WordPress APCu Object Cache

object-cache.php

<?php # -*- coding: utf-8 -*-
/**
 * Name: WP APCu Object Cache
 * Description: WordPress APCu Object Cache
 * Author: Daniel Hüsken
 * Author URI: https://dhue.de
 * Version: 1.0.0
 *
 * @link https://codex.wordpress.org/Function_Reference/WP_Cache
 * @link https://pecl.php.net/package/APCu
 *
 */

/**
 * Adds data to the cache, if the cache key doesn't already exist.
 *
 * @since 2.0.0
 * @uses $wp_object_cache Object Cache Class
 * @see WP_Object_Cache::add()
 *
 * @param int|string $key The cache key to use for retrieval later
 * @param mixed $data The data to add to the cache store
 * @param string $group The group to add the cache to
 * @param int $expire When the cache data should be expired
 * @return bool False if cache key and group already exist, true on success
 */
function wp_cache_add( $key, $data, $group = '', $expire = 0 ) {
	global $wp_object_cache;

	return $wp_object_cache->add( $key, $data, $group, (int) $expire );
}

/**
 * Closes the cache.
 *
 * This function has ceased to do anything since WordPress 2.5. The
 * functionality was removed along with the rest of the persistent cache. This
 * does not mean that plugins can't implement this function when they need to
 * make sure that the cache is cleaned up after WordPress no longer needs it.
 *
 * @since 2.0.0
 *
 * @return bool Always returns True
 */
function wp_cache_close() {
	return true;
}

/**
 * Decrement numeric cache item's value
 *
 * @since 3.3.0
 * @uses $wp_object_cache Object Cache Class
 * @see WP_Object_Cache::decr()
 *
 * @param int|string $key The cache key to increment
 * @param int $offset The amount by which to decrement the item's value. Default is 1.
 * @param string $group The group the key is in.
 * @return false|int False on failure, the item's new value on success.
 */
function wp_cache_decr( $key, $offset = 1, $group = '' ) {
	global $wp_object_cache;

	return $wp_object_cache->decr( $key, $offset, $group );
}

/**
 * Removes the cache contents matching key and group.
 *
 * @since 2.0.0
 * @uses $wp_object_cache Object Cache Class
 * @see WP_Object_Cache::delete()
 *
 * @param int|string $key What the contents in the cache are called
 * @param string $group Where the cache contents are grouped
 * @return bool True on successful removal, false on failure
 */
function wp_cache_delete($key, $group = '') {
	global $wp_object_cache;

	return $wp_object_cache->delete($key, $group);
}

/**
 * Removes all cache items.
 *
 * @since 2.0.0
 * @uses $wp_object_cache Object Cache Class
 * @see WP_Object_Cache::flush()
 *
 * @return bool False on failure, true on success
 */
function wp_cache_flush() {
	global $wp_object_cache;

	return $wp_object_cache->flush();
}

/**
 * Retrieves the cache contents from the cache by key and group.
 *
 * @since 2.0.0
 * @uses $wp_object_cache Object Cache Class
 * @see WP_Object_Cache::get()
 *
 * @param int|string $key What the contents in the cache are called
 * @param string $group Where the cache contents are grouped
 * @param bool $force Whether to force an update of the local cache from the persistent cache (default is false)
 * @param bool &$found Whether key was found in the cache. Disambiguates a return of false, a storable value.
 * @return bool|mixed False on failure to retrieve contents or the cache
 *		contents on success
 */
function wp_cache_get( $key, $group = '', $force = false, &$found = null ) {
	global $wp_object_cache;

	return $wp_object_cache->get( $key, $group, $force, $found );
}

/**
 * Increment numeric cache item's value
 *
 * @since 3.3.0
 * @uses $wp_object_cache Object Cache Class
 * @see WP_Object_Cache::incr()
 *
 * @param int|string $key The cache key to increment
 * @param int $offset The amount by which to increment the item's value. Default is 1.
 * @param string $group The group the key is in.
 * @return false|int False on failure, the item's new value on success.
 */
function wp_cache_incr( $key, $offset = 1, $group = '' ) {
	global $wp_object_cache;

	return $wp_object_cache->incr( $key, $offset, $group );
}

/**
 * Sets up Object Cache Global and assigns it.
 *
 * @since 2.0.0
 * @global WP_APCu_Object_Cache $wp_object_cache WordPress Object Cache
 */
function wp_cache_init() {

