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   1  <?php
   2  /**
   3   * Object Cache API
   4   *
   5   * @link http://codex.wordpress.org/Function_Reference/WP_Cache
   6   *
   7   * @package WordPress
   8   * @subpackage Cache
   9   */
  10  
  11  /**
  12   * Adds data to the cache, if the cache key doesn't aleady exist.
  13   *
  14   * @since 2.0.0
  15   * @uses $wp_object_cache Object Cache Class
  16   * @see WP_Object_Cache::add()
  17   *
  18   * @param int|string $key The cache ID to use for retrieval later
  19   * @param mixed $data The data to add to the cache store
  20   * @param string $flag The group to add the cache to
  21   * @param int $expire When the cache data should be expired
  22   * @return unknown
  23   */
  24  function wp_cache_add($key, $data, $flag = '', $expire = 0) {
  25      global $wp_object_cache;
  26  
  27      return $wp_object_cache->add($key, $data, $flag, $expire);
  28  }
  29  
  30  /**
  31   * Closes the cache.
  32   *
  33   * This function has ceased to do anything since WordPress 2.5. The
  34   * functionality was removed along with the rest of the persistant cache. This
  35   * does not mean that plugins can't implement this function when they need to
  36   * make sure that the cache is cleaned up after WordPress no longer needs it.
  37   *
  38   * @since 2.0.0
  39   *
  40   * @return bool Always returns True
  41   */
  42  function wp_cache_close() {
  43      return true;
  44  }
  45  
  46  /**
  47   * Removes the cache contents matching ID and flag.
  48   *
  49   * @since 2.0.0
  50   * @uses $wp_object_cache Object Cache Class
  51   * @see WP_Object_Cache::delete()
  52   *
  53   * @param int|string $id What the contents in the cache are called
  54   * @param string $flag Where the cache contents are grouped
  55   * @return bool True on successful removal, false on failure
  56   */
  57  function wp_cache_delete($id, $flag = '') {
  58      global $wp_object_cache;
  59  
  60      return $wp_object_cache->delete($id, $flag);
  61  }
  62  
  63  /**
  64   * Removes all cache items.
  65   *
  66   * @since 2.0.0
  67   * @uses $wp_object_cache Object Cache Class
  68   * @see WP_Object_Cache::flush()
  69   *
  70   * @return bool Always returns true
  71   */
  72  function wp_cache_flush() {
  73      global $wp_object_cache;
  74  
  75      return $wp_object_cache->flush();
  76  }
  77  
  78  /**
  79   * Retrieves the cache contents from the cache by ID and flag.
  80   *
  81   * @since 2.0.0
  82   * @uses $wp_object_cache Object Cache Class
  83   * @see WP_Object_Cache::get()
  84   *
  85   * @param int|string $id What the contents in the cache are called
  86   * @param string $flag Where the cache contents are grouped
  87   * @return bool|mixed False on failure to retrieve contents or the cache
  88   *        contents on success
  89   */
  90  function wp_cache_get($id, $flag = '') {
  91      global $wp_object_cache;
  92  
  93      return $wp_object_cache->get($id, $flag);
  94  }
  95  
  96  /**
  97   * Sets up Object Cache Global and assigns it.
  98   *
  99   * @since 2.0.0
 100   * @global WP_Object_Cache $wp_object_cache WordPress Object Cache
 101   */
 102  function wp_cache_init() {
 103      $GLOBALS['wp_object_cache'] =& new WP_Object_Cache();
 104  }
 105  
 106  /**
 107   * Replaces the contents of the cache with new data.
 108   *
 109   * @since 2.0.0
 110   * @uses $wp_object_cache Object Cache Class
 111   * @see WP_Object_Cache::replace()
 112   *
 113   * @param int|string $id What to call the contents in the cache
 114   * @param mixed $data The contents to store in the cache
 115   * @param string $flag Where to group the cache contents
 116   * @param int $expire When to expire the cache contents
 117   * @return bool False if cache ID and group already exists, true on success
 118   */
 119  function wp_cache_replace($key, $data, $flag = '', $expire = 0) {
 120      global $wp_object_cache;
 121  
 122      return $wp_object_cache->replace($key, $data, $flag, $expire);
 123  }
 124  
 125  /**
 126   * Saves the data to the cache.
 127   *
 128   * @since 2.0
 129   * @uses $wp_object_cache Object Cache Class
 130   * @see WP_Object_Cache::set()
 131   *
 132   * @param int|string $id What to call the contents in the cache
 133   * @param mixed $data The contents to store in the cache
 134   * @param string $flag Where to group the cache contents
 135   * @param int $expire When to expire the cache contents
 136   * @return bool False if cache ID and group already exists, true on success
 137   */
 138  function wp_cache_set($key, $data, $flag = '', $expire = 0) {
 139      global $wp_object_cache;
 140  
 141      return $wp_object_cache->set($key, $data, $flag, $expire);
 142  }
 143  
 144  /**
 145   * Adds a group or set of groups to the list of global groups.
