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/includes/ -> class.wp-object-cache.php (source)

   1  <?php
   2  // Last sync [WP11537]
   3  
   4  /**
   5   * WordPress Object Cache
   6   *
   7   * The WordPress Object Cache is used to save on trips to the database. The
   8   * Object Cache stores all of the cache data to memory and makes the cache
   9   * contents available by using a key, which is used to name and later retrieve
  10   * the cache contents.
  11   *
  12   * The Object Cache can be replaced by other caching mechanisms by placing files
  13   * in the wp-content folder which is looked at in wp-settings. If that file
  14   * exists, then this file will not be included.
  15   *
  16   * @package WordPress
  17   * @subpackage Cache
  18   * @since 2.0
  19   */
  20  class WP_Object_Cache {
  21  
  22      /**
  23       * Holds the cached objects
  24       *
  25       * @var array
  26       * @access private
  27       * @since 2.0.0
  28       */
  29      var $cache = array ();
  30  
  31      /**
  32       * Cache objects that do not exist in the cache
  33       *
  34       * @var array
  35       * @access private
  36       * @since 2.0.0
  37       */
  38      var $non_existant_objects = array ();
  39  
  40      /**
  41       * The amount of times the cache data was already stored in the cache.
  42       *
  43       * @since 2.5.0
  44       * @access private
  45       * @var int
  46       */
  47      var $cache_hits = 0;
  48  
  49      /**
  50       * Amount of times the cache did not have the request in cache
  51       *
  52       * @var int
  53       * @access public
  54       * @since 2.0.0
  55       */
  56      var $cache_misses = 0;
  57  
  58      /**
  59       * Adds data to the cache if it doesn't already exist.
  60       *
  61       * @uses WP_Object_Cache::get Checks to see if the cache already has data.
  62       * @uses WP_Object_Cache::set Sets the data after the checking the cache
  63       *        contents existance.
  64       *
  65       * @since 2.0.0
  66       *
  67       * @param int|string $id What to call the contents in the cache
  68       * @param mixed $data The contents to store in the cache
  69       * @param string $group Where to group the cache contents
  70       * @param int $expire When to expire the cache contents
  71       * @return bool False if cache ID and group already exists, true on success
  72       */
  73  	function add($id, $data, $group = 'default', $expire = '') {
  74          if (empty ($group))
  75              $group = 'default';
  76  
  77          if (false !== $this->get($id, $group, false))
  78              return false;
  79  
  80          return $this->set($id, $data, $group, $expire);
  81      }
  82  
  83      /**
  84       * Remove the contents of the cache ID in the group
  85       *
  86       * If the cache ID does not exist in the group and $force parameter is set
  87       * to false, then nothing will happen. The $force parameter is set to false
  88       * by default.
  89       *
  90       * On success the group and the id will be added to the
  91       * $non_existant_objects property in the class.
  92       *
  93       * @since 2.0.0
  94       *
  95       * @param int|string $id What the contents in the cache are called
  96       * @param string $group Where the cache contents are grouped
  97       * @param bool $force Optional. Whether to force the unsetting of the cache
  98       *        ID in the group
  99       * @return bool False if the contents weren't deleted and true on success
 100       */
 101  	function delete($id, $group = 'default', $force = false) {
 102          if (empty ($group))
 103              $group = 'default';
 104  
 105          if (!$force && false === $this->get($id, $group, false))
 106              return false;
 107  
 108          unset ($this->cache[$group][$id]);
 109          $this->non_existant_objects[$group][$id] = true;
 110          return true;
 111      }
 112  
 113      /**
 114       * Clears the object cache of all data
 115       *
 116       * @since 2.0.0
 117       *
 118       * @return bool Always returns true
 119       */
 120  	function flush( $group = null ) {
 121          // WP does not support group flushing
 122          if ( is_null($group) ) {
 123              $this->cache = array();
 124              $this->non_existant_objects = array();
 125              return true;
 126          }
 127  
 128          if ( isset($this->cache[$group]) )
 129              $this->cache[$group] = array();
 130          if ( isset($this->non_existant_objects[$group]) )
 131              $this->non_existant_objects[$group] = array();
 132      }
 133  
 134      /**
 135       * Retrieves the cache contents, if it exists
 136       *
 137       * The contents will be first attempted to be retrieved by searching by the
 138       * ID in the cache group. If the cache is hit (success) then the contents
 139       * are returned.
 140       *
 141       * On failure, the $non_existant_objects property is checked and if the
 142       * cache group and ID exist in there the cache misses will not be
 143       * incremented. If not in the nonexistant objects property, then the cache
 144       * misses will be incremented and the cache group and ID will be added to
 145       * the nonexistant objects.
