public function __construct(string $protocol = null)
{
if ($protocol !== null) {
$this->mConnection = Database::newInstance($protocol);
} else {
$this->mConnection = Database::getInstance();
}
if ($this->mConnection === null || !$this->mConnection->isConnected()) {
throw new Exception("Could not connect to the database '{$protocol}'");
}
if (mt_rand(0, 100) == 100) {
$time = time();
$this->mConnection->delete("cache")->cond("cExpires", "i", time(), "<")->cond("cExpires", "i", 0, ">")->execute();
}
}
