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
22 * @return bool False if cache key and group already exist, true on success
24 function wp_cache_add( $key, $data, $group = '', $expire = 0 ) {
25 global $wp_object_cache;
27 return $wp_object_cache->add( $key, $data, $group, (int) $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 False on failure, true on success
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 not exists, true if contents were replaced
157 function wp_cache_replace( $key, $data, $group = '', $expire = 0 ) {
158 global $wp_object_cache;
160 return $wp_object_cache->replace( $key, $data, $group, (int) $expire );
164 * Saves the data to the cache.
168 * @uses $wp_object_cache Object Cache Class
169 * @see WP_Object_Cache::set()
171 * @param int|string $key What to call the contents in the cache
172 * @param mixed $data The contents to store in the cache
173 * @param string $group Where to group the cache contents
174 * @param int $expire When to expire the cache contents
175 * @return bool False on failure, true on success
177 function wp_cache_set( $key, $data, $group = '', $expire = 0 ) {
178 global $wp_object_cache;
180 return $wp_object_cache->set( $key, $data, $group, (int) $expire );
184 * Switch the interal blog id.
186 * This changes the blog id used to create keys in blog specific groups.
190 * @param int $blog_id Blog ID
192 function wp_cache_switch_to_blog( $blog_id ) {
193 global $wp_object_cache;
195 return $wp_object_cache->switch_to_blog( $blog_id );
199 * Adds a group or set of groups to the list of global groups.
203 * @param string|array $groups A group or an array of groups to add
205 function wp_cache_add_global_groups( $groups ) {
206 global $wp_object_cache;
208 return $wp_object_cache->add_global_groups( $groups );
212 * Adds a group or set of groups to the list of non-persistent groups.
216 * @param string|array $groups A group or an array of groups to add
218 function wp_cache_add_non_persistent_groups( $groups ) {
219 // Default cache doesn't persist so nothing to do here.
224 * Reset internal cache keys and structures. If the cache backend uses global
225 * blog or site IDs as part of its cache keys, this function instructs the
226 * backend to reset those keys and perform any cleanup since blog or site IDs
227 * have changed since cache init.
229 * This function is deprecated. Use wp_cache_switch_to_blog() instead of this
230 * function when preparing the cache for a blog switch. For clearing the cache
231 * during unit tests, consider using wp_cache_init(). wp_cache_init() is not
232 * recommended outside of unit tests as the performance penality for using it is
238 function wp_cache_reset() {
239 _deprecated_function( __FUNCTION__, '3.5' );
241 global $wp_object_cache;
243 return $wp_object_cache->reset();
247 * WordPress Object Cache
249 * The WordPress Object Cache is used to save on trips to the database. The
250 * Object Cache stores all of the cache data to memory and makes the cache
251 * contents available by using a key, which is used to name and later retrieve
252 * the cache contents.
254 * The Object Cache can be replaced by other caching mechanisms by placing files
255 * in the wp-content folder which is looked at in wp-settings. If that file
256 * exists, then this file will not be included.
262 class WP_Object_Cache {
265 * Holds the cached objects
271 private $cache = array();
274 * The amount of times the cache data was already stored in the cache.
280 private $cache_hits = 0;
283 * Amount of times the cache did not have the request in cache
289 public $cache_misses = 0;
292 * List of global groups
298 protected $global_groups = array();
301 * The blog prefix to prepend to keys in non-global groups.
307 private $blog_prefix;
310 * Make private properties readable for backwards compatibility.
315 * @param string $name Property to get.
316 * @return mixed Property.
318 public function __get( $name ) {
323 * Make private properties settable for backwards compatibility.
328 * @param string $name Property to set.
329 * @param mixed $value Property value.
330 * @return mixed Newly-set property.
332 public function __set( $name, $value ) {
333 return $this->$name = $value;
337 * Make private properties checkable for backwards compatibility.
342 * @param string $name Property to check if set.
343 * @return bool Whether the property is set.
345 public function __isset( $name ) {
346 return isset( $this->$name );
350 * Make private properties un-settable for backwards compatibility.
355 * @param string $name Property to unset.
357 public function __unset( $name ) {
358 unset( $this->$name );
362 * Adds data to the cache if it doesn't already exist.
364 * @uses WP_Object_Cache::_exists Checks to see if the cache already has data.
