Java Matching Engine Demo

A high-performance order matching engine implemented in Java with Spring Boot. Designed to demonstrate real-time matching of buy and sell orders with minimal latency, using a concurrent, thread-safe order book.

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Features

• Buy and Sell Order Matching: Supports limit orders for BUY and SELL types.
• Concurrent Matching: Daemon thread continuously matches orders in real-time.
• Benchmark Ready: Allows measuring enqueue and match performance without blocking threads.
• Spring Boot Integration: MatchingEngine is a fully injectable Spring component.
• Flexible Order Book: Uses price-priority queues: descending for buyers, ascending for sellers.
• In-Trade Status: Tracks whether matching is currently in progress.
• Thread-Safe: Uses ReentrantLock to prevent race conditions.
• Testable: Provides benchmark and integration tests for verifying performance and correctness.

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Technology Stack

• Java 21+
• Spring Boot 3.5
• JUnit 5 for testing
• ReentrantLock for thread-safe order book operations
• Maven for build and dependency management

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Project Structure

src/main/java
└── com.alireza.engine
    ├── controller        # REST APIs for order operations
    ├── domain            # Order and OrderType classes
    ├── dto               # Data Transfer Objects
    ├── mapper            # Mapping between DTOs and entities
    ├── matching          # MatchingEngine component and logic
    ├── repository        # Repository interfaces (if DB used)
    └── service           # Service layer for business logic

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Benchmark Example

The engine can enqueue and match orders very quickly. Example performance:

Time to enqueue 100000 orders: 93 ms

This demonstrates the high throughput of the engine under sequential order submission.

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Running Tests

• Integration tests: Test MatchingEngine behavior as a Spring component.
• Benchmark test: Measures performance without blocking the matching thread.

Run with:

./mvnw test

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Usage

1. **Inject **`` into any Spring component or service.
2. Add orders using addOrder(Order order).
3. Monitor isInTrade() for active matching.
4. Use benchmark tests to measure performance for large order volumes.

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License

This project is licensed under the MIT License. You are free to use, modify, and distribute this software under the following conditions:

• Include the original license and copyright notice in all copies or substantial portions of the software.
• Provided "as-is" without warranty of any kind.

For full license text, see LICENSE file.

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Notes

• The matching engine runs a background thread for continuous matching.
• The inTrade flag allows checking if matching is actively processing orders.
• Suitable as a reference for building real trading systems or learning concurrent order matching logic.
• Designed for educational and benchmark purposes, not production trading.

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Contact

Created By: Alireza Dolatabadi
Email: alireza.dolatabadi.jc@gmail.com
GitHub: [https://github.com/AlirezaDa-jc/Java-Matching-Engine-Demo](https://github.com/AlirezaDa-jc/Java-Matching-Engine-Demo)