MemoryCache::freeMemory

static function freeMemory()
{
	foreach (static::$cache as $entityTypeId => &$tmp)
	{
		$hit = static::$hit[$entityTypeId] ?? 0;
		$miss = static::$miss[$entityTypeId] ?? 0;
		if (
			($miss + $hit) == 0 //no info
			|| ($hit / ($miss + $hit)) < static::$hitRatio //or bad ratio
		)
		{
			unset(static::$cache[$entityTypeId]);
			unset(static::$hit[$entityTypeId]);
			unset(static::$miss[$entityTypeId]);
		}
	}
	unset($tmp);
	static::$hitRatio += 0.1;
}