diff options
Diffstat (limited to 'rand/src/lib.rs')
| -rw-r--r-- | rand/src/lib.rs | 436 |
1 files changed, 152 insertions, 284 deletions
diff --git a/rand/src/lib.rs b/rand/src/lib.rs index ca231b5..b4167c3 100644 --- a/rand/src/lib.rs +++ b/rand/src/lib.rs @@ -17,7 +17,7 @@ //! To get you started quickly, the easiest and highest-level way to get //! a random value is to use [`random()`]; alternatively you can use //! [`thread_rng()`]. The [`Rng`] trait provides a useful API on all RNGs, while -//! the [`distributions` module] and [`seq` module] provide further +//! the [`distributions`] and [`seq`] modules provide further //! functionality on top of RNGs. //! //! ``` @@ -39,12 +39,6 @@ //! //! For the user guide and futher documentation, please read //! [The Rust Rand Book](https://rust-random.github.io/book). -//! -//! [`distributions` module]: distributions/index.html -//! [`random()`]: fn.random.html -//! [`Rng`]: trait.Rng.html -//! [`seq` module]: seq/index.html -//! [`thread_rng()`]: fn.thread_rng.html #![doc(html_logo_url = "https://www.rust-lang.org/logos/rust-logo-128x128-blk.png", @@ -56,112 +50,64 @@ #![doc(test(attr(allow(unused_variables), deny(warnings))))] #![cfg_attr(not(feature="std"), no_std)] -#![cfg_attr(all(feature="alloc", not(feature="std")), feature(alloc))] #![cfg_attr(all(feature="simd_support", feature="nightly"), feature(stdsimd))] -#[cfg(feature = "std")] extern crate core; -#[cfg(all(feature = "alloc", not(feature="std")))] #[macro_use] extern crate alloc; - -#[cfg(feature="simd_support")] extern crate packed_simd; +#![allow(clippy::excessive_precision, clippy::unreadable_literal, clippy::float_cmp)] -#[cfg(feature = "rand_os")] -extern crate rand_os; +#[cfg(all(feature="alloc", not(feature="std")))] +extern crate alloc; -extern crate rand_core; -extern crate rand_isaac; // only for deprecations -extern crate rand_chacha; // only for deprecations -extern crate rand_hc; -extern crate rand_pcg; -extern crate rand_xorshift; +#[cfg(feature = "getrandom")] +use getrandom_package as getrandom; -#[cfg(feature = "log")] #[macro_use] extern crate log; #[allow(unused)] -#[cfg(not(feature = "log"))] macro_rules! trace { ($($x:tt)*) => () } +macro_rules! trace { ($($x:tt)*) => ( + #[cfg(feature = "log")] { + log::trace!($($x)*) + } +) } #[allow(unused)] -#[cfg(not(feature = "log"))] macro_rules! debug { ($($x:tt)*) => () } +macro_rules! debug { ($($x:tt)*) => ( + #[cfg(feature = "log")] { + log::debug!($($x)*) + } +) } #[allow(unused)] -#[cfg(not(feature = "log"))] macro_rules! info { ($($x:tt)*) => () } +macro_rules! info { ($($x:tt)*) => ( + #[cfg(feature = "log")] { + log::info!($($x)*) + } +) } #[allow(unused)] -#[cfg(not(feature = "log"))] macro_rules! warn { ($($x:tt)*) => () } +macro_rules! warn { ($($x:tt)*) => ( + #[cfg(feature = "log")] { + log::warn!($($x)*) + } +) } #[allow(unused)] -#[cfg(not(feature = "log"))] macro_rules! error { ($($x:tt)*) => () } - +macro_rules! error { ($($x:tt)*) => ( + #[cfg(feature = "log")] { + log::error!