perf: cached fs utils with shared trees

[patak-dev]

Description

Follow up to:

• perf: cached fs utils #15279

Implements an idea we discussed with @sheremet-va, sharing the DirentCache trees between FsUtils of different servers. In Vitest workspace mode this should avoid duplicating the trees of overlapping roots.

Pushing it as a draft for now. We should first merge #15279.

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What is the purpose of this pull request?

• Bug fix
• New Feature
• Documentation update
• Other

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[patak-dev]

Given that we now use the workspace root, for most users what should happen is that servers started on the same monorepo will all share the same root, so connectRootCacheToActiveRoots will finish in this condition: https://github.com/vitejs/vite/pull/15294/files#diff-ff9e3d87ccc2b2e1b181bfbb4511b0f89263c19ef3c04cf212a8590ec2847812R200.

The PR also supports starting a server in a root that is a child of active config roots (in that case it is a matter of expanding one of the parent roots until it). This only happens if an active root was a parent out of the monorepo. If it isn't a child of any active config root, then we create a new direntCache (and expand it to connect it to any active config root that is a child of it).

[patak-dev]

/ecosystem-ci run

[patak-dev]

/ecosystem-ci run

[patak-dev]

/ecosystem-ci run

[patak-dev]

/ecosystem-ci run

[patak-dev]

/ecosystem-ci run

[vite-ecosystem-ci]

📝 Ran ecosystem CI on e11de80: Open

suite	result	latest scheduled
analogjs	✅ success	✅ success
astro	❌ failure	✅ success
histoire	✅ success	✅ success
ladle	✅ success	✅ success
laravel	❌ failure	❌ failure
marko	❌ failure	✅ success
nuxt	✅ success	✅ success
nx	❌ failure	❌ failure
previewjs	✅ success	✅ success
qwik	❌ failure	❌ failure
rakkas	❌ failure	✅ success
remix	❌ failure	❌ failure
sveltekit	❌ failure	❌ failure
unocss	✅ success	✅ success
vike	✅ success	✅ success
vite-plugin-pwa	✅ success	✅ success
vite-plugin-react	❌ failure	❌ failure
vite-plugin-react-pages	✅ success	✅ success
vite-plugin-react-swc	✅ success	✅ success
vite-plugin-svelte	✅ success	✅ success
vite-plugin-vue	❌ failure	❌ failure
vite-setup-catalogue	✅ success	✅ success
vitepress	❌ failure	✅ success
vitest	✅ success	✅ success

[patak-dev]

astro, marko, and vitepress are failing with this PR. Even with its simplest form of only sharing the cache if the root is exactly the same for a config (that it would still be good given that we now use the workspace root for each config).
I don't yet understand why. What I could think is that now we have two watchers over the same cache and both are going to try to add or remove files, but I don't see how this could affect things here. Ideas welcome if someone is curious about what's going on here.