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