	$GLOBALS['wp_object_cache'] = new WP_APCu_Object_Cache();
}

/**
 * Replaces the contents of the cache with new data.
 *
 * @since 2.0.0
 * @uses $wp_object_cache Object Cache Class
 * @see WP_Object_Cache::replace()
 *
 * @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 Where to group the cache contents
 * @param int $expire When to expire the cache contents
 * @return bool False if not exists, true if contents were replaced
 */
function wp_cache_replace( $key, $data, $group = '', $expire = 0 ) {
	global $wp_object_cache;

	return $wp_object_cache->replace( $key, $data, $group, (int) $expire );
}

/**
 * Saves the data to the cache.
 *
 * @since 2.0.0
 *
 * @uses $wp_object_cache Object Cache Class
 * @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 Where to group the cache contents
 * @param int $expire When to expire the cache contents
 * @return bool False on failure, true on success
 */
function wp_cache_set( $key, $data, $group = '', $expire = 0 ) {
	global $wp_object_cache;

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

/**
 * Switch the interal 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
 */
function wp_cache_switch_to_blog( $blog_id ) {
	global $wp_object_cache;

	return $wp_object_cache->switch_to_blog( $blog_id );
}

/**
 * Adds a group or set of groups to the list of global groups.
 *
 * @since 2.6.0
 *
 * @param string|array $groups A group or an array of groups to add
 */
function wp_cache_add_global_groups( $groups ) {
	global $wp_object_cache;

	return $wp_object_cache->add_global_groups( $groups );
}

/**
 * Adds a group or set of groups to the list of non-persistent groups.
 *
 * @since 2.6.0
 *
 * @param string|array $groups A group or an array of groups to add
 */
function wp_cache_add_non_persistent_groups( $groups ) {
	global $wp_object_cache;

	return $wp_object_cache->add_non_persistent_groups( $groups );
}

/**
 * Reset internal cache keys and structures. If the cache backend uses global
 * blog or site IDs as part of its cache keys, this function instructs the
 * backend to reset those keys and perform any cleanup since blog or site IDs
 * have changed since cache init.
 *
 * This function is deprecated. Use wp_cache_switch_to_blog() instead of this
 * function when preparing the cache for a blog switch. For clearing the cache
 * during unit tests, consider using wp_cache_init(). wp_cache_init() is not
 * recommended outside of unit tests as the performance penality for using it is
 * high.
 *
 * @since 2.6.0
 * @deprecated 3.5.0
 */
function wp_cache_reset() {
	_deprecated_function( __FUNCTION__, '3.5' );

	global $wp_object_cache;

	return $wp_object_cache->reset();
}


/**
 * WordPress APCu Object Cache
 *
 * @subpackage Cache
 * @since WP 2.0.0
 */
class WP_APCu_Object_Cache {

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

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

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

	/**
	 * The amount of times the APCu cache data was already stored in the cache.
	 *
	 * @since WP 2.5.0
	 * @access private
	 * @var int
	 */
	private $apcu_cache_hits = 0;

	/**
	 * Amount of times the APCu cache did not have the request in cache
	 *
	 * @var int
	 * @access public
	 * @since WP 2.0.0
	 */
	public $apcu_cache_misses = 0;

	/**
	 * List of global groups
	 *
	 * @var array
	 * @access protected
	 * @since WP 3.0.0
	 */
	protected $global_groups = array();

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

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

	/**
	 * Cache key prefix for multiple WordPress installations on one host
	 *
	 * @var string
	 * @access private
	 */
	private $prefix;

	/**
	 * List of non persistent groups
	 *
	 * @var array
	 * @access private
	 * @since WP 2.6.0
	 */
	private $non_persistent_groups = array();


	/**
	 * Make private properties readable for backwards compatibility.
	 *
	 * @since WP 4.0.0
	 * @access public
	 *
	 * @param string $name Property to get.
	 * @return mixed Property.
	 */
	public function __get( $name ) {

		return $this->$name;
	}

	/**
	 * Make private properties settable for backwards compatibility.
	 *
	 * @since WP 4.0.0
	 * @access public
	 *
	 * @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;
	}

	/**
	 * Make private properties checkable for backwards compatibility.
	 *
	 * @since WP 4.0.0
	 * @access public
	 *
	 * @param string $name Property to check if set.
	 * @return bool Whether the property is set.
	 */
	public function __isset( $name ) {

		return isset( $this->$name );
	}

	/**
	 * Make private properties un-settable for backwards compatibility.
	 *
	 * @since WP 4.0.0
	 * @access public
	 *
	 * @param string $name Property to unset.
	 */
	public function __unset( $name ) {

		unset( $this->$name );
	}

	/**
	 * Adds data to the cache if it doesn't already exist.
	 *
	 * @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.
	 *
	 * @since WP 2.0.0
	 *
	 * @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 Where to group the cache contents
	 * @param int $expire When to expire the cache contents
	 * @return bool False if cache key and group already exist, true on success
	 */
	public function add( $key, $data, $group = 'default', $expire = 0 ) {

		if ( wp_suspend_cache_addition() ) {
			return false;
		}

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

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

		if ( function_exists( 'apcu_exists' ) && apcu_exists( $this->prefix . ':' . $group . ':' . $id ) ) {
			return FALSE;
		}

		if ( isset( $this->non_persistent_groups[ $group ] ) && isset( $this->cache[ $group ][ $id ] ) ) {
			return FALSE;
		}

