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Use StdRng instead of ThreadRng in _random #1939

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Merged
merged 2 commits into from
May 23, 2020
Merged

Use StdRng instead of ThreadRng in _random #1939

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c7bb84f
Use StdRng instead of ThreadRng in _random
coolreader18 May 22, 2020
63873e3
Box StdRng
coolreader18 May 23, 2020
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89 changes: 26 additions & 63 deletions vm/src/stdlib/random.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -9,21 +9,21 @@ mod _random {
use crate::obj::objtype::PyClassRef;
use crate::pyobject::{PyClassImpl, PyRef, PyResult, PyValue};
use crate::VirtualMachine;
use generational_arena::{self, Arena};
use num_bigint::{BigInt, Sign};
use num_traits::Signed;
use rand::RngCore;
use std::cell::RefCell;
use rand::{rngs::StdRng, RngCore, SeedableRng};

use std::sync::Mutex;

#[derive(Debug)]
enum PyRng {
Std(rand::rngs::ThreadRng),
Std(Box<StdRng>),
MT(Box<mt19937::MT19937>),
}

impl Default for PyRng {
fn default() -> Self {
PyRng::Std(rand::thread_rng())
PyRng::Std(Box::new(StdRng::from_entropy()))
}
}

Expand Down Expand Up @@ -54,47 +54,10 @@ mod _random {
}
}

thread_local!(static RNG_HANDLES: RefCell<Arena<PyRng>> = RefCell::new(Arena::new()));

#[derive(Debug)]
struct RngHandle(generational_arena::Index);
impl RngHandle {
fn new(rng: PyRng) -> Self {
let idx = RNG_HANDLES.with(|arena| arena.borrow_mut().insert(rng));
RngHandle(idx)
}
fn exec<F, R>(&self, func: F) -> R
where
F: Fn(&mut PyRng) -> R,
{
RNG_HANDLES.with(|arena| {
func(
arena
.borrow_mut()
.get_mut(self.0)
.expect("index was removed"),
)
})
}
fn replace(&self, rng: PyRng) {
RNG_HANDLES.with(|arena| {
*arena
.borrow_mut()
.get_mut(self.0)
.expect("index was removed") = rng
})
}
}
impl Drop for RngHandle {
fn drop(&mut self) {
RNG_HANDLES.with(|arena| arena.borrow_mut().remove(self.0));
}
}

#[pyclass(name = "Random")]
#[derive(Debug)]
struct PyRandom {
rng: RngHandle,
rng: Mutex<PyRng>,
}

impl PyValue for PyRandom {
Expand All @@ -108,14 +71,15 @@ mod _random {
#[pyslot(new)]
fn new(cls: PyClassRef, vm: &VirtualMachine) -> PyResult<PyRef<Self>> {
PyRandom {
rng: RngHandle::new(PyRng::default()),
rng: Mutex::default(),
}
.into_ref_with_type(vm, cls)
}

#[pymethod]
fn random(&self) -> f64 {
self.rng.exec(mt19937::gen_res53)
let mut rng = self.rng.lock().unwrap();
mt19937::gen_res53(&mut *rng)
}

#[pymethod]
Expand All @@ -131,32 +95,31 @@ mod _random {
}
};

self.rng.replace(new_rng);
*self.rng.lock().unwrap() = new_rng;
}

#[pymethod]
fn getrandbits(&self, k: usize) -> BigInt {
self.rng.exec(|rng| {
let mut k = k;
let mut gen_u32 = |k| rng.next_u32() >> (32 - k) as u32;
let mut rng = self.rng.lock().unwrap();
let mut k = k;
let mut gen_u32 = |k| rng.next_u32() >> (32 - k) as u32;

if k <= 32 {
return gen_u32(k).into();
}
if k <= 32 {
return gen_u32(k).into();
}

let words = (k - 1) / 8 + 1;
let mut wordarray = vec![0u32; words];
let words = (k - 1) / 8 + 1;
let mut wordarray = vec![0u32; words];

let it = wordarray.iter_mut();
#[cfg(target_endian = "big")]
let it = it.rev();
for word in it {
*word = gen_u32(k);
k -= 32;
}
let it = wordarray.iter_mut();
#[cfg(target_endian = "big")]
let it = it.rev();
for word in it {
*word = gen_u32(k);
k -= 32;
}

BigInt::from_slice(Sign::NoSign, &wordarray)
})
BigInt::from_slice(Sign::NoSign, &wordarray)
}
}
}