5 * @link https://codex.wordpress.org/Class_Reference/WP_Object_Cache
12 * Adds data to the cache, if the cache key doesn't already exist.
16 * @see WP_Object_Cache::add()
17 * @global WP_Object_Cache $wp_object_cache Object cache global instance.
19 * @param int|string $key The cache key to use for retrieval later.
20 * @param mixed $data The data to add to the cache.
21 * @param string $group Optional. The group to add the cache to. Enables the same key
22 * to be used across groups. Default empty.
23 * @param int $expire Optional. When the cache data should expire, in seconds.
24 * Default 0 (no expiration).
25 * @return bool False if cache key and group already exist, true on success.
27 function wp_cache_add( $key, $data, $group = '', $expire = 0 ) {
28 global $wp_object_cache;
30 return $wp_object_cache->add( $key, $data, $group, (int) $expire );
36 * This function has ceased to do anything since WordPress 2.5. The
37 * functionality was removed along with the rest of the persistent cache.
39 * This does not mean that plugins can't implement this function when they need
40 * to make sure that the cache is cleaned up after WordPress no longer needs it.
44 * @return true Always returns true.
46 function wp_cache_close() {
51 * Decrements numeric cache item's value.
55 * @see WP_Object_Cache::decr()
56 * @global WP_Object_Cache $wp_object_cache Object cache global instance.
58 * @param int|string $key The cache key to decrement.
59 * @param int $offset Optional. The amount by which to decrement the item's value. Default 1.
60 * @param string $group Optional. The group the key is in. Default empty.
61 * @return false|int False on failure, the item's new value on success.
63 function wp_cache_decr( $key, $offset = 1, $group = '' ) {
64 global $wp_object_cache;
66 return $wp_object_cache->decr( $key, $offset, $group );
70 * Removes the cache contents matching key and group.
74 * @see WP_Object_Cache::delete()
75 * @global WP_Object_Cache $wp_object_cache Object cache global instance.
77 * @param int|string $key What the contents in the cache are called.
78 * @param string $group Optional. Where the cache contents are grouped. Default empty.
79 * @return bool True on successful removal, false on failure.
81 function wp_cache_delete( $key, $group = '' ) {
82 global $wp_object_cache;
84 return $wp_object_cache->delete($key, $group);
88 * Removes all cache items.
92 * @see WP_Object_Cache::flush()
93 * @global WP_Object_Cache $wp_object_cache Object cache global instance.
95 * @return bool False on failure, true on success
97 function wp_cache_flush() {
98 global $wp_object_cache;
100 return $wp_object_cache->flush();
104 * Retrieves the cache contents from the cache by key and group.
108 * @see WP_Object_Cache::get()
109 * @global WP_Object_Cache $wp_object_cache Object cache global instance.
111 * @param int|string $key The key under which the cache contents are stored.
112 * @param string $group Optional. Where the cache contents are grouped. Default empty.
113 * @param bool $force Optional. Whether to force an update of the local cache from the persistent
114 * cache. Default false.
115 * @param bool $found Optional. Whether the key was found in the cache. Disambiguates a return of false,
116 * a storable value. Passed by reference. Default null.
117 * @return bool|mixed False on failure to retrieve contents or the cache
118 * contents on success
120 function wp_cache_get( $key, $group = '', $force = false, &$found = null ) {
121 global $wp_object_cache;
123 return $wp_object_cache->get( $key, $group, $force, $found );
127 * Increment numeric cache item's value
131 * @see WP_Object_Cache::incr()
132 * @global WP_Object_Cache $wp_object_cache Object cache global instance.
134 * @param int|string $key The key for the cache contents that should be incremented.
135 * @param int $offset Optional. The amount by which to increment the item's value. Default 1.
136 * @param string $group Optional. The group the key is in. Default empty.
137 * @return false|int False on failure, the item's new value on success.
139 function wp_cache_incr( $key, $offset = 1, $group = '' ) {
140 global $wp_object_cache;
142 return $wp_object_cache->incr( $key, $offset, $group );
146 * Sets up Object Cache Global and assigns it.
150 * @global WP_Object_Cache $wp_object_cache
152 function wp_cache_init() {
153 $GLOBALS['wp_object_cache'] = new WP_Object_Cache();
157 * Replaces the contents of the cache with new data.
161 * @see WP_Object_Cache::replace()
162 * @global WP_Object_Cache $wp_object_cache Object cache global instance.
164 * @param int|string $key The key for the cache data that should be replaced.
165 * @param mixed $data The new data to store in the cache.
166 * @param string $group Optional. The group for the cache data that should be replaced.
168 * @param int $expire Optional. When to expire the cache contents, in seconds.
169 * Default 0 (no expiration).
