Added cache to "order status" labels in Mage_Sales_Model_Order_Config

[elidrissidev]

Description (*)

A small performance improvement when retrieving Order status labels (either from Mage_Sales_Model_Order or Mage_Sales_Model_Order_Status_History) which is now going to check an array that serves as a cache first before loading them from the database if they don't exist.

Before, this resulted in a database query per every invocation, which resulted in many duplicate queries (found it by DebugBar extension I'm creating ;) ).

Manual testing scenarios

<?php

require 'app/Mage.php';

Mage::app();

Mage::getSingleton('sales/order_config')->getStatusLabel('pending');
// performs a db request and returns "Pending"

Mage::getSingleton('sales/order_config')->getStatusLabel('pending');
// returns immediately "Pending"

Mage::app()->setCurrentStore(2);

Mage::getSingleton('sales/order_config')->getStatusLabel('pending');
// performs a db request and returns "En attente" assuming store has different label

Questions or comments

The key consists of the store id as well to prevent issues with emulation when labels are localized.

Contribution checklist (*)

• Pull request has a meaningful description of its purpose
• All commits are accompanied by meaningful commit messages
• All automated tests passed successfully (all builds are green)
• Add yourself to contributors list