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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      global $wp_object_cache;
 153  
 154      return $wp_object_cache->add_global_groups($groups);
 155  }
 156  
 157  /**
 158   * Adds a group or set of groups to the list of non-persistent groups.
 159   *
 160   * @since 2.6.0
 161   *
 162   * @param string|array $groups A group or an array of groups to add
 163   */
 164  function wp_cache_add_non_persistent_groups( $groups ) {
 165      // Default cache doesn't persist so nothing to do here.
 166      return;
 167  }
 168  
 169  /**
 170   * Reset internal cache keys and structures.  If the cache backend uses global blog or site IDs as part of its cache keys,
 171   * this function instructs the backend to reset those keys and perform any cleanup since blog or site IDs have changed since cache init.
 172   *
 173   * @since 2.6.0
 174   *
 175   * @param string|array $groups A group or an array of groups to add
 176   */
 177  function wp_cache_reset() {
 178      global $wp_object_cache;
 179  
 180      return $wp_object_cache->reset();
 181  }
 182  
 183  /**
 184   * WordPress Object Cache
 185   *
 186   * The WordPress Object Cache is used to save on trips to the database. The
 187   * Object Cache stores all of the cache data to memory and makes the cache
 188   * contents available by using a key, which is used to name and later retrieve
 189   * the cache contents.
 190   *
 191   * The Object Cache can be replaced by other caching mechanisms by placing files
 192   * in the wp-content folder which is looked at in wp-settings. If that file
 193   * exists, then this file will not be included.
 194   *
 195   * @package WordPress
 196   * @subpackage Cache
 197   * @since 2.0
 198   */
 199  class WP_Object_Cache {
 200  
 201      /**
 202       * Holds the cached objects
 203       *
 204       * @var array
 205       * @access private
 206       * @since 2.0.0
 207       */
 208      var $cache = array ();
 209  
 210      /**
 211       * Cache objects that do not exist in the cache
 212       *
 213       * @var array
 214       * @access private
 215       * @since 2.0.0
 216       */
 217      var $non_existent_objects = array ();
 218  
 219      /**
 220       * The amount of times the cache data was already stored in the cache.
 221       *
 222       * @since 2.5.0
 223       * @access private
 224       * @var int
 225       */
 226      var $cache_hits = 0;
 227  
 228      /**
 229       * Amount of times the cache did not have the request in cache
 230       *
 231       * @var int
 232       * @access public
 233       * @since 2.0.0
 234       */
 235      var $cache_misses = 0;
 236  
 237      /**
 238       * List of global groups
 239       *
 240       * @var array
 241       * @access protected
 242       * @since 3.0.0
 243       */
 244      var $global_groups = array();
 245  
 246      /**
 247       * Adds data to the cache if it doesn't already exist.
 248       *
 249       * @uses WP_Object_Cache::get Checks to see if the cache already has data.
 250       * @uses WP_Object_Cache::set Sets the data after the checking the cache
 251       *        contents existance.
 252       *
 253       * @since 2.0.0
 254       *
 255       * @param int|string $id What to call the contents in the cache
 256       * @param mixed $data The contents to store in the cache
 257       * @param string $group Where to group the cache contents
 258       * @param int $expire When to expire the cache contents
 259       * @return bool False if cache ID and group already exists, true on success
 260       */
 261  	function add( $id, $data, $group = 'default', $expire = '' ) {
 262          if ( empty ($group) )
 263              $group = 'default';
 264  
 265          if (false !== $this->get($id, $group))
 266              return false;
 267  
 268          return $this->set($id, $data, $group, $expire);
 269      }
 270  
 271      /**
 272       * Sets the list of global groups.
 273       *
 274       * @since 3.0.0
 275       *
 276       * @param array $groups List of groups that are global.
 277       */
 278  	function add_global_groups( $groups ) {
 279          $groups = (array) $groups;
 280  
 281          $this->global_groups = array_merge($this->global_groups, $groups);
 282          $this->global_groups = array_unique($this->global_groups);
 283      }
 284  
 285      /**
 286       * Remove the contents of the cache ID in the group
 287       *
 288       * If the cache ID does not exist in the group and $force parameter is set
 289       * to false, then nothing will happen. The $force parameter is set to false
 290       * by default.
 291       *
 292       * On success the group and the id will be added to the
 293       * $non_existent_objects property in the class.
 294       *
 295       * @since 2.0.0
 296       *
 297       * @param int|string $id What the contents in the cache are called
 298       * @param string $group Where the cache contents are grouped
 299       * @param bool $force Optional. Whether to force the unsetting of the cache
 300       *        ID in the group
 301       * @return bool False if the contents weren't deleted and true on success
 302       */
 303  	function delete($id, $group = 'default', $force = false) {
 304          if (empty ($group))
 305              $group = 'default';
 306  
 307          if (!$force && false === $this->get($id, $group))
 308              return false;
 309  
 310          unset ($this->cache[$group][$id]);
 311          $this->non_existent_objects[$group][$id] = true;
 312          return true;
 313      }
 314  
 315      /**
 316       * Clears the object cache of all data
 317       *
 318       * @since 2.0.0
 319       *
 320       * @return bool Always returns true
 321       */
 322  	function flush() {
 323          $this->cache = array ();
 324  
 325          return true;
 326      }
 327  
 328      /**
 329       * Retrieves the cache contents, if it exists
 330       *
 331       * The contents will be first attempted to be retrieved by searching by the
 332       * ID in the cache group. If the cache is hit (success) then the contents
 333       * are returned.
