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use crate::sync::batch_semaphore::*;
use futures::future::poll_fn;
use loom::future::block_on;
use loom::sync::atomic::AtomicUsize;
use loom::thread;
use std::future::Future;
use std::pin::Pin;
use std::sync::atomic::Ordering::SeqCst;
use std::sync::Arc;
use std::task::Poll::Ready;
use std::task::{Context, Poll};
#[test]
fn basic_usage() {
const NUM: usize = 2;
struct Shared {
semaphore: Semaphore,
active: AtomicUsize,
}
async fn actor(shared: Arc<Shared>) {
shared.semaphore.acquire(1).await.unwrap();
let actual = shared.active.fetch_add(1, SeqCst);
assert!(actual <= NUM - 1);
let actual = shared.active.fetch_sub(1, SeqCst);
assert!(actual <= NUM);
shared.semaphore.release(1);
}
loom::model(|| {
let shared = Arc::new(Shared {
semaphore: Semaphore::new(NUM),
active: AtomicUsize::new(0),
});
for _ in 0..NUM {
let shared = shared.clone();
thread::spawn(move || {
block_on(actor(shared));
});
}
block_on(actor(shared));
});
}
#[test]
fn release() {
loom::model(|| {
let semaphore = Arc::new(Semaphore::new(1));
{
let semaphore = semaphore.clone();
thread::spawn(move || {
block_on(semaphore.acquire(1)).unwrap();
semaphore.release(1);
});
}
block_on(semaphore.acquire(1)).unwrap();
semaphore.release(1);
});
}
#[test]
fn basic_closing() {
const NUM: usize = 2;
loom::model(|| {
let semaphore = Arc::new(Semaphore::new(1));
for _ in 0..NUM {
let semaphore = semaphore.clone();
thread::spawn(move || {
for _ in 0..2 {
block_on(semaphore.acquire(1)).map_err(|_| ())?;
semaphore.release(1);
}
Ok::<(), ()>(())
});
}
semaphore.close();
});
}
#[test]
fn concurrent_close() {
const NUM: usize = 3;
loom::model(|| {
let semaphore = Arc::new(Semaphore::new(1));
for _ in 0..NUM {
let semaphore = semaphore.clone();
thread::spawn(move || {
block_on(semaphore.acquire(1)).map_err(|_| ())?;
semaphore.release(1);
semaphore.close();
Ok::<(), ()>(())
});
}
});
}
#[test]
fn concurrent_cancel() {
async fn poll_and_cancel(semaphore: Arc<Semaphore>) {
let mut acquire1 = Some(semaphore.acquire(1));
let mut acquire2 = Some(semaphore.acquire(1));
poll_fn(|cx| {
// poll the acquire future once, and then immediately throw
// it away. this simulates a situation where a future is
// polled and then cancelled, such as by a timeout.
if let Some(acquire) = acquire1.take() {
pin!(acquire);
let _ = acquire.poll(cx);
}
if let Some(acquire) = acquire2.take() {
pin!(acquire);
let _ = acquire.poll(cx);
}
Poll::Ready(())
})
.await
}
loom::model(|| {
let semaphore = Arc::new(Semaphore::new(0));
let t1 = {
let semaphore = semaphore.clone();
thread::spawn(move || block_on(poll_and_cancel(semaphore)))
};
let t2 = {
let semaphore = semaphore.clone();
thread::spawn(move || block_on(poll_and_cancel(semaphore)))
};
let t3 = {
let semaphore = semaphore.clone();
thread::spawn(move || block_on(poll_and_cancel(semaphore)))
};
t1.join().unwrap();
semaphore.release(10);
t2.join().unwrap();
t3.join().unwrap();
});
}
#[test]
fn batch() {
let mut b = loom::model::Builder::new();
b.preemption_bound = Some(1);
b.check(|| {
let semaphore = Arc::new(Semaphore::new(10));
let active = Arc::new(AtomicUsize::new(0));
let mut ths = vec![];
for _ in 0..2 {
let semaphore = semaphore.clone();
let active = active.clone();
ths.push(thread::spawn(move || {
for n in &[4, 10, 8] {
block_on(semaphore.acquire(*n)).unwrap();
active.fetch_add(*n as usize, SeqCst);
let num_active = active.load(SeqCst);
assert!(num_active <= 10);
thread::yield_now();
active.fetch_sub(*n as usize, SeqCst);
semaphore.release(*n as usize);
}
}));
}
for th in ths.into_iter() {
th.join().unwrap();
}
assert_eq!(10, semaphore.available_permits());
});
}
#[test]
fn release_during_acquire() {
loom::model(|| {
let semaphore = Arc::new(Semaphore::new(10));
semaphore
.try_acquire(8)
.expect("try_acquire should succeed; semaphore uncontended");
let semaphore2 = semaphore.clone();
let thread = thread::spawn(move || block_on(semaphore2.acquire(4)).unwrap());
semaphore.release(8);
thread.join().unwrap();
semaphore.release(4);
assert_eq!(10, semaphore.available_permits());
})
}
#[test]
fn concurrent_permit_updates() {
loom::model(move || {
let semaphore = Arc::new(Semaphore::new(5));
let t1 = {
let semaphore = semaphore.clone();
thread::spawn(move || semaphore.release(3))
};
let t2 = {
let semaphore = semaphore.clone();
thread::spawn(move || {
semaphore
.try_acquire(1)
.expect("try_acquire should succeed")
})
};
let t3 = {
let semaphore = semaphore.clone();
thread::spawn(move || semaphore.forget_permits(2))
};
t1.join().unwrap();
t2.join().unwrap();
t3.join().unwrap();
assert_eq!(semaphore.available_permits(), 5);
})
}