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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 $key 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 $key 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  function wp_cache_reset() {
 176      global $wp_object_cache;
 177  
 178      return $wp_object_cache->reset();
 179  }
 180  
 181  /**
 182   * WordPress Object Cache
 183   *
 184   * The WordPress Object Cache is used to save on trips to the database. The
 185   * Object Cache stores all of the cache data to memory and makes the cache
 186   * contents available by using a key, which is used to name and later retrieve
 187   * the cache contents.
 188   *
 189   * The Object Cache can be replaced by other caching mechanisms by placing files
 190   * in the wp-content folder which is looked at in wp-settings. If that file
 191   * exists, then this file will not be included.
 192   *
 193   * @package WordPress
 194   * @subpackage Cache
 195   * @since 2.0
 196   */
 197  class WP_Object_Cache {
 198  
 199      /**
 200       * Holds the cached objects
 201       *
 202       * @var array
 203       * @access private
 204       * @since 2.0.0
 205       */
 206      var $cache = array ();
 207  
 208      /**
 209       * Cache objects that do not exist in the cache
 210       *
 211       * @var array
 212       * @access private
 213       * @since 2.0.0
 214       */
 215      var $non_existent_objects = array ();
 216  
 217      /**
 218       * The amount of times the cache data was already stored in the cache.
 219       *
 220       * @since 2.5.0
 221       * @access private
 222       * @var int
 223       */
 224      var $cache_hits = 0;
 225  
 226      /**
 227       * Amount of times the cache did not have the request in cache
 228       *
 229       * @var int
 230       * @access public
 231       * @since 2.0.0
 232       */
 233      var $cache_misses = 0;
 234  
 235      /**
 236       * List of global groups
 237       *
 238       * @var array
 239       * @access protected
 240       * @since 3.0.0
 241       */
 242      var $global_groups = array();
 243  
 244      /**
 245       * Adds data to the cache if it doesn't already exist.
 246       *
 247       * @uses WP_Object_Cache::get Checks to see if the cache already has data.
 248       * @uses WP_Object_Cache::set Sets the data after the checking the cache
 249       *        contents existance.
 250       *
 251       * @since 2.0.0
 252       *
 253       * @param int|string $id What to call the contents in the cache
 254       * @param mixed $data The contents to store in the cache
 255       * @param string $group Where to group the cache contents
 256       * @param int $expire When to expire the cache contents
 257       * @return bool False if cache ID and group already exists, true on success
 258       */
 259  	function add( $id, $data, $group = 'default', $expire = '' ) {
 260          if ( empty ($group) )
 261              $group = 'default';
 262  
 263          if (false !== $this->get($id, $group))
 264              return false;
 265  
 266          return $this->set($id, $data, $group, $expire);
 267      }
 268  
 269      /**
 270       * Sets the list of global groups.
 271       *
 272       * @since 3.0.0
 273       *
 274       * @param array $groups List of groups that are global.
 275       */
 276  	function add_global_groups( $groups ) {
 277          $groups = (array) $groups;
 278  
 279          $this->global_groups = array_merge($this->global_groups, $groups);
 280          $this->global_groups = array_unique($this->global_groups);
 281      }
 282  
 283      /**
 284       * Remove the contents of the cache ID in the group
 285       *
 286       * If the cache ID does not exist in the group and $force parameter is set
 287       * to false, then nothing will happen. The $force parameter is set to false
 288       * by default.
 289       *
 290       * On success the group and the id will be added to the
 291       * $non_existent_objects property in the class.
 292       *
 293       * @since 2.0.0
 294       *
 295       * @param int|string $id What the contents in the cache are called
 296       * @param string $group Where the cache contents are grouped
 297       * @param bool $force Optional. Whether to force the unsetting of the cache
 298       *        ID in the group
 299       * @return bool False if the contents weren't deleted and true on success
 300       */
 301  	function delete($id, $group = 'default', $force = false) {
 302          if (empty ($group))
 303              $group = 'default';
 304  
 305          if (!$force && false === $this->get($id, $group))
 306              return false;
 307  
 308          unset ($this->cache[$group][$id]);
 309          $this->non_existent_objects[$group][$id] = true;
 310          return true;
 311      }
 312  
 313      /**
 314       * Clears the object cache of all data
 315       *
 316       * @since 2.0.0
 317       *
 318       * @return bool Always returns true
 319       */
 320  	function flush() {
 321          $this->cache = array ();
 322  
 323          return true;
 324      }
 325  
 326      /**
 327       * Retrieves the cache contents, if it exists
 328       *
 329       * The contents will be first attempted to be retrieved by searching by the
 330       * ID in the cache group. If the cache is hit (success) then the contents
 331       * are returned.
 332       *
 333       * On failure, the $non_existent_objects property is checked and if the
 334       * cache group and ID exist in there the cache misses will not be
 335       * incremented. If not in the nonexistent objects property, then the cache
 336       * misses will be incremented and the cache group and ID will be added to
 337       * the nonexistent objects.
