use std::{
cell::LazyCell,
panic,
sync::{
atomic::{AtomicUsize, Ordering::SeqCst},
mpsc::channel,
Mutex,
},
sync::{LazyLock, OnceLock},
thread,
};
#[test]
fn lazy_default() {
static CALLED: AtomicUsize = AtomicUsize::new(0);
struct Foo(u8);
impl Default for Foo {
fn default() -> Self {
CALLED.fetch_add(1, SeqCst);
Foo(42)
}
}
let lazy: LazyCell<Mutex<Foo>> = <_>::default();
assert_eq!(CALLED.load(SeqCst), 0);
assert_eq!(lazy.lock().unwrap().0, 42);
assert_eq!(CALLED.load(SeqCst), 1);
lazy.lock().unwrap().0 = 21;
assert_eq!(lazy.lock().unwrap().0, 21);
assert_eq!(CALLED.load(SeqCst), 1);
}
#[test]
#[cfg_attr(all(target_arch = "arm", not(feature = "unwinding")), ignore)]
fn lazy_poisoning() {
let x: LazyCell<String> = LazyCell::new(|| panic!("kaboom"));
for _ in 0..2 {
let res = panic::catch_unwind(panic::AssertUnwindSafe(|| x.len()));
assert!(res.is_err());
}
}
fn spawn_and_wait<R: Send + 'static>(f: impl FnOnce() -> R + Send + 'static) -> R {
thread::spawn(f).join().unwrap()
}
#[test]
#[cfg_attr(target_os = "emscripten", ignore)]
fn sync_once_cell() {
static ONCE_CELL: OnceLock<i32> = OnceLock::new();
assert!(ONCE_CELL.get().is_none());
spawn_and_wait(|| {
ONCE_CELL.get_or_init(|| 92);
assert_eq!(ONCE_CELL.get(), Some(&92));
});
ONCE_CELL.get_or_init(|| panic!("Kabom!"));
assert_eq!(ONCE_CELL.get(), Some(&92));
}
#[test]
fn sync_once_cell_get_mut() {
let mut c = OnceLock::new();
assert!(c.get_mut().is_none());
c.set(90).unwrap();
*c.get_mut().unwrap() += 2;
assert_eq!(c.get_mut(), Some(&mut 92));
}
#[test]
#[cfg(feature = "private")]
fn sync_once_cell_get_unchecked() {
let c = OnceLock::new();
c.set(92).unwrap();
unsafe {
assert_eq!(c.get_unchecked(), &92);
}
}
#[test]
#[cfg_attr(target_os = "emscripten", ignore)]
fn sync_once_cell_drop() {
static DROP_CNT: AtomicUsize = AtomicUsize::new(0);
struct Dropper;
impl Drop for Dropper {
fn drop(&mut self) {
DROP_CNT.fetch_add(1, SeqCst);
}
}
let x = OnceLock::new();
spawn_and_wait(move || {
x.get_or_init(|| Dropper);
assert_eq!(DROP_CNT.load(SeqCst), 0);
drop(x);
});
assert_eq!(DROP_CNT.load(SeqCst), 1);
}
#[test]
fn sync_once_cell_drop_empty() {
let x = OnceLock::<String>::new();
drop(x);
}
#[test]
fn clone() {
let s = OnceLock::new();
let c = s.clone();
assert!(c.get().is_none());
s.set("hello".to_string()).unwrap();
let c = s.clone();
assert_eq!(c.get().map(String::as_str), Some("hello"));
}
#[test]
#[cfg_attr(all(target_arch = "arm", not(feature = "unwinding")), ignore)]
fn get_or_try_init() {
let cell: OnceLock<String> = OnceLock::new();
assert!(cell.get().is_none());
let res = panic::catch_unwind(|| cell.get_or_try_init(|| -> Result<_, ()> { panic!() }));
assert!(res.is_err());
#[cfg(feature = "private")]
assert!(!cell.is_initialized());
assert!(cell.get().is_none());
assert_eq!(cell.get_or_try_init(|| Err(())), Err(()));
assert_eq!(
cell.get_or_try_init(|| Ok::<_, ()>("hello".to_string())),
Ok(&"hello".to_string())
);
assert_eq!(cell.get(), Some(&"hello".to_string()));
}
#[test]
fn from_impl() {
assert_eq!(OnceLock::from("value").get(), Some(&"value"));
assert_ne!(OnceLock::from("foo").get(), Some(&"bar"));
}
#[test]
fn partialeq_impl() {
assert!(OnceLock::from("value") == OnceLock::from("value"));
assert!(OnceLock::from("foo") != OnceLock::from("bar"));
assert!(OnceLock::<String>::new() == OnceLock::new());
