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gh-123619: Add an unstable C API function for enabling deferred reference counting (GH-123635)

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Co-authored-by: Sam Gross <colesbury@gmail.com>
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Peter Bierma 2024-11-13 08:27:16 -05:00 • committed by GitHub
parent 29b5323c45
commit d00878b06a
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8 changed files with 128 additions and 1 deletions
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29
Objects/object.c
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@ -2519,6 +2519,35 @@ _PyObject_SetDeferredRefcount(PyObject *op)
#endif
}
int
PyUnstable_Object_EnableDeferredRefcount(PyObject *op)
{
#ifdef Py_GIL_DISABLED
if (!PyType_IS_GC(Py_TYPE(op))) {
// Deferred reference counting doesn't work
// on untracked types.
return 0;
}
uint8_t bits = _Py_atomic_load_uint8(&op->ob_gc_bits);
if ((bits & _PyGC_BITS_DEFERRED) != 0)
{
// Nothing to do.
return 0;
}
if (_Py_atomic_compare_exchange_uint8(&op->ob_gc_bits, &bits, bits | _PyGC_BITS_DEFERRED) == 0)
{
// Someone beat us to it!
return 0;
}
_Py_atomic_add_ssize(&op->ob_ref_shared, _Py_REF_SHARED(_Py_REF_DEFERRED, 0));
return 1;
#else
return 0;
#endif
}
void
_Py_ResurrectReference(PyObject *op)
{