Skip to content

lock: add an opt-in rwlock that detaches before it blocks #8556

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Merged
youknowone merged 15 commits into from
Aug 28, 2026
Merged

lock: add an opt-in rwlock that detaches before it blocks #8556

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
15 commits
Select commit Hold shift + click to select a range
c422c9a
lock: add an opt-in rwlock that detaches before it blocks
youknowone Aug 19, 2026
25639de
lock: stop detaching where the lock may already be held
youknowone Aug 19, 2026
72289fb
os.readinto: read aside when the fd can wait
youknowone Aug 19, 2026
1414831
fcntl: detach around the calls that wait
youknowone Aug 19, 2026
11b53f1
openssl: read aside instead of holding the caller's buffer locked
youknowone Aug 19, 2026
02a4b48
vm: add the inverse of allow_threads for callbacks
youknowone Aug 21, 2026
707b7c4
openssl: attach around the callbacks that run Python
youknowone Aug 21, 2026
ce8a00c
openssl: detach around the SSL calls that wait
youknowone Aug 21, 2026
5f2e1ea
lock: assert the opt-in rule against every stop-the-world section
youknowone Aug 21, 2026
f6c27e7
clippy: drop std_instead_of_core suppressions
youknowone Aug 21, 2026
c2af8b6
lock: spell out why the detaching rwlock exists
youknowone Aug 21, 2026
657964b
fcntl: raise the error the call returned
youknowone Aug 27, 2026
45331ef
openssl: allocate the read buffer through the vm
youknowone Aug 27, 2026
809b7fd
lock: leave no attached blocking acquire on a detaching lock
youknowone Aug 27, 2026
b0f5467
vm: wait for the actual block in the stop-the-world test
youknowone Aug 27, 2026
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
1 change: 0 additions & 1 deletion Cargo.toml
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -398,7 +398,6 @@ explicit_iter_loop = "warn"
filter_map_next = "warn"
flat_map_option = "warn"
format_collect = "warn"
from_iter_instead_of_collect = "warn"
inconsistent_struct_constructor = "warn"
index_refutable_slice = "warn"
inefficient_to_string = "warn"
Expand Down
16 changes: 15 additions & 1 deletion crates/common/src/borrow.rs
View file
Open in desktop
Original file line number Diff line number Diff line change
@@ -1,5 +1,6 @@
use crate::lock::{
MapImmutable, PyImmutableMappedMutexGuard, PyMappedMutexGuard, PyMappedRwLockReadGuard,
MapImmutable, PyImmutableMappedMutexGuard, PyMappedDetachingRwLockReadGuard,
PyMappedDetachingRwLockWriteGuard, PyMappedMutexGuard, PyMappedRwLockReadGuard,
PyMappedRwLockWriteGuard, PyMutexGuard, PyRwLockReadGuard, PyRwLockWriteGuard,
};
use alloc::fmt;
Expand All @@ -24,13 +25,15 @@ pub enum BorrowedValue<'a, T: ?Sized> {
MappedMuLock(PyImmutableMappedMutexGuard<'a, T>),
ReadLock(PyRwLockReadGuard<'a, T>),
MappedReadLock(PyMappedRwLockReadGuard<'a, T>),
MappedDetachingReadLock(PyMappedDetachingRwLockReadGuard<'a, T>),
}
impl_from!('a, T, BorrowedValue<'a, T>,
Ref(&'a T),
MuLock(PyMutexGuard<'a, T>),
MappedMuLock(PyImmutableMappedMutexGuard<'a, T>),
ReadLock(PyRwLockReadGuard<'a, T>),
MappedReadLock(PyMappedRwLockReadGuard<'a, T>),
MappedDetachingReadLock(PyMappedDetachingRwLockReadGuard<'a, T>),
);

impl<'a, T: ?Sized> BorrowedValue<'a, T> {
Expand Down Expand Up @@ -59,6 +62,9 @@ impl<'a, T: ?Sized> BorrowedValue<'a, T> {
Self::MappedReadLock(m) => {
BorrowedValue::MappedReadLock(PyMappedRwLockReadGuard::map(m, f))
}
Self::MappedDetachingReadLock(m) => {
BorrowedValue::MappedDetachingReadLock(PyMappedDetachingRwLockReadGuard::map(m, f))
}
}
}
}
Expand All @@ -73,6 +79,7 @@ impl<T: ?Sized> Deref for BorrowedValue<'_, T> {
Self::MappedMuLock(m) => m,
Self::ReadLock(r) => r,
Self::MappedReadLock(m) => m,
Self::MappedDetachingReadLock(m) => m,
}
}
}
Expand All @@ -90,6 +97,7 @@ pub enum BorrowedValueMut<'a, T: ?Sized> {
MappedMuLock(PyMappedMutexGuard<'a, T>),
WriteLock(PyRwLockWriteGuard<'a, T>),
MappedWriteLock(PyMappedRwLockWriteGuard<'a, T>),
MappedDetachingWriteLock(PyMappedDetachingRwLockWriteGuard<'a, T>),
}

impl_from!('a, T, BorrowedValueMut<'a, T>,
Expand All @@ -98,6 +106,7 @@ impl_from!('a, T, BorrowedValueMut<'a, T>,
MappedMuLock(PyMappedMutexGuard<'a, T>),
WriteLock(PyRwLockWriteGuard<'a, T>),
MappedWriteLock(PyMappedRwLockWriteGuard<'a, T>),
MappedDetachingWriteLock(PyMappedDetachingRwLockWriteGuard<'a, T>),
);

impl<'a, T: ?Sized> BorrowedValueMut<'a, T> {
Expand All @@ -113,6 +122,9 @@ impl<'a, T: ?Sized> BorrowedValueMut<'a, T> {
Self::MappedWriteLock(m) => {
BorrowedValueMut::MappedWriteLock(PyMappedRwLockWriteGuard::map(m, f))
}
Self::MappedDetachingWriteLock(m) => BorrowedValueMut::MappedDetachingWriteLock(
PyMappedDetachingRwLockWriteGuard::map(m, f),
),
}
}
}
Expand All @@ -127,6 +139,7 @@ impl<T: ?Sized> Deref for BorrowedValueMut<'_, T> {
Self::MappedMuLock(m) => m,
Self::WriteLock(w) => w,
Self::MappedWriteLock(w) => w,
Self::MappedDetachingWriteLock(w) => w,
}
}
}
Expand All @@ -139,6 +152,7 @@ impl<T: ?Sized> DerefMut for BorrowedValueMut<'_, T> {
Self::MappedMuLock(m) => &mut *m,
Self::WriteLock(w) => &mut *w,
Self::MappedWriteLock(w) => &mut *w,
Self::MappedDetachingWriteLock(w) => &mut *w,
}
}
}
16 changes: 16 additions & 0 deletions crates/common/src/lock.rs
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -8,6 +8,7 @@ use lock_api::{

cfg_select! {
feature = "threading" => {
pub use detaching::{BlockingWaitHook, set_blocking_wait_hook, set_world_stopped};
pub use parking_lot::{RawMutex, RawRwLock, RawThreadId};
pub use std::sync::OnceLock as OnceCell;
pub use core::cell::LazyCell;
Expand Down Expand Up @@ -47,6 +48,8 @@ cfg_select! {
}
}

mod detaching;
pub use detaching::RawDetachingRwLock;
mod immutable_mutex;
pub use immutable_mutex::*;
mod thread_mutex;
Expand All @@ -60,6 +63,19 @@ pub type PyThreadMutex<T> = ThreadMutex<RawMutex, RawThreadId, T>;
pub type PyThreadMutexGuard<'a, T> = ThreadMutexGuard<'a, RawMutex, RawThreadId, T>;
pub type PyMappedThreadMutexGuard<'a, T> = MappedThreadMutexGuard<'a, RawMutex, RawThreadId, T>;

/// A `PyRwLock` for data a thread may hold locked across a blocking call.
///
/// Waiting for one of these leaves the interpreter first, so a thread blocked
/// on it is a thread stop-the-world can park. That is only safe where a
/// collection never takes the same lock — see [`RawDetachingRwLock`] — so this
/// is opt-in per lock rather than what every `PyRwLock` does.
pub type PyDetachingRwLock<T> = RwLock<RawDetachingRwLock, T>;
pub type PyDetachingRwLockReadGuard<'a, T> = RwLockReadGuard<'a, RawDetachingRwLock, T>;
pub type PyDetachingRwLockWriteGuard<'a, T> = RwLockWriteGuard<'a, RawDetachingRwLock, T>;
pub type PyMappedDetachingRwLockReadGuard<'a, T> = MappedRwLockReadGuard<'a, RawDetachingRwLock, T>;
pub type PyMappedDetachingRwLockWriteGuard<'a, T> =
MappedRwLockWriteGuard<'a, RawDetachingRwLock, T>;

pub type PyRwLock<T> = RwLock<RawRwLock, T>;
pub type PyRwLockUpgradableReadGuard<'a, T> = RwLockUpgradableReadGuard<'a, RawRwLock, T>;
pub type PyRwLockReadGuard<'a, T> = RwLockReadGuard<'a, RawRwLock, T>;
Expand Down
Loading
Loading