[himsngh]

AppRefTracker.AppsForRef and RefsForApp take the tracker lock, but return the tracker's internal maps. The Secret and ConfigMap event handlers range over the map returned by AppsForRef after the lock is released, while App and PackageRepository reconcilers call ReconcileRefs and RemoveAppFromAllRefs from other goroutines, which modify the same maps. Concurrent iteration and modification of a map is a data race, and the Go runtime can terminate the controller with "fatal error: concurrent map iteration and map write", which is not recoverable.

Return a copy of the map from both accessors while the lock is held, so callers iterate a snapshot that is not modified by later tracker updates. Return types are unchanged, so callers do not need changes.

Changes:

1. pkg/reftracker/ref_tracker.go

   • Return maps.Clone of the internal map from AppsForRef and RefsForApp

2. pkg/reftracker/ref_tracker_test.go

   • Add Test_AppsForRef_RefsForApp_ReturnSnapshot verifying returned maps are not affected by later tracker changes and vice versa
   • Add Test_AppsForRef_ConcurrentWithReconcileRefs which iterates returned maps while another goroutine updates the tracker. Without this change it fails under -race, and without -race it usually crashes with "concurrent map iteration and map write".

What this PR does / why we need it:

Which issue(s) this PR fixes:

Fixes #

Does this PR introduce a user-facing change?

Additional Notes for your reviewer:

Review Checklist:

• Follows the developer guidelines
• Relevant tests are added or updated
• Relevant docs in this repo added or updated
• Relevant carvel.dev docs added or updated in a separate PR and there's
  a link to that PR
• Code is at least as readable and maintainable as it was before this
  change

Additional documentation e.g., Proposal, usage docs, etc.: