Penerapan algoritma fifo kedalam array web

Hallo ka, bagaimana cara saya menambahkan algoritma fifo kedalam kodingan array dalam web saya ya ka? Disini saya ingin menambahkan algoritma fifo kedalam list data pemesanan

<?php
defined('BASEPATH') OR exit('No direct script access allowed');

class Transaksi_model extends CI_Model {

	public function __construct()
	{
		parent::__construct();
		$this->load->database();
	}

	// Listing all transaksi
	public function listing()
	{
		$this->db->select('*');
		$this->db->from('transaksi');
		$this->db->order_by('id_transaksi', 'desc');
		$query = $this->db->get();
		return $query->result();
	}

	// Listing all transaksi berdasarkanheader
	public function kode_transaksi($kode_transaksi)
	{
		$this->db->select('transaksi.*,
			produk.nama_produk,
			produk.kode_produk');
		$this->db->from('transaksi');
		//join dg produk
		$this->db->join('produk', 'produk.id_produk = transaksi.id_produk', 'left');
		//end join
		$this->db->where('kode_transaksi', $kode_transaksi);
		$this->db->order_by('id_transaksi', 'desc');
		$query = $this->db->get();
		return $query->result();
	}

	// Detail transaksi
	public function detail($id_transaksi)
	{
		$this->db->select('*');
		$this->db->from('transaksi');
		$this->db->where('id_transaksi', $id_transaksi);
		$this->db->order_by('id_transaksi', 'desc');
		$query = $this->db->get();
		return $query->row();
	}

	// Detail slug transaksi
	public function read($slug_transaksi)
	{
		$this->db->select('*');
		$this->db->from('transaksi');
		$this->db->where('slug_transaksi', $slug_transaksi);
		$this->db->order_by('id_transaksi', 'desc');
		$query = $this->db->get();
		return $query->row();
	}

	// Login transaksi
	public function login($transaksiname,$password)
	{
		$this->db->select('*');
		$this->db->from('transaksi');
		$this->db->where(array('transaksiname'	=> $transaksiname,
								'password'	=> SHA1($password)));
		$this->db->order_by('id_transaksi', 'desc');
		$query = $this->db->get();
		return $query->row();
	}

	// Tambah
	public function tambah($data)
	{
		$this->db->insert('transaksi', $data);
	}

	// Edit
	public function edit($data)
	{
		$this->db->where('id_transaksi', $data['id_transaksi']);
		$this->db->update('transaksi',$data);
	}

	// Delete
	public function delete($data)
	{
		$this->db->where('id_transaksi', $data['id_transaksi']);
		$this->db->delete('transaksi',$data);
	}

}

/* End of file Transaksi_model.php */
/* Location: ./application/models/Transaksi_model.php */