/**
* Factory method that creates a CacheHandler instance and instantiate a
* BagOStuff object from available settings ($smwgCacheType) while
* invoking additional parameters ($wgCachePrefix etc.)
*
* @par Example:
* @code
* $cache = new CacheHandler::newFromId()->setkey( new CachIdGenerator( 'Foo' ) )
*
* $cache->set( 'CacheableObject' )
* $cache->get() returns 'CacheableObject'
* $cache->delete() deletes 'CacheableObject'
* @endcode
*
* @note If a BagOStuff instance is not available setCacheEnabled() is
* disabled by default which prevents to run into unintended behaviour
* while trying to access BagOStuff methods.
*
* @note This method is exposed to $wgObjectCaches, $wgCachePrefix globals
* which can't and shouldn't be accessed otherwise. It is the task of this
* method alone to invoke globals and avoid leakage into the object
* life cycle.
*
* @note This method serves invoked instances from a static variable due to
* the fact that the actual working object is being accessed through
* getCache() and therefore not in direct conflict with its testability.
*
* @since 1.9
*
* @param string $id Ids available in wgObjectCaches
*
* @return CacheHandler
*/
public static function newFromId($id = false)
{
$cacheType = $id ? $id : Settings::newFromGlobals()->get('smwgCacheType');
if (!isset(self::$instance[$cacheType])) {
if ($cacheType && array_key_exists($cacheType, $GLOBALS['wgObjectCaches'])) {
$cache = new self(ObjectCache::getInstance($cacheType));
} else {
$cache = new self();
}
$cache->setCacheEnabled(true);
self::$instance[$cacheType] = $cache;
}
return self::$instance[$cacheType];
}