 146   *
 147   * @since 2.6.0
 148   *
 149   * @param string|array $groups A group or an array of groups to add
 150   */
 151  function wp_cache_add_global_groups( $groups ) {
 152      // Default cache doesn't persist so nothing to do here.
 153      return;
 154  }
 155  
 156  /**
 157   * Adds a group or set of groups to the list of non-persistent groups.
 158   *
 159   * @since 2.6.0
 160   *
 161   * @param string|array $groups A group or an array of groups to add
 162   */
 163  function wp_cache_add_non_persistent_groups( $groups ) {
 164      // Default cache doesn't persist so nothing to do here.
 165      return;
 166  }
 167  
 168  /**
 169   * WordPress Object Cache
 170   *
 171   * The WordPress Object Cache is used to save on trips to the database. The
 172   * Object Cache stores all of the cache data to memory and makes the cache
 173   * contents available by using a key, which is used to name and later retrieve
 174   * the cache contents.
 175   *
 176   * The Object Cache can be replaced by other caching mechanisms by placing files
 177   * in the wp-content folder which is looked at in wp-settings. If that file
 178   * exists, then this file will not be included.
 179   *
 180   * @package WordPress
 181   * @subpackage Cache
 182   * @since 2.0
 183   */
 184  class WP_Object_Cache {
 185  
 186      /**
 187       * Holds the cached objects
 188       *
 189       * @var array
 190       * @access private
 191       * @since 2.0.0
 192       */
 193      var $cache = array ();
 194  
 195      /**
 196       * Cache objects that do not exist in the cache
 197       *
 198       * @var array
 199       * @access private
 200       * @since 2.0.0
 201       */
 202      var $non_existant_objects = array ();
 203  
 204      /**
 205       * The amount of times the cache data was already stored in the cache.
 206       *
 207       * @since 2.5.0
 208       * @access private
 209       * @var int
 210       */
 211      var $cache_hits = 0;
 212  
 213      /**
 214       * Amount of times the cache did not have the request in cache
 215       *
 216       * @var int
 217       * @access public
 218       * @since 2.0.0
 219       */
 220      var $cache_misses = 0;
 221  
 222      /**
 223       * Adds data to the cache if it doesn't already exist.
 224       *
 225       * @uses WP_Object_Cache::get Checks to see if the cache already has data.
 226       * @uses WP_Object_Cache::set Sets the data after the checking the cache
 227       *        contents existance.
 228       *
 229       * @since 2.0.0
 230       *
 231       * @param int|string $id What to call the contents in the cache
 232       * @param mixed $data The contents to store in the cache
 233       * @param string $group Where to group the cache contents
 234       * @param int $expire When to expire the cache contents
 235       * @return bool False if cache ID and group already exists, true on success
 236       */
 237  	function add($id, $data, $group = 'default', $expire = '') {
 238          if (empty ($group))
 239              $group = 'default';
 240  
 241          if (false !== $this->get($id, $group, false))
 242              return false;
 243  
 244          return $this->set($id, $data, $group, $expire);
 245      }
 246  
 247      /**
 248       * Remove the contents of the cache ID in the group
 249       *
 250       * If the cache ID does not exist in the group and $force parameter is set
 251       * to false, then nothing will happen. The $force parameter is set to false
 252       * by default.
 253       *
 254       * On success the group and the id will be added to the
 255       * $non_existant_objects property in the class.
 256       *
 257       * @since 2.0.0
 258       *
 259       * @param int|string $id What the contents in the cache are called
 260       * @param string $group Where the cache contents are grouped
 261       * @param bool $force Optional. Whether to force the unsetting of the cache
 262       *        ID in the group
 263       * @return bool False if the contents weren't deleted and true on success
 264       */
 265  	function delete($id, $group = 'default', $force = false) {
 266          if (empty ($group))
 267              $group = 'default';
 268  
 269          if (!$force && false === $this->get($id, $group, false))
 270              return false;
 271  
 272          unset ($this->cache[$group][$id]);
 273          $this->non_existant_objects[$group][$id] = true;
 274          return true;
 275      }
 276  
 277      /**
 278       * Clears the object cache of all data
 279       *
 280       * @since 2.0.0
 281       *
 282       * @return bool Always returns true
 283       */
 284  	function flush() {
 285          $this->cache = array ();
 286  
 287          return true;
 288      }
 289  
 290      /**
 291       * Retrieves the cache contents, if it exists
 292       *
 293       * The contents will be first attempted to be retrieved by searching by the
 294       * ID in the cache group. If the cache is hit (success) then the contents
 295       * are returned.
 296       *
 297       * On failure, the $non_existant_objects property is checked and if the
 298       * cache group and ID exist in there the cache misses will not be
 299       * incremented. If not in the nonexistant objects property, then the cache
 300       * misses will be incremented and the cache group and ID will be added to
 301       * the nonexistant objects.
