Fix pointer issue

[mooselumph]

Why are these changes needed?

Addresses a pointer issue in the below portion of the rate limiter implementation:

// Calculate updated bucket levels
	allowed := true
	for i, size := range d.globalRateParams.BucketSizes {

		// Determine bucket deduction
		deduction := time.Microsecond * time.Duration(1e6*float32(params.BlobSize)/float32(params.Rate)/d.globalRateParams.Multipliers[i])

		prevLevel := bucketParams.BucketLevels[i]

		// Update the bucket level
		bucketParams.BucketLevels[i] = getBucketLevel(bucketParams.BucketLevels[i], size, interval, deduction)
		allowed = allowed && bucketParams.BucketLevels[i] > 0

	}

This code returns the bucketParams struct, which is then push back to the rate limiter's KV store when the call is allowed.

The problem here is that bucketParams.BucketLevels is an array slice and the KV store is an in-memory LRU cache. Even though bucketParams is a copy of the object stored in the KV store, both objects reference the same slice. The code here will directly update the slice, so that when allowed is false, the bucket level is inadvertently updated.

Checks

• I've made sure the lint is passing in this PR.
• I've made sure the tests are passing. Note that there might be a few flaky tests, in that case, please comment that they are not relevant.
• I've checked the new test coverage and the coverage percentage didn't drop.
• Testing Strategy
  • Unit tests
  • Integration tests
  • This PR is not tested :(

[pschork]

RIP mutation roulette. Nice fix. LGTM

[dmanc]

I didn't fully understand how this change will fix the problem. A better description in the PR with an example would be helpful for me.

[dmanc]

Should we update the metric to use bucketLevels[i]?

[mooselumph]

Updated

[mooselumph]

I didn't fully understand how this change will fix the problem. A better description in the PR with an example would be helpful for me.

I updated the PR description with a better explanation!