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

	/**
	 * Sets the list of global groups.
	 *
	 * @since WP 3.0.0
	 *
	 * @param array $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 );
	}

	/**
	 * Sets the list of non persistent groups.
	 *
	 * @since WP 2.6.0
	 *
	 * @param array $groups List of non persistent groups.
	 */
	public function add_non_persistent_groups( $groups ) {
		$groups = (array) $groups;

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

	/**
	 * Decrement numeric cache item's value
	 *
	 * @since WP 3.3.0
	 *
	 * @param int|string $key The cache key to increment
	 * @param int $offset The amount by which to decrement the item's value. Default is 1.
	 * @param string $group The group the key is in.
	 * @return false|int False on failure, the item's new value on success.
	 */
	public function decr( $key, $offset = 1, $group = 'default' ) {

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

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

		if ( ! isset( $this->cache[ $group ][ $key ] ) || ! 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;
		}

		if ( function_exists( 'apcu_dec' ) && ! isset( $this->non_persistent_groups[ $group ] ) ) {
			if ( ! apcu_exists( $this->prefix . ':' . $group . ':' . $key ) ) {
				return FALSE;
			}

			$this->cache[ $group ][ $key ] = apcu_dec($this->prefix . ':' . $group . ':' . $key, $offset );
			if ( $this->cache[ $group ][ $key ] < 0 ) {
				apcu_store( $this->prefix . ':' . $group . ':' . $key, 0 );
				$this->cache[ $group ][ $key ] = 0;
			}
		}

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

	/**
	 * Remove the contents of the cache key in the group
	 *
	 * If the cache key does not exist in the group, then nothing will happen.
	 *
	 * @since WP 2.0.0
	 *
	 * @param int|string $key What the contents in the cache are called
	 * @param string $group Where the cache contents are grouped
	 *
	 * @return bool False if the contents weren't deleted and true on success
	 */
	public function delete( $key, $group = 'default' ) {

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

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

		if ( isset( $this->cache[ $group ][ $key ] ) ) {
			unset( $this->cache[ $group ][ $key ] );
		}

		if ( !isset( $this->non_persistent_groups[ $group ] ) && function_exists( 'apcu_delete' ) ) {
			return apcu_delete( $this->prefix . ':' . $group . ':' . $key );
		} else {
			return TRUE;
		}
	}

	/**
	 * Clears the object cache of all data
	 *
	 * @since WP 2.0.0
	 *
	 * @return bool Always returns true
	 */
	public function flush() {

		$this->cache = array();

		if ( function_exists( 'apcu_cache_info' ) ) {
			$cache_info = apcu_cache_info();
			if ( ! empty( $cache_info[ 'cache_list' ] ) ) {
				foreach( $cache_info[ 'cache_list' ] as $entry ) {
					if ( strstr( $entry[ 'info' ], $this->prefix . ':' ) ) {
						apcu_delete( $entry[ 'info' ] );
					}
				}
			}
		}

		return true;
	}

	/**
	 * 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 WP 2.0.0
	 *
	 * @param int|string $key What the contents in the cache are called
	 * @param string $group Where the cache contents are grouped
	 * @param bool $force Whether to force a refetch rather than relying on the local cache (default is false)
	 * @return bool|mixed False on failure to retrieve contents or the cache
	 *		contents on success
	 */
	public function get( $key, $group = 'default', $force = false, &$found = null ) {

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

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

		if ( isset( $this->cache[ $group ][ $key ] ) && ( isset( $this->non_persistent_groups[ $group ] ) || ! $force ) ) {
			$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 ];
			}
		} elseif ( function_exists( 'apcu_fetch' ) && ! isset( $this->non_persistent_groups[ $group ] ) ) {
			$this->cache[ $group ][ $key ] = apcu_fetch( $this->prefix . ':' . $group . ':' . $key, $found );
			if ( $found ) {
				$this->apcu_cache_hits += 1;
				if ( is_object( $this->cache[ $group ][ $key ] ) ) {
					return clone $this->cache[ $group ][ $key ];
				} else {
					return $this->cache[ $group ][ $key ];
				}
			} else {
				$this->apcu_cache_misses += 1;
				return FALSE;
			}
		}

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

	/**
	 * Increment numeric cache item's value
	 *
	 * @since WP 3.3.0
	 *
	 * @param int|string $key The cache key to increment
	 * @param int $offset The amount by which to increment the item's value. Default is 1.
	 * @param string $group The group the key is in.
	 * @return false|int False on failure, the item's new value on success.
	 */
	public function incr( $key, $offset = 1, $group = 'default' ) {

