ben-manes / caffeine / #5326

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master: 100%

Build Type

push

github

Committed by ben-manes

Commit Message

minor edge case handling

Avoid slight bias in the frequency sketch from sentinel keys. If the
access reordering is applied after the node was deleted, while other
operations no-op'd the popularity sketch would still increment for the
key. The key was replaced by a sentinel, so this inflates those hash
locations, which by collisions could inflate the popularity of another
entry.

Better timer wheel rollback on exception handling for the current
timestamp. In that case it would have simply forced a delayed full
sweep, so considered benign. More so, since the cache is not supposed
to throw any exceptions, it only acted as a failsafe in case of a bug
and therefore perfect handling was not necessary. Yet because code
walkthroughs keep flagging it, it's best to fix as the previous
approach was too subtle.

Previously, a failed computation could result in duplicate eviction
notifications. This occurred because the old entry was not removed
before the mapping function's / weigher's / Expiry's exception was
propagated. A repeatedly broken computation might notify the listener
multiple times until the entry was removed by the maintenance cycle.
As the listener is generally used for resource clean up, which is
usually idempotent, this double notification was likely fine. The
notification is still handled prior to running the mapping function to
ensure linearizability, e.g. removing a file prior to recreating it.

Coverage Stats

3847 of 3862 branches covered (99.61%)

65 of 70 new or added lines in 2 files covered. (92.86%)

1 existing line in 1 file now uncovered.

7903 of 7914 relevant lines covered (99.86%)

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