Work · Production · jpteam / C1X Inc.
QR campaigns
QR campaigns where many people scan against the same limited inventory at the same moment, and a unit must never be redeemed twice.
- 90%+statement coverage across modules
- 0database calls on the ad redirect path
What it does
Businesses run dynamic QR campaigns with sponsor ads, live scanning, redemption tracking and dashboards. The scan path is where correctness matters most.
- 01Scan
- 02Pre-validation
- 03Inventory check
- 04Redis lock
- 05Atomic redemption
- 06SSE stats → dashboard
What I built
- The scan path: pre-checks before the database to shed load, then an atomic inventory decrement under a Redis lock so concurrent scans can't double-redeem.
- The campaign lifecycle engine — draft → live → completed → inactive — with timezone-aware validation, so campaigns activate and expire correctly across regions.
- Sponsor ads with a server-side UTM redirect whose parameters are prebuilt, so the redirect itself does no lookup.
- Live inventory stats over SSE; QR generation with logo embedding and Japanese text on generated PDFs.
Decisions
- Archived campaign lines are filtered in the query, not the service, so deleted data is never instantiated as an entity.
- Ad placement moved from a strategy pattern to direct injection into the response pipeline — less indirection for one real variation.