Web.Admin/2014/wordpress/wp-includes/cache.php
<?php
/**
* Object Cache API
*
* @link http://codex.wordpress.org/Function_Reference/WP_Cache
*
* @package WordPress
* @subpackage Cache
*/
/**
* Adds data to the cache, if the cache key doesn't aleady exist.
*
* @since 2.0.0
* @uses $wp_object_cache Object Cache Class
* @see WP_Object_Cache::add()
*
* @param int|string $key The cache ID to use for retrieval later
* @param mixed $data The data to add to the cache store
* @param string $flag The group to add the cache to
* @param int $expire When the cache data should be expired
* @return unknown
*/
function wp_cache_add($key, $data, $flag = '', $expire = 0) {
global $wp_object_cache;
return $wp_object_cache->add($key, $data, $flag, $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 persistant 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;
}
/**
* Removes the cache contents matching ID and flag.
*
* @since 2.0.0
* @uses $wp_object_cache Object Cache Class
* @see WP_Object_Cache::delete()
*
* @param int|string $id What the contents in the cache are called
* @param string $flag Where the cache contents are grouped
* @return bool True on successful removal, false on failure
*/
function wp_cache_delete($id, $flag = '') {
global $wp_object_cache;
return $wp_object_cache->delete($id, $flag);
}
/**
* Removes all cache items.
*
* @since 2.0.0
* @uses $wp_object_cache Object Cache Class
* @see WP_Object_Cache::flush()
*
* @return bool Always returns true
*/
function wp_cache_flush() {
global $wp_object_cache;
return $wp_object_cache->flush();
}
/**
* Retrieves the cache contents from the cache by ID and flag.
*
* @since 2.0.0
* @uses $wp_object_cache Object Cache Class
* @see WP_Object_Cache::get()
*
* @param int|string $id What the contents in the cache are called
* @param string $flag Where the cache contents are grouped
* @return bool|mixed False on failure to retrieve contents or the cache
* contents on success
*/
function wp_cache_get($id, $flag = '') {
global $wp_object_cache;
return $wp_object_cache->get($id, $flag);
}
/**
* Sets up Object Cache Global and assigns it.
*
* @since 2.0.0
* @global WP_Object_Cache $wp_object_cache WordPress Object Cache
*/
function wp_cache_init() {
$GLOBALS['wp_object_cache'] =& new WP_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 $id What to call the contents in the cache
* @param mixed $data The contents to store in the cache
* @param string $flag Where to group the cache contents
* @param int $expire When to expire the cache contents
* @return bool False if cache ID and group already exists, true on success
*/
function wp_cache_replace($key, $data, $flag = '', $expire = 0) {
global $wp_object_cache;
return $wp_object_cache->replace($key, $data, $flag, $expire);
}
/**
* Saves the data to the cache.
*
* @since 2.0
* @uses $wp_object_cache Object Cache Class
* @see WP_Object_Cache::set()
*
* @param int|string $id What to call the contents in the cache
* @param mixed $data The contents to store in the cache
* @param string $flag Where to group the cache contents
* @param int $expire When to expire the cache contents
* @return bool False if cache ID and group already exists, true on success
*/
function wp_cache_set($key, $data, $flag = '', $expire = 0) {
global $wp_object_cache;
return $wp_object_cache->set($key, $data, $flag, $expire);
}
/**
* 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 ) {
// Default cache doesn't persist so nothing to do here.
return;
}
/**
* 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 ) {
// Default cache doesn't persist so nothing to do here.
return;
}
/**
* WordPress 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.
*
* @package WordPress
* @subpackage Cache
* @since 2.0
*/
class WP_Object_Cache {
/**
* Holds the cached objects
*
* @var array
* @access private
* @since 2.0.0
*/
var $cache = array ();
/**
* Cache objects that do not exist in the cache
*
* @var array
* @access private
* @since 2.0.0
*/
var $non_existant_objects = array ();
/**
* The amount of times the cache data was already stored in the cache.
*
* @since 2.5.0
* @access private
* @var int
*/
var $cache_hits = 0;
/**
* Amount of times the cache did not have the request in cache
*
* @var int
* @access public
* @since 2.0.0
*/
var $cache_misses = 0;
/**
* Adds data to the cache if it doesn't already exist.
*
* @uses WP_Object_Cache::get Checks to see if the cache already has data.
* @uses WP_Object_Cache::set Sets the data after the checking the cache
* contents existance.
