Simple UDP Load Balancer with Consistent Hashing

This project demonstrates a basic, in-memory UDP-based load balancer where servers self-register via UDP, send periodic pings to stay active, and client requests are routed using consistent hashing for session affinity.

Features

• Server Registration & Keep-Alive: Servers send REGISTER and PING messages to the listener on a well-known port. The load balancer tracks each server's last-seen timestamp in memory.

• Consistent Hashing: Client requests (UDP or TCP) are mapped to backend servers using a consistent hash ring built on each server's IP and port. This ensures minimal remapping when servers join or leave.

• In-Memory State: All server metadata is stored in process memory.

• Stateless Forwarding: Client requests are forwarded statelessly to chosen servers, making the balancer simple and easy to extend.

Repository Structure

./
├── consistentHashing.cpp   # Implementation of the consistent hash ring
├── serverManager.h/.cpp    # ServerRegistry and LoadBalancer logic (add, remove, ping)
├── load-balancer.cpp       # Main entry: UDP listener hooking into LoadBalancer
├── readme.md               # (This file) Project overview & build instructions
└── CMakeLists.txt          # (Optional) For building with CMake

Build Instructions

# Using g++ directly:
g++ -std=c++17 -pthread load-balancer.cpp serverManager.cpp consistentHashing.cpp -o udp_load_balancer

## Future Improvements

- **TTL-Based Eviction**: Remove servers automatically if no `PING` received within a configurable timeout.
- **Virtual Nodes**: Improve key distribution by adding multiple replicas per server in the hash ring.
- **Thread Pool**: Handle incoming packets and forwarding concurrently with worker threads.
- **Configuration**: Externalize settings (ports, TTL, number of replicas) via a config file or flags.

## License

This project is provided "as is" for educational purposes. Feel free to use and modify it in your own experiments.