lib/system/cache/source/DiskCacheSource.class.php

   1 <?php
   2 namespace dns\system\cache\source;
   3
   4 /**
   5  * DiskCacheSource is an implementation of CacheSource that stores the cache as simple files in the file system.
   6  *
   7  * @author      Alexander Ebert, Marcel Werk
   8  * @copyright   2001-2014 WoltLab GmbH
   9  * @license     GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  10  * @package     com.woltlab.wcf
  11  * @subpackage  system.cache.source
  12  * @category    Community Framework
  13  */
  14 class DiskCacheSource implements ICacheSource {
  15         /**
  16          * @see \dns\system\cache\source\ICacheSource::flush()
  17          */
  18         public function flush($cacheName, $useWildcard) {
  19                 if ($useWildcard) {
  20                         $this->removeFiles('cache.'.$cacheName.'*.php');
  21                 }
  22                 else {
  23                         $this->removeFiles('cache.'.$cacheName.'.php');
  24                 }
  25         }
  26
  27         /**
  28          * @see \dns\system\cache\source\ICacheSource::flushAll()
  29          */
  30         public function flushAll() {
  31                 $this->removeFiles('cache.*.php');
  32         }
  33
  34         /**
  35          * @see \dns\system\cache\source\ICacheSource::get()
  36          */
  37         public function get($cacheName, $maxLifetime) {
  38                 $filename = $this->getFilename($cacheName);
  39                 if ($this->needRebuild($filename, $maxLifetime)) {
  40                         return null;
  41                 }
  42
  43                 // load cache
  44                 try {
  45                         return $this->readCache($cacheName, $filename);
  46                 }
  47                 catch (\Exception $e) {
  48                         return null;
  49                 }
  50         }
  51
  52         /**
  53          * @see \dns\system\cache\source\ICacheSource::set()
  54          */
  55         public function set($cacheName, $value, $maxLifetime) {
  56                 $filename = $this->getFilename($cacheName);
  57                 $content = "<?php exit; /* cache: ".$cacheName." (generated at ".gmdate('r').") DO NOT EDIT THIS FILE */ ?>\n";
  58                 $content .= serialize($value);
  59
  60                 if (!file_exists($filename)) {
  61                         @touch($filename);
  62                 }
  63
  64                 $handler = fOpen($filename, "a+");
  65                 fWrite($handler, $content);
  66                 fClose($handler);
  67         }
  68
  69         /**
  70          * Returns cache filename.
  71          *
  72          * @param       string          $cacheName
  73          * @return      string
  74          */
  75         protected function getFilename($cacheName) {
  76                 return DNS_DIR.'/cache/cache.'.$cacheName.'.php';
  77         }
  78
  79         /**
  80          * Removes files matching given pattern.
  81          *
  82          * @param       string          $pattern
  83          */
  84         protected function removeFiles($pattern) {
  85                 $directory = DNS_DIR.'cache/';
  86
  87                 foreach (glob($directory.$pattern) as $filename) {
  88                         @unlink($filename);
  89                 }
  90         }
  91
  92         /**
  93          * Determines wheater the cache needs to be rebuild or not.
  94          *
  95          * @param       string          $filename
  96          * @param       integer         $maxLifetime
  97          * @return      boolean
  98          */
  99         protected function needRebuild($filename, $maxLifetime) {
 100                 // cache does not exist
 101                 if (!file_exists($filename)) {
 102                         return true;
 103                 }
 104
 105                 // cache is empty
 106                 if (!@filesize($filename)) {
 107                         return true;
 108                 }
 109
 110                 // cache resource was marked as obsolete
 111                 if (($mtime = filemtime($filename)) <= 1) {
 112                         return true;
 113                 }
 114
 115                 // maxlifetime expired
 116                 if ($maxLifetime > 0 && (time() - $mtime) > $maxLifetime) {
 117                         return true;
 118                 }
 119
 120                 // do not rebuild cache
 121                 return false;
 122         }
 123
 124         /**
 125          * Loads the file of a cached resource.
 126          *
 127          * @param       string          $cacheName
 128          * @param       string          $filename
 129          * @return      mixed
 130          */
 131         protected function readCache($cacheName, $filename) {
 132                 // get file contents
 133                 $contents = file_get_contents($filename);
 134
 135                 // find first newline
 136                 $position = strpos($contents, "\n");
 137                 if ($position === false) {
 138                         throw new \Exception("Unable to load cache resource '".$cacheName."'");
 139                 }
 140
 141                 // cut contents
 142                 $contents = substr($contents, $position + 1);
 143
 144                 // unserialize
 145                 $value = @unserialize($contents);
 146                 if ($value === false) {
 147                         throw new \Exception("Unable to load cache resource '".$cacheName."'");
 148                 }
 149
 150                 return $value;
 151         }
 152 }