1698
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Ran 14 Apr 2016 06:04PM UTC

Jobs 1

Files 64

Run time 3s

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Build # 1698

Build Type

push

travis-ci

Committed by

ben-manes

Commit Message

CASSANDRA-11452: Improved resistence to hash collision attacks

When the candidate and victim's hash code are equal they have the same
estimated frequency. This results in the candidate being rejected. If
a hash collision attack then the cache will not admit any new entries
and the hit rate will be very low (causing poor response times).

Ideally we'd use a 64-bit hash, but Java does not provide that natively
and, for now, I'd prefer not exposing a builder function (K -> long). A
longHashCode() would not fix the problem, but greatly reduce its
likelihood.

This patch evicts the victim in the case of a collision. This should
allow candidates to flow through the eden -> probation segments. This
should have a similar effect as using freq1 >= freq2 comparision (not
strictly >) without degrading the hit rate in the LIRS traces.

@blambov please review so that we can iterate and find a good
compromise solution

Coverage Stats

5069 of 5373 relevant lines covered (94.34%)

0.94 hits per line

Jobs

ID	Job ID	Ran	Files	Coverage
1	1698.1 (TERM=dumb)	14 Apr 2016 06:04PM UTC	0	94.34	Travis Job 1698.1

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