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We already carefully handle re-entrancy for OWNED_OBJECTS, so let's avoid the runtime checking overhead.

This commit is contained in:
Adam Reichold 2023-06-17 14:00:28 +02:00
parent 85d5b6ee77
commit 96ad57d783
1 changed files with 23 additions and 13 deletions
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36
src/gil.rs
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@ -3,7 +3,7 @@
use crate::impl_::not_send::{NotSend, NOT_SEND};
use crate::{ffi, Python};
use parking_lot::{const_mutex, Mutex, Once};
use std::cell::{Cell, RefCell};
use std::cell::{Cell, UnsafeCell};
use std::{mem, ptr::NonNull};
static START: Once = Once::new();
@ -33,7 +33,7 @@ thread_local_const_init! {
static GIL_COUNT: Cell<isize> = const { Cell::new(0) };
/// Temporarily hold objects that will be released when the GILPool drops.
static OWNED_OBJECTS: RefCell<Vec<NonNull<ffi::PyObject>>> = const { RefCell::new(Vec::new()) };
static OWNED_OBJECTS: UnsafeCell<PyObjVec> = const { UnsafeCell::new(Vec::new()) };
}
const GIL_LOCKED_DURING_TRAVERSE: isize = -1;
@ -373,7 +373,12 @@ impl GILPool {
// Update counts of PyObjects / Py that have been cloned or dropped since last acquisition
POOL.update_counts(Python::assume_gil_acquired());
GILPool {
start: OWNED_OBJECTS.try_with(|o| o.borrow().len()).ok(),
start: OWNED_OBJECTS
.try_with(|owned_objects| {
// SAFETY: This is not re-entrant.
unsafe { (*owned_objects.get()).len() }
})
.ok(),
_not_send: NOT_SEND,
}
}
@ -387,18 +392,18 @@ impl GILPool {
impl Drop for GILPool {
fn drop(&mut self) {
if let Some(obj_len_start) = self.start {
let dropping_obj = OWNED_OBJECTS.with(|holder| {
// `holder` must be dropped before calling Py_DECREF, or Py_DECREF may call
// `GILPool::drop` recursively, resulting in invalid borrowing.
let mut holder = holder.borrow_mut();
if obj_len_start < holder.len() {
holder.split_off(obj_len_start)
if let Some(start) = self.start {
let owned_objects = OWNED_OBJECTS.with(|owned_objects| {
// SAFETY: `OWNED_OBJECTS` is released before calling Py_DECREF,
// or Py_DECREF may call `GILPool::drop` recursively, resulting in invalid borrowing.
let owned_objects = unsafe { &mut *owned_objects.get() };
if start < owned_objects.len() {
owned_objects.split_off(start)
} else {
Vec::new()
}
});
for obj in dropping_obj {
for obj in owned_objects {
unsafe {
ffi::Py_DECREF(obj.as_ptr());
}
@ -447,7 +452,12 @@ pub unsafe fn register_decref(obj: NonNull<ffi::PyObject>) {
pub unsafe fn register_owned(_py: Python<'_>, obj: NonNull<ffi::PyObject>) {
debug_assert!(gil_is_acquired());
// Ignores the error in case this function called from `atexit`.
let _ = OWNED_OBJECTS.try_with(|holder| holder.borrow_mut().push(obj));
let _ = OWNED_OBJECTS.try_with(|owned_objects| {
// SAFETY: This is not re-entrant.
unsafe {
(*owned_objects.get()).push(obj);
}
});
}
/// Increments pyo3's internal GIL count - to be called whenever GILPool or GILGuard is created.
@ -496,7 +506,7 @@ mod tests {
}
fn owned_object_count() -> usize {
OWNED_OBJECTS.with(|holder| holder.borrow().len())
OWNED_OBJECTS.with(|owned_objects| unsafe { (*owned_objects.get()).len() })
}
fn pool_inc_refs_does_not_contain(obj: &PyObject) -> bool {