1. Entities & Domain Modeling
The ride-sharing domain revolves around five core entities: `Rider`, `Driver`, `Trip`, `Location`, and `PricingStrategy`. A trip passes through strict sequential states: REQUESTED -> MATCHED -> DRIVER_ARRIVED -> IN_PROGRESS -> COMPLETED (or CANCELLED).
2. Matching Strategies: Pluggable Algorithms
We define a `DriverMatchingStrategy` interface with concrete implementations: `NearestDriverStrategy` (Euclidean distance), `HighestRatedDriverStrategy`, and `PoolMatchingStrategy`. This allows runtime swapping based on user tier or service level.
3. Concurrency & Race-Free Driver Assignment
To prevent two concurrent trips from matching the same driver, the `Driver` entity maintains an atomic availability status. Matching uses a compare-and-swap operation: a driver is offered a trip with an atomic status check (`driver.compareAndSetAvailable(true, false)`).
enum TripStatus { REQUESTED, MATCHED, IN_PROGRESS, COMPLETED, CANCELLED }
class Trip {
public status: TripStatus = TripStatus.REQUESTED;
constructor(
public id: string,
public riderId: string,
public pickup: [number, number],
public dropoff: [number, number]
) {}
public completeTrip() {
if (this.status !== TripStatus.IN_PROGRESS) throw new Error('Invalid state transition');
this.status = TripStatus.COMPLETED;
}
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Written by HLDForge Architecture Team
Lead Machine Coding Specialist
The HLDForge Architecture Team publishes practical engineering guides, real-world case studies, and high-concurrency blueprints to help engineers build scalable and fault-tolerant software.