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[C API] Make Py_REFCNT() opaque in limited C API 3.14 #124127
Description
In the limited C API 3.14 and newer, I propose to change Py_REFCNT() implementation to an opaque function call to hide implementation details. I made a similar change for Py_INCREF() and Py_DECREF() in Python 3.12.
The problem is that with Free Threading (PEP 703), the implementation of this functions becomes less trivial than just getting the object member PyObject.ob_refcnt:
static inline Py_ssize_t _Py_REFCNT(PyObject *ob) {
uint32_t local = _Py_atomic_load_uint32_relaxed(&ob->ob_ref_local);
if (local == _Py_IMMORTAL_REFCNT_LOCAL) {
return _Py_IMMORTAL_REFCNT;
}
Py_ssize_t shared = _Py_atomic_load_ssize_relaxed(&ob->ob_ref_shared);
return _Py_STATIC_CAST(Py_ssize_t, local) +
Py_ARITHMETIC_RIGHT_SHIFT(Py_ssize_t, shared, _Py_REF_SHARED_SHIFT);
}_Py_atomic_load_uint32_relaxed() and _Py_atomic_load_ssize_relaxed() must now be called. But I would prefer to not "leak" such implementation detail into the limited C API.
cc @colesbury @Fidget-Spinner @encukou
Activity
pythongh-124127: Make Py_REFCNT() opaque in limited C API 3.14
pythongh-124127: Make Py_REFCNT() opaque in limited C API 3.14
pythongh-124127: Make Py_REFCNT() opaque in limited C API 3.14
pythongh-124127: Make Py_REFCNT() opaque in limited C API 3.14
vstinner commentedon Sep 16, 2024
Previous issue about Py_TYPE(): #120600
gh-124127: Make Py_REFCNT() opaque in limited C API 3.14 (#124128)
vstinner commentedon Sep 24, 2024
Implemented in 9d344fa.
vstinner commentedon Sep 24, 2024
Functions implemented as opaque function calls in limited C API 3.14:
Py_SET_TYPE() is not implemented as an opaque function call since it should not be used in the limited C API, it's only useful with static types.