Use Matchit to Resolve Per-File Settings

[ibraheemdev]

Summary

Continuation of #9444.

When the formatter is fully cached, it turns out we actually spend meaningful time mapping from file to Settings (since we use a hierarchical approach to settings). Using matchit rather than BTreeMap improves fully-cached performance by anywhere from 2-5% depending on the project, and since these are all implementation details of Resolver, it's minimally invasive.

matchit supports escaping routing characters so this change should now be fully compatible.

Test Plan

On my machine I'm seeing a ~3% improvement with this change.

hyperfine --warmup 20 -i "./target/release/main format ../airflow" "./target/release/ruff format ../airflow"
Benchmark 1: ./target/release/main format ../airflow
  Time (mean ± σ):      58.1 ms ±   1.4 ms    [User: 63.1 ms, System: 66.5 ms]
  Range (min … max):    56.1 ms …  62.9 ms    49 runs
 
Benchmark 2: ./target/release/ruff format ../airflow
  Time (mean ± σ):      56.6 ms ±   1.5 ms    [User: 57.8 ms, System: 67.7 ms]
  Range (min … max):    54.1 ms …  63.0 ms    51 runs
 
Summary
  ./target/release/ruff format ../airflow ran
    1.03 ± 0.04 times faster than ./target/release/main format ../airflow

[github-actions]

ruff-ecosystem results

Linter (stable)

✅ ecosystem check detected no linter changes.

Linter (preview)

✅ ecosystem check detected no linter changes.

Formatter (stable)

✅ ecosystem check detected no format changes.

Formatter (preview)

✅ ecosystem check detected no format changes.

[BurntSushi]

Nice!!!

[BurntSushi]

I was curious about this, and I think I convinced myself that this is correct because all other possible errors (aside from Conflict) can only occur as a result of characters that the router treats as special. And the escaping done above means that there should be precisely zero special characters in the path.

(It might make sense to add an escape routine to matchit. Similar to regex::escape. That way, you can provide more of a stronger guarantee here.)

[ibraheemdev]

Yeah after escaping we guarantee that we're inserting a static route, so none of the other errors are possible (barring a bug in matchit). An escape function in matchit is a good idea. I was also considering optimizing the double String::replace but decided it wasn't worth it for us.

[charliermarsh]

Are there any other characters that we need to watch out for here? In my previous PR I mentioned colons, which seems irrelevant, but e.g. {*foo} is a special routing parameter in matchit, right? I assume that's also irrelevant as long as we're escaping the { and } characters.

[ibraheemdev]

* is only considered after a non-escaped {, so that shouldn't be a problem.