 146       *
 147       * @since 2.0.0
 148       *
 149       * @param int|string $id What the contents in the cache are called
 150       * @param string $group Where the cache contents are grouped
 151       * @return bool|mixed False on failure to retrieve contents or the cache
 152       *        contents on success
 153       */
 154  	function get($id, $group = 'default') {
 155          if (empty ($group))
 156              $group = 'default';
 157  
 158          if (isset ($this->cache[$group][$id])) {
 159              $this->cache_hits += 1;
 160              if ( is_object($this->cache[$group][$id]) )
 161                  return wp_clone($this->cache[$group][$id]);
 162              else
 163                  return $this->cache[$group][$id];
 164          }
 165  
 166          if ( isset ($this->non_existant_objects[$group][$id]) )
 167              return false;
 168  
 169          $this->non_existant_objects[$group][$id] = true;
 170          $this->cache_misses += 1;
 171          return false;
 172      }
 173  
 174      /**
 175       * Replace the contents in the cache, if contents already exist
 176       *
 177       * @since 2.0.0
 178       * @see WP_Object_Cache::set()
 179       *
 180       * @param int|string $id What to call the contents in the cache
 181       * @param mixed $data The contents to store in the cache
 182       * @param string $group Where to group the cache contents
 183       * @param int $expire When to expire the cache contents
 184       * @return bool False if not exists, true if contents were replaced
 185       */
 186  	function replace($id, $data, $group = 'default', $expire = '') {
 187          if (empty ($group))
 188              $group = 'default';
 189  
 190          if (false === $this->get($id, $group, false))
 191              return false;
 192  
 193          return $this->set($id, $data, $group, $expire);
 194      }
 195  
 196      /**
 197       * Sets the data contents into the cache
 198       *
 199       * The cache contents is grouped by the $group parameter followed by the
 200       * $id. This allows for duplicate ids in unique groups. Therefore, naming of
 201       * the group should be used with care and should follow normal function
 202       * naming guidelines outside of core WordPress usage.
 203       *
 204       * The $expire parameter is not used, because the cache will automatically
 205       * expire for each time a page is accessed and PHP finishes. The method is
 206       * more for cache plugins which use files.
 207       *
 208       * @since 2.0.0
 209       *
 210       * @param int|string $id What to call the contents in the cache
 211       * @param mixed $data The contents to store in the cache
 212       * @param string $group Where to group the cache contents
 213       * @param int $expire Not Used
 214       * @return bool Always returns true
 215       */
 216  	function set($id, $data, $group = 'default', $expire = '') {
 217          if (empty ($group))
 218              $group = 'default';
 219  
 220          if (NULL === $data)
 221              $data = '';
 222  
 223          if ( is_object($data) )
 224              $data = wp_clone($data);
 225  
 226          $this->cache[$group][$id] = $data;
 227  
 228          if(isset($this->non_existant_objects[$group][$id]))
 229              unset ($this->non_existant_objects[$group][$id]);
 230  
 231          return true;
 232      }
 233  
 234      /**
 235       * Echos the stats of the caching.
 236       *
 237       * Gives the cache hits, and cache misses. Also prints every cached group,
 238       * key and the data.
 239       *
 240       * @since 2.0.0
 241       */
 242  	function stats() {
 243          echo "<p>";
 244          echo "<strong>Cache Hits:</strong> {$this->cache_hits}<br />";
 245          echo "<strong>Cache Misses:</strong> {$this->cache_misses}<br />";
 246          echo "</p>";
 247  
 248          foreach ($this->cache as $group => $cache) {
 249              echo "<p>";
 250              echo "<strong>Group:</strong> $group<br />";
 251              echo "<strong>Cache:</strong>";
 252              echo "<pre>";
 253              print_r($cache);
 254              echo "</pre>";
 255          }
 256      }
 257  
 258  	function add_global_groups( $groups )
 259      {
 260          return true;
 261      }
 262  
 263  	function add_non_persistent_groups( $groups )
 264      {
 265          return true;
 266      }
 267  
 268      /**
 269       * PHP4 constructor; Calls PHP 5 style constructor
 270       *
 271       * @since 2.0.0
 272       *
 273       * @return WP_Object_Cache
 274       */
 275  	function WP_Object_Cache() {
 276          return self::__construct();
 277      }
 278  
 279      /**
 280       * Sets up object properties; PHP 5 style constructor
 281       *
 282       * @since 2.0.8
 283       * @return null|WP_Object_Cache If cache is disabled, returns null.
 284       */
 285  	function __construct() {
 286          /**
 287           * @todo This should be moved to the PHP4 style constructor, PHP5
 288           * already calls __destruct()
 289           */
 290          register_shutdown_function(array(&$this, "__destruct"));
 291      }
 292  
 293      /**
 294       * Will save the object cache before object is completely destroyed.
 295       *
 296       * Called upon object destruction, which should be when PHP ends.
 297       *
 298       * @since  2.0.8
 299       *
 300       * @return bool True value. Won't be used by PHP
 301       */
 302  	function __destruct() {
 303          return true;
 304      }
 305  }


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