Simple Page Caching

Hi,
first of all I want to say that I really like the changes in WB 2.8 RC1, and I hope WB continues being awesome!
--
Anyways:

I wrote a little php script that caches wb pages automatically and ouputs them.

Here's how it works:

1. It checks if there exists a cachefile for the requested page (via the modified_date and the page_id)
2. If there exists one it will include it and its done
3. If there doesn't exist a cachefile it will display the page normally (wb will generate the page as usual), and it will create a new cachefile.
3. If there exists a cachefile but the cachefile is outdated, wb will display the page as usual and the script will generate a new cachefile and delete the outdated one.

Notes:
- All cachefiles are stored in WB_PATH."/cache/" (folder must already exist)
- The cachefiles look like this:

creationdate-pid-page_id.html

for example: 1248370168-pid-7.html

- The script also uses the ob_start("ob_gzhandler"); php-function to compress the page
- It appends an html-comment with the time it took to create the page

HowTo INSTALL:

- rename the index.php file in the wb directory to index-1.php and comment out

echo $output;

in the last line ( //echo $output )

- copy the cachescript in the wb folder and name it index.php (it replaces the old index.php)

Here's the script (with german comments):

index.php

Code:

<?php
// seite komprimieren
ob_start("ob_gzhandler");

// function to measure speed of page
function getmicrotime($t)
{
list($usec, $sec) = explode(" ",$t);
return ((float)$usec + (float)$sec);
}
$starttime = microtime();
ob_start();

//$starttime = array_sum(explode(" ",microtime()));

// Include config file
require_once(dirname(__FILE__).'/config.php');
// Check if the config file has been set-up
if(!defined('WB_PATH')) {
    header("Location: install/index.php");
    exit(0);
}

// modified date aus der db holen
$sql_result = $database->query("SELECT * FROM `".TABLE_PREFIX."pages` WHERE `page_id` = '$page_id'");
$sql_row = $sql_result->fetchRow();
$last_modified = $sql_row['modified_when'];

        $pid = $page_id;
        // modified date aufräumen (wird eig. nicht mehr benötigt)
        $badwords = array("/", "am", ":", " ", ",");
        $ddate = str_replace($badwords, "", $last_modified);
        // name des cache files
        $ddate = $ddate."-pid-".$pid;
        // pfad des cache files
        $cachefile = WB_PATH."/cache/".$ddate.".html";
        // überprüfen ob ein cachefile existiert das zum modified date passt
        if (file_exists($cachefile) && (filemtime("includes/".$ddate)
           < filemtime($cachefile))) {
            // cache file einbinden
           include($cachefile);
            // informationen übers caching anhängen
            echo "";
        }
        else {
        // falls kein passendes cachefile existiert
        include(WB_PATH.'/index-2.php');

        $sitecontent = $output;

        // veraltetes cachefile suchfunktion
        function boost_array_find($needle, $haystack, $a_not = array()) {
              $out = array();
              foreach($haystack as $key=>$value) {
                if (strpos($value, $needle) !== FALSE) {
                      $good = TRUE;
                      foreach($a_not as $not) {
                if (strpos($key, $not) !== FALSE) {
                      $good = FALSE;
                }
              }
              if ($good) {
                $out[$key] = $value;
              }
        }
          }
          return $out;
        }

    // cachefiles auflisten
    $dir = WB_PATH."/cache/";
    $files = scandir($dir);
    $forthis = "-pid-".$pid;
    // cachefile finden
    $out = boost_array_find($forthis, $files);

    // cachefile löschen
    foreach ($out as $value) {
        $oldfile = $dir.$value;
        if (file_exists($oldfile)) {
            // alte datei löschen
            unlink($oldfile);
        } else {
            //print "The file $filename does not exist";
        }
    }

    // neues cachefile anlegen
    if (!$handle = fopen($cachefile, "w+")) {
         print "Kann die Datei $cachefile nicht oeffnen";
         exit;
    }
    // Schreibe seiteninhalt ins cachefile
    if (!fwrite($handle, $sitecontent)) {
        print "Kann in die Datei $cachefile nicht schreiben";
        exit;
    }
    fclose($handle);

    // content ausgeben damit die seite beim ersten aufruf nicht leer ist
    echo $output;
}

ob_end_flush();
// function to output speed of page
$endtime = microtime();
$diff = getmicrotime($endtime) - getmicrotime($starttime);
echo "";

// komprimierte seite ausgeben
ob_end_flush();

?>

WARNING:
I'm not a developer and therefore the script is probably not optimal and it probably contains design errors and so on...
Please improve it if you can.

It's of course gpl.