 338       *
 339       * @since 2.0.0
 340       *
 341       * @param int|string $id What the contents in the cache are called
 342       * @param string $group Where the cache contents are grouped
 343       * @return bool|mixed False on failure to retrieve contents or the cache
 344       *        contents on success
 345       */
 346  	function get($id, $group = 'default') {
 347          if ( empty ($group) )
 348              $group = 'default';
 349  
 350          if ( isset ($this->cache[$group][$id]) ) {
 351              $this->cache_hits += 1;
 352              if ( is_object($this->cache[$group][$id]) )
 353                  return clone $this->cache[$group][$id];
 354              else
 355                  return $this->cache[$group][$id];
 356          }
 357  
 358          if ( isset ($this->non_existent_objects[$group][$id]) )
 359              return false;
 360  
 361          $this->non_existent_objects[$group][$id] = true;
 362          $this->cache_misses += 1;
 363          return false;
 364      }
 365  
 366      /**
 367       * Replace the contents in the cache, if contents already exist
 368       *
 369       * @since 2.0.0
 370       * @see WP_Object_Cache::set()
 371       *
 372       * @param int|string $id What to call the contents in the cache
 373       * @param mixed $data The contents to store in the cache
 374       * @param string $group Where to group the cache contents
 375       * @param int $expire When to expire the cache contents
 376       * @return bool False if not exists, true if contents were replaced
 377       */
 378  	function replace($id, $data, $group = 'default', $expire = '') {
 379          if (empty ($group))
 380              $group = 'default';
 381  
 382          if ( false === $this->get($id, $group) )
 383              return false;
 384  
 385          return $this->set($id, $data, $group, $expire);
 386      }
 387  
 388      /**
 389       * Reset keys
 390       *
 391       * @since 3.0.0
 392       */
 393  	function reset() {
 394          // Clear out non-global caches since the blog ID has changed.
 395          foreach ( array_keys($this->cache) as $group ) {
 396              if ( !in_array($group, $this->global_groups) )
 397                  unset($this->cache[$group]);
 398          }
 399      }
 400  
 401      /**
 402       * Sets the data contents into the cache
 403       *
 404       * The cache contents is grouped by the $group parameter followed by the
 405       * $id. This allows for duplicate ids in unique groups. Therefore, naming of
 406       * the group should be used with care and should follow normal function
 407       * naming guidelines outside of core WordPress usage.
 408       *
 409       * The $expire parameter is not used, because the cache will automatically
 410       * expire for each time a page is accessed and PHP finishes. The method is
 411       * more for cache plugins which use files.
 412       *
 413       * @since 2.0.0
 414       *
 415       * @param int|string $id What to call the contents in the cache
 416       * @param mixed $data The contents to store in the cache
 417       * @param string $group Where to group the cache contents
 418       * @param int $expire Not Used
 419       * @return bool Always returns true
 420       */
 421  	function set($id, $data, $group = 'default', $expire = '') {
 422          if ( empty ($group) )
 423              $group = 'default';
 424  
 425          if ( NULL === $data )
 426              $data = '';
 427  
 428          if ( is_object($data) )
 429              $data = clone $data;
 430  
 431          $this->cache[$group][$id] = $data;
 432  
 433          if ( isset($this->non_existent_objects[$group][$id]) )
 434              unset ($this->non_existent_objects[$group][$id]);
 435  
 436          return true;
 437      }
 438  
 439      /**
 440       * Echoes the stats of the caching.
 441       *
 442       * Gives the cache hits, and cache misses. Also prints every cached group,
 443       * key and the data.
 444       *
 445       * @since 2.0.0
 446       */
 447  	function stats() {
 448          echo "<p>";
 449          echo "<strong>Cache Hits:</strong> {$this->cache_hits}<br />";
 450          echo "<strong>Cache Misses:</strong> {$this->cache_misses}<br />";
 451          echo "</p>";
 452          echo '<ul>';
 453          foreach ($this->cache as $group => $cache) {
 454              echo "<li><strong>Group:</strong> $group - ( " . number_format( strlen( serialize( $cache ) ) / 1024, 2 ) . 'k )</li>';
 455          }
 456          echo '</ul>';
 457      }
 458  
 459      /**
 460       * Sets up object properties; PHP 5 style constructor
 461       *
 462       * @since 2.0.8
 463       * @return null|WP_Object_Cache If cache is disabled, returns null.
 464       */
 465  	function __construct() {
 466          /**
 467           * @todo This should be moved to the PHP4 style constructor, PHP5
 468           * already calls __destruct()
 469           */
 470          register_shutdown_function(array(&$this, "__destruct"));
 471      }
 472  
 473      /**
 474       * Will save the object cache before object is completely destroyed.
 475       *
 476       * Called upon object destruction, which should be when PHP ends.
 477       *
 478       * @since  2.0.8
 479       *
 480       * @return bool True value. Won't be used by PHP
 481       */
 482  	function __destruct() {
 483          return true;
 484      }
 485  }
 486  ?>