KjwCache.php

<?php // vim:ts=4:sw=4:noet
/*====================================================================== 
Copyright (C) 2006-2009, Walter Doekes
This file is part of KjwLib-php45.
 
KjwLib-php45 is free software: you can redistribute it and/or modify 
it under the terms of the GNU General Public License as published by 
the Free Software Foundation, either version 3 of the License, or 
(at your option) any later version. 

KjwLib-php45 is distributed in the hope that it will be useful, 
but WITHOUT ANY WARRANTY; without even the implied warranty of 
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the 
GNU General Public License for more details. 

You should have received a copy of the GNU General Public License 
along with KjwLib-php45.  If not, see <http://www.gnu.org/licenses/>. 
======================================================================*/

class KjwCache {
        var $_cachePath = null;
        var $_cacheFile = null;
        var $_enabled = false;
        var $_expire = null;
        
        function KjwCache($cachePath = 'cache') {
                $this->_cachePath = $cachePath;
        }

        function expire($seconds) {
                $this->_expire = $seconds;
        }

        function start() {
                // Check if we're in a session by checking SESSID,
                // if we're in a session, do not cache anything..
//              echo "<!-- " . session_name();
//              print_r($_REQUEST);
//              echo " -->";
                if (!isset($_REQUEST[session_name()])) {
                
                        $this->_cacheFile = $this->_cachePath . '/' . md5($_SERVER['REQUEST_URI']) . '.cache';

                        // We have a file that is recent enough, output it and die.
                        if (@file_exists($this->_cacheFile)
                                        && ($this->_expire === null || filemtime($this->_cacheFile) + $this->_expire > time())) {
                                // Send last-modified
                                header('Last-Modified: ' . gmdate('D, d M Y H:i:s T', filemtime($this->_cacheFile)));
                                if ($this->_expire !== null)
                                        header('Expires: ' . gmdate('D, d M Y H:i:s T', filemtime($this->_cacheFile) + $this->_expire));
                                
                                // Enable 304 not modified.
                                if (function_exists('apache_request_headers')) {
                                        $headers = apache_request_headers();
                                        if (isset($headers['If-Modified-Since'])
                                                        && filemtime($this->_cacheFile) <= strtotime($headers['If-Modified-Since'])) {
                                                header("HTTP/1.0 304 Not Modified");
                                                exit;
                                        }
                                }

                                // Write file for those that didn't have it already.
                                readfile($this->_cacheFile);
                                exit;
                        }

                        // Send expires header if we have it set.
                        if ($this->_expire !== null)
                                header('Expires: ' . gmdate('D, d M Y H:i:s T', time() + $this->_expire));
                                
                        // Start output buffering so we can store the page.
                        ob_start();
                        $this->_enabled = true;
                        
                } else {

                        // When we use sessions, we're doing dynamic data,
                        // and we won't be doing caching.
                        header('Cache-Control: no-cache, must-revalidate'); // HTTP/1.1
                        header('Last-Modified: ' . gmdate('D, d M Y H:i:s T', time()));
                        header('Expires: Mon, 26 Jul 1997 05:00:00 GMT'); // Date in the past

                }
        }

        function setDirty() {
                $n = 0;
                $dp = opendir($this->_cachePath);
                while (($entry = readdir($dp)) !== false)
                        if (substr($entry, -6) == '.cache')
                                if (unlink($this->_cachePath . '/' . $entry))
                                        ++$n;
                closedir($dp);
                return $n;
        }

        function saveCache() {
                $n = 0;
                $dp = opendir($this->_cachePath);
                while (($entry = readdir($dp)) !== false)
                        if (substr($entry, -10) == '.cache.bak')
                                unlink($this->_cachePath . '/' . $entry);
                rewinddir($dp);
                while (($entry = readdir($dp)) !== false)
                        if (substr($entry, -6) == '.cache')
                                if (copy($this->_cachePath . '/' . $entry, $this->_cachePath . '/' . $entry . '.bak'))
                                        ++$n;
                closedir($dp);
                return $n;
        }

        function loadCache() {
                $n = 0;
                $dp = opendir($this->_cachePath);
                while (($entry = readdir($dp)) !== false)
                        if (substr($entry, -6) == '.cache')
                                unlink($this->_cachePath . '/' . $entry);
                rewinddir($dp);
                while (($entry = readdir($dp)) !== false)
                        if (substr($entry, -10) == '.cache.bak')
                                if (copy($this->_cachePath . '/' . $entry, $this->_cachePath . '/' . substr($entry, 0, -4)))
                                        ++$n;
                closedir($dp);
                return $n;
        }

        function destroy() {
                if ($this->_enabled) {
                        echo "<!-- cached file created: " . gmdate("Y-m-d H:i") . " UTC -->";
                        if (($fp = @fopen($this->_cacheFile, 'w')) !== false) {
                                $success = @fwrite($fp, ($towrite = ob_get_contents())) === strlen($towrite);
                                @fclose($fp);
                                if ($success === false)
                                        unlink($this->_cacheFile);
                        }
                        ob_end_flush();
                }
        }
}

?>

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