[API] KVCache: support block hashes

[DwyaneShi]

Pull Request Description

• KVCache API supports block hashes
• Change parameter name tokens to query in all APIs to improve readability

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 significantly enhances the KVCache API by introducing support for block hashes as cache keys, alongside the existing token list views. This allows for more flexible and potentially more efficient caching strategies, especially in scenarios where block-level identification is more natural. Additionally, a comprehensive refactoring has been undertaken to improve API readability by consistently renaming the tokens parameter to query across the entire KVCache codebase. A new utility function parse_kvcache_api_args was added to standardize argument parsing for KVCache operations, enabling overloaded method signatures for better usability.

Highlights

• KVCache API Extension: The KVCache API now officially supports 'block hashes' as a new type of cache key, alongside the existing 'token list views'. This introduces BlockHashes and KVCacheKey types, allowing for more flexible caching strategies.
• API Readability and Consistency: The parameter name tokens has been consistently renamed to query across all relevant KVCache APIs to improve readability and align with common terminology in data querying contexts.
• Standardized Argument Parsing: A new utility function, parse_kvcache_api_args, has been introduced to centralize and standardize the parsing of various argument combinations for KVCache API calls, enabling more robust and user-friendly overloaded method signatures.
• Core Logic Adaptation: Underlying cache management, L1/L2 cache operations, and memory region handling have been updated to seamlessly integrate and support both TokenListView and BlockHashes as valid key types, ensuring compatibility and correct behavior across the system.

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[gemini-code-assist]

Code Review

This pull request introduces support for block hashes in the KVCache API, which is a significant feature enhancement. It also refactors the API by renaming the tokens parameter to query for improved readability and consistency. The use of @overload and a dedicated argument parsing function (parse_kvcache_api_args) is a good approach to handle the increased API flexibility.

My review focuses on a critical correctness issue in the BlockHashes equality and hashing logic, which could lead to incorrect cache behavior. I've also identified opportunities to improve code maintainability by simplifying a complex argument parsing function and ensuring naming consistency.

[DwyaneShi]

@yapple has integrated into sglang with the newly introduced API in this PR and passed e2e UTs. merge it.