 302       *
 303       * @since 2.0.0
 304       *
 305       * @param int|string $id What the contents in the cache are called
 306       * @param string $group Where the cache contents are grouped
 307       * @return bool|mixed False on failure to retrieve contents or the cache
 308       *        contents on success
 309       */
 310  	function get($id, $group = 'default') {
 311          if (empty ($group))
 312              $group = 'default';
 313  
 314          if (isset ($this->cache[$group][$id])) {
 315              $this->cache_hits += 1;
 316              if ( is_object($this->cache[$group][$id]) )
 317                  return wp_clone($this->cache[$group][$id]);
 318              else
 319                  return $this->cache[$group][$id];
 320          }
 321  
 322          if ( isset ($this->non_existant_objects[$group][$id]) )
 323              return false;
 324  
 325          $this->non_existant_objects[$group][$id] = true;
 326          $this->cache_misses += 1;
 327          return false;
 328      }
 329  
 330      /**
 331       * Replace the contents in the cache, if contents already exist
 332       *
 333       * @since 2.0.0
 334       * @see WP_Object_Cache::set()
 335       *
 336       * @param int|string $id What to call the contents in the cache
 337       * @param mixed $data The contents to store in the cache
 338       * @param string $group Where to group the cache contents
 339       * @param int $expire When to expire the cache contents
 340       * @return bool False if not exists, true if contents were replaced
 341       */
 342  	function replace($id, $data, $group = 'default', $expire = '') {
 343          if (empty ($group))
 344              $group = 'default';
 345  
 346          if (false === $this->get($id, $group, false))
 347              return false;
 348  
 349          return $this->set($id, $data, $group, $expire);
 350      }
 351  
 352      /**
 353       * Sets the data contents into the cache
 354       *
 355       * The cache contents is grouped by the $group parameter followed by the
 356       * $id. This allows for duplicate ids in unique groups. Therefore, naming of
 357       * the group should be used with care and should follow normal function
 358       * naming guidelines outside of core WordPress usage.
 359       *
 360       * The $expire parameter is not used, because the cache will automatically
 361       * expire for each time a page is accessed and PHP finishes. The method is
 362       * more for cache plugins which use files.
 363       *
 364       * @since 2.0.0
 365       *
 366       * @param int|string $id What to call the contents in the cache
 367       * @param mixed $data The contents to store in the cache
 368       * @param string $group Where to group the cache contents
 369       * @param int $expire Not Used
 370       * @return bool Always returns true
 371       */
 372  	function set($id, $data, $group = 'default', $expire = '') {
 373          if (empty ($group))
 374              $group = 'default';
 375  
 376          if (NULL === $data)
 377              $data = '';
 378  
 379          if ( is_object($data) )
 380              $data = wp_clone($data);
 381  
 382          $this->cache[$group][$id] = $data;
 383  
 384          if(isset($this->non_existant_objects[$group][$id]))
 385              unset ($this->non_existant_objects[$group][$id]);
 386  
 387          return true;
 388      }
 389  
 390      /**
 391       * Echos the stats of the caching.
 392       *
 393       * Gives the cache hits, and cache misses. Also prints every cached group,
 394       * key and the data.
 395       *
 396       * @since 2.0.0
 397       */
 398  	function stats() {
 399          echo "<p>";
 400          echo "<strong>Cache Hits:</strong> {$this->cache_hits}<br />";
 401          echo "<strong>Cache Misses:</strong> {$this->cache_misses}<br />";
 402          echo "</p>";
 403  
 404          foreach ($this->cache as $group => $cache) {
 405              echo "<p>";
 406              echo "<strong>Group:</strong> $group<br />";
 407              echo "<strong>Cache:</strong>";
 408              echo "<pre>";
 409              print_r($cache);
 410              echo "</pre>";
 411          }
 412      }
 413  
 414      /**
 415       * PHP4 constructor; Calls PHP 5 style constructor
 416       *
 417       * @since 2.0.0
 418       *
 419       * @return WP_Object_Cache
 420       */
 421  	function WP_Object_Cache() {
 422          return $this->__construct();
 423      }
 424  
 425      /**
 426       * Sets up object properties; PHP 5 style constructor
 427       *
 428       * @since 2.0.8
 429       * @return null|WP_Object_Cache If cache is disabled, returns null.
 430       */
 431  	function __construct() {
 432          /**
 433           * @todo This should be moved to the PHP4 style constructor, PHP5
 434           * already calls __destruct()
 435           */
 436          register_shutdown_function(array(&$this, "__destruct"));
 437      }
 438  
 439      /**
 440       * Will save the object cache before object is completely destroyed.
 441       *
 442       * Called upon object destruction, which should be when PHP ends.
 443       *
 444       * @since  2.0.8
 445       *
 446       * @return bool True value. Won't be used by PHP
 447       */
 448  	function __destruct() {
 449          return true;
 450      }
 451  }
 452  ?>