TL;DR

Updated the rate limiting implementation to improve handling of concurrent requests and added support for custom increment values.

What changed?

• Modified the Redis interface to use get and incrBy instead of just incr
• Changed the rate limiting logic to first read the current request count before incrementing
• Added support for a custom increment parameter to allow incrementing by values other than 1
• Improved error handling for Redis connection failures
• Added more comprehensive test cases for various scenarios including Redis failures, concurrent requests, and custom increment values

How to test?

• Run the existing test suite which now includes additional test cases for:
  • Redis connection failures
  • Handling of null/zero responses
  • Low sample rates
  • Concurrent requests with Redis lag
  • Custom increment values
• Manually test the rate limiting functionality with different increment values

Why make this change?

This change addresses race conditions that could occur with concurrent requests by separating the read and increment operations. It also adds flexibility with the new increment parameter, allowing services to count certain requests as multiple units against the rate limit. The improved error handling makes the system more resilient to Redis connection issues.

PR-Codex overview

This PR focuses on updating the rateLimit function in the service-utils package to enhance its functionality by allowing custom increments and improving error handling for Redis operations.

Detailed summary

• Added get, expire, and incrBy methods to the IRedis type.
• Introduced an increment parameter to the rateLimit function.
• Modified the logic to read request counts from Redis using get.
• Implemented a new asynchronous increment logic for Redis.
• Updated tests to reflect changes in Redis interactions and added new test cases for error handling and custom increments.

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