($($x)*) + } +) } // Re-exports from rand_core -pub use rand_core::{RngCore, CryptoRng, SeedableRng}; -pub use rand_core::{ErrorKind, Error}; +pub use rand_core::{RngCore, CryptoRng, SeedableRng, Error}; // Public exports -#[cfg(feature="std")] pub use rngs::thread::thread_rng; +#[cfg(feature="std")] pub use crate::rngs::thread::thread_rng; // Public modules pub mod distributions; pub mod prelude; -#[deprecated(since="0.6.0")] -pub mod prng; pub mod rngs; pub mod seq; -//////////////////////////////////////////////////////////////////////////////// -// Compatibility re-exports. Documentation is hidden; will be removed eventually. - -#[doc(hidden)] mod deprecated; - -#[allow(deprecated)] -#[doc(hidden)] pub use deprecated::ReseedingRng; - -#[allow(deprecated)] -#[cfg(feature="std")] #[doc(hidden)] pub use deprecated::EntropyRng; - -#[allow(deprecated)] -#[cfg(feature="rand_os")] -#[doc(hidden)] -pub use deprecated::OsRng; - -#[allow(deprecated)] -#[doc(hidden)] pub use deprecated::{ChaChaRng, IsaacRng, Isaac64Rng, XorShiftRng}; -#[allow(deprecated)] -#[doc(hidden)] pub use deprecated::StdRng; - - -#[allow(deprecated)] -#[doc(hidden)] -pub mod jitter { - pub use deprecated::JitterRng; - pub use rngs::TimerError; -} -#[allow(deprecated)] -#[cfg(feature="rand_os")] -#[doc(hidden)] -pub mod os { - pub use deprecated::OsRng; -} -#[allow(deprecated)] -#[doc(hidden)] -pub mod chacha { - pub use deprecated::ChaChaRng; -} -#[allow(deprecated)] -#[doc(hidden)] -pub mod isaac { - pub use deprecated::{IsaacRng, Isaac64Rng}; -} -#[allow(deprecated)] -#[cfg(feature="std")] -#[doc(hidden)] -pub mod read { - pub use deprecated::ReadRng; -} - -#[allow(deprecated)] -#[cfg(feature="std")] #[doc(hidden)] pub use deprecated::ThreadRng; - -//////////////////////////////////////////////////////////////////////////////// - use core::{mem, slice}; -use distributions::{Distribution, Standard}; -use distributions::uniform::{SampleUniform, UniformSampler, SampleBorrow}; +use core::num::Wrapping; +use crate::distributions::{Distribution, Standard}; +use crate::distributions::uniform::{SampleUniform, UniformSampler, SampleBorrow}; /// An automatically-implemented extension trait on [`RngCore`] providing high-level /// generic methods for sampling values and other convenience methods. @@ -200,13 +146,9 @@ use distributions::uniform::{SampleUniform, UniformSampler, SampleBorrow}; /// /// # let v = foo(&mut thread_rng()); /// ``` -/// -/// [`RngCore`]: trait.RngCore.html pub trait Rng: RngCore { /// Return a random value supporting the [`Standard`] distribution. /// - /// [`Standard`]: distributions/struct.Standard.html - /// /// # Example /// /// ``` @@ -217,8 +159,31 @@ pub trait Rng: RngCore { /// println!("{}", x); /// println!("{:?}", rng.gen::<(f64, bool)>()); /// ``` + /// + /// # Arrays and tuples + /// + /// The `rng.gen()` method is able to generate arrays (up to 32 elements) + /// and tuples (up to 12 elements), so long as all element types can be + /// generated. + /// + /// For arrays of integers, especially for those with small element types + /// (< 64 bit), it will likely be faster to instead use [`Rng::fill`]. + /// + /// ``` + /// use rand::{thread_rng, Rng}; + /// + /// let mut rng = thread_rng(); + /// let tuple: (u8, i32, char) = rng.gen(); // arbitrary tuple support + /// + /// let arr1: [f32; 32] = rng.gen(); // array construction + /// let mut arr2 = [0u8; 128]; + /// rng.fill(&mut arr2); // array fill + /// ``` + /// + /// [`Standard`]: distributions::Standard #[inline] - fn gen<T>(&mut self) -> T where Standard: Distribution<T> { + fn gen<T>(&mut self) -> T + where Standard: Distribution<T> { Standard.sample(self) } @@ -245,10 +210,12 @@ pub trait Rng: RngCore { /// println!