170 * @return bool False if original value does not exist, true if contents were replaced
172 function wp_cache_replace( $key, $data, $group = '', $expire = 0 ) {
173 global $wp_object_cache;
175 return $wp_object_cache->replace( $key, $data, $group, (int) $expire );
179 * Saves the data to the cache.
181 * Differs from wp_cache_add() and wp_cache_replace() in that it will always write data.
185 * @see WP_Object_Cache::set()
186 * @global WP_Object_Cache $wp_object_cache Object cache global instance.
188 * @param int|string $key The cache key to use for retrieval later.
189 * @param mixed $data The contents to store in the cache.
190 * @param string $group Optional. Where to group the cache contents. Enables the same key
191 * to be used across groups. Default empty.
192 * @param int $expire Optional. When to expire the cache contents, in seconds.
193 * Default 0 (no expiration).
194 * @return bool False on failure, true on success
196 function wp_cache_set( $key, $data, $group = '', $expire = 0 ) {
197 global $wp_object_cache;
199 return $wp_object_cache->set( $key, $data, $group, (int) $expire );
203 * Switches the internal blog ID.
205 * This changes the blog id used to create keys in blog specific groups.
209 * @see WP_Object_Cache::switch_to_blog()
210 * @global WP_Object_Cache $wp_object_cache Object cache global instance.
212 * @param int $blog_id Site ID.
214 function wp_cache_switch_to_blog( $blog_id ) {
215 global $wp_object_cache;
217 $wp_object_cache->switch_to_blog( $blog_id );
221 * Adds a group or set of groups to the list of global groups.
225 * @see WP_Object_Cache::add_global_groups()
226 * @global WP_Object_Cache $wp_object_cache Object cache global instance.
228 * @param string|array $groups A group or an array of groups to add.
230 function wp_cache_add_global_groups( $groups ) {
231 global $wp_object_cache;
233 $wp_object_cache->add_global_groups( $groups );
237 * Adds a group or set of groups to the list of non-persistent groups.
241 * @param string|array $groups A group or an array of groups to add.
243 function wp_cache_add_non_persistent_groups( $groups ) {
244 // Default cache doesn't persist so nothing to do here.
248 * Reset internal cache keys and structures.
250 * If the cache back end uses global blog or site IDs as part of its cache keys,
251 * this function instructs the back end to reset those keys and perform any cleanup
252 * since blog or site IDs have changed since cache init.
254 * This function is deprecated. Use wp_cache_switch_to_blog() instead of this
255 * function when preparing the cache for a blog switch. For clearing the cache
256 * during unit tests, consider using wp_cache_init(). wp_cache_init() is not
257 * recommended outside of unit tests as the performance penalty for using it is
261 * @deprecated 3.5.0 WP_Object_Cache::reset()
262 * @see WP_Object_Cache::reset()
264 * @global WP_Object_Cache $wp_object_cache Object cache global instance.
266 function wp_cache_reset() {
267 _deprecated_function( __FUNCTION__, '3.5.0' );
269 global $wp_object_cache;
271 $wp_object_cache->reset();
275 * Core class that implements an object cache.
277 * The WordPress Object Cache is used to save on trips to the database. The
278 * Object Cache stores all of the cache data to memory and makes the cache
279 * contents available by using a key, which is used to name and later retrieve
280 * the cache contents.
282 * The Object Cache can be replaced by other caching mechanisms by placing files
283 * in the wp-content folder which is looked at in wp-settings. If that file
284 * exists, then this file will not be included.
290 class WP_Object_Cache {
293 * Holds the cached objects.
299 private $cache = array();
302 * The amount of times the cache data was already stored in the cache.
308 public $cache_hits = 0;
311 * Amount of times the cache did not have the request in cache.
317 public $cache_misses = 0;
320 * List of global cache groups.
326 protected $global_groups = array();
329 * The blog prefix to prepend to keys in non-global groups.
335 private $blog_prefix;
338 * Holds the value of is_multisite().
347 * Makes private properties readable for backward compatibility.
352 * @param string $name Property to get.
353 * @return mixed Property.
355 public function __get( $name ) {
360 * Makes private properties settable for backward compatibility.
365 * @param string $name Property to set.
366 * @param mixed $value Property value.
367 * @return mixed Newly-set property.
369 public function __set( $name, $value ) {
370 return $this->$name = $value;
374 * Makes private properties checkable for backward compatibility.
379 * @param string $name Property to check if set.
380 * @return bool Whether the property is set.
382 public function __isset( $name ) {
383 return isset( $this->$name );
387 * Makes private properties un-settable for backward compatibility.
392 * @param string $name Property to unset.
394 public function __unset( $name ) {
395 unset( $this->$name );
399 * Adds data to the cache if it doesn't already exist.
