[Feature request] Allow to use a faster PRNG

[mratsim]

Currently Quicktest uses nim-random/Random which uses the cryptographic data from /dev/urandom.

This doesn't scale, especially on servers in controlled environment (Travis, Appveyor) with no inputs/processes that serve as source of randomness.

The /dev/urandom quickly gets starved and Quicktest stalls.

I tried running millions of tests overnight, but I couldn't complete the first one: or-ing 2 arrays - https://github.com/status-im/nim-stint/blob/master/tests/property_based_uint256.nim#L26

The fastest PRNG in Nim currently is from stdlib random which also exhibits nice randomness property is xoroshiro128+. Benchmarks: http://xoshiro.di.unimi.it/

In nim-random it's probably the XorShift128+

[data-man]

I prefer PCG.

[zah]

We'll be posting a bounty on fixing this issue, together with few additional requirements. The details are in the linked issue above.

@alehander42 would be the best person to claim the bounty as the author of the library. To do this, please submit a simple pull request in our repo, bumpting the quicktest version number when the fixes are available.

[alehander92]

thank you, I'll continue the discussion in linked

@mratsim I'll add support for a private generator, just a note, I think urandom should never block: it might produce very unrandom results with low entropy, but it still should always return valid results at least on Linux: I can easily run a million tests in 10 seconds.

[mratsim]

Edited my first post, "the fastest prng in Nim is stdlib random".

I'll check what was taking time then, it's strange.