* fix(dashboard): prevent memory leak in CUE validation by using fresh contexts
Fixes#114344
The CUE validation was reusing a single cue.Context across all
validations, which caused unbounded memory growth due to CUE's internal
caching of intermediate computation results (disjunctions, unifications,
etc.).
Root Cause:
- A single cue.Context was created and reused via getValidator()
- Each validation added entries to the context's internal caches
- These caches grew unboundedly over time
- Memory could not be garbage collected because the context held references
Solution:
- Store the schema source string instead of a compiled cue.Value
- Create a fresh cuecontext.New() for each validation
- This allows the context and its caches to be garbage collected after
each validation completes
Performance Impact:
- ~2x slower due to schema recompilation per validation
- Acceptable trade-off to prevent memory leaks
- Memory usage stays bounded instead of growing unboundedly
* fix(dashboard): use periodic context recreation to prevent CUE memory leaks
Replace fresh context creation with periodic context recreation approach.
The context is reused for up to 100 validations, then recreated to allow
garbage collection of cached values while maintaining good performance.
This balances performance (only 19% slower than leaky approach) with memory
safety (stable at ~5 MB vs ~2 GB leak).
See https://github.com/grafana/grafana/issues/114344#issuecomment-3605562491
* refactor(cuevalidator): simplify to use mutex instead of atomic counter
Since CUE is not thread-safe, we need the mutex for the entire validation
operation anyway. Using a regular int counter protected by the mutex is
simpler and cleaner than using atomic operations.
Roberto Jiménez Sánchez
e5259c2ad4