add ภาพพร้อมกันลงฐานข้อมูล แต่ไม่ให้ชื่อภาพซ้ำกัน

function newName($len)
			{
					srand((double)microtime()*10000000);
					$chars = "ABCDEFGHJKLMNPQRSTUVWXYZ0123456789";
					$ret_str = "";
					$num = strlen($chars);
					for($i = 0; $i < $len; $i++)
					{
						$ret_str.= $chars[rand()%$num];
						$ret_str.=""; 
					}
					return $ret_str; 
			} 

sleep(2);
if(!empty($_FILES)) {
	$path = "../images/product/";
	//@chmod($path,0777);
	$name = $_FILES['Filedata']['name'];
	$size = $_FILES['Filedata']['size'];
	if(strlen($name)){
	list($txt, $ext) = explode(".", $name);
		$actual_image_name = time().substr(str_replace(" ", "_", $txt), 20).".".$ext;
		$tmp = $_FILES['Filedata']['tmp_name'];
		move_uploaded_file($tmp,$path.$actual_image_name);
	}