WP_Object_Cache{}WP 2.0.0AllowDynamicProperties

Core class that implements an object cache.

The WordPress Object Cache is used to save on trips to the database. The Object Cache stores all of the cache data to memory and makes the cache contents available by using a key, which is used to name and later retrieve the cache contents.

The Object Cache can be replaced by other caching mechanisms by placing files in the wp-content folder which is looked at in wp-settings. If that file exists, then this file will not be included.

No Hooks.

Usage

$WP_Object_Cache = new WP_Object_Cache();
// use class methods

Methods

  1. public __construct()
  2. public __get( $name )
  3. public __isset( $name )
  4. public __set( $name, $value )
  5. public __unset( $name )
  6. protected _exists( $key, $group )
  7. public add( $key, $data, $group = 'default', $expire = 0 )
  8. public add_global_groups( $groups )
  9. public add_multiple( array $data, $group = '', $expire = 0 )
  10. public decr( $key, $offset = 1, $group = 'default' )
  11. public delete( $key, $group = 'default', $deprecated = false )
  12. public delete_multiple( array $keys, $group = '' )
  13. public flush()
  14. public flush_group( $group )
  15. public get( $key, $group = 'default', $force = false, &$found = null )
  16. public get_multiple( $keys, $group = 'default', $force = false )
  17. public incr( $key, $offset = 1, $group = 'default' )
  18. protected is_valid_key( $key )
  19. public replace( $key, $data, $group = 'default', $expire = 0 )
  20. public reset()
  21. public set( $key, $data, $group = 'default', $expire = 0 )
  22. public set_multiple( array $data, $group = '', $expire = 0 )
  23. public stats()
  24. public switch_to_blog( $blog_id )

Changelog

Since 2.0.0 Introduced.

WP_Object_Cache{} code WP 6.1.1

class WP_Object_Cache {

	/**
	 * Holds the cached objects.
	 *
	 * @since 2.0.0
	 * @var array
	 */
	private $cache = array();

	/**
	 * The amount of times the cache data was already stored in the cache.
	 *
	 * @since 2.5.0
	 * @var int
	 */
	public $cache_hits = 0;

	/**
	 * Amount of times the cache did not have the request in cache.
	 *
	 * @since 2.0.0
	 * @var int
	 */
	public $cache_misses = 0;

	/**
	 * List of global cache groups.
	 *
	 * @since 3.0.0
	 * @var string[]
	 */
	protected $global_groups = array();

	/**
	 * The blog prefix to prepend to keys in non-global groups.
	 *
	 * @since 3.5.0
	 * @var string
	 */
	private $blog_prefix;

	/**
	 * Holds the value of is_multisite().
	 *
	 * @since 3.5.0
	 * @var bool
	 */
	private $multisite;

	/**
	 * Sets up object properties; PHP 5 style constructor.
	 *
	 * @since 2.0.8
	 */
	public function __construct() {
		$this->multisite   = is_multisite();
		$this->blog_prefix = $this->multisite ? get_current_blog_id() . ':' : '';
	}

	/**
	 * Makes private properties readable for backward compatibility.
	 *
	 * @since 4.0.0
	 *
	 * @param string $name Property to get.
	 * @return mixed Property.
	 */
	public function __get( $name ) {
		return $this->$name;
	}

	/**
	 * Makes private properties settable for backward compatibility.
	 *
	 * @since 4.0.0
	 *
	 * @param string $name  Property to set.
	 * @param mixed  $value Property value.
	 * @return mixed Newly-set property.
	 */
	public function __set( $name, $value ) {
		return $this->$name = $value;
	}

	/**
	 * Makes private properties checkable for backward compatibility.
	 *
	 * @since 4.0.0
	 *
	 * @param string $name Property to check if set.
	 * @return bool Whether the property is set.
	 */
	public function __isset( $name ) {
		return isset( $this->$name );
	}

	/**
	 * Makes private properties un-settable for backward compatibility.
	 *
	 * @since 4.0.0
	 *
	 * @param string $name Property to unset.
	 */
	public function __unset( $name ) {
		unset( $this->$name );
	}