365 * @uses WP_Object_Cache::set Sets the data after the checking the cache
366 * contents existence.
370 * @param int|string $key What to call the contents in the cache
371 * @param mixed $data The contents to store in the cache
372 * @param string $group Where to group the cache contents
373 * @param int $expire When to expire the cache contents
374 * @return bool False if cache key and group already exist, true on success
376 public function add( $key, $data, $group = 'default', $expire = 0 ) {
377 if ( wp_suspend_cache_addition() )
380 if ( empty( $group ) )
384 if ( $this->multisite && ! isset( $this->global_groups[ $group ] ) )
385 $id = $this->blog_prefix . $key;
387 if ( $this->_exists( $id, $group ) )
390 return $this->set( $key, $data, $group, (int) $expire );
394 * Sets the list of global groups.
398 * @param array $groups List of groups that are global.
400 public function add_global_groups( $groups ) {
401 $groups = (array) $groups;
403 $groups = array_fill_keys( $groups, true );
404 $this->global_groups = array_merge( $this->global_groups, $groups );
408 * Decrement numeric cache item's value
412 * @param int|string $key The cache key to increment
413 * @param int $offset The amount by which to decrement the item's value. Default is 1.
414 * @param string $group The group the key is in.
415 * @return false|int False on failure, the item's new value on success.
417 public function decr( $key, $offset = 1, $group = 'default' ) {
418 if ( empty( $group ) )
421 if ( $this->multisite && ! isset( $this->global_groups[ $group ] ) )
422 $key = $this->blog_prefix . $key;
424 if ( ! $this->_exists( $key, $group ) )
427 if ( ! is_numeric( $this->cache[ $group ][ $key ] ) )
428 $this->cache[ $group ][ $key ] = 0;
430 $offset = (int) $offset;
432 $this->cache[ $group ][ $key ] -= $offset;
434 if ( $this->cache[ $group ][ $key ] < 0 )
435 $this->cache[ $group ][ $key ] = 0;
437 return $this->cache[ $group ][ $key ];
441 * Remove the contents of the cache key in the group
443 * If the cache key does not exist in the group, then nothing will happen.
447 * @param int|string $key What the contents in the cache are called
448 * @param string $group Where the cache contents are grouped
449 * @param bool $deprecated Deprecated.
451 * @return bool False if the contents weren't deleted and true on success
453 public function delete( $key, $group = 'default', $deprecated = false ) {
454 if ( empty( $group ) )
457 if ( $this->multisite && ! isset( $this->global_groups[ $group ] ) )
458 $key = $this->blog_prefix . $key;
460 if ( ! $this->_exists( $key, $group ) )
463 unset( $this->cache[$group][$key] );
468 * Clears the object cache of all data
472 * @return bool Always returns true
474 public function flush() {
475 $this->cache = array ();
481 * Retrieves the cache contents, if it exists
483 * The contents will be first attempted to be retrieved by searching by the
484 * key in the cache group. If the cache is hit (success) then the contents
487 * On failure, the number of cache misses will be incremented.
491 * @param int|string $key What the contents in the cache are called
492 * @param string $group Where the cache contents are grouped
493 * @param string $force Whether to force a refetch rather than relying on the local cache (default is false)
494 * @return bool|mixed False on failure to retrieve contents or the cache
495 * contents on success
497 public function get( $key, $group = 'default', $force = false, &$found = null ) {
498 if ( empty( $group ) )
501 if ( $this->multisite && ! isset( $this->global_groups[ $group ] ) )
502 $key = $this->blog_prefix . $key;
504 if ( $this->_exists( $key, $group ) ) {
506 $this->cache_hits += 1;
507 if ( is_object($this->cache[$group][$key]) )
508 return clone $this->cache[$group][$key];
510 return $this->cache[$group][$key];
514 $this->cache_misses += 1;
519 * Increment numeric cache item's value
523 * @param int|string $key The cache key to increment
524 * @param int $offset The amount by which to increment the item's value. Default is 1.
525 * @param string $group The group the key is in.
526 * @return false|int False on failure, the item's new value on success.
