This post is first created by CodingMrWang, 作者 @Zexian Wang ,please keep the original link if you want to repost it.
Requirement
Functional
- Users should be able to reserve a parking lot for a type of vehical.
- Users should be able to pay for the reservation.
Non-Functional
- Consistency (no two user got reservered for the same parking lot)
Assumption
Estimation
Traffic
- Make reservation 20000/day
- Check reservation 40000/day
data size
100B/record
QPS
Storage
Service
- Reservation Service
- Payment Service
API
External
- makeReservation(garageId, userId, startTime, endTime, verhicalType(Optional)) [reservationId, spotId]
- makePayment(reservationId)
- cancelReservation(garageId)
- login/signup (Optional)
Internal
- getAvailableSpots(garageId, startTime, endTime, verhicalType)
- calculatePrice(reservationId)
- allocateSpot(garageId, time, spotId)
Data Storage
- We want high consistency, data is not large and qps is not high, postgre could be a good choice.
Tradeoff made here, we want strong consistency higher than latency. One user won’t make many reservations per day.
Schema
| Reservation |
|
| id |
primary key |
| garage_id |
foreign key, int |
| spot_id |
foreign key, int |
| start |
timestamp |
| end |
timestamp |
| paid |
boolean |
| Garage |
|
| id |
primary key |
| zip_code |
varchar |
| compact rate |
decimal |
| large rate |
decimal |
| electric rate |
decimal |
| Spot |
|
| id |
primary key |
| level |
int |
| location |
varchar |
| type |
enum |
| User |
|
| id |
primary key |
| email |
varchar |
Diagram
Useful link:
