<?php
/**
 * Implementation methode Memoization
 *
 * @package SPIP\memoization\Memo
 **/

// Sécurité
if (!defined('_ECRIRE_INC_VERSION')){
	return;
}

# http://xcache.lighttpd.net/wiki/XcacheApi
if (!defined('_CACHE_NAMESPACE')){
	define('_CACHE_NAMESPACE', $_SERVER["SERVER_NAME"] . ":" . $_SERVER["SERVER_PORT"] . ":");
}
if (!defined('_LOCK_MAX')){
	define('_LOCK_MAX', 30);
} # max lock time (seconds)


class MCacheBackend_xcache implements MCacheBackend {

	/* Interface */

	public function init($params = null){

	}

	public function get($key){
		$a = @xcache_get(_CACHE_NAMESPACE . $key);
		// maybe_unserialize
		if (is_array($a)){
			return @unserialize($a[0]);
		} else {
			return $a;
		}
	}

	public function set($key, $value, $ttl = null){
		// maybe_serialize
		if (is_object($value) or is_array($value)){
			$value = array(serialize($value));
		}
		return is_null($ttl)
			? xcache_set(_CACHE_NAMESPACE . $key, $value)
			: xcache_set(_CACHE_NAMESPACE . $key, $value, $ttl);
	}

	public function exists($key){
		return xcache_isset(_CACHE_NAMESPACE . $key);
	}

	public function del($key){
		return xcache_unset(_CACHE_NAMESPACE . $key);
	}

	public function inc($key, $value = null, $ttl = null){
		$a = func_get_args();
		$a[0] = _CACHE_NAMESPACE . $key;
		return call_user_func_array('xcache_inc', $a);
	}

	public function dec($key, $value = null, $ttl = null){
		$a = func_get_args();
		$a[0] = _CACHE_NAMESPACE . $key;
		return call_user_func_array('xcache_dec', $a);
	}

	public function lock($key, /* private */ $unlock = false){
		static $locks = array();

		/* unlock */
		if ($unlock){
			unset($locks[$key]);
			$this->del('lock::' . $key);
		} /* lock */
		else {
			# si on l'a deja, ok
			if (isset($locks[$key])){
				return true;
			}

			# sinon s'il existe, on attend qu'il se libere
			$wait = 0;
			while ($this->exists('lock::' . $key)){
				if ($wait++<_LOCK_MAX){
					sleep(1);
				} else {
					return false;
				}
			}

			# ... puis on le pose
			if ($this->inc('lock::' . $key, 1, _LOCK_MAX)<=1){
				$locks[$key] = true;
				register_shutdown_function(array($this, 'unlock'), $key);
				return true;
			}

			return false;
		}
	}

	public function unlock($key){
		$this->lock($key, true);
	}

	public function size(){
		# necessite xcache.admin.user
		#$a = xcache_list();
		#var_dump($a);
		return false;
	}

	public function purge(){
		return false;
	}

}