[Misc] Rename DecodingConfig to StructuredOutputConfig

[njhill]

I'm not sure whether there was previously discussion on this but "decoding config" seems incorrect/misleading to me - these are specifically structured output / guided decoding parameters.

This is just a proposal.

[gemini-code-assist]

Summary of Changes

Hello @njhill, 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 focuses on a significant refactoring effort to rename the DecodingConfig class to StructuredOutputConfig. This change aims to provide a more accurate and less misleading name for the configuration parameters that govern structured output and guided decoding within the system. The update is propagated throughout the codebase to ensure consistency and improve code readability.

Highlights

• Refactoring/Renaming: The primary change is a comprehensive rename of the DecodingConfig class to StructuredOutputConfig across the codebase. This change clarifies the purpose of the configuration, as it specifically pertains to parameters for structured output and guided decoding, rather than general decoding.
• Codebase Updates: All references to the DecodingConfig class, its instances, and related methods (e.g., get_decoding_config) have been updated to reflect the new StructuredOutputConfig name. This includes updates in configuration definitions, engine arguments, API documentation, test files, and various engine and structured output backend implementations.
• Improved Clarity: The renaming improves the clarity and accuracy of the codebase by using a more descriptive name for the configuration class, aligning it better with its actual functionality related to structured output and guided decoding.

Using Gemini Code Assist

The full guide for Gemini Code Assist can be found on our documentation page, here are some quick tips.

Invoking Gemini

You can request assistance from Gemini at any point in your pull request via creating an issue comment (i.e. comment on the pull request page) using either /gemini <command> or @gemini-code-assist <command>. Below is a summary of the supported commands.

Feature	Command	Description
Code Review	/gemini review	Performs a code review for the current pull request in its current state.
Pull Request Summary	/gemini summary	Provides a summary of the current pull request in its current state.
Comment	@gemini-code-assist	Responds in comments when explicitly tagged, both in issue comments and review comments.
Help	/gemini help	Displays a list of available commands.

Customization

To customize Gemini Code Assist for GitHub experience, repository maintainers can create a configuration file and/or provide a custom code review style guide (such as PEP-8 for Python) by creating and adding files to a .gemini/ folder in the base of the repository. Detailed instructions can be found here.

Limitations & Feedback

Gemini Code Assist is currently in preview and may make mistakes. Please leave feedback on any instances where its feedback is incorrect or counter productive. You can react with 👍 and 👎 on @gemini-code-assist comments to provide feedback.

You can also get AI-powered code generation, chat, as well as code reviews directly in the IDE at no cost with the Gemini Code Assist IDE Extension.

Footnotes

1. Review the Privacy Notices, Generative AI Prohibited Use Policy, Terms of Service, and learn how to configure Gemini Code Assist in GitHub here. Gemini can make mistakes, so double check it and use code with caution. ↩

[github-actions]

👋 Hi! Thank you for contributing to the vLLM project.

💬 Join our developer Slack at https://slack.vllm.ai to discuss your PR in #pr-reviews, coordinate on features in #feat- channels, or join special interest groups in #sig- channels.

Just a reminder: PRs would not trigger full CI run by default. Instead, it would only run fastcheck CI which starts running only a small and essential subset of CI tests to quickly catch errors. You can run other CI tests on top of those by going to your fastcheck build on Buildkite UI (linked in the PR checks section) and unblock them. If you do not have permission to unblock, ping simon-mo or khluu to add you in our Buildkite org.

Once the PR is approved and ready to go, your PR reviewer(s) can run CI to test the changes comprehensively before merging.

To run CI, PR reviewers can either: Add ready label to the PR or enable auto-merge.

🚀

[gemini-code-assist]

Code Review

This pull request is a great improvement for code clarity. Renaming DecodingConfig to StructuredOutputConfig makes the purpose of the configuration much clearer. The changes are applied consistently across the codebase. I've found a few minor areas for improvement to further enhance maintainability and correctness, mostly related to docstrings and type hints. Overall, a solid refactoring.

[hmellor]

Agreed, I think @aarnphm had a PR doing the same thing

[aarnphm]

Ah yes I have a PR for this 😃 Will revisit this this afternoon.

#17420

[yewentao256]

LGTM, thanks!

[mergify]

This pull request has merge conflicts that must be resolved before it can be
merged. Please rebase the PR, @njhill.

https://docs.github.com/en/pull-requests/collaborating-with-pull-requests/working-with-forks/syncing-a-fork

[hmellor]

Should we close this in favour of @aarnphm's PR?

The two design questions from the original PR are:

• StructuredOutput (used elsewhere in vLLM) vs StructuredOutputs (the term OpenAI uses in their docs)?
• Do we deprecate all explicit structured output CLI arguments and rely on JSON blobs to configure structured output? The argument for JSON only structured output configuration (from @aarnphm):
  • With --structured-output-config.key val the configs could still be passed individually
  • The config for structured outputs would be in JSON for users sending requests anyway

What do we think?

[aarnphm]

Yeah, let me actually find time to clean up the other PR 😄 work are a bit hectic atm.

edit: should be ready now, will close this PR in favor of mine, but will cred nick on this as well.