Refactor to use single loop for least request pod selection

[jiangxiaobin96]

Unify code for selecting minimum value code which is the same with least_util and least_gpu_cache and avoid two for loop.

[gemini-code-assist]

Summary of Changes

Hello @jiangxiaobin96, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

I've refactored the code responsible for selecting the minimum value in the least_request algorithm. The primary goal was to unify the logic that was previously duplicated across similar functions and, more importantly, to eliminate a redundant loop, making the code more efficient.

Highlights

• Code Unification & Optimization: I've optimized the selectTargetPodWithLeastRequestCount function in pkg/plugins/gateway/algorithms/least_request.go by consolidating two separate loops into a single, more efficient iteration. This change streamlines the process of identifying pods with the minimum request count.

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[gemini-code-assist]

Code Review

The pull request aims to unify the code for selecting the minimum value by refactoring two loops into a single one. While this is a good optimization for performance, the new implementation contains a logical flaw that will cause incorrect behavior. The condition to find the minimum value should be a strict less-than comparison, not less-than-or-equal, to correctly handle cases where multiple pods have the same minimum request count. I've provided a critical review comment with a suggested fix to address this issue.

[gemini-code-assist]

The logic for finding the pods with the minimum request count is flawed. The condition totalReq <= minCount will cause targetPods to be reset every time a pod with the same minimum count is found, effectively only keeping the last one encountered. Additionally, the else if totalReq == minCount block is unreachable because the first condition totalReq <= minCount already covers the equality case.

To fix this, you should use a strict less-than comparison (<) to identify a new minimum, and handle the equality case to append pods with the same minimum count.

Suggested change

	if totalReq <= minCount {
	minCount = totalReq
	}
	}
	for podname, totalReq := range podRequestCount {
	if totalReq == minCount {
	targetPods = []string{podname}
	} else if totalReq == minCount {
	targetPods = append(targetPods, podname)
	}
	if totalReq < minCount {
	minCount = totalReq
	targetPods = []string{podname}
	} else if totalReq == minCount {
	targetPods = append(targetPods, podname)
	}

[Jeffwan]

/cc @varungup90 @Xunzhuo

[Jeffwan]

seem this is not reviewed yet. the change is very straightforward and it looks good to me.

[Jeffwan]

@jiangxiaobin96 thanks for the improvement and apologies for the delay in reviewing. I changed the PR title a little bit to make it more self-explainable.