	/**
	 * Serves as a utility function to determine whether a key is valid.
	 *
	 * @since 6.1.0
	 *
	 * @param int|string $key Cache key to check for validity.
	 * @return bool Whether the key is valid.
	 */
	protected function is_valid_key( $key ) {
		if ( is_int( $key ) ) {
			return true;
		}

		if ( is_string( $key ) && trim( $key ) !== '' ) {
			return true;
		}

		$type = gettype( $key );

		if ( ! function_exists( '__' ) ) {
			wp_load_translations_early();
		}

		$message = is_string( $key )
			? __( 'Cache key must not be an empty string.' )
			/* translators: %s: The type of the given cache key. */
			: sprintf( __( 'Cache key must be integer or non-empty string, %s given.' ), $type );

		_doing_it_wrong(
			sprintf( '%s::%s', __CLASS__, debug_backtrace( DEBUG_BACKTRACE_IGNORE_ARGS, 2 )[1]['function'] ),
			$message,
			'6.1.0'
		);

		return false;
	}

	/**
	 * Serves as a utility function to determine whether a key exists in the cache.
	 *
	 * @since 3.4.0
	 *
	 * @param int|string $key   Cache key to check for existence.
	 * @param string     $group Cache group for the key existence check.
	 * @return bool Whether the key exists in the cache for the given group.
	 */
	protected function _exists( $key, $group ) {
		return isset( $this->cache[ $group ] ) && ( isset( $this->cache[ $group ][ $key ] ) || array_key_exists( $key, $this->cache[ $group ] ) );
	}

	/**
	 * Adds data to the cache if it doesn't already exist.
	 *
	 * @since 2.0.0
	 *
	 * @uses WP_Object_Cache::_exists() Checks to see if the cache already has data.
	 * @uses WP_Object_Cache::set()     Sets the data after the checking the cache
	 *                                  contents existence.
	 *
	 * @param int|string $key    What to call the contents in the cache.
	 * @param mixed      $data   The contents to store in the cache.
	 * @param string     $group  Optional. Where to group the cache contents. Default 'default'.
	 * @param int        $expire Optional. When to expire the cache contents, in seconds.
	 *                           Default 0 (no expiration).
	 * @return bool True on success, false if cache key and group already exist.
	 */
	public function add( $key, $data, $group = 'default', $expire = 0 ) {
		if ( wp_suspend_cache_addition() ) {
			return false;
		}

		if ( ! $this->is_valid_key( $key ) ) {
			return false;
		}

		if ( empty( $group ) ) {
			$group = 'default';
		}

		$id = $key;
		if ( $this->multisite && ! isset( $this->global_groups[ $group ] ) ) {
			$id = $this->blog_prefix . $key;
		}

		if ( $this->_exists( $id, $group ) ) {
			return false;
		}

		return $this->set( $key, $data, $group, (int) $expire );
	}

	/**
	 * Adds multiple values to the cache in one call.
	 *
	 * @since 6.0.0
	 *
	 * @param array  $data   Array of keys and values to be added.
	 * @param string $group  Optional. Where the cache contents are grouped. Default empty.
	 * @param int    $expire Optional. When to expire the cache contents, in seconds.
	 *                       Default 0 (no expiration).
	 * @return bool[] Array of return values, grouped by key. Each value is either
	 *                true on success, or false if cache key and group already exist.
	 */
	public function add_multiple( array $data, $group = '', $expire = 0 ) {
		$values = array();

		foreach ( $data as $key => $value ) {
			$values[ $key ] = $this->add( $key, $value, $group, $expire );
		}

