Use exponential distribution for P2P session timeouts #1244
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src/Chainweb/Time.hs
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| timeSpanToSeconds :: Integral a => TimeSpan a -> Seconds | ||
| timeSpanToSeconds (TimeSpan ms) = Seconds . int $ ms `div` 1000000 | ||
| timeSpanToSeconds (TimeSpan us) = Seconds . int $ us `div` 1000000 |
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While you're here -- maybe make these functions strict?
| -- | ||
| sessionTimeout :: TimeSpan Int -> IO (TimeSpan Int) | ||
| sessionTimeout expected = do | ||
| x <- exponential (1 / us) :: IO Double |
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Use System.Random.MWC instead, it's better in basically every way -- including already shipping with a truncated exponential distribution. I used it for exactly this in https://github.com/kadena-io/chainweb-node/pull/1254/files, you could crib the code from there
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I'd like to use it. However, I run into compatibility issues with our rather old nix snapshot. I don't remember the details. However, this implementation should be the same than what is used in mac-random. Also, I think, modern versions of the random package have much better performance than previous versions.
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Lars -- mwc-random was already in the deps list?
Along the way, fix implementation of
timeSpanToMicrosand add roundtrip tests for time span conversions.