5 * @link http://codex.wordpress.org/Function_Reference/WP_Cache
12 * Adds data to the cache, if the cache key doesn't already exist.
15 * @uses $wp_object_cache Object Cache Class
16 * @see WP_Object_Cache::add()
18 * @param int|string $key The cache key to use for retrieval later
19 * @param mixed $data The data to add to the cache store
20 * @param string $group The group to add the cache to
21 * @param int $expire When the cache data should be expired
24 function wp_cache_add($key, $data, $group = '', $expire = 0) {
25 global $wp_object_cache;
27 return $wp_object_cache->add($key, $data, $group, $expire);
33 * This function has ceased to do anything since WordPress 2.5. The
34 * functionality was removed along with the rest of the persistent 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.
40 * @return bool Always returns True
42 function wp_cache_close() {
47 * Decrement numeric cache item's value
50 * @uses $wp_object_cache Object Cache Class
51 * @see WP_Object_Cache::decr()
53 * @param int|string $key The cache key to increment
54 * @param int $offset The amount by which to decrement the item's value. Default is 1.
55 * @param string $group The group the key is in.
56 * @return false|int False on failure, the item's new value on success.
58 function wp_cache_decr( $key, $offset = 1, $group = '' ) {
59 global $wp_object_cache;
61 return $wp_object_cache->decr( $key, $offset, $group );
65 * Removes the cache contents matching key and group.
68 * @uses $wp_object_cache Object Cache Class
69 * @see WP_Object_Cache::delete()
71 * @param int|string $key What the contents in the cache are called
72 * @param string $group Where the cache contents are grouped
73 * @return bool True on successful removal, false on failure
75 function wp_cache_delete($key, $group = '') {
76 global $wp_object_cache;
78 return $wp_object_cache->delete($key, $group);
82 * Removes all cache items.
85 * @uses $wp_object_cache Object Cache Class
86 * @see WP_Object_Cache::flush()
88 * @return bool Always returns true
90 function wp_cache_flush() {
91 global $wp_object_cache;
93 return $wp_object_cache->flush();
97 * Retrieves the cache contents from the cache by key and group.
100 * @uses $wp_object_cache Object Cache Class
101 * @see WP_Object_Cache::get()
103 * @param int|string $key What the contents in the cache are called
104 * @param string $group Where the cache contents are grouped
105 * @param bool $force Whether to force an update of the local cache from the persistent cache (default is false)
106 * @param &bool $found Whether key was found in the cache. Disambiguates a return of false, a storable value.
107 * @return bool|mixed False on failure to retrieve contents or the cache
108 * contents on success
110 function wp_cache_get( $key, $group = '', $force = false, &$found = null ) {
111 global $wp_object_cache;
113 return $wp_object_cache->get( $key, $group, $force, $found );
117 * Increment numeric cache item's value
120 * @uses $wp_object_cache Object Cache Class
121 * @see WP_Object_Cache::incr()
123 * @param int|string $key The cache key to increment
124 * @param int $offset The amount by which to increment the item's value. Default is 1.
125 * @param string $group The group the key is in.
126 * @return false|int False on failure, the item's new value on success.
128 function wp_cache_incr( $key, $offset = 1, $group = '' ) {
129 global $wp_object_cache;
131 return $wp_object_cache->incr( $key, $offset, $group );
135 * Sets up Object Cache Global and assigns it.
138 * @global WP_Object_Cache $wp_object_cache WordPress Object Cache
140 function wp_cache_init() {
141 $GLOBALS['wp_object_cache'] = new WP_Object_Cache();
145 * Replaces the contents of the cache with new data.
148 * @uses $wp_object_cache Object Cache Class
149 * @see WP_Object_Cache::replace()
151 * @param int|string $key What to call the contents in the cache
152 * @param mixed $data The contents to store in the cache
153 * @param string $group Where to group the cache contents
154 * @param int $expire When to expire the cache contents
155 * @return bool False if cache key and group already exist, true on success
157 function wp_cache_replace($key, $data, $group = '', $expire = 0) {
158 global $wp_object_cache;
160 return $wp_object_cache->replace($key, $data, $group, $expire);
164 * Saves the data to the cache.
