Method upgrade

crates/vm/src/object/core.rs:829–849

_PyWeakref_GET_REF: attempt to upgrade the weakref to a strong reference.

(&self)

impl PyWeak {
    /// _PyWeakref_GET_REF: attempt to upgrade the weakref to a strong reference.
    pub(crate) fn upgrade(&self) -> Option<PyObjectRef> {
        let obj_ptr = self.wr_object.load(Ordering::Acquire);
        if obj_ptr.is_null() {
            return None;
        }

        let _lock = weakref_lock::lock(obj_ptr as usize);

        // Double-check under lock (clear may have run between our check and lock)
        let obj_ptr = self.wr_object.load(Ordering::Relaxed);
        if obj_ptr.is_null() {
            return None;
        }

        unsafe {
            if !(*obj_ptr).0.ref_count.safe_inc() {
                return None;
            }
            Some(PyObjectRef::from_raw(NonNull::new_unchecked(obj_ptr)))
        }
    }

    pub(crate) fn is_dead(&self) -> bool {
        self.wr_object.load(Ordering::Acquire).is_null()