Moja implementacja "keszu" Opcje

[q.michal]

Witam,

Chcialbym dzis pdozielic sie swoim kolejnym wynalazkiem - obsluga keszu. Jest to co prawda dopiero zalazek tego co chce zrobic, albowiem brakuje metod odpowiedzialnych za obsluge danych, niemniej sposob 'komunikacji' ze sterownikiem widac na przykladzie metody Cache::dumpCache(); Docelowo zamierzam napisac takze wiecej sterownikow, zapewniajac dostep do: APC, eAccelerator, Dummy, File, MemCache, SQLite, WinCache, XCache. Zastanawiam sie takze nad mozliwoscia przechowywania keszu w cookies.

Jednoczesnie prosze o ocene oraz komentarze - czyli ogolnie mowiac code review (IMG:style_emoticons/default/wink.gif)
Jestem otwarty na wszelkie sugestie i uwagi poparte jakimkolwiek argumentem.

Pozdrawiam serdecznie.

[PHP] pobierz, plaintext 
abstract class CacheAbstract {
 
	/**
	 * Disables object cloning
	 *
	 * @return	void		does not return any value
	 */
	protected function __clone() {
		throw new Exception('Cloning Cache objects is not allowed!');
	}
 
	/**
	 * Class constructor
	 *
	 * @return	void		does not return any value
	 */
	protected function __construct() {
	}
 
} /* class */
 
 
interface CacheDriver {
 
	/**
	 * Adds an object to the cache
	 *
	 * @param	string		stores the variable using this name, should be a cache-unique name
	 * @param	mixed		the variable to store in cache
	 * @param	integer		time-to-live of cached data
	 * @return	boolean		TRUE on success, FALSE otherwise
	 */
	public function addValue($key, $var, $ttl = 300);
 
	/**
	 * Returns a dump of all files and user variables from the cache
	 *
	 * @return	string		dump of the user variables, or NULL if an unknown error encountered
	 */
	public function dumpCache();
 
	/**
	 * Flushes (clears) the user and system cache
	 *
	 * @return	void		does not return any value
	 */
	public function flushCache();
 
	/**
	 * Provides a statistics and meta-data of caching subsystem
	 *
	 * @return	array		array containing cache statistics
	 */
	public function getStatistics();
 
	/**
	 * Fetches a stored variable from the cache
	 *
	 * @param	string		key name used to store the value
	 * @return	mixed		stored variable on success, FALSE otherwise
	 */
	public function getValue($key);
 
	/**
	 * Checks if container contains an item stored under this key name
	 *
	 * @param	string		key name used to store the value
	 * @return	boolean		TRUE if the key exists, FALSE otherwise
	 */
	public function isCached($key);
 
	/**
	 * Checks whether the chosen driver is supported by PHP installation
	 *
	 * @return	boolean		TRUE if driver can be used, FALSE otherwise
	 */
	public function isSupported();
 
	/**
	 * Removes a stored variable from the cache
	 * @param	string		key name used to store the value
	 * @return	boolean		TRUE on success, FALSE otherwise
	 */
	public function removeValue($key);
 
} /* class */
 
 
final class CacheDriverApc extends CacheAbstract implements CacheDriver {
 
	/**
	 * Adds an object to the cache
	 *
	 * @param	string		stores the variable using this name, should be a cache-unique name
	 * @param	mixed		the variable to store in cache
	 * @param	integer		time-to-live of cached data
	 * @return	boolean		TRUE on success, FALSE otherwise
	 */
	public function addValue($key, $var, $ttl = 300) {
		return apc_store($key, $var, $ttl);
	}
 
	/**
	 * Returns a dump of all files and user variables from the cache
	 *
	 * @return	string		dump of the user variables, or NULL if an unknown error encountered
	 */
	public function dumpCache() {
		return apc_bin_dump();
	}
 
	/**
	 * Flushes (clears) the user and system cache
	 *
	 * @return	void		does not return any value
	 */
	public function flushCache() {
		apc_clear_cache();
		apc_clear_cache('user');
	}
 
	/**
	 * Provides a statistics and meta-data of caching subsystem
	 *
	 * @return	array		array containing cache statistics
	 */
	public function getStatistics() {
		return array('data' => apc_cache_info('user'), 'info' => '', 'size' => '');
	}
 
	/**
	 * Fetches a stored variable from the cache
	 *
	 * @param	string		key name used to store the value
	 * @return	mixed		stored variable on success, FALSE otherwise
	 */
	public function getValue($key) {
		$var = apc_fetch($key, $result);
		if(!$result) {
			return false;
		}
		return $var;
	}
 
