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Rollup merge of #102412 - joboet:dont_panic, r=m-ou-se

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Never panic in `thread::park` and `thread::park_timeout`

fixes #102398

`@rustbot` label +T-libs +T-libs-api
This commit is contained in:
Yuki Okushi 2022-10-11 18:37:53 +09:00 committed by GitHub
commit e0954cadc8
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1 changed files with 20 additions and 2 deletions
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22
library/std/src/thread/mod.rs
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@ -160,7 +160,7 @@ use crate::ffi::{CStr, CString};
use crate::fmt; use crate::fmt;
use crate::io; use crate::io;
use crate::marker::PhantomData; use crate::marker::PhantomData;
use crate::mem; use crate::mem::{self, forget};
use crate::num::NonZeroU64; use crate::num::NonZeroU64;
use crate::num::NonZeroUsize; use crate::num::NonZeroUsize;
use crate::panic; use crate::panic;
@ -851,10 +851,22 @@ pub fn sleep(dur: Duration) {
imp::Thread::sleep(dur) imp::Thread::sleep(dur)
} }
/// Used to ensure that `park` and `park_timeout` do not unwind, as that can
/// cause undefined behaviour if not handled correctly (see #102398 for context).
struct PanicGuard;
impl Drop for PanicGuard {
fn drop(&mut self) {
rtabort!("an irrecoverable error occurred while synchronizing threads")
}
}
/// Blocks unless or until the current thread's token is made available. /// Blocks unless or until the current thread's token is made available.
/// ///
/// A call to `park` does not guarantee that the thread will remain parked /// A call to `park` does not guarantee that the thread will remain parked
/// forever, and callers should be prepared for this possibility. /// forever, and callers should be prepared for this possibility. However,
/// it is guaranteed that this function will not panic (it may abort the
/// process if the implementation encounters some rare errors).
/// ///
/// # park and unpark /// # park and unpark
/// ///
@ -939,10 +951,13 @@ pub fn sleep(dur: Duration) {
/// [`thread::park_timeout`]: park_timeout /// [`thread::park_timeout`]: park_timeout
#[stable(feature = "rust1", since = "1.0.0")] #[stable(feature = "rust1", since = "1.0.0")]
pub fn park() { pub fn park() {
let guard = PanicGuard;
// SAFETY: park_timeout is called on the parker owned by this thread. // SAFETY: park_timeout is called on the parker owned by this thread.
unsafe { unsafe {
current().inner.as_ref().parker().park(); current().inner.as_ref().parker().park();
} }
// No panic occurred, do not abort.
forget(guard);
} }
/// Use [`park_timeout`]. /// Use [`park_timeout`].
@ -1003,10 +1018,13 @@ pub fn park_timeout_ms(ms: u32) {
/// ``` /// ```
#[stable(feature = "park_timeout", since = "1.4.0")] #[stable(feature = "park_timeout", since = "1.4.0")]
pub fn park_timeout(dur: Duration) { pub fn park_timeout(dur: Duration) {
let guard = PanicGuard;
// SAFETY: park_timeout is called on the parker owned by this thread. // SAFETY: park_timeout is called on the parker owned by this thread.
unsafe { unsafe {
current().inner.as_ref().parker().park_timeout(dur); current().inner.as_ref().parker().park_timeout(dur);
} }
// No panic occurred, do not abort.
forget(guard);
} }
//////////////////////////////////////////////////////////////////////////////// ////////////////////////////////////////////////////////////////////////////////