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Jason Brown edited comment on CASSANDRA-13291 at 9/28/17 12:21 PM:
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I'm +1 on the code. [~mkjellman] wdyt about including the microbenchmark I put
together?
UPDATE: Actually, I did have a few comments/questions:
- it would be nice to have a unit test class for {{HashingUtils}}. mostly, i'm
thinking it would be nice to cover the different cases in {{#updateBytes}}:
empty buffer, on-heap, and off-heap (large and small).
- {{RandomPartitioner#hashToBigInteger}} - is this suppossed to explicitly use
{{MD5Digest#hash}} still? If so, can we add a comment that it's intentionally
doing so?
- for the {{Validator.CountingHasher#put*}} primitive functions, I think you
need to increment the {{count}} member field by the appropriate number of
bytes. I *think* the way the existing {{MessageDigest}} works is that for each
byte {{#updateEngine}} is invoked, so we would count it in the original.
- petty nits for for petty nits gods: clean up the added but unused imports on
{{MessagingService}} and {{SchemaConstants}}
was (Author: jasobrown):
I'm +1 on the code. [~mkjellman] wdyt about including the microbenchmark I put
together?
> Replace usages of MessageDigest with Guava's Hasher
> ---------------------------------------------------
>
> Key: CASSANDRA-13291
> URL: https://issues.apache.org/jira/browse/CASSANDRA-13291
> Project: Cassandra
> Issue Type: Improvement
> Components: Core
> Reporter: Michael Kjellman
> Assignee: Michael Kjellman
> Attachments: CASSANDRA-13291-trunk.diff
>
>
> During my profiling of C* I frequently see lots of aggregate time across
> threads being spent inside the MD5 MessageDigest implementation. Given that
> there are tons of modern alternative hashing functions better than MD5
> available -- both in terms of providing better collision resistance and
> actual computational speed -- I wanted to switch out our usage of MD5 for
> alternatives (like adler128 or murmur3_128) and test for performance
> improvements.
> Unfortunately, I found given the fact we use MessageDigest everywhere --
> switching out the hashing function to something like adler128 or murmur3_128
> (for example) -- which don't ship with the JDK -- wasn't straight forward.
> The goal of this ticket is to propose switching out usages of MessageDigest
> directly in favor of Hasher from Guava. This means going forward we can
> change a single line of code to switch the hashing algorithm being used
> (assuming there is an implementation in Guava).
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