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

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

		if ( ! isset( $this->cache[ $group ][ $key ] ) || ! 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;
		}

		if ( function_exists( 'apcu_inc' ) && ! isset( $this->non_persistent_groups[ $group ] ) ) {
			if ( ! apcu_exists( $this->prefix . ':' . $group . ':' . $key ) ) {
				return FALSE;
			}

			$this->cache[ $group ][ $key ] = apcu_inc( $this->prefix . ':' . $group . ':' . $key, $offset );
			if ( $this->cache[ $group ][ $key ] < 0 ) {
				apcu_store( $this->prefix . ':' . $group . ':' . $key, 0 );
				$this->cache[ $group ][ $key ] = 0;
			}
		}

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

	/**
	 * Replace the contents in the cache, if contents already exist
	 *
	 * @since WP 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 Where to group the cache contents
	 * @param int $expire When to expire the cache contents
	 * @return bool False if not exists, true if contents were replaced
	 */
	public function replace( $key, $data, $group = 'default', $expire = 0 ) {

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

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

		if ( ! isset( $this->cache[ $group ][ $id ] ) ) {
			return FALSE;
		}

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

	/**
	 * Reset keys
	 *
	 * @since WP 3.0.0
	 * @deprecated WP 3.5.0
	 */
	public function reset() {

		_deprecated_function( __FUNCTION__, '3.5', '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 ] );
			}
		}

		if ( function_exists( 'apcu_cache_info' ) ) {
			$cache_info = apcu_cache_info();
			if ( ! empty( $cache_info[ 'cache_list' ] ) ) {
				foreach( $cache_info[ 'cache_list' ] as $entry ) {
					list( $prefix, $group, $key ) = explode( ':', $entry[ 'info' ], 3 );
					if ( $prefix == $this->prefix && ! isset( $this->global_groups[ $group ] ) ) {
						apcu_delete( $entry[ 'info' ] );
					}
				}
			}
		}
	}

	/**
	 * Sets the data contents into the cache
	 *
	 * The cache contents is 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 WP 2.0.0
	 *
	 * @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 Where to group the cache contents
	 * @param int $expire Not Used
	 * @return bool Always returns true
	 */
	public function set( $key, $data, $group = 'default', $expire = 0 ) {

		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;

		if ( ! isset( $this->non_persistent_groups[ $group ] ) && function_exists( 'apcu_store' ) ) {
			return apcu_store( $this->prefix . ':' . $group . ':' . $key, $data, (int) $expire );
		}

		return TRUE;
	}

	/**
	 * Echoes the stats of the caching.
	 *
	 * Gives the cache hits, and cache misses. Also prints every cached group,
	 * key and the data.
	 *
	 * @since WP 2.0.0
	 */
	public function stats() {

		$non_persistent_groups = implode( ' ,', array_keys( $this->non_persistent_groups ) );

		echo "<p>";
		echo "<strong>Cache Hits:</strong> {$this->cache_hits}<br />";
		echo "<strong>Cache Misses:</strong> {$this->cache_misses}<br />";
		echo "<strong>APCu Cache Hits:</strong> {$this->apcu_cache_hits}<br />";
		echo "<strong>APCu Cache Misses:</strong> {$this->apcu_cache_misses}<br />";
		echo "<strong>Non persistent Groups:</strong> {$non_persistent_groups}<br />";
		echo "</p>";
		echo '<ul>';
		foreach ( $this->cache as $group => $cache ) {
			echo "<li><strong>Group:</strong> $group - ( " . number_format( strlen( serialize( $cache ) ) / 1024, 2 ) . 'k )</li>';
		}
		echo '</ul>';
	}

	/**
	 * Switch the interal blog id.
	 *
	 * This changes the blog id used to create keys in blog specific groups.
	 *
	 * @since WP 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 . ':' : '';
	}


	/**
	 * Sets up object properties
	 *
	 * @since WP 2.0.8
	 */
	public function __construct() {
		global $blog_id;

		$this->multisite = is_multisite();
		$this->blog_prefix = $this->multisite ? $blog_id . ':' : '';

		if ( defined( 'WP_APCU_CACHE_PREFIX' ) && WP_APCU_CACHE_PREFIX != '' ) {
			$this->prefix = WP_APCU_CACHE_PREFIX ;
		} else {
			$this->prefix = 'oc_' . trim( DB_NAME );
		}
	}

	/**
	 * Will save the object cache before object is completely destroyed.
	 *
	 * Called upon object destruction, which should be when PHP ends.
	 *
	 * @since  WP 2.0.8
	 *
	 * @return bool True value. Won't be used by PHP
	 */
	public function __destruct() {

		return true;
	}
}