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std::rand: move TaskRng off @mut. 

Replace with some unsafe code by storing a pointer into TLS-owned heap
data.
This commit is contained in:
Huon Wilson 2013-11-21 19:46:29 +11:00
parent 6a25ba374b
commit 020126ef75
4 changed files with 61 additions and 30 deletions
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16
src/libstd/rand/distributions/mod.rs
View File

@ -444,17 +444,17 @@ mod tests {
fn test_rand_sample() {
let mut rand_sample = RandSample::<ConstRand>;
assert_eq!(*rand_sample.sample(task_rng()), 0);
assert_eq!(*rand_sample.ind_sample(task_rng()), 0);
assert_eq!(*rand_sample.sample(&mut task_rng()), 0);
assert_eq!(*rand_sample.ind_sample(&mut task_rng()), 0);
}
#[test]
fn test_normal() {
let mut norm = Normal::new(10.0, 10.0);
let rng = task_rng();
let mut rng = task_rng();
for _ in range(0, 1000) {
norm.sample(rng);
norm.ind_sample(rng);
norm.sample(&mut rng);
norm.ind_sample(&mut rng);
}
}
#[test]
@ -466,10 +466,10 @@ mod tests {
#[test]
fn test_exp() {
let mut exp = Exp::new(10.0);
let rng = task_rng();
let mut rng = task_rng();
for _ in range(0, 1000) {
assert!(exp.sample(rng) >= 0.0);
assert!(exp.ind_sample(rng) >= 0.0);
assert!(exp.sample(&mut rng) >= 0.0);
assert!(exp.ind_sample(&mut rng) >= 0.0);
}
}
#[test]

12
src/libstd/rand/distributions/range.rs
View File

@ -183,7 +183,7 @@ mod tests {
#[test]
fn test_integers() {
let rng = task_rng();
let mut rng = task_rng();
macro_rules! t (
($($ty:ty),*) => {{
$(
@ -193,9 +193,9 @@ mod tests {
for &(low, high) in v.iter() {
let mut sampler: Range<$ty> = Range::new(low, high);
for _ in range(0, 1000) {
let v = sampler.sample(rng);
let v = sampler.sample(&mut rng);
assert!(low <= v && v < high);
let v = sampler.ind_sample(rng);
let v = sampler.ind_sample(&mut rng);
assert!(low <= v && v < high);
}
}
@ -208,7 +208,7 @@ mod tests {
#[test]
fn test_floats() {
let rng = task_rng();
let mut rng = task_rng();
macro_rules! t (
($($ty:ty),*) => {{
$(
@ -219,9 +219,9 @@ mod tests {
for &(low, high) in v.iter() {
let mut sampler: Range<$ty> = Range::new(low, high);
for _ in range(0, 1000) {
let v = sampler.sample(rng);
let v = sampler.sample(&mut rng);
assert!(low <= v && v < high);
let v = sampler.ind_sample(rng);
let v = sampler.ind_sample(&mut rng);
assert!(low <= v && v < high);
}
}

45
src/libstd/rand/mod.rs
View File

@ -577,11 +577,24 @@ impl reseeding::Reseeder<StdRng> for TaskRngReseeder {
}
}
static TASK_RNG_RESEED_THRESHOLD: uint = 32_768;
type TaskRngInner = reseeding::ReseedingRng<StdRng, TaskRngReseeder>;
/// The task-local RNG.
pub type TaskRng = reseeding::ReseedingRng<StdRng, TaskRngReseeder>;
#[no_send]
pub struct TaskRng {
// This points into TLS (specifically, it points to the endpoint
// of a ~ stored in TLS, to make it robust against TLS moving
// things internally) and so this struct cannot be legally
// transferred between tasks *and* it's unsafe to deallocate the
// RNG other than when a task is finished.
//
// The use of unsafe code here is OK if the invariants above are
// satisfied; and it allows us to avoid (unnecessarily) using a
// GC'd or RC'd pointer.
priv rng: *mut TaskRngInner
}
// used to make space in TLS for a random number generator
local_data_key!(TASK_RNG_KEY: @mut TaskRng)
local_data_key!(TASK_RNG_KEY: ~TaskRngInner)
/// Retrieve the lazily-initialized task-local random number
/// generator, seeded by the system. Intended to be used in method
@ -594,34 +607,34 @@ local_data_key!(TASK_RNG_KEY: @mut TaskRng)
/// if the operating system random number generator is rigged to give
/// the same sequence always. If absolute consistency is required,
/// explicitly select an RNG, e.g. `IsaacRng` or `Isaac64Rng`.
pub fn task_rng() -> @mut TaskRng {
let r = local_data::get(TASK_RNG_KEY, |k| k.map(|k| *k));
match r {
pub fn task_rng() -> TaskRng {
local_data::get_mut(TASK_RNG_KEY, |rng| match rng {
None => {
let rng = @mut reseeding::ReseedingRng::new(StdRng::new(),
let mut rng = ~reseeding::ReseedingRng::new(StdRng::new(),
TASK_RNG_RESEED_THRESHOLD,
TaskRngReseeder);
let ptr = &mut *rng as *mut TaskRngInner;
local_data::set(TASK_RNG_KEY, rng);
rng
TaskRng { rng: ptr }
}
Some(rng) => rng
}
Some(rng) => TaskRng { rng: &mut **rng }
})
}
// Allow direct chaining with `task_rng`
impl<R: Rng> Rng for @mut R {
#[inline]
impl Rng for TaskRng {
fn next_u32(&mut self) -> u32 {
(**self).next_u32()
unsafe { (*self.rng).next_u32() }
}
#[inline]
fn next_u64(&mut self) -> u64 {
(**self).next_u64()
unsafe { (*self.rng).next_u64() }
}
#[inline]
fn fill_bytes(&mut self, bytes: &mut [u8]) {
(**self).fill_bytes(bytes);
unsafe { (*self.rng).fill_bytes(bytes) }
}
}

18
src/test/compile-fail/task-rng-isnt-sendable.rs Normal file
View File

@ -0,0 +1,18 @@
// Copyright 2013 The Rust Project Developers. See the COPYRIGHT
// file at the top-level directory of this distribution and at
// http://rust-lang.org/COPYRIGHT.
//
// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
// option. This file may not be copied, modified, or distributed
// except according to those terms.
// ensure that the TaskRng isn't/doesn't become accidentally sendable.
fn test_send<S: Send>() {}
pub fn main() {
test_send::<::std::rand::TaskRng>();
//~^ ERROR: incompatible type `std::rand::TaskRng`, which does not fulfill `Send`
}