Use the underlying reproducible random impls instead of StdRng. #7717
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mina86
approved these changes
Sep 28, 2022
mzhangmzz
approved these changes
Sep 28, 2022
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Thank you for the fix! |
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Thanks for the additional fixes @mina86 ! |
nikurt
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Sep 29, 2022
* Use the underlying reproducible random impls. * Improve testing * fix deny * fmt Co-authored-by: Michal Nazarewicz <mina86@mina86.com>
matklad
reviewed
Sep 29, 2022
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| fn shuffle_duplicate_proposals(dup_proposals: &mut Vec<u64>, rng_seed: RngSeed) { | ||
| let mut rng: Hc128Rng = SeedableRng::from_seed(rng_seed); | ||
| dup_proposals.shuffle(&mut rng); |
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One thing I am worried here is that the specific shuffling algorithm that rand is using is unspecified. So in theory upgrading rand might change the result here.
If we are replacing protocol_defining_rand with a fixed rng (which is ❤️ ), I'd sleep better if we also vendored our own knuth_shuffle, so that we avoid problems a-la rust-lang/rust#85773.
We have tests here, so they'll probably catch drastic changes in the algorithm, but if it is something more subtle (like, use some super-advanced simd on specific CPUs or whatever), we might miss it.
nikurt
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Nov 9, 2022
* Use the underlying reproducible random impls. * Improve testing * fix deny * fmt Co-authored-by: Michal Nazarewicz <mina86@mina86.com>
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StdRng isn’t reproducible. As recommended by the comment on top of
StdRng, use the underlying specific algorithms. For proposals this is
Hc128 (what StdRng uses at rand=0.6.5), and for receipt shuffling this
is ChaCha20 (what StdRng uses at rand=0.7).
Added two unit tests to sanity check that the underlying impl does not
change. I've manually checked with similar testing using the
appropriate version of StdRng that the results do match what we
would've produced before this change.