	/**
	 * Checks if container contains an item stored under this key name
	 *
	 * @param	string		key name used to store the value
	 * @return	boolean		TRUE if the key exists, FALSE otherwise
	 */
	public function isCached($key) {
		return (bool) apc_exists($key);
	}
 
	/**
	 * Checks whether the chosen driver is supported by PHP installation
	 *
	 * @return	boolean		TRUE if driver can be used, FALSE otherwise
	 */
	public function isSupported() {
		if(!extension_loaded('apc') || !ini_get('apc.enabled')) {
			return false;
		}
		return true;
	}
 
	/**
	 * Removes a stored variable from the cache
	 * @param	string		key name used to store the value
	 * @return	boolean		TRUE on success, FALSE otherwise
	 */
	public function removeValue($key) {
		return apc_delete($key);
	}
 
} /* class */
 
 
final class Cache extends CacheAbstract {
	private $driver;
	private $storage;
 
	/**
	 * Class constructor.
	 *
	 * @param	string		specifies primary cache driver
	 * @param	string		specifies secondary (failover) cache driver
	 * @return	object		the Cache object
	 */
	protected function __construct($driver, $failover) {
		if(!$this->loadDriver($driver)) {
			if(!$this->loadDriver($failover)) {
				$this->loadDriver('dummy');
			}
		}
	}
 
	/**
	 * Returns a dump of all files and user variables from the cache
	 *
	 * @return	string		dump of the user variables, or NULL if an unknown error encountered
	 */
	public function dumpCache() {
		return $this->storage->dumpCache();
	}
 
	/**
	 * Returns a name of currently used cache storage driver
	 *
	 * @return	string		name of used storage driver
	 */
	public function getDriver() {
		return $this->driver;
	}
 
	/**
	 * Returns the global Cache object, creating it only if it does not exist already
	 *
	 * @param	string		specifies primary cache driver
	 * @param	string		specifies secondary (failover) cache driver
	 * @return	object		the Cache object
	 */
	public static function getInstance($driver = 'file', $failover = 'dummy') {
		static $instance;
		if(!isset($instance)) {
			$instance = new Cache($driver, $failover);
		}
		return $instance;
	}
 
	/**
	 * Returns a list of available cache storage drivers
	 *
	 * @return	array		an array containing a list of available cache drivers
	 */
	public static function getStorageList() {
		$list = array();
		$directory = System::getSystemDir() . '/cache/driver';
		$dh = opendir($directory);
		while(($filename = readdir($dh)) !== false) {
			$driver = substr($filename, 0, strrpos($filename, '.'));
			if($driver != '' && $driver != '.') {
				$list[] = $driver;
			}
		}
		return $list;
	}
 
	/**
	 * Loads the specified cache driver
	 *
	 * @param	string		cache driver to load
	 * @return	boolean		TRUE on success, FALSE otherwise
	 */
	private function loadDriver($driver) {
		if(in_array($driver, $this->getStorageList())) {
			$class = 'CacheDriver' . ucfirst($driver);
			$this->storage = new $class();
			if($this->storage->isSupported()) {
				$this->driver = $driver;
				return true;
			}
		}
		return false;
	}
 
} /* class */
[PHP] pobierz, plaintext 

[q.michal]

Ciekawe zestawienie. Watpie jednak, aby ktos pakowal tak duze porcje danych do cache. Sporo interpreterow ma limit pamieci ustawiony na 64-128MB AFAIK. Wynika wiec z tego ze musialbys wsadzic (niemal) caly skrypt do cache.
Pytajac o serializacja bardziej oabwialem sie narzutu pamieci/CPU niezbednego na wykonanie serializacji przy zapisie i deserializacji przy odczycie. Z tego benchmarku wynika jednak, ze to nie powinno byc problemem.

Lockowanie ma ta zalete, ze inny watek (request) nie nadpisze Ci tych danych. Teoretycznie istnieje ryzyko, ze 2 requesty odpalone w tym samym czasie beda chcialy cos zapisac do tego pliku i wtedy jego zawartosc moze byc inna niz sie tego spodziewasz. Exclusive lock sprawia, ze inny watek nie bedzie w stanie sie w miedzyczasie dokleic do pliku i uwazam ze warto to dopisac. Sam zreszta stosuje tego locka (IMG:style_emoticons/default/wink.gif)

Przemysle odsmiecanie, choc nie jestem teraz pewien czy we wszystkich magazynach da sie to osiagnac i jaki bylby narzut.
Jezeli chodzi o pliki, to trzeba byloby sie przeiterowac po wszystkich istniejacych plikach, zaladowac je, sprawdzic czy nie wygasly i ew usunac. Musialbym jeszcze sprawdzic czy np. APC oferuje taka mozliwosc.