		return $values;
	}

	/**
	 * Replaces the contents in the cache, if contents already exist.
	 *
	 * @since 2.0.0
	 *
	 * @see WP_Object_Cache::set()
	 *
	 * @param int|string $key    What to call the contents in the cache.
	 * @param mixed      $data   The contents to store in the cache.
	 * @param string     $group  Optional. Where to group the cache contents. Default 'default'.
	 * @param int        $expire Optional. When to expire the cache contents, in seconds.
	 *                           Default 0 (no expiration).
	 * @return bool True if contents were replaced, false if original value does not exist.
	 */
	public function replace( $key, $data, $group = 'default', $expire = 0 ) {
		if ( ! $this->is_valid_key( $key ) ) {
			return false;
		}

		if ( empty( $group ) ) {
			$group = 'default';
		}

		$id = $key;
		if ( $this->multisite && ! isset( $this->global_groups[ $group ] ) ) {
			$id = $this->blog_prefix . $key;
		}

		if ( ! $this->_exists( $id, $group ) ) {
			return false;
		}

		return $this->set( $key, $data, $group, (int) $expire );
	}

	/**
	 * Sets the data contents into the cache.
	 *
	 * The cache contents are grouped by the $group parameter followed by the
	 * $key. This allows for duplicate IDs in unique groups. Therefore, naming of
	 * the group should be used with care and should follow normal function
	 * naming guidelines outside of core WordPress usage.
	 *
	 * The $expire parameter is not used, because the cache will automatically
	 * expire for each time a page is accessed and PHP finishes. The method is
	 * more for cache plugins which use files.
	 *
	 * @since 2.0.0
	 * @since 6.1.0 Returns false if cache key is invalid.
	 *
	 * @param int|string $key    What to call the contents in the cache.
	 * @param mixed      $data   The contents to store in the cache.
	 * @param string     $group  Optional. Where to group the cache contents. Default 'default'.
	 * @param int        $expire Optional. Not used.
	 * @return bool True if contents were set, false if key is invalid.
	 */
	public function set( $key, $data, $group = 'default', $expire = 0 ) {
		if ( ! $this->is_valid_key( $key ) ) {
			return false;
		}

		if ( empty( $group ) ) {
			$group = 'default';
		}

		if ( $this->multisite && ! isset( $this->global_groups[ $group ] ) ) {
			$key = $this->blog_prefix . $key;
		}

		if ( is_object( $data ) ) {
			$data = clone $data;
		}

		$this->cache[ $group ][ $key ] = $data;
		return true;
	}

	/**
	 * Sets multiple values to the cache in one call.
	 *
	 * @since 6.0.0
	 *
	 * @param array  $data   Array of key and value to be set.
	 * @param string $group  Optional. Where the cache contents are grouped. Default empty.
	 * @param int    $expire Optional. When to expire the cache contents, in seconds.
	 *                       Default 0 (no expiration).
	 * @return bool[] Array of return values, grouped by key. Each value is always true.
	 */
	public function set_multiple( array $data, $group = '', $expire = 0 ) {
		$values = array();

		foreach ( $data as $key => $value ) {
			$values[ $key ] = $this->set( $key, $value, $group, $expire );
		}

		return $values;
	}

	/**
	 * Retrieves the cache contents, if it exists.
	 *
	 * The contents will be first attempted to be retrieved by searching by the
	 * key in the cache group. If the cache is hit (success) then the contents
	 * are returned.
	 *
	 * On failure, the number of cache misses will be incremented.
	 *
	 * @since 2.0.0
	 *
	 * @param int|string $key   The key under which the cache contents are stored.
	 * @param string     $group Optional. Where the cache contents are grouped. Default 'default'.
	 * @param bool       $force Optional. Unused. Whether to force an update of the local cache
	 *                          from the persistent cache. Default false.
	 * @param bool       $found Optional. Whether the key was found in the cache (passed by reference).
	 *                          Disambiguates a return of false, a storable value. Default null.
	 * @return mixed|false The cache contents on success, false on failure to retrieve contents.
	 */
	public function get( $key, $group = 'default', $force = false, &$found = null ) {
		if ( ! $this->is_valid_key( $key ) ) {
			return false;
		}

		if ( empty( $group ) ) {
			$group = 'default';
		}

		if ( $this->multisite && ! isset( $this->global_groups[ $group ] ) ) {
			$key = $this->blog_prefix . $key;
		}

		if ( $this->_exists( $key, $group ) ) {
			$found             = true;
			$this->cache_hits += 1;
			if ( is_object( $this->cache[ $group ][ $key ] ) ) {
				return clone $this->cache[ $group ][ $key ];
			} else {
				return $this->cache[ $group ][ $key ];
			}
		}