("{}", m); /// ``` /// - /// [`Uniform`]: distributions/uniform/struct.Uniform.html + /// [`Uniform`]: distributions::uniform::Uniform fn gen_range<T: SampleUniform, B1, B2>(&mut self, low: B1, high: B2) -> T - where B1: SampleBorrow<T> + Sized, - B2: SampleBorrow<T> + Sized { + where + B1: SampleBorrow<T> + Sized, + B2: SampleBorrow<T> + Sized, + { T::Sampler::sample_single(low, high, self) } @@ -272,34 +239,39 @@ pub trait Rng: RngCore { /// Create an iterator that generates values using the given distribution. /// + /// Note that this function takes its arguments by value. This works since + /// `(&mut R): Rng where R: Rng` and + /// `(&D): Distribution where D: Distribution`, + /// however borrowing is not automatic hence `rng.sample_iter(...)` may + /// need to be replaced with `(&mut rng).sample_iter(...)`. + /// /// # Example /// /// ``` /// use rand::{thread_rng, Rng}; /// use rand::distributions::{Alphanumeric, Uniform, Standard}; /// - /// let mut rng = thread_rng(); + /// let rng = thread_rng(); /// /// // Vec of 16 x f32: - /// let v: Vec<f32> = thread_rng().sample_iter(&Standard).take(16).collect(); + /// let v: Vec<f32> = rng.sample_iter(Standard).take(16).collect(); /// /// // String: - /// let s: String = rng.sample_iter(&Alphanumeric).take(7).collect(); + /// let s: String = rng.sample_iter(Alphanumeric).take(7).collect(); /// /// // Combined values - /// println!("{:?}", thread_rng().sample_iter(&Standard).take(5) + /// println!("{:?}", rng.sample_iter(Standard).take(5) /// .collect::<Vec<(f64, bool)>>()); /// /// // Dice-rolling: /// let die_range = Uniform::new_inclusive(1, 6); - /// let mut roll_die = rng.sample_iter(&die_range); + /// let mut roll_die = rng.sample_iter(die_range); /// while roll_die.next().unwrap() != 6 { /// println!("Not a 6; rolling again!"); /// } /// ``` - fn sample_iter<'a, T, D: Distribution<T>>(&'a mut self, distr: &'a D) - -> distributions::DistIter<'a, D, Self, T> where Self: Sized - { + fn sample_iter<T, D>(self, distr: D) -> distributions::DistIter<D, Self, T> + where D: Distribution<T>, Self: Sized { distr.sample_iter(self) } @@ -323,9 +295,8 @@ pub trait Rng: RngCore { /// thread_rng().fill(&mut arr[..]); /// ``` /// - /// [`fill_bytes`]: trait.RngCore.html#method.fill_bytes - /// [`try_fill`]: trait.Rng.html#method.try_fill - /// [`AsByteSliceMut`]: trait.AsByteSliceMut.html + /// [`fill_bytes`]: RngCore::fill_bytes + /// [`try_fill`]: Rng::try_fill fn fill<T: AsByteSliceMut + ?Sized>(&mut self, dest: &mut T) { self.fill_bytes(dest.as_byte_slice_mut()); dest.to_le(); @@ -338,10 +309,8 @@ pub trait Rng: RngCore { /// On big-endian platforms this performs byte-swapping to ensure /// portability of results from reproducible generators. /// - /// This uses [`try_fill_bytes`] internally and forwards all RNG errors. In - /// some cases errors may be resolvable; see [`ErrorKind`] and - /// documentation for the RNG in use. If you do not plan to handle these - /// errors you may prefer to use [`fill`]. + /// This is identical to [`fill`] except that it uses [`try_fill_bytes`] + /// internally and forwards RNG errors. /// /// # Example /// @@ -358,10 +327,8 @@ pub trait Rng: RngCore { /// # try_inner().unwrap() /// ``` /// - /// [`ErrorKind`]: enum.ErrorKind.html - /// [`try_fill_bytes`]: trait.RngCore.html#method.try_fill_bytes - /// [`fill`]: trait.Rng.html#method.fill - /// [`AsByteSliceMut`]: trait.AsByteSliceMut.html + /// [`try_fill_bytes`]: RngCore::try_fill_bytes + /// [`fill`]: Rng::fill fn try_fill<T: AsByteSliceMut + ?Sized>(&mut self, dest: &mut T) -> Result<(), Error> { self.try_fill_bytes(dest.as_byte_slice_mut())?; dest.to_le(); @@ -386,10 +353,10 @@ pub trait Rng: RngCore { /// /// If `p < 0` or `p > 1`. /// - /// [`Bernoulli`]: distributions/bernoulli/struct.Bernoulli.html + /// [`Bernoulli`]: distributions::bernoulli::Bernoulli #[inline] fn gen_bool(&mut self, p: f64) -> bool { - let d = distributions::Bernoulli::new(p); + let d = distributions::Bernoulli::new(p).unwrap(); self.sample(d) } @@ -415,55 +382,19 @@ pub trait Rng: RngCore { /// println!