[MISC] correct copy_blocks src_to_dists param type

[andyxning]

Essential Elements of an Effective PR Description Checklist

• The purpose of the PR, such as "Fix some issue (link existing issues this PR will resolve)".
• The test plan, such as providing test command.
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Purpose

Type fix for copy_blocks parameter src_to_dists.

Test Plan

NA

Test Result

NA

(Optional) Documentation Update

[github-actions]

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[gemini-code-assist]

Summary of Changes

Hello @andyxning, 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 contains a minor fix to correct a type annotation for a parameter used in the IPEX attention implementation's block copying logic. This improves the accuracy of the type information for the function signature.

Highlights

• Type Hint Correction: Corrected the type hint for the src_to_dists parameter in the copy_blocks method within the IPEX attention implementation from Dict[int, List[int]] to torch.Tensor.

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[gemini-code-assist]

Code Review

The pull request correctly changes the type hint for the src_to_dists parameter in _PagedAttention.copy_blocks from Dict[int, List[int]] to torch.Tensor. This is a good correction because:

1. The src_to_dists parameter is passed as the block_mapping argument to vllm._custom_ops.copy_blocks.
2. The vllm._custom_ops.copy_blocks function (and its underlying C++ implementation) expects this argument to be a torch.Tensor.

This change aligns the type hint with the actual runtime usage, improving code clarity and aiding static analysis. The change also makes the signature consistent with other copy_blocks implementations in the codebase, such as vllm.attention.ops.paged_attn.PagedAttention.copy_blocks and vllm.attention.backends.ipex_attn.IpexAttnBackend.copy_blocks.

I've added one comment regarding an unused *args parameter in the method signature, which could be considered for removal to further simplify the code, though it's not directly related to the primary type fix of this PR.