Specifying socket option on mysqli_connect

I have two mysql.sock file.

One is at /opt/lampp/var/mysql/mysql.sock.

Another one is at /var/run/mysqld/mysqld.sock.

I want to create a connection using first mysql.sock file.

I also set the default_socket in php.ini.

But it always connect to second one.

The program won't be error, even if I use wrong path of mysql.sock.

This is my code:

<?php
$servername = "127.0.0.1";
$username = "my_username";
$password = "my_password";
$database = "";
$port = "3306";
$socket = "/opt/lampp/var/mysql/mysql.sock";

// Create connection
$conn = new mysqli($servername, $username, $password, $database, $port, $socket);

//Check the host info
echo $conn->host_info."\n";

// Check connection
if ($conn->connect_errno) {
    printf("Connect failed: %s\n", $conn->connect_error);
    exit();
}

$conn->query("set character set utf8");

//Which socket did I connect?
$result = $conn->query("SHOW VARIABLES WHERE Variable_name = 'socket';");
$row = mysqli_fetch_assoc($result);
echo $row['Value']."\n";

//Check the default_socket in php.ini file
echo ini_get("mysqli.default_socket");
?>

The output is:

127.0.0.1 via TCP/IP

/var/run/mysqld/mysqld.sock

/opt/lampp/var/mysql/mysql.sock

How to solve this problem?

Update:

ls -l /opt/lampp/var/mysql/mysql.sock /var/run/mysqld/mysqld.sock

Output is

srwxrwxrwx 1 mysql mysql 0 7月 13 18:10 /opt/lampp/var/mysql/mysql.sock

srwxrwxrwx 1 mysql mysql 0 7月 6 21:06 /var/run/mysqld/mysqld.sock