fix: completely prune the program cache when cache limit is hit

[bmuddha]

Summary by CodeRabbit

Release Notes

• Chores
  • Updated program cache eviction mechanism to incorporate epoch information during retry scenarios. This enhancement improves cache management precision when capacity limits are reached, ensuring more accurate resource allocation and better system stability during periods of high program loading.

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[coderabbitai]

Walkthrough

Updated the ProgramCache pruning method call in the program cache retry handler from prune_by_deployment_slot(self.slot) to prune(self.slot, self.epoch). This change adds the epoch parameter to the pruning operation that executes when the cache hits its maximum limit during retry.

Changes

Cohort / File(s)	Summary
ProgramCache pruning API update src/transaction_processor.rs	Updated retry path to pass epoch parameter to pruning method; changed from prune_by_deployment_slot(self.slot) to prune(self.slot, self.epoch)

Estimated code review effort

🎯 1 (Trivial) | ⏱️ ~3 minutes

Possibly related PRs

• fix: re-attempt to replenish the program cache on error #8: Introduced the retry+prune-by-deployment-slot logic in the same ProgramCacheHitMaxLimit retry path that this PR now updates to include epoch parameter.

Suggested reviewers

• GabrielePicco

Pre-merge checks and finishing touches

✅ Passed checks (3 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly describes the main change: updating program cache pruning to include epoch parameter for complete pruning when cache limit is reached.
Docstring Coverage	✅ Passed	Docstring coverage is 100.00% which is sufficient. The required threshold is 80.00%.

✨ Finishing touches

• 📝 Generate docstrings

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Post copyable unit tests in a comment
• Commit unit tests in branch bmuddha/fix/prune-program-cache

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📥 Commits

Reviewing files that changed from the base of the PR and between 1e6cfeb and 6f74a99.

📒 Files selected for processing (1)

• src/transaction_processor.rs (1 hunks)

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• GitHub Check: Run cargo test

🔇 Additional comments (1)

src/transaction_processor.rs (1)

381-388: Updated prune call aligns with newer ProgramCache API; verify against dependency version

Switching from prune_by_deployment_slot(self.slot) to prune(self.slot, self.epoch) in the retry path when hit_max_limit is true looks correct and matches the newer API that takes both slot and epoch. It also better fits the PR goal of fully pruning the cache before retrying.

Please:

• Confirm that solana_program_runtime::loaded_programs::ProgramCache::prune in version 2.2.1 (or the version in Cargo.toml) indeed has the (slot: Slot, epoch: Epoch) signature and that this call compiles as expected.
• Optionally add a focused test that simulates hit_max_limit and asserts that a second replenish_program_cache attempt succeeds after pruning, to guard this behavior against regressions.

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[GabrielePicco]

LGTM!