SeatLock: High-Performance Real-Time Reservation Engine

A high-performance C++20 engine for handling seat reservations with sub-microsecond latency and lock-free concurrency. Now features a real-time React frontend and WebSocket broadcasting.

🎯 Architecture

┌─────────────────────────────┐      ┌─────────────────────────────┐
│   User A (Browser)          │      │   User B (Browser)          │
│   React + WebSockets        │◄────►│   React + WebSockets        │
└──────────▲──────────────────┘      └──────────▲──────────────────┘
           │                                    │
           │           Real-time Updates        │
           └──────────────────┐  ┌──────────────┘
                              │  │
┌─────────────────────────────▼──▼──────────────────────────┐
│   FastAPI Gateway (Python)                                │
│   • REST API for Holds/Confirms                           │
│   • WebSocket Broadcaster                                 │
└──────────┬────────────────────────────────────────────────┘
           │ gRPC / FFI
┌──────────▼────────────────────────────────────────────────┐
│   C++ SeatLock Engine                                     │
│   • Atomic State Management (32M ops/sec)                 │
│   • Expiry Worker                                         │
└───────────────────────────────────────────────────────────┘

📊 Performance Benchmark

Benchmark Results (16 threads, 1.6M operations):

Ops/Sec: 32,240,000
Time:    0.05 seconds
Throughput: Sub-millisecond lock acquisition

🚀 One-Minute Quick Start

1. Build the Engine (C++)

# Windows
build_seatlock.bat

2. Start the Backend (Python)

cd backend
pip install -r requirements.txt
uvicorn main:app --reload

3. Open the Frontend

Simply open frontend/index.html in your browser.

• Green: Available
• Orange: Held (Real-time update)
• Red: Sold (Real-time update)

✨ Key Features

• Lock-Free Core: Uses std::atomic and CAS loops for maximum throughput.
• Real-Time Sync: WebSockets broadcast seat state changes instantly to all connected clients.
• Fine-Grained Locking: Alternative implementation available for comparison.
• Auto-Expiry: Background thread automatically releases held seats after timeout.

📂 Project Structure

seatlock/
├── src/                  # C++ Source
│   ├── AtomicSeatManager.cpp
│   └── ...
├── include/              # C++ Headers
├── backend/
│   ├── main.py           # FastAPI + WebSockets
│   └── requirements.txt
├── frontend/             # Real-time UI
│   ├── index.html
│   ├── app.js
│   └── styles.css
├── build_seatlock.bat    # Automated Build Script
└── README.md

🎓 Interview Talking Points

1. System Design: "I extended the C++ engine with a FastAPI gateway to support web clients. I implemented WebSockets to solve the 'stale view' problem in ticketing, ensuring users see taken seats instantly."
2. Concurrency: "The core engine handles 32M ops/sec using lock-free structures, while the frontend handles eventual consistency via WebSocket events."
3. Full Stack: "Demonstrates integration from low-level C++ memory management up to high-level React UI state."

☁️ Deployment

• Frontend: Configured for Vercel (vercel.json)
• Backend: Configured for Railway/Heroku (Procfile)

📸 Gallery

Real-Time Frontend (React)

Live seat updates with color-coded status (Available, Held, Sold)

API Documentation (FastAPI/Swagger)

Interactive REST API testing interface

👤 Author

Kid of Dynamic

• GitHub: @Raphasha27