assert!(OnceLock::<String>::new() != OnceLock::from("value".to_owned()));
}
#[test]
fn into_inner() {
let cell: OnceLock<String> = OnceLock::new();
assert_eq!(cell.into_inner(), None);
let cell = OnceLock::new();
cell.set("hello".to_string()).unwrap();
assert_eq!(cell.into_inner(), Some("hello".to_string()));
}
#[test]
#[cfg_attr(target_os = "emscripten", ignore)]
fn sync_lazy_new() {
static CALLED: AtomicUsize = AtomicUsize::new(0);
static SYNC_LAZY: LazyLock<i32> = LazyLock::new(|| {
CALLED.fetch_add(1, SeqCst);
92
});
assert_eq!(CALLED.load(SeqCst), 0);
spawn_and_wait(|| {
let y = *SYNC_LAZY - 30;
assert_eq!(y, 62);
assert_eq!(CALLED.load(SeqCst), 1);
});
let y = *SYNC_LAZY - 30;
assert_eq!(y, 62);
assert_eq!(CALLED.load(SeqCst), 1);
}
#[test]
fn sync_lazy_default() {
static CALLED: AtomicUsize = AtomicUsize::new(0);
struct Foo(u8);
impl Default for Foo {
fn default() -> Self {
CALLED.fetch_add(1, SeqCst);
Foo(42)
}
}
let lazy: LazyLock<Mutex<Foo>> = <_>::default();
assert_eq!(CALLED.load(SeqCst), 0);
assert_eq!(lazy.lock().unwrap().0, 42);
assert_eq!(CALLED.load(SeqCst), 1);
lazy.lock().unwrap().0 = 21;
assert_eq!(lazy.lock().unwrap().0, 21);
assert_eq!(CALLED.load(SeqCst), 1);
}
#[test]
#[cfg_attr(target_os = "emscripten", ignore)]
fn static_sync_lazy() {
static XS: LazyLock<Vec<i32>> = LazyLock::new(|| {
let mut xs = Vec::new();
xs.push(1);
xs.push(2);
xs.push(3);
xs
});
spawn_and_wait(|| {
assert_eq!(&*XS, &vec![1, 2, 3]);
});
assert_eq!(&*XS, &vec![1, 2, 3]);
}
#[test]
fn static_sync_lazy_via_fn() {
fn xs() -> &'static Vec<i32> {
static XS: OnceLock<Vec<i32>> = OnceLock::new();
XS.get_or_init(|| {
let mut xs = Vec::new();
xs.push(1);
xs.push(2);
xs.push(3);
xs
})
}
assert_eq!(xs(), &vec![1, 2, 3]);
}
#[test]
#[cfg_attr(all(target_arch = "arm", not(feature = "unwinding")), ignore)]
fn sync_lazy_poisoning() {
let x: LazyLock<String> = LazyLock::new(|| panic!("kaboom"));
for _ in 0..2 {
let res = panic::catch_unwind(|| x.len());
assert!(res.is_err());
}
}
#[test]
fn is_sync_send() {
fn assert_traits<T: Send + Sync>() {}
assert_traits::<OnceLock<String>>();
assert_traits::<LazyLock<String>>();
}
#[test]
fn eval_once_macro() {
macro_rules! eval_once {
(|| -> $ty:ty {
$($body:tt)*
}) => {{
static ONCE_CELL: OnceLock<$ty> = OnceLock::new();
fn init() -> $ty {
$($body)*
}
ONCE_CELL.get_or_init(init)
}};
}
let fib: &'static Vec<i32> = eval_once! {
|| -> Vec<i32> {
let mut res = vec![1, 1];
for i in 0..10 {
let next = res[i] + res[i + 1];
res.push(next);
}
res
}
};
assert_eq!(fib[5], 8)
}
#[test]
#[cfg_attr(target_os = "emscripten", ignore)]
fn sync_once_cell_does_not_leak_partially_constructed_boxes() {
static ONCE_CELL: OnceLock<String> = OnceLock::new();
let n_readers = 10;
let n_writers = 3;
const MSG: &str = "Hello, World";
let (tx, rx) = channel();
for _ in 0..n_readers {
let tx = tx.clone();
thread::spawn(move || loop {
if let Some(msg) = ONCE_CELL.get() {
tx.send(msg).unwrap();
break;
}
#[cfg(target_env = "sgx")]
std::thread::yield_now();
});
}
for _ in 0..n_writers {
thread::spawn(move || {
let _ = ONCE_CELL.set(MSG.to_owned());
});
}
for _ in 0..n_readers {
let msg = rx.recv().unwrap();
assert_eq!(msg, MSG);
}
}
#[test]
fn dropck() {
let cell = OnceLock::new();
{
let s = String::new();
cell.set(&s).unwrap();
}
}