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audit-linearizability

Testing & Quality
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Analyze the cache for linearizability violations across all public methods

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Source SKILL.md: https://github.com/ben-manes/caffeine/blob/HEAD/.claude/skills/audit-linearizability/SKILL.md

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Analyze the cache for linearizability violations. For each public method below, identify its LINEARIZATION POINT — the single atomic step at which the operation appears to take effect.

Methods to analyze:

Single-key operations:

  • get(key), getIfPresent(key)
  • put(key, value), putIfAbsent(key, value)
  • remove(key), remove(key, value)
  • replace(key, value), replace(key, oldValue, newValue)
  • computeIfAbsent(key, function), compute(key, function), merge(key, value, function)

Bulk / aggregate operations:

  • getAll(keys) / getAllPresent(keys)
  • putAll(map)
  • invalidateAll(keys) / invalidateAll()
  • size(), containsKey(key), containsValue(value)

Note: Bulk operations are typically NOT linearizable as a unit. State whether each provides any atomicity beyond per-element linearizability.

For each method:

  1. State the linearization point (e.g., "CAS on CHM bin at line X").
  2. If conditional, enumerate all cases.
  3. Construct a 2-thread scenario confirming the linearization point.

Then attempt to construct violations: 4. Can two threads observe operations in an inconsistent order?

  • put(k, v1) / put(k, v2) / get(k): Can C see v2 then v1?
  • computeIfAbsent(k, f): Can f execute twice concurrently?
  • remove(k) / get(k): Can get return a value after remove linearized?
  1. Is size() linearizable or documented as an estimate? Bounds on error?
  2. For async cache variants: is the linearization point the future insertion or completion? Can get() return an already-replaced future?

For each candidate violation:

  • Provide the full interleaving
  • Show the sequential history it violates
  • Verify the interleaving is JMM-legal

Do not analyze internal consistency, only external observability.