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use crate::sync::rwlock::*;
use loom::future::block_on;
use loom::thread;
use std::sync::Arc;
#[test]
fn concurrent_write() {
let b = loom::model::Builder::new();
b.check(|| {
let rwlock = Arc::new(RwLock::<u32>::new(0));
let rwclone = rwlock.clone();
let t1 = thread::spawn(move || {
block_on(async {
let mut guard = rwclone.write().await;
*guard += 5;
});
});
let rwclone = rwlock.clone();
let t2 = thread::spawn(move || {
block_on(async {
let mut guard = rwclone.write().await;
*guard += 5;
});
});
t1.join().expect("thread 1 write should not panic");
t2.join().expect("thread 2 write should not panic");
//when all threads have finished the value on the lock should be 10
let guard = block_on(rwlock.read());
assert_eq!(10, *guard);
});
}
#[test]
fn concurrent_read_write() {
let b = loom::model::Builder::new();
b.check(|| {
let rwlock = Arc::new(RwLock::<u32>::new(0));
let rwclone = rwlock.clone();
let t1 = thread::spawn(move || {
block_on(async {
let mut guard = rwclone.write().await;
*guard += 5;
});
});
let rwclone = rwlock.clone();
let t2 = thread::spawn(move || {
block_on(async {
let mut guard = rwclone.write().await;
*guard += 5;
});
});
let rwclone = rwlock.clone();
let t3 = thread::spawn(move || {
block_on(async {
let guard = rwclone.read().await;
//at this state the value on the lock may either be 0, 5, or 10
assert!(*guard == 0 || *guard == 5 || *guard == 10);
});
});
t1.join().expect("thread 1 write should not panic");
t2.join().expect("thread 2 write should not panic");
t3.join().expect("thread 3 read should not panic");
let guard = block_on(rwlock.read());
//when all threads have finished the value on the lock should be 10
assert_eq!(10, *guard);
});
}
#[test]
fn downgrade() {
loom::model(|| {
let lock = Arc::new(RwLock::new(1));
let n = block_on(lock.write());
let cloned_lock = lock.clone();
let handle = thread::spawn(move || {
let mut guard = block_on(cloned_lock.write());
*guard = 2;
});
let n = n.downgrade();
assert_eq!(*n, 1);
drop(n);
handle.join().unwrap();
assert_eq!(*block_on(lock.read()), 2);
});
}
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