- Add max_concurrent_requests config option (default: 1000)
- Implement global AtomicUsize counter for concurrent request tracking
- Return status 41 'Server unavailable' when limit exceeded
- Proper counter management with decrements on all exit paths
- Add comprehensive config validation (1-1,000,000 range)
- Update documentation with rate limiting details
- Add unit tests for config parsing
- Thread-safe implementation using Ordering::Relaxed
This provides effective DDoS protection by limiting concurrent
connections to prevent server overload while maintaining
configurability for different deployment scenarios.
