Implement a Sliding Window Rate Limiter for Cloud API Calls
Last updated: December 9, 2025
Quick Overview
Implement a sliding window rate limiter that enforces per-tenant, per-cloud-provider API call limits. Support multiple time windows (per-second, per-minute, per-hour) simultaneously.
Wiz
December 9, 202513
6
2,169 solved
Implement a sliding window rate limiter that enforces per-tenant, per-cloud-provider API call limits. Support multiple time windows (per-second, per-minute, per-hour) simultaneously.
Wiz's scanning infrastructure makes millions of cloud API calls. Each cloud provider has rate limits, and exceeding them causes throttling that degrades scan performance for all tenants. A robust rate limiter ensures fair API usage across tenants while respecting provider limits. The interviewer evaluates your ability to design a clean, production-quality data structure.
What the Interviewer Expects
- Implement sliding window using sorted sets or circular buffers
- Support multi-dimensional limiting (per-tenant AND per-provider)
- Handle concurrent access safely
- Provide accurate rate information for backoff decisions
- Write clean, well-tested code
Key Topics to Cover
How to Approach This
- Clarify input constraints and edge cases before writing code.
- Walk through your approach verbally and confirm with the interviewer before coding.
- Start with a brute force solution, then optimize. Mention time and space complexity.
- Test your solution with examples, including edge cases like empty input or duplicates.
- Consider common patterns: sliding window, two pointers, hash map, BFS/DFS, dynamic programming.
Possible Follow-up Questions
- How would you distribute this rate limiter across multiple scanning workers?
- What happens when a rate limit is hit? How should the caller handle it?
- How would you handle bursty traffic patterns?
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Problem Analysis
In this problem, we need to implement a sliding window rate limiter that enforces API call limits based on multiple dimensions: per-tenant and per-cloud-provider. The sliding window algorithm is appro...
Approach
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Data Structure: We will use a dictionary of sorted sets (or a circular buffer) for each tenant and cloud provider combination. Each sorted set will store timestamps of API calls.
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**Add Cal...
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