Sliding Window Counter Slots

Parameters

• Parameters: maxRequests, windowSize.
• Default: by default the slots size is 6.

Description

• Divides the window into smaller slots for a more granular count.
• Slides the window by updating slot counts, allowing a smooth transition and more evenly distributed rate limiting.
• Approximates actual sliding window behavior with improved performance.

Example: windowSize = 1 min, slots = 6 (10 sec/slot), maxRequests = 10.

• T0 (01:00:00): Window starts, 6 slots initialized with 0 requests.
• T1 (01:00:20): 4 requests arrive, distributed in the first 2 slots.
• T2 (01:00:40): Window slides, first 2 slots cleared, 4 requests in next 2 slots.
• T3 (01:00:50): 3 more requests, fit into the 5th slot, total 7 requests allowed.

How to use

When creating your API, you can use the RateLimitFactory to create a leaking bucket rate limit.

Api.create(8080)
      .rateLimit(RateLimitFactory.customSlidingWindowCounterSlots(4, Duration.ofSeconds(1)))
      .addRoute(Route.builder("/"),
      .path(RouteMethod.GET, "/", controller::handler))
      .start();
          

Factory

The RateLimitFactory provides a default and a custom method for this rate limiter.

• For more details on the check the source code of the RateLimitFactory

See more in our blog post about Rate Limiters