		$found               = false;
		$this->cache_misses += 1;
		return false;
	}

	/**
	 * Retrieves multiple values from the cache in one call.
	 *
	 * @since 5.5.0
	 *
	 * @param array  $keys  Array of keys under which the cache contents are stored.
	 * @param string $group Optional. Where the cache contents are grouped. Default 'default'.
	 * @param bool   $force Optional. Whether to force an update of the local cache
	 *                      from the persistent cache. Default false.
	 * @return array Array of return values, grouped by key. Each value is either
	 *               the cache contents on success, or false on failure.
	 */
	public function get_multiple( $keys, $group = 'default', $force = false ) {
		$values = array();

		foreach ( $keys as $key ) {
			$values[ $key ] = $this->get( $key, $group, $force );
		}

		return $values;
	}

	/**
	 * Removes the contents of the cache key in the group.
	 *
	 * If the cache key does not exist in the group, then nothing will happen.
	 *
	 * @since 2.0.0
	 *
	 * @param int|string $key        What the contents in the cache are called.
	 * @param string     $group      Optional. Where the cache contents are grouped. Default 'default'.
	 * @param bool       $deprecated Optional. Unused. Default false.
	 * @return bool True on success, false if the contents were not deleted.
	 */
	public function delete( $key, $group = 'default', $deprecated = false ) {
		if ( ! $this->is_valid_key( $key ) ) {
			return false;
		}

		if ( empty( $group ) ) {
			$group = 'default';
		}

		if ( $this->multisite && ! isset( $this->global_groups[ $group ] ) ) {
			$key = $this->blog_prefix . $key;
		}

		if ( ! $this->_exists( $key, $group ) ) {
			return false;
		}

		unset( $this->cache[ $group ][ $key ] );
		return true;
	}

	/**
	 * Deletes multiple values from the cache in one call.
	 *
	 * @since 6.0.0
	 *
	 * @param array  $keys  Array of keys to be deleted.
	 * @param string $group Optional. Where the cache contents are grouped. Default empty.
	 * @return bool[] Array of return values, grouped by key. Each value is either
	 *                true on success, or false if the contents were not deleted.
	 */
	public function delete_multiple( array $keys, $group = '' ) {
		$values = array();

		foreach ( $keys as $key ) {
			$values[ $key ] = $this->delete( $key, $group );
		}

		return $values;
	}

	/**
	 * Increments numeric cache item's value.
	 *
	 * @since 3.3.0
	 *
	 * @param int|string $key    The cache key to increment.
	 * @param int        $offset Optional. The amount by which to increment the item's value.
	 *                           Default 1.
	 * @param string     $group  Optional. The group the key is in. Default 'default'.
	 * @return int|false The item's new value on success, false on failure.
	 */
	public function incr( $key, $offset = 1, $group = 'default' ) {
		if ( ! $this->is_valid_key( $key ) ) {
			return false;
		}

		if ( empty( $group ) ) {
			$group = 'default';
		}

		if ( $this->multisite && ! isset( $this->global_groups[ $group ] ) ) {
			$key = $this->blog_prefix . $key;
		}

		if ( ! $this->_exists( $key, $group ) ) {
			return false;
		}

		if ( ! is_numeric( $this->cache[ $group ][ $key ] ) ) {
			$this->cache[ $group ][ $key ] = 0;
		}

		$offset = (int) $offset;

