Using a cache
*
*
* // foo is any name (try to be specific), and is used to get configuration
* // & storage info
* $cache = SS_Cache::factory('foo');
*
* if (!($result = $cache->load($cachekey))) {
* $result = caluate some how;
* $cache->save($result);
* }
*
* return $result;
*
*
* Normally there's no need to remove things from the cache - the cache
* backends clear out entries based on age & maximum allocated storage. If you
* include the version of the object in the cache key, even object changes
* don't need any invalidation.
*
* Disabling cache in dev mode
*
*
* // _config.php
* if (Director::isDev()) {
* SS_Cache::set_cache_lifetime('any', -1, 100);
* //
*
*
* Using memcached as a store
*
*
* // _config.php
* SS_Cache::add_backend(
* 'primary_memcached',
* 'Memcached',
* array(
* 'host' => 'localhost',
* 'port' => 11211,
* 'persistent' => true,
* 'weight' => 1,
* 'timeout' => 5,
* 'retry_interval' => 15,
* 'status' => true,
* 'failure_callback' => ''
* )
* );
*
* SS_Cache::pick_backend('primary_memcached', 'any', 10);
*
* // Aggregate needs a backend with tag support, which memcached doesn't
* // provide
* SS_Cache::pick_backend('default', 'aggregate', 20);
*
*
* Using APC as a store
*
*
* SS_Cache::add_backend('two-level', 'TwoLevels', array(
* 'slow_backend' => 'File',
* 'fast_backend' => 'Apc',
* 'slow_backend_options' => array(
* 'cache_dir' => TEMP_FOLDER . DIRECTORY_SEPARATOR . 'cache'
* )
* ));
*
* // No need for special backend for aggregate - TwoLevels with a File slow
* // backend supports tags
* SS_Cache::pick_backend('two-level', 'any', 10);
*
*
* Invalidate an element
*
*
* $cache = SS_Cache::factory('foo');
* $cache->remove($cachekey);
*
*
* Clear the cache
*
* This clears the entire backend, not just this named cache partition.
*
*
* $cache = SS_Cache::factory('foo');
* $cache->clean(Zend_Cache::CLEANING_MODE_ALL);
*
*
* @package framework
* @subpackage core
*/
class SS_Cache {
/**
* @var array $backends
*/
protected static $backends = array();
/**
* @var array $backend_picks
*/
protected static $backend_picks = array();
/**
* @var array $cache_lifetime
*/
protected static $cache_lifetime = array();
/**
* Initialize the 'default' named cache backend.
*/
protected static function init(){
if (!isset(self::$backends['default'])) {
$cachedir = TEMP_FOLDER . DIRECTORY_SEPARATOR . 'cache';
if (!is_dir($cachedir)) {
mkdir($cachedir);
}
self::$backends['default'] = array(
'File',
array(
'cache_dir' => $cachedir
)
);
self::$cache_lifetime['default'] = array(
'lifetime' => 600,
'priority' => 1
);
}
}
/**
* Add a new named cache backend.
*
* @see http://framework.zend.com/manual/en/zend.cache.html
*
* @param string $name The name of this backend as a freeform string
* @param string $type The Zend_Cache backend ('File' or 'Sqlite' or ...)
* @param array $options The Zend_Cache backend options
*
* @return none
*/
public static function add_backend($name, $type, $options = array()) {
self::init();
self::$backends[$name] = array($type, $options);
}
/**
* Pick a named cache backend for a particular named cache.
*
* The priority call with the highest number will be the actual backend
* picked. A backend picked for a specific cache name will always be used
* instead of 'any' if it exists, no matter the priority.
*
* @param string $name The name of the backend, as passed as the first argument to add_backend
* @param string $for The name of the cache to pick this backend for (or 'any' for any backend)
* @param integer $priority The priority of this pick
*
* @return none
*/
public static function pick_backend($name, $for, $priority = 1) {
self::init();
$current = -1;
if (isset(self::$backend_picks[$for])) {
$current = self::$backend_picks[$for]['priority'];
}
if ($priority >= $current) {
self::$backend_picks[$for] = array(
'name' => $name,
'priority' => $priority
);
}
}
/**
* Return the cache lifetime for a particular named cache.
*
* @param string $for
*
* @return string
*/
public static function get_cache_lifetime($for) {
if(isset(self::$cache_lifetime[$for])) {
return self::$cache_lifetime[$for];
}
return null;
}
/**
* Set the cache lifetime for a particular named cache
*
* @param string $for The name of the cache to set this lifetime for (or 'any' for all backends)
* @param integer $lifetime The lifetime of an item of the cache, in seconds, or -1 to disable caching
* @param integer $priority The priority. The highest priority setting is used. Unlike backends, 'any' is not
* special in terms of priority.
*/
public static function set_cache_lifetime($for, $lifetime=600, $priority=1) {
self::init();
$current = -1;
if (isset(self::$cache_lifetime[$for])) {
$current = self::$cache_lifetime[$for]['priority'];
}
if ($priority >= $current) {
self::$cache_lifetime[$for] = array(
'lifetime' => $lifetime,
'priority' => $priority
);
}
}
/**
* Build a cache object.
*
* @see http://framework.zend.com/manual/en/zend.cache.html
*
* @param string $for The name of the cache to build
* @param string $frontend (optional) The type of Zend_Cache frontend
* @param array $frontendOptions (optional) Any frontend options to use.
*
* @return Zend_Cache_Frontend The cache object
*/
public static function factory($for, $frontend='Output', $frontendOptions=null) {
self::init();
$backend_name = 'default';
$backend_priority = -1;
$cache_lifetime = self::$cache_lifetime['default']['lifetime'];
$lifetime_priority = -1;
foreach(array('any', $for) as $name) {
if(isset(self::$backend_picks[$name])) {
if(self::$backend_picks[$name]['priority'] > $backend_priority) {
$backend_name = self::$backend_picks[$name]['name'];
$backend_priority = self::$backend_picks[$name]['priority'];
}
}
if (isset(self::$cache_lifetime[$name])) {
if(self::$cache_lifetime[$name]['priority'] > $lifetime_priority) {
$cache_lifetime = self::$cache_lifetime[$name]['lifetime'];
$lifetime_priority = self::$cache_lifetime[$name]['priority'];
}
}
}
$backend = self::$backends[$backend_name];
$basicOptions = array('cache_id_prefix' => $for);
if ($cache_lifetime >= 0) {
$basicOptions['lifetime'] = $cache_lifetime;
} else {
$basicOptions['caching'] = false;
}
$frontendOptions = $frontendOptions ? array_merge($basicOptions, $frontendOptions) : $basicOptions;
require_once 'Zend/Cache.php';
return Zend_Cache::factory(
$frontend, $backend[0], $frontendOptions, $backend[1]
);
}
}