salsa/tests/parallel/race.rs

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use crate::setup::{InputQuery, ParDatabase, ParDatabaseImpl};
use salsa::{Database, ParallelDatabase};
/// Test where a read and a set are racing with one another.
/// Should be atomic.
#[test]
fn in_par_get_set_race() {
let mut db = ParDatabaseImpl::default();
db.query_mut(InputQuery).set('a', 100);
db.query_mut(InputQuery).set('b', 010);
db.query_mut(InputQuery).set('c', 001);
let thread1 = std::thread::spawn({
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let db = db.snapshot();
move || {
let v = db.sum("abc");
v
}
});
let thread2 = std::thread::spawn(move || {
db.query_mut(InputQuery).set('a', 1000);
db.sum("a")
});
// If the 1st thread runs first, you get 111, otherwise you get
// 1011; if they run concurrently and the 1st thread observes the
// cancelation, you get back usize::max.
let value1 = thread1.join().unwrap();
assert!(
value1 == 111 || value1 == 1011 || value1 == std::usize::MAX,
"illegal result {}",
value1
);
assert_eq!(thread2.join().unwrap(), 1000);
}