Optional Practice Lab 2 of 2 · 35 min
Debug and Prove a Fixed-Window Limiter
Work through fixed-window boundaries, atomic updates, concurrency evidence, retry calculations, and the move from process-local correctness to shared enforcement.
Covers Lesson 3
What you will practice
- Calculate window IDs and reason about requests near a reset boundary.
- Put the fixed-window state transition into one safe critical section.
- Choose tests that prove the admission invariant under concurrency.
- Identify the shared atomic operation required across replicas.
Step 1 of 6
Pass with 80% · unlimited retries
0% correct
01
Calculate the window ID
The injected clock returns 125,000 milliseconds since the Unix epoch. The policy window is 60,000 milliseconds. What fixed-window ID does integer division produce?