fix: guard against race conditions when resolving $refs

[vlindhol]

What/Why/How?

We were using a global AJV instance shared for all documents, which might lead to race conditions.

Add a WeakMap holding an AJV instance for each document, and add some extra deduplication logic to prevent trying to look up the same reference multiple times within a document, just in case.

Reference

?

Testing

Race conditions are hard to trigger reliably, I think the best I can do right now is say "all existing tests must pass".

I have failures triggered by processing a large amount of .yaml files at once at work, but can't post those files publicly :/

Example of the type of errors I get:

Example validation errored: can't resolve reference #/components/schemas/Product from <filename>

as if local references can't be resolved! After applying this fix those errors go away.

Screenshots (optional)

Check yourself

• [ ] Code changed? - Tested with redoc (internal)
• [x] All new/updated code is covered with tests
• [ ] New package installed? - Tested in different environments (browser/node)

Security

• [ ] Security impact of change has been considered
• [ ] Code follows company security practices and guidelines

[changeset-bot[bot]]

🦋 Changeset detected

Latest commit: fd87451c05866ef01231c58330571caeb6fc955b

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 3 packages

Name	Type
@redocly/openapi-core	Patch
@redocly/cli	Patch
@redocly/respect-core	Patch

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[tatomyr]

Thanks for the contribution! We'll take a look at your PR in a bit.

[vlindhol]

@tatomyr Great! Any updates on this? 😇

[tatomyr]

@vlindhol sorry, haven't had a chance to look at it yet. We're currently busy with preparing the next version release. Will review it after we finish that.

[tatomyr]

Closing this due to inactivity.