167 * @uses $wp_object_cache Object Cache Class
168 * @see WP_Object_Cache::set()
170 * @param int|string $key What to call the contents in the cache
171 * @param mixed $data The contents to store in the cache
172 * @param string $group Where to group the cache contents
173 * @param int $expire When to expire the cache contents
174 * @return bool False if cache key and group already exist, true on success
176 function wp_cache_set($key, $data, $group = '', $expire = 0) {
177 global $wp_object_cache;
179 return $wp_object_cache->set($key, $data, $group, $expire);
183 * Adds a group or set of groups to the list of global groups.
187 * @param string|array $groups A group or an array of groups to add
189 function wp_cache_add_global_groups( $groups ) {
190 global $wp_object_cache;
192 return $wp_object_cache->add_global_groups($groups);
196 * Adds a group or set of groups to the list of non-persistent groups.
200 * @param string|array $groups A group or an array of groups to add
202 function wp_cache_add_non_persistent_groups( $groups ) {
203 // Default cache doesn't persist so nothing to do here.
208 * Reset internal cache keys and structures. If the cache backend uses global blog or site IDs as part of its cache keys,
209 * this function instructs the backend to reset those keys and perform any cleanup since blog or site IDs have changed since cache init.
213 function wp_cache_reset() {
214 global $wp_object_cache;
216 return $wp_object_cache->reset();
220 * WordPress Object Cache
222 * The WordPress Object Cache is used to save on trips to the database. The
223 * Object Cache stores all of the cache data to memory and makes the cache
224 * contents available by using a key, which is used to name and later retrieve
225 * the cache contents.
227 * The Object Cache can be replaced by other caching mechanisms by placing files
228 * in the wp-content folder which is looked at in wp-settings. If that file
229 * exists, then this file will not be included.
235 class WP_Object_Cache {
238 * Holds the cached objects
244 var $cache = array ();
247 * The amount of times the cache data was already stored in the cache.
256 * Amount of times the cache did not have the request in cache
262 var $cache_misses = 0;
265 * List of global groups
271 var $global_groups = array();
274 * Adds data to the cache if it doesn't already exist.
276 * @uses WP_Object_Cache::_exists Checks to see if the cache already has data.
277 * @uses WP_Object_Cache::set Sets the data after the checking the cache
278 * contents existence.
282 * @param int|string $key What to call the contents in the cache
283 * @param mixed $data The contents to store in the cache
284 * @param string $group Where to group the cache contents
285 * @param int $expire When to expire the cache contents
286 * @return bool False if cache key and group already exist, true on success
288 function add( $key, $data, $group = 'default', $expire = '' ) {
289 if ( wp_suspend_cache_addition() )
292 if ( empty( $group ) )
295 if ( $this->_exists($key, $group) )
298 return $this->set($key, $data, $group, $expire);
302 * Sets the list of global groups.
306 * @param array $groups List of groups that are global.
308 function add_global_groups( $groups ) {
309 $groups = (array) $groups;
311 $this->global_groups = array_merge($this->global_groups, $groups);
312 $this->global_groups = array_unique($this->global_groups);
316 * Decrement numeric cache item's value
320 * @param int|string $key The cache key to increment
321 * @param int $offset The amount by which to decrement the item's value. Default is 1.
322 * @param string $group The group the key is in.
323 * @return false|int False on failure, the item's new value on success.
325 function decr( $key, $offset = 1, $group = 'default' ) {
326 if ( ! $this->_exists( $key, $group ) )
329 if ( ! is_numeric( $this->cache[ $group ][ $key ] ) )
330 $this->cache[ $group ][ $key ] = 0;
332 $offset = (int) $offset;
334 $this->cache[ $group ][ $key ] -= $offset;
336 if ( $this->cache[ $group ][ $key ] < 0 )
337 $this->cache[ $group ][ $key ] = 0;
339 return $this->cache[ $group ][ $key ];
343 * Remove the contents of the cache key in the group
345 * If the cache key does not exist in the group and $force parameter is set
346 * to false, then nothing will happen. The $force parameter is set to false
351 * @param int|string $key What the contents in the cache are called
352 * @param string $group Where the cache contents are grouped
353 * @param bool $force Optional. Whether to force the unsetting of the cache
355 * @return bool False if the contents weren't deleted and true on success
357 function delete($key, $group = 'default', $force = false) {
358 if ( empty( $group ) )
361 if ( ! $force && ! $this->_exists( $key, $group ) )
364 unset( $this->cache[$group][$key] );
369 * Clears the object cache of all data
373 * @return bool Always returns true
376 $this->cache = array ();
382 * Retrieves the cache contents, if it exists
384 * The contents will be first attempted to be retrieved by searching by the
385 * key in the cache group. If the cache is hit (success) then the contents
388 * On failure, the number of cache misses will be incremented.
