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FILL IN THE PR DESCRIPTION HERE

FIX #xxxx (link existing issues this PR will resolve)

BEFORE SUBMITTING, PLEASE READ THE CHECKLIST BELOW AND FILL IN THE DESCRIPTION ABOVE


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Summary of Changes

Hello @BrianPark314, 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!

This pull request implements a new prefix-aware routing mechanism for the inference gateway, designed to intelligently direct requests based on prompt similarity to optimize resource utilization and performance. It includes the core Go logic for this new routing strategy, updates to the build process, and an example Kubernetes configuration for a vLLM runtime.

Highlights

  • New Routing Strategy: I've introduced a new PrefixMatchPicker within the gateway-api-inference-extension to enable prefix-aware routing of inference requests. This picker uses a hashTrie to perform longest-prefix matching on incoming prompts, aiming to route similar prompts to the same backend inference engine (pod) to potentially improve cache hit rates and overall efficiency.
  • Kubernetes Integration: The new PrefixMatchPicker is integrated into the build process of the gateway-api-inference-extension Docker image. Additionally, a new example VLLMRuntime configuration (vllm-runtime.yaml) has been added, demonstrating how a vLLM model can be configured within the Kubernetes environment, which would leverage such a routing mechanism.
  • Scheduler Configuration Update: The scheduler.patch file has been updated to include the new PrefixAwarePicker as a potential or default picker in the scheduling configuration, allowing the inference extension to utilize this new routing logic.
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Code Review

The pull request introduces a prefix-aware routing mechanism. However, there's a critical issue where multiple pickers are added to the scheduler, which will cause only the last one to be used. Additionally, there's an ignored error in the prefix-aware picker, and a hardcoded copyright year.

# Conflicts:
#	src/gateway_inference_extension/configs/vllm/vllm-runtime.yaml
@BrianPark314 BrianPark314 force-pushed the feature/prefix-aware-routing branch from db38fc4 to 9cb5ea8 Compare June 28, 2025 03:50
return &hashTrie{children: make(map[rune]*hashTrie)}
}

func (t *hashTrie) insert(key, endpoint string) {
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If the key is very long (such as a complete natural language sentence), will it cause excessive memory usage? 🤔

}

/*---------------------------- trie implementation ---------------------------*/

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Do we need a mechanism just like limiting the cache size or LRU to ensure that our services will not be caused by the infinitely growing prefix cache? 🤔

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Could you take a look at the python implementation? I think it would be better to align different implementation methods so that the logic can be consistent.

return &types.Result{}
}

prompt, _ := ctx.RequestBody["prompt"].(string)
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In chat endpoint, there isn't a prompt in the body, should we consider this kind of scenario too?

defer t.mu.Unlock()

node := t
for _, r := range key {
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should we do prefix chunk hash instead of treating each character one by one? Like the python version implementation.

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Could you take a look at the python implementation? I think it would be better to align different implementation methods so that the logic can be consistent.

Do you mean the python implementation of the routing logics are inconsistent? If so, that should be worked on a seperate PR.

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Hi Brian, In the python implementation, the prompt is chunked and hashed, however in this go version, it is per char/token. Maybe chunk and hash would be better and it aligns python implementation.

Signed-off-by: BrianPark314 <[email protected]>
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3 participants