109 lines
2.6 KiB
Rust
109 lines
2.6 KiB
Rust
// ignore-windows: Concurrency on Windows is not supported yet.
|
|
// compile-flags: -Zmiri-ignore-leaks -Zmiri-preemption-rate=0
|
|
|
|
// Tests showing weak memory behaviours are exhibited. All tests
|
|
// return true when the desired behaviour is seen.
|
|
// This is scheduler and pseudo-RNG dependent, so each test is
|
|
// run multiple times until one try returns true.
|
|
// Spurious failure is possible, if you are really unlucky with
|
|
// the RNG and always read the latest value from the store buffer.
|
|
|
|
use std::sync::atomic::AtomicUsize;
|
|
use std::sync::atomic::Ordering::*;
|
|
use std::thread::spawn;
|
|
|
|
#[derive(Copy, Clone)]
|
|
struct EvilSend<T>(pub T);
|
|
|
|
unsafe impl<T> Send for EvilSend<T> {}
|
|
unsafe impl<T> Sync for EvilSend<T> {}
|
|
|
|
// We can't create static items because we need to run each test
|
|
// multiple times
|
|
fn static_atomic(val: usize) -> &'static AtomicUsize {
|
|
let ret = Box::leak(Box::new(AtomicUsize::new(val)));
|
|
ret
|
|
}
|
|
|
|
// Spins until it reads the given value
|
|
fn reads_value(loc: &AtomicUsize, val: usize) -> usize {
|
|
while loc.load(Relaxed) != val {
|
|
std::hint::spin_loop();
|
|
}
|
|
val
|
|
}
|
|
|
|
fn relaxed() -> bool {
|
|
let x = static_atomic(0);
|
|
let j1 = spawn(move || {
|
|
x.store(1, Relaxed);
|
|
x.store(2, Relaxed);
|
|
});
|
|
|
|
let j2 = spawn(move || x.load(Relaxed));
|
|
|
|
j1.join().unwrap();
|
|
let r2 = j2.join().unwrap();
|
|
|
|
r2 == 1
|
|
}
|
|
|
|
// https://www.doc.ic.ac.uk/~afd/homepages/papers/pdfs/2017/POPL.pdf Figure 8
|
|
fn seq_cst() -> bool {
|
|
let x = static_atomic(0);
|
|
|
|
let j1 = spawn(move || {
|
|
x.store(1, Relaxed);
|
|
});
|
|
|
|
let j2 = spawn(move || {
|
|
x.store(2, SeqCst);
|
|
x.store(3, SeqCst);
|
|
});
|
|
|
|
let j3 = spawn(move || x.load(SeqCst));
|
|
|
|
j1.join().unwrap();
|
|
j2.join().unwrap();
|
|
let r3 = j3.join().unwrap();
|
|
|
|
r3 == 1
|
|
}
|
|
|
|
fn initialization_write() -> bool {
|
|
let x = static_atomic(11);
|
|
assert_eq!(x.load(Relaxed), 11);
|
|
|
|
let wait = static_atomic(0);
|
|
|
|
let j1 = spawn(move || {
|
|
x.store(22, Relaxed);
|
|
// Relaxed is intentional. We want to test if the thread 2 reads the initialisation write
|
|
// after a relaxed write
|
|
wait.store(1, Relaxed);
|
|
});
|
|
|
|
let j2 = spawn(move || {
|
|
reads_value(wait, 1);
|
|
x.load(Relaxed)
|
|
});
|
|
|
|
j1.join().unwrap();
|
|
let r2 = j2.join().unwrap();
|
|
|
|
r2 == 11
|
|
}
|
|
|
|
// Asserts that the function returns true at least once in 100 runs
|
|
macro_rules! assert_once {
|
|
($f:ident) => {
|
|
assert!(std::iter::repeat_with(|| $f()).take(100).any(|x| x));
|
|
};
|
|
}
|
|
|
|
pub fn main() {
|
|
assert_once!(relaxed);
|
|
assert_once!(seq_cst);
|
|
assert_once!(initialization_write);
|
|
}
|