Pool::decreaseSize

protected function decreaseSize(int $delta, array $items): array
{
	if($delta <= 0 || count($items) <= 0)
	{
		return $items;
	}

	do
	{
		reset($items);
		unset($items[key($items)]);
		$delta--;
	}
	while($delta > 0);

	return $items;
}