/ The Arena

🏆 Track 1 Grand Finale Capstone Challenge: Distributed Rate Limiter ⚔️

In this landmark capstone challenge, you will implement an industrial-strength Sliding Window Rate Limiter Engine supporting microsecond timestamp tracking, dynamic capacity checks, and accurate retry-after calculation.

Requirements:

1. Sliding Window Precision:
   • Maintain timestamps within the rolling interval $(\text{nowMs}-\text{windowSizeMs},\text{nowMs}]$.
   • Prune stale timestamps on every evaluation.
2. Deterministic Capacity Checks:
   • Allow requests when $\text{currentCount}<\text{limit}$ and calculate remaining.
   • Reject requests when $\text{currentCount}\ge \text{limit}$ and compute retryAfterMs = (oldestTimestamp + windowSizeMs) - nowMs.
3. Multi-Key Isolation:
   • Ensure independent limit tracking across different client keys.