("{}", rng.gen_ratio(2, 3)); /// ``` /// - /// [`Bernoulli`]: distributions/bernoulli/struct.Bernoulli.html + /// [`Bernoulli`]: distributions::bernoulli::Bernoulli #[inline] fn gen_ratio(&mut self, numerator: u32, denominator: u32) -> bool { - let d = distributions::Bernoulli::from_ratio(numerator, denominator); + let d = distributions::Bernoulli::from_ratio(numerator, denominator).unwrap(); self.sample(d) } - - /// Return a random element from `values`. - /// - /// Deprecated: use [`SliceRandom::choose`] instead. - /// - /// [`SliceRandom::choose`]: seq/trait.SliceRandom.html#method.choose - #[deprecated(since="0.6.0", note="use SliceRandom::choose instead")] - fn choose<'a, T>(&mut self, values: &'a [T]) -> Option<&'a T> { - use seq::SliceRandom; - values.choose(self) - } - - /// Return a mutable pointer to a random element from `values`. - /// - /// Deprecated: use [`SliceRandom::choose_mut`] instead. - /// - /// [`SliceRandom::choose_mut`]: seq/trait.SliceRandom.html#method.choose_mut - #[deprecated(since="0.6.0", note="use SliceRandom::choose_mut instead")] - fn choose_mut<'a, T>(&mut self, values: &'a mut [T]) -> Option<&'a mut T> { - use seq::SliceRandom; - values.choose_mut(self) - } - - /// Shuffle a mutable slice in place. - /// - /// Deprecated: use [`SliceRandom::shuffle`] instead. - /// - /// [`SliceRandom::shuffle`]: seq/trait.SliceRandom.html#method.shuffle - #[deprecated(since="0.6.0", note="use SliceRandom::shuffle instead")] - fn shuffle<T>(&mut self, values: &mut [T]) { - use seq::SliceRandom; - values.shuffle(self) - } } impl<R: RngCore + ?Sized> Rng for R {} /// Trait for casting types to byte slices /// -/// This is used by the [`fill`] and [`try_fill`] methods. -/// -/// [`fill`]: trait.Rng.html#method.fill -/// [`try_fill`]: trait.Rng.html#method.try_fill +/// This is used by the [`Rng::fill`] and [`Rng::try_fill`] methods. pub trait AsByteSliceMut { /// Return a mutable reference to self as a byte slice fn as_byte_slice_mut(&mut self) -> &mut [u8]; @@ -481,6 +412,7 @@ impl AsByteSliceMut for [u8] { } macro_rules! impl_as_byte_slice { + () => {}; ($t:ty) => { impl AsByteSliceMut for [$t] { fn as_byte_slice_mut(&mut self) -> &mut [u8] { @@ -491,8 +423,7 @@ macro_rules! impl_as_byte_slice { } } else { unsafe { - slice::from_raw_parts_mut(&mut self[0] - as *mut $t + slice::from_raw_parts_mut(self.as_mut_ptr() as *mut u8, self.len() * mem::size_of::<$t>() ) @@ -506,26 +437,47 @@ macro_rules! impl_as_byte_slice { } } } + + impl AsByteSliceMut for [Wrapping<$t>] { + fn as_byte_slice_mut(&mut self) -> &mut [u8] { + if self.len() == 0 { + unsafe { + // must not use null pointer + slice::from_raw_parts_mut(0x1 as *mut u8, 0) + } + } else { + unsafe { + slice::from_raw_parts_mut(self.as_mut_ptr() + as *mut u8, + self.len() * mem::size_of::<$t>() + ) + } + } + } + + fn to_le(&mut self) { + for x in self { + *x = Wrapping(x.0.to_le()); + } + } + } + }; + ($t:ty, $($tt:ty,)*) => { + impl_as_byte_slice!($t); + // TODO: this could replace above impl once Rust #32463 is fixed + // impl_as_byte_slice!(Wrapping<$t>); + impl_as_byte_slice!