Core: Fix race condition during empty folder init

[valentinpalkovic]

Closes #

What I did

Initializing Storybook in an empty directory currently fails due to a race condition with the following error:

/.npm/_npx/aa1ee7aee97d6cac/node_modules/create-storybook/bin/index.cjs:23
  throw error;
  ^

[Error: ENOENT: no such file or directory, open '/projects/testing/react-vite-84/.cache/storybook/default/dev-server/storybook-e35710dcf9c6d4f837d5dae15e56122e'] {
  errno: -2,
  code: 'ENOENT',
  syscall: 'open',
  path: '/projects/testing/react-vite-84/.cache/storybook/default/dev-server/storybook-e35710dcf9c6d4f837d5dae15e56122e'
}

Node.js v18.20.3

The issue was, that we introduced an alternative implementation for our internal caching, where we relied on file-system-cache, but we removed the package to use a custom caching solution.

The problem with the new solution is that every time we want to write into the cache, we don’t check, whether the cache folder actually exists. The cache folder itself gets initialized during module loading, so it should be, in theory, in place. Now, the crux is that when we initialize into an empty directory, we remove especially a .cache folder before continuing because in the past, we had issues initializing into an empty directory if it wasn’t empty.

Checklist for Contributors

Testing

The changes in this PR are covered in the following automated tests:

• stories
• unit tests
• integration tests
• end-to-end tests

Manual testing

This section is mandatory for all contributions. If you believe no manual test is necessary, please state so explicitly. Thanks!

Documentation

• Add or update documentation reflecting your changes
• If you are deprecating/removing a feature, make sure to update
  MIGRATION.MD

Checklist for Maintainers

• When this PR is ready for testing, make sure to add ci:normal, ci:merged or ci:daily GH label to it to run a specific set of sandboxes. The particular set of sandboxes can be found in code/lib/cli/src/sandbox-templates.ts

• Make sure this PR contains one of the labels below:

  Available labels

  • bug: Internal changes that fixes incorrect behavior.
  • maintenance: User-facing maintenance tasks.
  • dependencies: Upgrading (sometimes downgrading) dependencies.
  • build: Internal-facing build tooling & test updates. Will not show up in release changelog.
  • cleanup: Minor cleanup style change. Will not show up in release changelog.
  • documentation: Documentation only changes. Will not show up in release changelog.
  • feature request: Introducing a new feature.
  • BREAKING CHANGE: Changes that break compatibility in some way with current major version.
  • other: Changes that don't fit in the above categories.

🦋 Canary release

This PR does not have a canary release associated. You can request a canary release of this pull request by mentioning the @storybookjs/core team here.

core team members can create a canary release here or locally with gh workflow run --repo storybookjs/storybook canary-release-pr.yml --field pr=<PR_NUMBER>

name	before	after	diff	z	%
createSize	0 B	0 B	0 B	-	-
generateSize	77.7 MB	77.7 MB	0 B	0.92	0%
initSize	143 MB	143 MB	370 B	-0.49	0%
diffSize	65.1 MB	65.1 MB	370 B	-0.5	0%
buildSize	6.87 MB	6.87 MB	0 B	0.58	0%
buildSbAddonsSize	1.51 MB	1.51 MB	0 B	0.51	0%
buildSbCommonSize	195 kB	195 kB	0 B	-	0%
buildSbManagerSize	1.9 MB	1.9 MB	0 B	0.58	0%
buildSbPreviewSize	271 kB	271 kB	0 B	-	0%
buildStaticSize	0 B	0 B	0 B	-	-
buildPrebuildSize	3.88 MB	3.88 MB	0 B	0.58	0%
buildPreviewSize	3 MB	3 MB	0 B	-	0%
testBuildSize	0 B	0 B	0 B	-	-
testBuildSbAddonsSize	0 B	0 B	0 B	-	-
testBuildSbCommonSize	0 B	0 B	0 B	-	-
testBuildSbManagerSize	0 B	0 B	0 B	-	-
testBuildSbPreviewSize	0 B	0 B	0 B	-	-
testBuildStaticSize	0 B	0 B	0 B	-	-
testBuildPrebuildSize	0 B	0 B	0 B	-	-
testBuildPreviewSize	0 B	0 B	0 B	-	-

name	before	after	diff	z	%
createTime	17.4s	8.6s	-8s -808ms	-0.82	-102%
generateTime	27.1s	24.8s	-2s -374ms	0.78	-9.6%
initTime	20.5s	17.6s	-2s -895ms	0.58	-16.4%
buildTime	10.1s	9s	-1s -96ms	-0.07	-12.1%
testBuildTime	0ms	0ms	0ms	-	-
devPreviewResponsive	5.9s	6s	162ms	-0.46	2.7%
devManagerResponsive	4.2s	3.9s	-311ms	-0.34	-7.9%
devManagerHeaderVisible	648ms	599ms	-49ms	-0.55	-8.2%
devManagerIndexVisible	722ms	685ms	-37ms	-0.37	-5.4%
devStoryVisibleUncached	1.9s	1.1s	-831ms	-0.22	-74.6%
devStoryVisible	720ms	684ms	-36ms	-0.35	-5.3%
devAutodocsVisible	565ms	536ms	-29ms	-0.6	-5.4%
devMDXVisible	556ms	519ms	-37ms	-0.56	-7.1%
buildManagerHeaderVisible	742ms	661ms	-81ms	0.24	-12.3%
buildManagerIndexVisible	752ms	718ms	-34ms	0.62	-4.7%
buildStoryVisible	744ms	652ms	-92ms	0.18	-14.1%
buildAutodocsVisible	553ms	600ms	47ms	0.74	7.8%
buildMDXVisible	517ms	524ms	7ms	0.01	1.3%

Greptile Summary

This PR fixes a race condition in FileSystemCache by ensuring the cache directory exists before writing files during initialization of empty folders.

• Added mkdirSync call with recursive: true in set() and setSync() methods in /code/core/src/common/utils/file-cache.ts
• Prevents file write failures when cache directory is missing during concurrent operations
• Maintains backward compatibility since directory creation is safe even if directory exists

[greptile-apps]

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