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use crate::convert::Convert;
use crate::{AHasher};
#[cfg(all(not(feature = "std"), feature = "compile-time-rng"))]
use const_random::const_random;
use core::fmt;
use core::hash::BuildHasher;
use core::hash::Hasher;
#[cfg(feature = "std")]
use lazy_static::*;
use core::sync::atomic::{AtomicUsize, Ordering};
#[cfg(feature = "std")]
lazy_static! {
static ref SEEDS: [u64; 8] = {
let mut result: [u8; 64] = [0; 64];
getrandom::getrandom(&mut result).expect("getrandom::getrandom() failed.");
result.convert()
};
}
static COUNTER: AtomicUsize = AtomicUsize::new(0);
pub(crate) const PI: [u64;4] = [0x243f_6a88_85a3_08d3, 0x1319_8a2e_0370_7344, 0xA409_3822_299F_31D0, 0x082E_FA98_EC4E_6C89];
#[derive(Clone)]
pub struct RandomState {
pub(crate) k0: u64,
pub(crate) k1: u64,
pub(crate) k2: u64,
pub(crate) k3: u64,
}
impl fmt::Debug for RandomState {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
f.pad("RandomState { .. }")
}
}
impl RandomState {
#[inline]
#[cfg(feature = "std")]
pub fn new() -> RandomState {
let seeds = *SEEDS;
let mut hasher = AHasher::from_random_state(&RandomState{k0: seeds[0], k1: seeds[1], k2: seeds[2], k3: seeds[3]});
let stack_mem_loc = &hasher as *const _ as usize;
hasher.write_usize(COUNTER.fetch_add(stack_mem_loc, Ordering::Relaxed));
let mix = |k: u64| {
let mut h = hasher.clone();
h.write_u64(k);
h.finish()
};
RandomState { k0: mix(seeds[4]), k1: mix(seeds[5]), k2: mix(seeds[6]), k3: mix(seeds[7]) }
}
#[inline]
#[cfg(all(not(feature = "std"), feature = "compile-time-rng"))]
pub fn new() -> RandomState {
let mut hasher = AHasher::from_random_state(&RandomState::with_fixed_keys());
let stack_mem_loc = &hasher as *const _ as usize;
hasher.write_usize(COUNTER.fetch_add(stack_mem_loc, Ordering::Relaxed));
let mix = |k: u64| {
let mut h = hasher.clone();
h.write_u64(k);
h.finish()
};
RandomState { k0: mix(const_random!(u64)), k1: mix(const_random!(u64)), k2: mix(const_random!(u64)), k3: mix(const_random!(u64)) }
}
#[inline]
pub(crate) fn with_fixed_keys() -> RandomState {
#[cfg(feature = "std")]
{
let seeds = *SEEDS;
RandomState { k0: seeds[4], k1: seeds[5], k2: seeds[6], k3: seeds[7] }
}
#[cfg(all(not(feature = "std"), feature = "compile-time-rng"))]
{
RandomState { k0: const_random!(u64), k1: const_random!(u64), k2: const_random!(u64), k3: const_random!(u64) }
}
#[cfg(all(not(feature = "std"), not(feature = "compile-time-rng")))]
{
RandomState { k0: PI[3], k1: PI[2], k2: PI[1], k3: PI[0] }
}
}
pub const fn with_seeds(k0: u64, k1: u64, k2: u64, k3: u64) -> RandomState {
RandomState { k0, k1, k2, k3 }
}
}
#[cfg(any(feature = "std", feature = "compile-time-rng"))]
impl Default for RandomState {
#[inline]
fn default() -> Self {
Self::new()
}
}
impl BuildHasher for RandomState {
type Hasher = AHasher;
#[inline]
fn build_hasher(&self) -> AHasher {
AHasher::from_random_state(self)
}
}
#[cfg(test)]
mod test {
use super::*;
#[cfg(feature = "std")]
#[test]
fn test_unique() {
let a = RandomState::new();
let b = RandomState::new();
assert_ne!(a.build_hasher().finish(), b.build_hasher().finish());
}
#[test]
fn test_with_seeds_const() {
const _CONST_RANDOM_STATE: RandomState = RandomState::with_seeds(17, 19, 21, 23);
}
}