feat(core): Cache ignore instances for performance

[EricRahm]

Summary

This commit optimizes file filtering by caching compiled ignore instances within the GitIgnoreParser instead of raw string arrays.

Details

Previously, .gitignore files were parsed into an array of rule strings on every check, leading to redundant processing. The node-ignore library supports adding pre-compiled ignore instances, which is more efficient.

This change modifies the internal cache from Map<string, string[]> to Map<string, Ignore> and updates the logic in isIgnored to create, cache, and reuse these compiled instances. This reduces the overhead associated with parsing ignore files, especially in large projects with many nested .gitignore files.

Related Issues

Fixes #11610

How to Validate

• Existing unit/integration tests cover this code
• Run gemini-cli in a directory with a root .gitignore and nested .gitignore files

Pre-Merge Checklist

• Updated relevant documentation and README (if needed)
• Added/updated tests (if needed)
• Noted breaking changes (if any)
• Validated on required platforms/methods:
  • MacOS
    • npm run
    • npx
    • Docker
    • Podman
    • Seatbelt
  • Windows
    • npm run
    • npx
    • Docker
  • Linux
    • npm run
    • npx
    • Docker

[gemini-code-assist]

Summary of Changes

Hello @EricRahm, 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 introduces a performance enhancement to the GitIgnoreParser by optimizing how .gitignore files are processed and cached. Instead of repeatedly parsing raw ignore patterns, the system now stores and reuses pre-compiled ignore objects, leading to more efficient file filtering, especially in projects with complex or deeply nested .gitignore structures. This change directly addresses and fixes issue #11610.

Highlights

• Performance Optimization: Switched from caching raw .gitignore rule strings to caching compiled ignore instances from the node-ignore library, significantly reducing parsing overhead during file filtering.
• Type System Update: Updated internal cache types from Map<string, string[]> to Map<string, Ignore> and globalPatterns from string[] to Ignore to reflect the new caching strategy.
• GitIgnoreParser Refinement: Modified loadPatternsForFile to directly return Ignore instances and ensured empty Ignore instances are cached or returned when no patterns are found, streamlining the ignore logic.

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[gemini-code-assist]

Code Review

This pull request introduces a performance optimization by caching compiled ignore instances instead of raw string arrays in the GitIgnoreParser. The changes are logical and correctly implement the caching strategy for .gitignore files and global git exclude files. My review focuses on ensuring this optimization is applied consistently. I've identified one area where the optimization was missed, which could impact performance when extra ignore patterns are used. Overall, this is a valuable improvement.

[gemini-code-assist]

This change to cache Ignore instances is a great performance improvement. For consistency and to fully realize the performance gains, processedExtraPatterns should also be converted to an Ignore instance. Currently, it remains a string[] and its patterns are re-parsed on every isIgnored call, which partially undermines the goal of this optimization when extraPatterns are provided. I recommend changing processedExtraPatterns to be of type Ignore and initializing it once in the constructor.

[Adib234]

Can this comment be addressed?

[EricRahm]

Yep, I'll push an updated PR.

[EricRahm]

Updated! @gemini-code-assist please review again.

[gemini-code-assist]

Thanks for the update, EricRahm! I've reviewed the changes, and they successfully address the feedback regarding processedExtraPatterns. Converting it to an Ignore instance and initializing it in the constructor, along with simplifying its usage in isIgnored, fully realizes the performance gains as intended. Great work!