392 * @param int|string $key What the contents in the cache are called
393 * @param string $group Where the cache contents are grouped
394 * @param string $force Whether to force a refetch rather than relying on the local cache (default is false)
395 * @return bool|mixed False on failure to retrieve contents or the cache
396 * contents on success
398 function get( $key, $group = 'default', $force = false, &$found = null ) {
399 if ( empty( $group ) )
402 if ( $this->_exists( $key, $group ) ) {
404 $this->cache_hits += 1;
405 if ( is_object($this->cache[$group][$key]) )
406 return clone $this->cache[$group][$key];
408 return $this->cache[$group][$key];
412 $this->cache_misses += 1;
417 * Increment numeric cache item's value
421 * @param int|string $key The cache key to increment
422 * @param int $offset The amount by which to increment the item's value. Default is 1.
423 * @param string $group The group the key is in.
424 * @return false|int False on failure, the item's new value on success.
426 function incr( $key, $offset = 1, $group = 'default' ) {
427 if ( empty( $group ) )
430 if ( ! $this->_exists( $key, $group ) )
433 if ( ! is_numeric( $this->cache[ $group ][ $key ] ) )
434 $this->cache[ $group ][ $key ] = 0;
436 $offset = (int) $offset;
438 $this->cache[ $group ][ $key ] += $offset;
440 if ( $this->cache[ $group ][ $key ] < 0 )
441 $this->cache[ $group ][ $key ] = 0;
443 return $this->cache[ $group ][ $key ];
447 * Replace the contents in the cache, if contents already exist
450 * @see WP_Object_Cache::set()
452 * @param int|string $key What to call the contents in the cache
453 * @param mixed $data The contents to store in the cache
454 * @param string $group Where to group the cache contents
455 * @param int $expire When to expire the cache contents
456 * @return bool False if not exists, true if contents were replaced
458 function replace($key, $data, $group = 'default', $expire = '') {
459 if ( empty( $group ) )
462 if ( ! $this->_exists( $key, $group ) )
465 return $this->set($key, $data, $group, $expire);
474 // Clear out non-global caches since the blog ID has changed.
475 foreach ( array_keys($this->cache) as $group ) {
476 if ( !in_array($group, $this->global_groups) )
477 unset($this->cache[$group]);
482 * Sets the data contents into the cache
484 * The cache contents is grouped by the $group parameter followed by the
485 * $key. This allows for duplicate ids in unique groups. Therefore, naming of
486 * the group should be used with care and should follow normal function
487 * naming guidelines outside of core WordPress usage.
489 * The $expire parameter is not used, because the cache will automatically
490 * expire for each time a page is accessed and PHP finishes. The method is
491 * more for cache plugins which use files.
495 * @param int|string $key What to call the contents in the cache
496 * @param mixed $data The contents to store in the cache
497 * @param string $group Where to group the cache contents
498 * @param int $expire Not Used
499 * @return bool Always returns true
501 function set($key, $data, $group = 'default', $expire = '') {
502 if ( empty( $group ) )
505 if ( is_object($data) )
508 $this->cache[$group][$key] = $data;
513 * Echoes the stats of the caching.
515 * Gives the cache hits, and cache misses. Also prints every cached group,
522 echo "<strong>Cache Hits:</strong> {$this->cache_hits}<br />";
523 echo "<strong>Cache Misses:</strong> {$this->cache_misses}<br />";
526 foreach ($this->cache as $group => $cache) {
527 echo "<li><strong>Group:</strong> $group - ( " . number_format( strlen( serialize( $cache ) ) / 1024, 2 ) . 'k )</li>';
533 * Utility function to determine whether a key exists in the cache.
536 protected function _exists($key, $group) {
537 return isset( $this->cache[$group] ) && is_array( $this->cache[$group] ) && array_key_exists( $key, $this->cache[$group] );
541 * Sets up object properties; PHP 5 style constructor
544 * @return null|WP_Object_Cache If cache is disabled, returns null.
546 function __construct() {
548 * @todo This should be moved to the PHP4 style constructor, PHP5
549 * already calls __destruct()
551 register_shutdown_function(array(&$this, "__destruct"));
555 * Will save the object cache before object is completely destroyed.
557 * Called upon object destruction, which should be when PHP ends.
561 * @return bool True value. Won't be used by PHP
563 function __destruct() {