[Bug] KVCache: fix max seq len support

[DwyaneShi]

Pull Request Description

[Please provide a clear and concise description of your changes here]

Related Issues

Resolves: #[Insert issue number(s)]

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[gemini-code-assist]

Summary of Changes

Hello @DwyaneShi, 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 addresses a bug in the KVCache's put method by ensuring that kv_tensors are properly released under specific error conditions. Previously, if an invalid prefix length was provided or if the sequence length exceeded the maximum allowed, the kv_tensors might not have been released, potentially leading to resource leaks. The changes introduce explicit release() calls in these error paths to maintain proper resource management.

Highlights

• Resource Management: The put method in cache_manager.py now explicitly releases kv_tensors when an invalid prefix length alignment is detected (i.e., pref_len is not a multiple of block_ntokens). This ensures that resources are properly freed even in early exit conditions.
• Error Handling and Resource Release: The put method now includes a kv_tensors.release() call when the provided pref_len is greater than or equal to _max_seq_len, preventing resource leaks when a sequence exceeds the maximum allowed length.

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[gemini-code-assist]

Code Review

This pull request fixes two potential resource leaks in BaseKVCacheManager.put by ensuring kv_tensors are released on early exit paths. The changes are correct and improve robustness. I've added one comment pointing to another similar leak that could also be addressed as part of this fix.