Audit Feature Interaction

Analyze the cache for defects arising from multiple features operating simultaneously on the same entry.

Assume at least one feature interaction bug exists. If your analysis yields zero findings, re-examine the top-priority pairs below — explain specifically why no interleaving produces a bug.

Priority ranking (from confirmed historical bugs):

1. Refresh + expiration (D+B) — most-bugged interaction historically
2. Reference collection + any feature (C+*) — value reference visibility
3. Async completion + any feature (F+*) — future lifecycle edge cases
4. Eviction + weight change (A+H) — counter drift during transitions

Features: A. Eviction (size/weight limit exceeded) B. Expiration (afterAccess, afterWrite, variable) C. Reference collection (weak key, weak value, soft value GC) D. Refresh (automatic reload) E. Loading (CacheLoader / computeIfAbsent) F. Async completion (CompletableFuture values) G. Listener notification (removal listener, eviction listener) H. Weight change (Weigher returning different weight for new value)

For each pair (A,B), (A,C), ..., (G,H) — 28 pairs total:

1. Can both features trigger simultaneously on the same entry?
2. If yes, construct the most adversarial interleaving.
3. Trace step-by-step: correct processing? notifications? final state? cleanup?

After all pairs, identify highest-risk TRIPLE interactions:

• Eviction + expiration + listener exception
• Refresh + async completion + GC collection
• Weight change + eviction + compute

High-risk pairwise combinations:

• Eviction during refresh (entry evicted while refreshing)
• Expiration during compute (entry expires mid-computation)
• GC during async completion (future completes after weak ref collected)
• Weight change during eviction
• Listener exception during any other feature

For each defect: state the features involved, provide the interleaving, state the incorrect behavior.

Source: ben-manes/caffeine — distributed by TomeVault.