404 * @uses WP_Object_Cache::_exists() Checks to see if the cache already has data.
405 * @uses WP_Object_Cache::set() Sets the data after the checking the cache
406 * contents existence.
408 * @param int|string $key What to call the contents in the cache.
409 * @param mixed $data The contents to store in the cache.
410 * @param string $group Optional. Where to group the cache contents. Default 'default'.
411 * @param int $expire Optional. When to expire the cache contents. Default 0 (no expiration).
412 * @return bool False if cache key and group already exist, true on success
414 public function add( $key, $data, $group = 'default', $expire = 0 ) {
415 if ( wp_suspend_cache_addition() )
418 if ( empty( $group ) )
422 if ( $this->multisite && ! isset( $this->global_groups[ $group ] ) )
423 $id = $this->blog_prefix . $key;
425 if ( $this->_exists( $id, $group ) )
428 return $this->set( $key, $data, $group, (int) $expire );
432 * Sets the list of global cache groups.
437 * @param array $groups List of groups that are global.
439 public function add_global_groups( $groups ) {
440 $groups = (array) $groups;
442 $groups = array_fill_keys( $groups, true );
443 $this->global_groups = array_merge( $this->global_groups, $groups );
447 * Decrements numeric cache item's value.
452 * @param int|string $key The cache key to decrement.
453 * @param int $offset Optional. The amount by which to decrement the item's value. Default 1.
454 * @param string $group Optional. The group the key is in. Default 'default'.
455 * @return false|int False on failure, the item's new value on success.
457 public function decr( $key, $offset = 1, $group = 'default' ) {
458 if ( empty( $group ) )
461 if ( $this->multisite && ! isset( $this->global_groups[ $group ] ) )
462 $key = $this->blog_prefix . $key;
464 if ( ! $this->_exists( $key, $group ) )
467 if ( ! is_numeric( $this->cache[ $group ][ $key ] ) )
468 $this->cache[ $group ][ $key ] = 0;
470 $offset = (int) $offset;
472 $this->cache[ $group ][ $key ] -= $offset;
474 if ( $this->cache[ $group ][ $key ] < 0 )
475 $this->cache[ $group ][ $key ] = 0;
477 return $this->cache[ $group ][ $key ];
481 * Removes the contents of the cache key in the group.
483 * If the cache key does not exist in the group, then nothing will happen.
488 * @param int|string $key What the contents in the cache are called.
489 * @param string $group Optional. Where the cache contents are grouped. Default 'default'.
490 * @param bool $deprecated Optional. Unused. Default false.
491 * @return bool False if the contents weren't deleted and true on success.
493 public function delete( $key, $group = 'default', $deprecated = false ) {
494 if ( empty( $group ) )
497 if ( $this->multisite && ! isset( $this->global_groups[ $group ] ) )
498 $key = $this->blog_prefix . $key;
500 if ( ! $this->_exists( $key, $group ) )
503 unset( $this->cache[$group][$key] );
508 * Clears the object cache of all data.
513 * @return true Always returns true.
515 public function flush() {
516 $this->cache = array();
522 * Retrieves the cache contents, if it exists.
524 * The contents will be first attempted to be retrieved by searching by the
525 * key in the cache group. If the cache is hit (success) then the contents
528 * On failure, the number of cache misses will be incremented.
533 * @param int|string $key What the contents in the cache are called.
534 * @param string $group Optional. Where the cache contents are grouped. Default 'default'.
535 * @param string $force Optional. Unused. Whether to force a refetch rather than relying on the local
536 * cache. Default false.
537 * @param bool $found Optional. Whether the key was found in the cache. Disambiguates a return of
538 * false, a storable value. Passed by reference. Default null.
539 * @return false|mixed False on failure to retrieve contents or the cache contents on success.
541 public function get( $key, $group = 'default', $force = false, &$found = null ) {
542 if ( empty( $group ) )
545 if ( $this->multisite && ! isset( $this->global_groups[ $group ] ) )
546 $key = $this->blog_prefix . $key;
548 if ( $this->_exists( $key, $group ) ) {
550 $this->cache_hits += 1;
551 if ( is_object($this->cache[$group][$key]) )
552 return clone $this->cache[$group][$key];
554 return $this->cache[$group][$key];
558 $this->cache_misses += 1;
563 * Increments numeric cache item's value.
568 * @param int|string $key The cache key to increment
569 * @param int $offset Optional. The amount by which to increment the item's value. Default 1.
570 * @param string $group Optional. The group the key is in. Default 'default'.
571 * @return false|int False on failure, the item's new value on success.
