view CONTRIBUTING @ 44802:e0414fcd35e0

rust-filepatterns: match exact `rootglob`s with a `HashSet`, not in the regex

This optimization yields some very interesting results in `rootglob`-heavy
repositories.

I build a test repository of the following structure:

```
root
    /<uuid>/build/empty_file
    ... repeat for 4000 entries
```

and a `.hgignore` containing the corresponding 4000 `rootglob` entries pointing
to all `build/` folders.

Rust+c `hg status` goes from 350ms down to 110ms.

Differential Revision: https://phab.mercurial-scm.org/D8491

Our full contribution guidelines are in our wiki, please see:

https://www.mercurial-scm.org/wiki/ContributingChanges

If you just want a checklist to follow, you can go straight to

https://www.mercurial-scm.org/wiki/ContributingChanges#Submission_checklist

If you can't run the entire testsuite for some reason (it can be
difficult on Windows), please at least run `contrib/check-code.py` on
any files you've modified and run `python contrib/check-commit` on any
commits you've made (for example, `python contrib/check-commit
273ce12ad8f1` will report some style violations on a very old commit).