Cache eslint in pre-commit script (makes git commit 5x faster)

[aloisklink]

📑 Summary

Run eslint with --cache to speed up pre-commit scripts.

This was added to the pnpm run lint script in b7f9495 and doesn't seem to be causing any issues.

On my PC, this speeds up git commit on a single file from ~10 seconds to ~2 seconds.

Discussed in #4035 (comment)

📏 Design Decisions

Not enabling --cache for prettier

I haven't enabled --cache for prettier since as of prettier 2.8.0, their cache invalidation doesn't yet work with prettier plugins.

It's not too big of a deal, since prettier doesn't use up much time: prettier takes about 0.5s on a single-file, but eslint takes 8.5s without --cache and 1.4s with --cache.

Changing eslint to use --cache-strategy content

I also had to change eslint to use --cache-strategy content to get it working with lint-staged.

By default, eslint uses the file metadata (e.g. modification time) to detect when the cache should be invalidated.

However, this is not efficient with git, since git constantly changes the modification time, e.g. running git switch main && git switch original-branch would not change the file contents, but would change the file mtimes and force eslint to re-lint everything.

Using the file contents is slower (~3% for me, going from 1.51s to 1.46s), but more resilient. However, I have a pretty fast SSD, so I imagine the slowdown would be higher on computers with a slower disk.

📋 Tasks

Make sure you

• 📖 have read the contribution guidelines
• 💻 have added unit/e2e tests (if appropriate)
• 📓 have added documentation (if appropriate)
• 🔖 targeted develop branch

[sidharthv96]

LGTM, Speeding up pre commit hook is a very welcome change!

[sidharthv96]

Don't we need cache here too?

[aloisklink]

Good idea! I didn't add it previously since I was worried about cache invalidation, but --cache-strategy content should mean that we have no issues.

PR in #4073
(hope you don't mind, I made you a co-author of the commit, since you suggested the idea 😄)