HFT Trading Execution Engine

Project Summary

A low-latency, multithreaded trading execution engine built with Spring Boot 3. This system simulates a High-Frequency Trading (HFT) environment, utilizing pessimistic locking and asynchronous processing to ensure strict ACID compliance and thread safety under intense concurrency.

Core Technical Features

• Concurrency Control: Implements PESSIMISTIC_WRITE database locking to serialize concurrent ledger updates and prevent race conditions.
• Asynchronous Processing: Decouples order ingestion from execution using CompletableFuture and non-blocking I/O.
• Numerical Precision: Uses BigDecimal exclusively for financial arithmetic to avoid floating-point rounding errors.

Build & Run

1. Build: mvn clean install

2. Start the application: mvn spring-boot:run. The server will start on: http://localhost:8080

Interactive API Documentation (Swagger UI)

• Once the application is running, open your browser and go to: http://localhost:8080/swagger-ui/index.html to explore all endpoints

API Endpoints

Execute Trade

POST /api/v1/trading/execute

Request Body (JSON)

{
  "userId":     1,          // integer - ID of the user placing the order 
  "symbol":     "BTC",      // string  - Trading pair symbol (e.g. BTC, ETH, AAPL) 
  "payWith":    "USD",      // string  - Quote currency (e.g. USD, USDT, EUR)
  "quantity":   0.05        // number  - Quantity to buy in base asset
}

View Portfolio

GET /api/v1/trading/portfolio/{userId}

Testing Idempotency

A bash script is provided to verify the exactly-once execution logic:

chmod +x test_idempotency.sh `````./test_idempotency.sh``` `` This script verifies that the engine processes a specific trade exactly once by simulating a network retry and confirming that the user's balance is only deducted once, despite receiving multiple identical requests.