 334       *
 335       * On failure, the $non_existent_objects property is checked and if the
 336       * cache group and ID exist in there the cache misses will not be
 337       * incremented. If not in the nonexistent objects property, then the cache
 338       * misses will be incremented and the cache group and ID will be added to
 339       * the nonexistent objects.
 340       *
 341       * @since 2.0.0
 342       *
 343       * @param int|string $id What the contents in the cache are called
 344       * @param string $group Where the cache contents are grouped
 345       * @return bool|mixed False on failure to retrieve contents or the cache
 346       *        contents on success
 347       */
 348  	function get($id, $group = 'default') {
 349          if ( empty ($group) )
 350              $group = 'default';
 351  
 352          if ( isset ($this->cache[$group][$id]) ) {
 353              $this->cache_hits += 1;
 354              if ( is_object($this->cache[$group][$id]) )
 355                  return wp_clone($this->cache[$group][$id]);
 356              else
 357                  return $this->cache[$group][$id];
 358          }
 359  
 360          if ( isset ($this->non_existent_objects[$group][$id]) )
 361              return false;
 362  
 363          $this->non_existent_objects[$group][$id] = true;
 364          $this->cache_misses += 1;
 365          return false;
 366      }
 367  
 368      /**
 369       * Replace the contents in the cache, if contents already exist
 370       *
 371       * @since 2.0.0
 372       * @see WP_Object_Cache::set()
 373       *
 374       * @param int|string $id What to call the contents in the cache
 375       * @param mixed $data The contents to store in the cache
 376       * @param string $group Where to group the cache contents
 377       * @param int $expire When to expire the cache contents
 378       * @return bool False if not exists, true if contents were replaced
 379       */
 380  	function replace($id, $data, $group = 'default', $expire = '') {
 381          if (empty ($group))
 382              $group = 'default';
 383  
 384          if ( false === $this->get($id, $group) )
 385              return false;
 386  
 387          return $this->set($id, $data, $group, $expire);
 388      }
 389  
 390      /**
 391       * Reset keys
 392       *
 393       * @since 3.0.0
 394       */
 395  	function reset() {
 396          // Clear out non-global caches since the blog ID has changed.
 397          foreach ( array_keys($this->cache) as $group ) {
 398              if ( !in_array($group, $this->global_groups) )
 399                  unset($this->cache[$group]);
 400          }
 401      }
 402  
 403      /**
 404       * Sets the data contents into the cache
 405       *
 406       * The cache contents is grouped by the $group parameter followed by the
 407       * $id. This allows for duplicate ids in unique groups. Therefore, naming of
 408       * the group should be used with care and should follow normal function
 409       * naming guidelines outside of core WordPress usage.
 410       *
 411       * The $expire parameter is not used, because the cache will automatically
 412       * expire for each time a page is accessed and PHP finishes. The method is
 413       * more for cache plugins which use files.
 414       *
 415       * @since 2.0.0
 416       *
 417       * @param int|string $id What to call the contents in the cache
 418       * @param mixed $data The contents to store in the cache
 419       * @param string $group Where to group the cache contents
 420       * @param int $expire Not Used
 421       * @return bool Always returns true
 422       */
 423  	function set($id, $data, $group = 'default', $expire = '') {
 424          if ( empty ($group) )
 425              $group = 'default';
 426  
 427          if ( NULL === $data )
 428              $data = '';
 429  
 430          if ( is_object($data) )
 431              $data = wp_clone($data);
 432  
 433          $this->cache[$group][$id] = $data;
 434  
 435          if ( isset($this->non_existent_objects[$group][$id]) )
 436              unset ($this->non_existent_objects[$group][$id]);
 437  
 438          return true;
 439      }
 440  
 441      /**
 442       * Echos the stats of the caching.
 443       *
 444       * Gives the cache hits, and cache misses. Also prints every cached group,
 445       * key and the data.
 446       *
 447       * @since 2.0.0
 448       */
 449  	function stats() {
 450          echo "<p>";
 451          echo "<strong>Cache Hits:</strong> {$this->cache_hits}<br />";
 452          echo "<strong>Cache Misses:</strong> {$this->cache_misses}<br />";
 453          echo "</p>";
 454  
 455          foreach ($this->cache as $group => $cache) {
 456              echo "<p>";
 457              echo "<strong>Group:</strong> $group<br />";
 458              echo "<strong>Cache:</strong>";
 459              echo "<pre>";
 460              print_r($cache);
 461              echo "</pre>";
 462          }
 463      }
 464  
 465      /**
 466       * PHP4 constructor; Calls PHP 5 style constructor
 467       *
 468       * @since 2.0.0
 469       *
 470       * @return WP_Object_Cache
 471       */
 472  	function WP_Object_Cache() {
 473          return $this->__construct();
 474      }
 475  
 476      /**
 477       * Sets up object properties; PHP 5 style constructor
 478       *
 479       * @since 2.0.8
 480       * @return null|WP_Object_Cache If cache is disabled, returns null.
 481       */
 482  	function __construct() {
 483          /**
 484           * @todo This should be moved to the PHP4 style constructor, PHP5
 485           * already calls __destruct()
 486           */
 487          register_shutdown_function(array(&$this, "__destruct"));
 488      }
 489  
 490      /**
 491       * Will save the object cache before object is completely destroyed.
 492       *
 493       * Called upon object destruction, which should be when PHP ends.
 494       *
 495       * @since  2.0.8
 496       *
 497       * @return bool True value. Won't be used by PHP
 498       */
 499  	function __destruct() {
 500          return true;
 501      }
 502  }
 503  ?>