($($tt,)*); } } -impl_as_byte_slice!(u16); -impl_as_byte_slice!(u32); -impl_as_byte_slice!(u64); -#[cfg(all(rustc_1_26, not(target_os = "emscripten")))] impl_as_byte_slice!(u128); -impl_as_byte_slice!(usize); -impl_as_byte_slice!(i8); -impl_as_byte_slice!(i16); -impl_as_byte_slice!(i32); -impl_as_byte_slice!(i64); -#[cfg(all(rustc_1_26, not(target_os = "emscripten")))] impl_as_byte_slice!(i128); -impl_as_byte_slice!(isize); +impl_as_byte_slice!(u16, u32, u64, usize,); +#[cfg(not(target_os = "emscripten"))] impl_as_byte_slice!(u128); +impl_as_byte_slice!(i8, i16, i32, i64, isize,); +#[cfg(not(target_os = "emscripten"))] impl_as_byte_slice!(i128); macro_rules! impl_as_byte_slice_arrays { ($n:expr,) => {}; - ($n:expr, $N:ident, $($NN:ident,)*) => { - impl_as_byte_slice_arrays!($n - 1, $($NN,)*); - + ($n:expr, $N:ident) => { impl<T> AsByteSliceMut for [T; $n] where [T]: AsByteSliceMut { fn as_byte_slice_mut(&mut self) -> &mut [u8] { self[..].as_byte_slice_mut() @@ -536,96 +488,19 @@ macro_rules! impl_as_byte_slice_arrays { } } }; + ($n:expr, $N:ident, $($NN:ident,)*) => { + impl_as_byte_slice_arrays!($n, $N); + impl_as_byte_slice_arrays!($n - 1, $($NN,)*); + }; (!div $n:expr,) => {}; (!div $n:expr, $N:ident, $($NN:ident,)*) => { + impl_as_byte_slice_arrays!($n, $N); impl_as_byte_slice_arrays!(!div $n / 2, $($NN,)*); - - impl<T> AsByteSliceMut for [T; $n] where [T]: AsByteSliceMut { - fn as_byte_slice_mut(&mut self) -> &mut [u8] { - self[..].as_byte_slice_mut() - } - - fn to_le(&mut self) { - self[..].to_le() - } - } }; } impl_as_byte_slice_arrays!(32, N,N,N,N,N,N,N,N,N,N,N,N,N,N,N,N,N,N,N,N,N,N,N,N,N,N,N,N,N,N,N,N,N,); impl_as_byte_slice_arrays!(!div 4096, N,N,N,N,N,N,N,); - -/// A convenience extension to [`SeedableRng`] allowing construction from fresh -/// entropy. This trait is automatically implemented for any PRNG implementing -/// [`SeedableRng`] and is not intended to be implemented by users. -/// -/// This is equivalent to using `SeedableRng::from_rng(EntropyRng::new())` then -/// unwrapping the result. -/// -/// Since this is convenient and secure, it is the recommended way to create -/// PRNGs, though two alternatives may be considered: -/// -/// * Deterministic creation using [`SeedableRng::from_seed`] with a fixed seed -/// * Seeding from `thread_rng`: `SeedableRng::from_rng(thread_rng())?`; -/// this will usually be faster and should also be secure, but requires -/// trusting one extra component. -/// -/// ## Example -/// -/// ``` -/// use rand::{Rng, FromEntropy}; -/// use rand::rngs::StdRng; -/// -/// let mut rng = StdRng::from_entropy(); -/// println!("Random die roll: {}", rng.gen_range(1, 7)); -/// ``` -/// -/// [`EntropyRng`]: rngs/struct.EntropyRng.html -/// [`SeedableRng`]: trait.SeedableRng.html -/// [`SeedableRng::from_seed`]: trait.SeedableRng.html#tymethod.from_seed -#[cfg(feature="std")] -pub trait FromEntropy: SeedableRng { - /// Creates a new instance, automatically seeded with fresh entropy. - /// - /// Normally this will use `OsRng`, but if that fails `JitterRng` will be - /// used instead. Both should be suitable for cryptography. It is possible - /// that both entropy sources will fail though unlikely; failures would - /// almost certainly be platform limitations or build issues, i.e. most - /// applications targetting PC/mobile platforms should not need to worry - /// about this failing. - /// - /// # Panics - /// - /// If all entropy sources fail this will panic. If you need to handle - /// errors, use the following code, equivalent aside from error handling: - /// - /// ``` - /// # use rand::Error; - /// use rand::prelude::*; - /// use rand::rngs::EntropyRng; - /// - /// # fn try_inner() -> Result<(), Error> { - /// // This uses StdRng, but is valid for any R: SeedableRng - /// let mut rng = StdRng::from_rng(EntropyRng::new())?; - /// - /// println!