310 lines
7.5 KiB
Rust
310 lines
7.5 KiB
Rust
use std::{
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sync::atomic::{AtomicUsize, Ordering::SeqCst},
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thread::scope,
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};
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#[cfg(feature = "std")]
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use std::sync::Barrier;
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#[cfg(not(feature = "std"))]
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use core::cell::Cell;
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use once_cell::sync::{Lazy, OnceCell};
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#[test]
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fn once_cell() {
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let c = OnceCell::new();
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assert!(c.get().is_none());
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scope(|s| {
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s.spawn(|| {
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c.get_or_init(|| 92);
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assert_eq!(c.get(), Some(&92));
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});
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});
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c.get_or_init(|| panic!("Kabom!"));
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assert_eq!(c.get(), Some(&92));
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}
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#[test]
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fn once_cell_with_value() {
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static CELL: OnceCell<i32> = OnceCell::with_value(12);
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assert_eq!(CELL.get(), Some(&12));
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}
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#[test]
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fn once_cell_get_mut() {
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let mut c = OnceCell::new();
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assert!(c.get_mut().is_none());
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c.set(90).unwrap();
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*c.get_mut().unwrap() += 2;
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assert_eq!(c.get_mut(), Some(&mut 92));
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}
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#[test]
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fn once_cell_get_unchecked() {
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let c = OnceCell::new();
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c.set(92).unwrap();
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unsafe {
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assert_eq!(c.get_unchecked(), &92);
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}
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}
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#[test]
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fn once_cell_drop() {
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static DROP_CNT: AtomicUsize = AtomicUsize::new(0);
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struct Dropper;
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impl Drop for Dropper {
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fn drop(&mut self) {
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DROP_CNT.fetch_add(1, SeqCst);
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}
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}
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let x = OnceCell::new();
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scope(|s| {
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s.spawn(|| {
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x.get_or_init(|| Dropper);
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assert_eq!(DROP_CNT.load(SeqCst), 0);
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drop(x);
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});
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});
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assert_eq!(DROP_CNT.load(SeqCst), 1);
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}
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#[test]
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fn once_cell_drop_empty() {
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let x = OnceCell::<String>::new();
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drop(x);
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}
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#[test]
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fn clone() {
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let s = OnceCell::new();
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let c = s.clone();
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assert!(c.get().is_none());
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s.set("hello".to_string()).unwrap();
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let c = s.clone();
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assert_eq!(c.get().map(String::as_str), Some("hello"));
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}
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#[test]
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fn get_or_try_init() {
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let cell: OnceCell<String> = OnceCell::new();
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assert!(cell.get().is_none());
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let res = std::panic::catch_unwind(|| cell.get_or_try_init(|| -> Result<_, ()> { panic!() }));
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assert!(res.is_err());
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assert!(cell.get().is_none());
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assert_eq!(cell.get_or_try_init(|| Err(())), Err(()));
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assert_eq!(cell.get_or_try_init(|| Ok::<_, ()>("hello".to_string())), Ok(&"hello".to_string()));
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assert_eq!(cell.get(), Some(&"hello".to_string()));
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}
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#[cfg(feature = "std")]
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#[test]
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fn wait() {
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let cell: OnceCell<String> = OnceCell::new();
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scope(|s| {
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s.spawn(|| cell.set("hello".to_string()));
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let greeting = cell.wait();
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assert_eq!(greeting, "hello")
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});
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}
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#[cfg(feature = "std")]
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#[test]
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fn get_or_init_stress() {
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let n_threads = if cfg!(miri) { 30 } else { 1_000 };
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let n_cells = if cfg!(miri) { 30 } else { 1_000 };
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let cells: Vec<_> = std::iter::repeat_with(|| (Barrier::new(n_threads), OnceCell::new()))
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.take(n_cells)
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.collect();
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scope(|s| {
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for t in 0..n_threads {
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let cells = &cells;
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s.spawn(move || {
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for (i, (b, s)) in cells.iter().enumerate() {
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b.wait();
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let j = if t % 2 == 0 { s.wait() } else { s.get_or_init(|| i) };
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assert_eq!(*j, i);
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}
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});
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}
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});
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}
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#[test]
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fn from_impl() {
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assert_eq!(OnceCell::from("value").get(), Some(&"value"));
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assert_ne!(OnceCell::from("foo").get(), Some(&"bar"));
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}
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#[test]
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fn partialeq_impl() {
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assert!(OnceCell::from("value") == OnceCell::from("value"));
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assert!(OnceCell::from("foo") != OnceCell::from("bar"));
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assert!(OnceCell::<String>::new() == OnceCell::new());
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assert!(OnceCell::<String>::new() != OnceCell::from("value".to_owned()));
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}
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#[test]
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fn into_inner() {
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let cell: OnceCell<String> = OnceCell::new();
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assert_eq!(cell.into_inner(), None);
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let cell = OnceCell::new();
