Calling cancelation endpoint on an order with coupon code multiple times can result in multiple decrements on the coupon usages about magento2-frontend

[vinodsowdagar]

Hi @anthonyvdg-se ,

Thank you for your message.

We have looked into this before and the tricky part is that we actually do process the cancel of the order inside the incoming MultiSafepay webhook to the notification controller, but sometimes this webhook can have a few seconds delay. So whenever someone clicks on the cancel button and we would process the decrement of the coupon on the webhook instead, it could be that their quote will not have the restored coupon inside it, because Magento restored the quote at the moment the coupon was not decremented yet. So someone could then see their quote restore, but their coupon not being returned.

They can still add the coupon back to the quote, but only after the webhook has processed the decrement. You could also argue for the reason why we do not decrement the coupon in both places, the incoming webhook and the Cancel controller, but sometimes the incoming webhook will process the decrement at exactly the same time and will result in double decrements due to race conditions.

I will look into decrementing the coupon when we cancel the order in the incoming webhook and come back to you with an update later.