528 public function incr( $key, $offset = 1, $group = 'default' ) {
529 if ( empty( $group ) )
532 if ( $this->multisite && ! isset( $this->global_groups[ $group ] ) )
533 $key = $this->blog_prefix . $key;
535 if ( ! $this->_exists( $key, $group ) )
538 if ( ! is_numeric( $this->cache[ $group ][ $key ] ) )
539 $this->cache[ $group ][ $key ] = 0;
541 $offset = (int) $offset;
543 $this->cache[ $group ][ $key ] += $offset;
545 if ( $this->cache[ $group ][ $key ] < 0 )
546 $this->cache[ $group ][ $key ] = 0;
548 return $this->cache[ $group ][ $key ];
552 * Replace the contents in the cache, if contents already exist
555 * @see WP_Object_Cache::set()
557 * @param int|string $key What to call the contents in the cache
558 * @param mixed $data The contents to store in the cache
559 * @param string $group Where to group the cache contents
560 * @param int $expire When to expire the cache contents
561 * @return bool False if not exists, true if contents were replaced
563 public function replace( $key, $data, $group = 'default', $expire = 0 ) {
564 if ( empty( $group ) )
568 if ( $this->multisite && ! isset( $this->global_groups[ $group ] ) )
569 $id = $this->blog_prefix . $key;
571 if ( ! $this->_exists( $id, $group ) )
574 return $this->set( $key, $data, $group, (int) $expire );
583 public function reset() {
584 _deprecated_function( __FUNCTION__, '3.5', 'switch_to_blog()' );
586 // Clear out non-global caches since the blog ID has changed.
587 foreach ( array_keys( $this->cache ) as $group ) {
588 if ( ! isset( $this->global_groups[ $group ] ) )
589 unset( $this->cache[ $group ] );
594 * Sets the data contents into the cache
596 * The cache contents is grouped by the $group parameter followed by the
597 * $key. This allows for duplicate ids in unique groups. Therefore, naming of
598 * the group should be used with care and should follow normal function
599 * naming guidelines outside of core WordPress usage.
601 * The $expire parameter is not used, because the cache will automatically
602 * expire for each time a page is accessed and PHP finishes. The method is
603 * more for cache plugins which use files.
607 * @param int|string $key What to call the contents in the cache
608 * @param mixed $data The contents to store in the cache
609 * @param string $group Where to group the cache contents
610 * @param int $expire Not Used
611 * @return bool Always returns true
613 public function set( $key, $data, $group = 'default', $expire = 0 ) {
614 if ( empty( $group ) )
617 if ( $this->multisite && ! isset( $this->global_groups[ $group ] ) )
618 $key = $this->blog_prefix . $key;
620 if ( is_object( $data ) )
623 $this->cache[$group][$key] = $data;
628 * Echoes the stats of the caching.
630 * Gives the cache hits, and cache misses. Also prints every cached group,
635 public function stats() {
637 echo "<strong>Cache Hits:</strong> {$this->cache_hits}<br />";
638 echo "<strong>Cache Misses:</strong> {$this->cache_misses}<br />";
641 foreach ($this->cache as $group => $cache) {
642 echo "<li><strong>Group:</strong> $group - ( " . number_format( strlen( serialize( $cache ) ) / 1024, 2 ) . 'k )</li>';
648 * Switch the interal blog id.
650 * This changes the blog id used to create keys in blog specific groups.
654 * @param int $blog_id Blog ID
656 public function switch_to_blog( $blog_id ) {
657 $blog_id = (int) $blog_id;
658 $this->blog_prefix = $this->multisite ? $blog_id . ':' : '';
662 * Utility function to determine whether a key exists in the cache.
668 * @param string $group
671 protected function _exists( $key, $group ) {
672 return isset( $this->cache[ $group ] ) && ( isset( $this->cache[ $group ][ $key ] ) || array_key_exists( $key, $this->cache[ $group ] ) );
676 * Sets up object properties; PHP 5 style constructor
679 * @return null|WP_Object_Cache If cache is disabled, returns null.
681 public function __construct() {
684 $this->multisite = is_multisite();
685 $this->blog_prefix = $this->multisite ? $blog_id . ':' : '';
689 * @todo This should be moved to the PHP4 style constructor, PHP5
690 * already calls __destruct()
692 register_shutdown_function( array( $this, '__destruct' ) );
696 * Will save the object cache before object is completely destroyed.
698 * Called upon object destruction, which should be when PHP ends.
702 * @return bool True value. Won't be used by PHP
704 public function __destruct() {