573 public function incr( $key, $offset = 1, $group = 'default' ) {
574 if ( empty( $group ) )
577 if ( $this->multisite && ! isset( $this->global_groups[ $group ] ) )
578 $key = $this->blog_prefix . $key;
580 if ( ! $this->_exists( $key, $group ) )
583 if ( ! is_numeric( $this->cache[ $group ][ $key ] ) )
584 $this->cache[ $group ][ $key ] = 0;
586 $offset = (int) $offset;
588 $this->cache[ $group ][ $key ] += $offset;
590 if ( $this->cache[ $group ][ $key ] < 0 )
591 $this->cache[ $group ][ $key ] = 0;
593 return $this->cache[ $group ][ $key ];
597 * Replaces the contents in the cache, if contents already exist.
602 * @see WP_Object_Cache::set()
604 * @param int|string $key What to call the contents in the cache.
605 * @param mixed $data The contents to store in the cache.
606 * @param string $group Optional. Where to group the cache contents. Default 'default'.
607 * @param int $expire Optional. When to expire the cache contents. Default 0 (no expiration).
608 * @return bool False if not exists, true if contents were replaced.
610 public function replace( $key, $data, $group = 'default', $expire = 0 ) {
611 if ( empty( $group ) )
615 if ( $this->multisite && ! isset( $this->global_groups[ $group ] ) )
616 $id = $this->blog_prefix . $key;
618 if ( ! $this->_exists( $id, $group ) )
621 return $this->set( $key, $data, $group, (int) $expire );
630 * @deprecated 3.5.0 Use switch_to_blog()
631 * @see switch_to_blog()
633 public function reset() {
634 _deprecated_function( __FUNCTION__, '3.5.0', 'switch_to_blog()' );
636 // Clear out non-global caches since the blog ID has changed.
637 foreach ( array_keys( $this->cache ) as $group ) {
638 if ( ! isset( $this->global_groups[ $group ] ) )
639 unset( $this->cache[ $group ] );
644 * Sets the data contents into the cache.
646 * The cache contents is grouped by the $group parameter followed by the
647 * $key. This allows for duplicate ids in unique groups. Therefore, naming of
648 * the group should be used with care and should follow normal function
649 * naming guidelines outside of core WordPress usage.
651 * The $expire parameter is not used, because the cache will automatically
652 * expire for each time a page is accessed and PHP finishes. The method is
653 * more for cache plugins which use files.
658 * @param int|string $key What to call the contents in the cache.
659 * @param mixed $data The contents to store in the cache.
660 * @param string $group Optional. Where to group the cache contents. Default 'default'.
661 * @param int $expire Not Used.
662 * @return true Always returns true.
664 public function set( $key, $data, $group = 'default', $expire = 0 ) {
665 if ( empty( $group ) )
668 if ( $this->multisite && ! isset( $this->global_groups[ $group ] ) )
669 $key = $this->blog_prefix . $key;
671 if ( is_object( $data ) )
674 $this->cache[$group][$key] = $data;
679 * Echoes the stats of the caching.
681 * Gives the cache hits, and cache misses. Also prints every cached group,
687 public function stats() {
689 echo "<strong>Cache Hits:</strong> {$this->cache_hits}<br />";
690 echo "<strong>Cache Misses:</strong> {$this->cache_misses}<br />";
693 foreach ($this->cache as $group => $cache) {
694 echo "<li><strong>Group:</strong> $group - ( " . number_format( strlen( serialize( $cache ) ) / KB_IN_BYTES, 2 ) . 'k )</li>';
700 * Switches the internal blog ID.
702 * This changes the blog ID used to create keys in blog specific groups.
707 * @param int $blog_id Blog ID.
709 public function switch_to_blog( $blog_id ) {
710 $blog_id = (int) $blog_id;
711 $this->blog_prefix = $this->multisite ? $blog_id . ':' : '';
715 * Serves as a utility function to determine whether a key exists in the cache.
720 * @param int|string $key Cache key to check for existence.
721 * @param string $group Cache group for the key existence check.
722 * @return bool Whether the key exists in the cache for the given group.
724 protected function _exists( $key, $group ) {
725 return isset( $this->cache[ $group ] ) && ( isset( $this->cache[ $group ][ $key ] ) || array_key_exists( $key, $this->cache[ $group ] ) );
729 * Sets up object properties; PHP 5 style constructor.
733 public function __construct() {
734 $this->multisite = is_multisite();
735 $this->blog_prefix = $this->multisite ? get_current_blog_id() . ':' : '';
739 * @todo This should be moved to the PHP4 style constructor, PHP5
740 * already calls __destruct()
742 register_shutdown_function( array( $this, '__destruct' ) );
746 * Saves the object cache before object is completely destroyed.
748 * Called upon object destruction, which should be when PHP ends.
752 * @return true Always returns true.
754 public function __destruct() {