		$this->cache[ $group ][ $key ] += $offset;

		if ( $this->cache[ $group ][ $key ] < 0 ) {
			$this->cache[ $group ][ $key ] = 0;
		}

		return $this->cache[ $group ][ $key ];
	}

	/**
	 * Decrements numeric cache item's value.
	 *
	 * @since 3.3.0
	 *
	 * @param int|string $key    The cache key to decrement.
	 * @param int        $offset Optional. The amount by which to decrement the item's value.
	 *                           Default 1.
	 * @param string     $group  Optional. The group the key is in. Default 'default'.
	 * @return int|false The item's new value on success, false on failure.
	 */
	public function decr( $key, $offset = 1, $group = 'default' ) {
		if ( ! $this->is_valid_key( $key ) ) {
			return false;
		}

		if ( empty( $group ) ) {
			$group = 'default';
		}

		if ( $this->multisite && ! isset( $this->global_groups[ $group ] ) ) {
			$key = $this->blog_prefix . $key;
		}

		if ( ! $this->_exists( $key, $group ) ) {
			return false;
		}

		if ( ! is_numeric( $this->cache[ $group ][ $key ] ) ) {
			$this->cache[ $group ][ $key ] = 0;
		}

		$offset = (int) $offset;

		$this->cache[ $group ][ $key ] -= $offset;

		if ( $this->cache[ $group ][ $key ] < 0 ) {
			$this->cache[ $group ][ $key ] = 0;
		}

		return $this->cache[ $group ][ $key ];
	}

	/**
	 * Clears the object cache of all data.
	 *
	 * @since 2.0.0
	 *
	 * @return true Always returns true.
	 */
	public function flush() {
		$this->cache = array();

		return true;
	}

	/**
	 * Removes all cache items in a group.
	 *
	 * @since 6.1.0
	 *
	 * @param string $group Name of group to remove from cache.
	 * @return true Always returns true.
	 */
	public function flush_group( $group ) {
		unset( $this->cache[ $group ] );

		return true;
	}

	/**
	 * Sets the list of global cache groups.
	 *
	 * @since 3.0.0
	 *
	 * @param string|string[] $groups List of groups that are global.
	 */
	public function add_global_groups( $groups ) {
		$groups = (array) $groups;

		$groups              = array_fill_keys( $groups, true );
		$this->global_groups = array_merge( $this->global_groups, $groups );
	}

	/**
	 * Switches the internal blog ID.
	 *
	 * This changes the blog ID used to create keys in blog specific groups.
	 *
	 * @since 3.5.0
	 *
	 * @param int $blog_id Blog ID.
	 */
	public function switch_to_blog( $blog_id ) {
		$blog_id           = (int) $blog_id;
		$this->blog_prefix = $this->multisite ? $blog_id . ':' : '';
	}

	/**
	 * Resets cache keys.
	 *
	 * @since 3.0.0
	 *
	 * @deprecated 3.5.0 Use WP_Object_Cache::switch_to_blog()
	 * @see switch_to_blog()
	 */
	public function reset() {
		_deprecated_function( __FUNCTION__, '3.5.0', 'WP_Object_Cache::switch_to_blog()' );

		// Clear out non-global caches since the blog ID has changed.
		foreach ( array_keys( $this->cache ) as $group ) {
			if ( ! isset( $this->global_groups[ $group ] ) ) {
				unset( $this->cache[ $group ] );
			}
		}
	}

	/**
	 * Echoes the stats of the caching.
	 *
	 * Gives the cache hits, and cache misses. Also prints every cached group,
	 * key and the data.
	 *
	 * @since 2.0.0
	 */
	public function stats() {
		echo '<p>';
		echo "<strong>Cache Hits:</strong> {$this->cache_hits}<br />";
		echo "<strong>Cache Misses:</strong> {$this->cache_misses}<br />";
		echo '</p>';
		echo '<ul>';
		foreach ( $this->cache as $group => $cache ) {
			echo '<li><strong>Group:</strong> ' . esc_html( $group ) . ' - ( ' . number_format( strlen( serialize( $cache ) ) / KB_IN_BYTES, 2 ) . 'k )</li>';
		}
		echo '</ul>';
	}
}