Twig + PHP static page caching example. Caching based on unique URL

Twig+PHP static page caching.php

<?php
// CONFIG
define("DEBUG", true);
define("CACHE", false);
define("CACHE_TIME", 86400);
define("CACHE_GZ_HANDLER", true);
define("BASE_DIR", __DIR__);
define("CACHE_DIR", BASE_DIR.'/cache/');
define("SITE_URL", 'http://' . $_SERVER['HTTP_HOST'] );
// . $_SERVER['QUERY_STRING']); // In this page we don't use query string
// strtok don't use part ? in url
define("DYNAMIC_URL", SITE_URL . strtok($_SERVER["REQUEST_URI"],'?'));
/*
.
.
.
*/

// GET FROM CACHE PART
if(!DEBUG && CACHE)
{
	$cache_file = CACHE_DIR . md5( DYNAMIC_URL ).'.html';
	if(file_exists($cache_file) && (time() - CACHE_TIME < filemtime($cache_file)))
	{
		ob_start(CACHE_GZ_HANDLER ? 'ob_gzhandler' : null);
		readfile($cache_file);
		ob_end_flush();
		exit();
	}
}
else
{
	$files = glob(CACHE_DIR . '*'); // get all file names
	foreach($files as $file){ // iterate files
		if(is_file($file))
		{
			unlink($file); // delete file
		}
	}
}


/*
.
.
.
*/

// Create cache
$html = $twig->render($template, $context);
if(!DEBUG && CACHE)
{
	$cache_file = CACHE_DIR . md5( DYNAMIC_URL ).'.html';
	$fp = fopen( $cache_file, 'w' );
	fwrite( $fp, $html );
	fclose( $fp );
}
echo $html; // output html