("random number: {}", rng.gen_range(1, 10)); - /// # Ok(()) - /// # } - /// - /// # try_inner().unwrap() - /// ``` - fn from_entropy() -> Self; -} - -#[cfg(feature="std")] -impl<R: SeedableRng> FromEntropy for R { - fn from_entropy() -> R { - R::from_rng(rngs::EntropyRng::new()).unwrap_or_else(|err| - panic!("FromEntropy::from_entropy() failed: {}", err)) - } -} - - /// Generates a random value using the thread-local random number generator. /// /// This is simply a shortcut for `thread_rng().gen()`. See [`thread_rng`] for @@ -667,40 +542,26 @@ impl<R: SeedableRng> FromEntropy for R { /// } /// ``` /// -/// [`thread_rng`]: fn.thread_rng.html -/// [`Standard`]: distributions/struct.Standard.html +/// [`Standard`]: distributions::Standard #[cfg(feature="std")] #[inline] -pub fn random<T>() -> T where Standard: Distribution<T> { +pub fn random<T>() -> T +where Standard: Distribution<T> { thread_rng().gen() } #[cfg(test)] mod test { - use rngs::mock::StepRng; - use rngs::StdRng; + use crate::rngs::mock::StepRng; use super::*; #[cfg(all(not(feature="std"), feature="alloc"))] use alloc::boxed::Box; - pub struct TestRng<R> { inner: R } - - impl<R: RngCore> RngCore for TestRng<R> { - fn next_u32(&mut self) -> u32 { - self.inner.next_u32() - } - fn next_u64(&mut self) -> u64 { - self.inner.next_u64() - } - fn fill_bytes(&mut self, dest: &mut [u8]) { - self.inner.fill_bytes(dest) - } - fn try_fill_bytes(&mut self, dest: &mut [u8]) -> Result<(), Error> { - self.inner.try_fill_bytes(dest) - } - } - - pub fn rng(seed: u64) -> TestRng<StdRng> { - TestRng { inner: StdRng::seed_from_u64(seed) } + /// Construct a deterministic RNG with the given seed + pub fn rng(seed: u64) -> impl RngCore { + // For tests, we want a statistically good, fast, reproducible RNG. + // PCG32 will do fine, and will be easy to embed if we ever need to. + const INC: u64 = 11634580027462260723; + rand_pcg::Pcg32::new(seed, INC) } #[test] @@ -740,6 +601,12 @@ mod test { rng.fill(&mut array[..]); assert_eq!(array, [x as u32, (x >> 32) as u32]); assert_eq!(rng.next_u32(), x as u32); + + // Check equivalence using wrapped arrays + let mut warray = [Wrapping(0u32); 2]; + rng.fill(&mut warray[..]); + assert_eq!(array[0], warray[0].0); + assert_eq!(array[1], warray[1].0); } #[test] @@ -796,9 +663,9 @@ mod test { #[test] fn test_rng_trait_object() { - use distributions::{Distribution, Standard}; + use crate::distributions::{Distribution, Standard}; let mut rng = rng(109); - let mut r = &mut rng as &mut RngCore; + let mut r = &mut rng as &mut dyn RngCore; r.next_u32(); r.gen::<i32>(); assert_eq!(r.gen_range(0, 1), 0); @@ -808,9 +675,9 @@ mod test { #[test] #[cfg(feature="alloc")] fn test_rng_boxed_trait() { - use distributions::{Distribution, Standard}; + use crate::distributions::{Distribution, Standard}; let rng = rng(110); - let mut r = Box::new(rng) as Box<RngCore>; + let mut r = Box::new(rng) as Box<dyn RngCore>; r.next_u32(); r.gen::<i32>(); assert_eq!(r.gen_range(0, 1), 0); @@ -833,6 +700,7 @@ mod test { } #[test] + #[cfg(not(miri))] // Miri is too slow fn test_gen_ratio_average() { const NUM: u32 = 3; const DENOM: u32 = 10; |