library/HTMLPurifier/DefinitionCache.php

   1 <?php
   2
   3 /**
   4  * Abstract class representing Definition cache managers that implements
   5  * useful common methods and is a factory.
   6  * @todo Create a separate maintenance file advanced users can use to
   7  *       cache their custom HTMLDefinition, which can be loaded
   8  *       via a configuration directive
   9  * @todo Implement memcached
  10  */
  11 abstract class HTMLPurifier_DefinitionCache
  12 {
  13
  14     public $type;
  15
  16     /**
  17      * @param $name Type of definition objects this instance of the
  18      *      cache will handle.
  19      */
  20     public function __construct($type) {
  21         $this->type = $type;
  22     }
  23
  24     /**
  25      * Generates a unique identifier for a particular configuration
  26      * @param Instance of HTMLPurifier_Config
  27      */
  28     public function generateKey($config) {
  29         return $config->version . ',' . // possibly replace with function calls
  30                $config->getBatchSerial($this->type) . ',' .
  31                $config->get($this->type . '.DefinitionRev');
  32     }
  33
  34     /**
  35      * Tests whether or not a key is old with respect to the configuration's
  36      * version and revision number.
  37      * @param $key Key to test
  38      * @param $config Instance of HTMLPurifier_Config to test against
  39      */
  40     public function isOld($key, $config) {
  41         if (substr_count($key, ',') < 2) return true;
  42         list($version, $hash, $revision) = explode(',', $key, 3);
  43         $compare = version_compare($version, $config->version);
  44         // version mismatch, is always old
  45         if ($compare != 0) return true;
  46         // versions match, ids match, check revision number
  47         if (
  48             $hash == $config->getBatchSerial($this->type) &&
  49             $revision < $config->get($this->type . '.DefinitionRev')
  50         ) return true;
  51         return false;
  52     }
  53
  54     /**
  55      * Checks if a definition's type jives with the cache's type
  56      * @note Throws an error on failure
  57      * @param $def Definition object to check
  58      * @return Boolean true if good, false if not
  59      */
  60     public function checkDefType($def) {
  61         if ($def->type !== $this->type) {
  62             trigger_error("Cannot use definition of type {$def->type} in cache for {$this->type}");
  63             return false;
  64         }
  65         return true;
  66     }
  67
  68     /**
  69      * Adds a definition object to the cache
  70      */
  71     abstract public function add($def, $config);
  72
  73     /**
  74      * Unconditionally saves a definition object to the cache
  75      */
  76     abstract public function set($def, $config);
  77
  78     /**
  79      * Replace an object in the cache
  80      */
  81     abstract public function replace($def, $config);
  82
  83     /**
  84      * Retrieves a definition object from the cache
  85      */
  86     abstract public function get($config);
  87
  88     /**
  89      * Removes a definition object to the cache
  90      */
  91     abstract public function remove($config);
  92
  93     /**
  94      * Clears all objects from cache
  95      */
  96     abstract public function flush($config);
  97
  98     /**
  99      * Clears all expired (older version or revision) objects from cache
 100      * @note Be carefuly implementing this method as flush. Flush must
 101      *       not interfere with other Definition types, and cleanup()
 102      *       should not be repeatedly called by userland code.
 103      */
 104     abstract public function cleanup($config);
 105
 106 }
 107
 108 // vim: et sw=4 sts=4