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cell.set("hello".to_string()).unwrap();
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assert_eq!(cell.into_inner(), Some("hello".to_string()));
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}
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#[test]
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fn debug_impl() {
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let cell = OnceCell::new();
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assert_eq!(format!("{:#?}", cell), "OnceCell(Uninit)");
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cell.set(vec!["hello", "world"]).unwrap();
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assert_eq!(
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format!("{:#?}", cell),
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r#"OnceCell(
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[
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"hello",
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"world",
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],
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)"#
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);
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}
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#[test]
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#[cfg_attr(miri, ignore)] // miri doesn't support processes
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#[cfg(feature = "std")]
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fn reentrant_init() {
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let examples_dir = {
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let mut exe = std::env::current_exe().unwrap();
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exe.pop();
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exe.pop();
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exe.push("examples");
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exe
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};
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let bin = examples_dir
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.join("reentrant_init_deadlocks")
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.with_extension(std::env::consts::EXE_EXTENSION);
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let mut guard = Guard { child: std::process::Command::new(bin).spawn().unwrap() };
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std::thread::sleep(std::time::Duration::from_secs(2));
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let status = guard.child.try_wait().unwrap();
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assert!(status.is_none());
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struct Guard {
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child: std::process::Child,
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}
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impl Drop for Guard {
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fn drop(&mut self) {
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let _ = self.child.kill();
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}
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}
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}
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#[cfg(not(feature = "std"))]
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#[test]
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#[should_panic(expected = "reentrant init")]
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fn reentrant_init() {
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let x: OnceCell<Box<i32>> = OnceCell::new();
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let dangling_ref: Cell<Option<&i32>> = Cell::new(None);
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x.get_or_init(|| {
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let r = x.get_or_init(|| Box::new(92));
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dangling_ref.set(Some(r));
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Box::new(62)
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});
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eprintln!("use after free: {:?}", dangling_ref.get().unwrap());
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}
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#[test]
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fn eval_once_macro() {
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macro_rules! eval_once {
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(|| -> $ty:ty {
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$($body:tt)*
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}) => {{
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static ONCE_CELL: OnceCell<$ty> = OnceCell::new();
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fn init() -> $ty {
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$($body)*
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}
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ONCE_CELL.get_or_init(init)
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}};
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}
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let fib: &'static Vec<i32> = eval_once! {
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|| -> Vec<i32> {
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let mut res = vec![1, 1];
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for i in 0..10 {
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let next = res[i] + res[i + 1];
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res.push(next);
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}
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res
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}
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};
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assert_eq!(fib[5], 8)
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}
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#[test]
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fn once_cell_does_not_leak_partially_constructed_boxes() {
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let n_tries = if cfg!(miri) { 10 } else { 100 };
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let n_readers = 10;
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let n_writers = 3;
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const MSG: &str = "Hello, World";
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for _ in 0..n_tries {
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let cell: OnceCell<String> = OnceCell::new();
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scope(|scope| {
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for _ in 0..n_readers {
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scope.spawn(|| loop {
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if let Some(msg) = cell.get() {
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assert_eq!(msg, MSG);
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break;
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}
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});
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}
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for _ in 0..n_writers {
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let _ = scope.spawn(|| cell.set(MSG.to_owned()));
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}
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});
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}
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}
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#[cfg(feature = "std")]
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#[test]
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fn get_does_not_block() {
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let cell = OnceCell::new();
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let barrier = Barrier::new(2);
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scope(|scope| {
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scope.spawn(|| {
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cell.get_or_init(|| {
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barrier.wait();
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barrier.wait();
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"hello".to_string()
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});
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});
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barrier.wait();
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assert_eq!(cell.get(), None);
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barrier.wait();
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});
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assert_eq!(cell.get(), Some(&"hello".to_string()));
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}
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#[test]
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// https://github.com/rust-lang/rust/issues/34761#issuecomment-256320669
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fn arrrrrrrrrrrrrrrrrrrrrr() {
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let cell = OnceCell::new();
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{
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let s = String::new();
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cell.set(&s).unwrap();
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}
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}
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#[test]
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fn once_cell_is_sync_send() {
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fn assert_traits<T: Send + Sync>() {}
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assert_traits::<OnceCell<String>>();
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assert_traits::<Lazy<String>>();
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}
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