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use std::sync::Once;
use std::sync::atomic::AtomicBool;
use std::sync::atomic::Ordering::Relaxed;
use std::sync::mpsc::channel;
use std::time::Duration;
use std::{panic, thread};
#[test]
fn smoke_once() {
static O: Once = Once::new();
let mut a = 0;
O.call_once(|| a += 1);
assert_eq!(a, 1);
O.call_once(|| a += 1);
assert_eq!(a, 1);
}
#[test]
fn stampede_once() {
static O: Once = Once::new();
static mut RUN: bool = false;
let (tx, rx) = channel();
for _ in 0..10 {
let tx = tx.clone();
thread::spawn(move || {
for _ in 0..4 {
thread::yield_now()
}
unsafe {
O.call_once(|| {
assert!(!RUN);
RUN = true;
});
assert!(RUN);
}
tx.send(()).unwrap();
});
}
unsafe {
O.call_once(|| {
assert!(!RUN);
RUN = true;
});
assert!(RUN);
}
for _ in 0..10 {
rx.recv().unwrap();
}
}
#[test]
fn poison_bad() {
static O: Once = Once::new();
// poison the once
let t = panic::catch_unwind(|| {
O.call_once(|| panic!());
});
assert!(t.is_err());
// poisoning propagates
let t = panic::catch_unwind(|| {
O.call_once(|| {});
});
assert!(t.is_err());
// we can subvert poisoning, however
let mut called = false;
O.call_once_force(|p| {
called = true;
assert!(p.is_poisoned())
});
assert!(called);
// once any success happens, we stop propagating the poison
O.call_once(|| {});
}
#[test]
fn wait_for_force_to_finish() {
static O: Once = Once::new();
// poison the once
let t = panic::catch_unwind(|| {
O.call_once(|| panic!());
});
assert!(t.is_err());
// make sure someone's waiting inside the once via a force
let (tx1, rx1) = channel();
let (tx2, rx2) = channel();
let t1 = thread::spawn(move || {
O.call_once_force(|p| {
assert!(p.is_poisoned());
tx1.send(()).unwrap();
rx2.recv().unwrap();
});
});
rx1.recv().unwrap();
// put another waiter on the once
let t2 = thread::spawn(|| {
let mut called = false;
O.call_once(|| {
called = true;
});
assert!(!called);
});
tx2.send(()).unwrap();
assert!(t1.join().is_ok());
assert!(t2.join().is_ok());
}
#[test]
fn wait() {
for _ in 0..50 {
let val = AtomicBool::new(false);
let once = Once::new();
thread::scope(|s| {
for _ in 0..4 {
s.spawn(|| {
once.wait();
assert!(val.load(Relaxed));
});
}
once.call_once(|| val.store(true, Relaxed));
});
}
}
#[test]
fn wait_on_poisoned() {
let once = Once::new();
panic::catch_unwind(|| once.call_once(|| panic!())).unwrap_err();
panic::catch_unwind(|| once.wait()).unwrap_err();
}
#[test]
fn wait_force_on_poisoned() {
let once = Once::new();
thread::scope(|s| {
panic::catch_unwind(|| once.call_once(|| panic!())).unwrap_err();
s.spawn(|| {
thread::sleep(Duration::from_millis(100));
once.call_once_force(|_| {});
});
once.wait_force();
})
}
|
