	function _display($output = '') {
		$elapsed = $BM->elapsed_time('total_execution_time_start', 'total_execution_time_end');
		$output = str_replace('{elapsed_time}', $elapsed, $output);

		$memory	 = ( ! function_exists('memory_get_usage')) ? '0' : round(memory_get_usage()/1024/1024, 2).'MB';
		$output = str_replace('{memory_usage}', $memory, $output);

		// Grab the super object.  We'll need it in a moment...
		$CI =& get_instance();

		// TRAP OUTPUT
		if(!empty($output) && ! $CI->access->logged_in() && class_exists('Memcache')) {
			$output .= '<!-- DYNAMICALLY GENERATED -->';
			$ns = "outputcachememc#".$_SERVER['HTTP_HOST'] . $_SERVER['REQUEST_URI'];
			$m = new Memcache;
			$m->addServer('127.0.0.1', '11211', 1);
			$m->set($ns, $output, MEMCACHE_COMPRESSED, 60*5);
			
			$output = str_replace('{elapsed_time_cc}', $elapsed, $output);
		}
		$output = str_replace('{elapsed_time_cc}', $elapsed, $output);
		
		if (method_exists($CI, '_output')) {
			$CI->_output($output);
		} else {
			echo $output;
		}

		log_message('debug', "Final output sent to browser");
		log_message('debug', "Total execution time: ".$elapsed);
	}

}

/* End of file Output.php */
/* Location: ./system/libraries/Output.php */