Thanks to visit codestin.com
Credit goes to GitHub.com

Skip to content

Align del behavior #6772

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

Draft
youknowone wants to merge 1 commit into
base: main
Choose a base branch
from
Draft

Align del behavior #6772

Changes from all commits
Commits
Show all changes
1 commit
Select commit
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
119 changes: 107 additions & 12 deletions crates/vm/src/object/core.rs
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -220,6 +220,11 @@ impl WeakRefList {
}))
});
let mut inner = unsafe { inner_ptr.as_ref().lock() };
// If obj was cleared by GC but object is still alive (e.g., new weakref
// created during __del__), restore the obj pointer
if inner.obj.is_none() {
inner.obj = Some(NonNull::from(obj));
}
if is_generic && let Some(generic_weakref) = inner.generic_weakref {
let generic_weakref = unsafe { generic_weakref.as_ref() };
if generic_weakref.0.ref_count.get() != 0 {
Expand All @@ -243,14 +248,72 @@ impl WeakRefList {
weak
}

/// Clear all weakrefs and call their callbacks.
/// This is the main clear function called when the owner object is being dropped.
/// It decrements ref_count and deallocates if needed.
fn clear(&self) {
self.clear_inner(true, true)
}

/// Clear all weakrefs but DON'T call callbacks. Instead, return them for later invocation.
/// This is used by GC to ensure ALL weakrefs are cleared BEFORE any callbacks are invoked.
/// Returns a vector of (PyRef<PyWeak>, callback) pairs.
fn clear_for_gc_collect_callbacks(&self) -> Vec<(PyRef<PyWeak>, PyObjectRef)> {
let ptr = match self.inner.get() {
Some(ptr) => ptr,
None => return vec![],
};
let mut inner = unsafe { ptr.as_ref().lock() };

// Clear the object reference
inner.obj = None;

// Collect weakrefs with callbacks
let mut callbacks = Vec::new();
let mut v = Vec::with_capacity(16);
loop {
let inner2 = &mut *inner;
let iter = inner2
.list
.drain_filter(|_| true)
.filter_map(|wr| {
let wr = ManuallyDrop::new(wr);

if Some(NonNull::from(&**wr)) == inner2.generic_weakref {
inner2.generic_weakref = None
}

// if strong_count == 0 there's some reentrancy going on
(wr.as_object().strong_count() > 0).then(|| (*wr).clone())
})
.take(16);
v.extend(iter);
if v.is_empty() {
break;
}
for wr in v.drain(..) {
let cb = unsafe { wr.callback.get().replace(None) };
if let Some(cb) = cb {
callbacks.push((wr, cb));
}
}
}
callbacks
}

fn clear_inner(&self, call_callbacks: bool, decrement_ref_count: bool) {
let to_dealloc = {
let ptr = match self.inner.get() {
Some(ptr) => ptr,
None => return,
};
let mut inner = unsafe { ptr.as_ref().lock() };

// If already cleared (obj is None), skip the ref_count decrement
// to avoid double decrement when called by both GC and drop_slow_inner
let already_cleared = inner.obj.is_none();
inner.obj = None;

// TODO: can be an arrayvec
let mut v = Vec::with_capacity(16);
loop {
Expand Down Expand Up @@ -278,20 +341,33 @@ impl WeakRefList {
if v.is_empty() {
break;
}
PyMutexGuard::unlocked(&mut inner, || {
for wr in v.drain(..) {
let cb = unsafe { wr.callback.get().replace(None) };
if let Some(cb) = cb {
crate::vm::thread::with_vm(&cb, |vm| {
// TODO: handle unraisable exception
let _ = cb.call((wr.clone(),), vm);
});
if call_callbacks {
PyMutexGuard::unlocked(&mut inner, || {
for wr in v.drain(..) {
let cb = unsafe { wr.callback.get().replace(None) };
if let Some(cb) = cb {
crate::vm::thread::with_vm(&cb, |vm| {
// TODO: handle unraisable exception
let _ = cb.call((wr.clone(),), vm);
});
}
}
})
} else {
// Just drain without calling callbacks
for wr in v.drain(..) {
let _ = unsafe { wr.callback.get().replace(None) };
}
})
}
}

// Only decrement ref_count if requested AND not already cleared
if decrement_ref_count && !already_cleared {
inner.ref_count -= 1;
(inner.ref_count == 0).then_some(ptr)
} else {
None
}
inner.ref_count -= 1;
(inner.ref_count == 0).then_some(ptr)
};
if let Some(ptr) = to_dealloc {
unsafe { Self::dealloc(ptr) }
Expand Down Expand Up @@ -835,15 +911,34 @@ impl PyObject {
slot_del: fn(&PyObject, &VirtualMachine) -> PyResult<()>,
) -> Result<(), ()> {
let ret = crate::vm::thread::with_vm(zelf, |vm| {
// Note: inc() from 0 does a double increment (0→2) for thread safety.
// This gives us "permission" to decrement twice.
zelf.0.ref_count.inc();
let after_inc = zelf.strong_count(); // Should be 2

if let Err(e) = slot_del(zelf, vm) {
let del_method = zelf.get_class_attr(identifier!(vm, __del__)).unwrap();
vm.run_unraisable(e, None, del_method);
}

let after_del = zelf.strong_count();

// First decrement
zelf.0.ref_count.dec();

// Check for resurrection: if ref_count increased beyond our expected 2,
// then __del__ created new references (resurrection occurred).
if after_del > after_inc {
// Resurrected - don't do second decrement, leave object alive
return false;
}

// No resurrection - do second decrement to get back to 0
// This matches the double increment from inc()
zelf.0.ref_count.dec()
});
match ret {
// the decref right above set ref_count back to 0
// the decref set ref_count back to 0
Some(true) => Ok(()),
// we've been resurrected by __del__
Some(false) => Err(()),
Expand Down
Loading