*
* @since 2.0.0
*
* @param int|string $id 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 $expire When to expire the cache contents
* @return bool False if cache ID and group already exists, true on success
*/
function add($id, $data, $group = 'default', $expire = '') {
if (empty ($group))
$group = 'default';
if (false !== $this->get($id, $group, false))
return false;
return $this->set($id, $data, $group, $expire);
}
/**
* Remove the contents of the cache ID in the group
*
* If the cache ID does not exist in the group and $force parameter is set
* to false, then nothing will happen. The $force parameter is set to false
* by default.
*
* On success the group and the id will be added to the
* $non_existant_objects property in the class.
*
* @since 2.0.0
*
* @param int|string $id What the contents in the cache are called
* @param string $group Where the cache contents are grouped
* @param bool $force Optional. Whether to force the unsetting of the cache
* ID in the group
* @return bool False if the contents weren't deleted and true on success
*/
function delete($id, $group = 'default', $force = false) {
if (empty ($group))
$group = 'default';
if (!$force && false === $this->get($id, $group, false))
return false;
unset ($this->cache[$group][$id]);
$this->non_existant_objects[$group][$id] = true;
return true;
}
/**
* Clears the object cache of all data
*
* @since 2.0.0
*
* @return bool Always returns true
*/
function flush() {
$this->cache = array ();
return true;
}
/**
* Retrieves the cache contents, if it exists
*
* The contents will be first attempted to be retrieved by searching by the
* ID in the cache group. If the cache is hit (success) then the contents
* are returned.
*
* On failure, the $non_existant_objects property is checked and if the
* cache group and ID exist in there the cache misses will not be
* incremented. If not in the nonexistant objects property, then the cache
* misses will be incremented and the cache group and ID will be added to
* the nonexistant objects.
*
* @since 2.0.0
*
* @param int|string $id What the contents in the cache are called
* @param string $group Where the cache contents are grouped
* @return bool|mixed False on failure to retrieve contents or the cache
* contents on success
*/
function get($id, $group = 'default') {
if (empty ($group))
$group = 'default';
if (isset ($this->cache[$group][$id])) {
$this->cache_hits += 1;
if ( is_object($this->cache[$group][$id]) )
return wp_clone($this->cache[$group][$id]);
else
return $this->cache[$group][$id];
}
if ( isset ($this->non_existant_objects[$group][$id]) )
return false;
$this->non_existant_objects[$group][$id] = true;
$this->cache_misses += 1;
return false;
}
/**
* Replace the contents in the cache, if contents already exist
*
* @since 2.0.0
* @see WP_Object_Cache::set()
*
* @param int|string $id 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 $expire When to expire the cache contents
* @return bool False if not exists, true if contents were replaced
*/
function replace($id, $data, $group = 'default', $expire = '') {
if (empty ($group))
$group = 'default';
if (false === $this->get($id, $group, false))
return false;
return $this->set($id, $data, $group, $expire);
}
/**
* Sets the data contents into the cache
*
* The cache contents is grouped by the $group parameter followed by the
* $id. 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
*
* @param int|string $id 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 $expire Not Used
* @return bool Always returns true
*/
function set($id, $data, $group = 'default', $expire = '') {
if (empty ($group))
$group = 'default';
if (NULL === $data)
$data = '';
if ( is_object($data) )
$data = wp_clone($data);
$this->cache[$group][$id] = $data;
if(isset($this->non_existant_objects[$group][$id]))
unset ($this->non_existant_objects[$group][$id]);
return true;
}
/**
* Echos the stats of the caching.
*
* Gives the cache hits, and cache misses. Also prints every cached group,
* key and the data.
*
* @since 2.0.0
*/
function stats() {
echo "<p>";
echo "<strong>Cache Hits:</strong> {$this->cache_hits}<br />";
echo "<strong>Cache Misses:</strong> {$this->cache_misses}<br />";
echo "</p>";
foreach ($this->cache as $group => $cache) {
echo "<p>";
echo "<strong>Group:</strong> $group<br />";
echo "<strong>Cache:</strong>";
echo "<pre>";
print_r($cache);
echo "</pre>";
}
}
/**
* PHP4 constructor; Calls PHP 5 style constructor
*
* @since 2.0.0
*
* @return WP_Object_Cache
*/
function WP_Object_Cache() {
return $this->__construct();
}
/**
* Sets up object properties; PHP 5 style constructor
*
* @since 2.0.8
* @return null|WP_Object_Cache If cache is disabled, returns null.
*/
function __construct() {
/**
* @todo This should be moved to the PHP4 style constructor, PHP5
* already calls __destruct()
*/
register_shutdown_function(array(&$this, "__destruct"));
}
/**
* Will save the object cache before object is completely destroyed.
*
* Called upon object destruction, which should be when PHP ends.
*
* @since 2.0.8
*
* @return bool True value. Won't be used by PHP
*/
function __destruct() {
return true;
}
}
?>