simplyboys/shop_coupon

Flash Coupon Delivery Mechanism is a prototype that handles the kind of sudden, high-traffic rush you get when a limited number of coupons drop at a specific time and everyone tries to grab them at once. Think of it as a controlled way to run a flash sale where you know exactly how many coupons exist and want to give users a fair shot at getting one. The system works in three stages. First, during a five-minute window before the drop, users reserve a spot. At the scheduled time, the system counts how many people reserved and creates coupons equal to 20% of that number. Then for one minute, users try to grab one. The challenge the project tackles is making sure each user's chance of success stays close to that 20% mark, even when traffic spikes and everyone hits the system at the same moment. Someone running daily promotional drops, limited inventory releases, or timed reward events would use this. For example, a shopping app that gives out discount coupons every evening at 11pm and wants the process to be fair, fast, and resistant to cheating or crashes under load. The project includes load testing tooling, so you can simulate a flood of users and verify the system holds up. The project is written in Go, a language known for handling many simultaneous requests efficiently, and uses PostgreSQL for storing reservations and coupon data. The README doesn't go into detail on the specific algorithm used to keep probabilities fair during the grab window, so the inner workings of that part remain unclear. Overall, it is a focused prototype for a specific operational problem rather than a full-featured coupon platform.