59 lines
2.1 KiB
C
59 lines
2.1 KiB
C
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#ifndef Py_CPYTHON_WEAKREFOBJECT_H
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# error "this header file must not be included directly"
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#endif
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/* PyWeakReference is the base struct for the Python ReferenceType, ProxyType,
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* and CallableProxyType.
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*/
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struct _PyWeakReference {
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PyObject_HEAD
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/* The object to which this is a weak reference, or Py_None if none.
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* Note that this is a stealth reference: wr_object's refcount is
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* not incremented to reflect this pointer.
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*/
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PyObject *wr_object;
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/* A callable to invoke when wr_object dies, or NULL if none. */
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PyObject *wr_callback;
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/* A cache for wr_object's hash code. As usual for hashes, this is -1
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* if the hash code isn't known yet.
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*/
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Py_hash_t hash;
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/* If wr_object is weakly referenced, wr_object has a doubly-linked NULL-
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* terminated list of weak references to it. These are the list pointers.
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* If wr_object goes away, wr_object is set to Py_None, and these pointers
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* have no meaning then.
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*/
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PyWeakReference *wr_prev;
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PyWeakReference *wr_next;
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vectorcallfunc vectorcall;
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};
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PyAPI_FUNC(Py_ssize_t) _PyWeakref_GetWeakrefCount(PyWeakReference *head);
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PyAPI_FUNC(void) _PyWeakref_ClearRef(PyWeakReference *self);
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static inline PyObject* PyWeakref_GET_OBJECT(PyObject *ref_obj) {
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PyWeakReference *ref;
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PyObject *obj;
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assert(PyWeakref_Check(ref_obj));
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ref = _Py_CAST(PyWeakReference*, ref_obj);
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obj = ref->wr_object;
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// Explanation for the Py_REFCNT() check: when a weakref's target is part
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// of a long chain of deallocations which triggers the trashcan mechanism,
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// clearing the weakrefs can be delayed long after the target's refcount
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// has dropped to zero. In the meantime, code accessing the weakref will
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// be able to "see" the target object even though it is supposed to be
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// unreachable. See issue gh-60806.
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if (Py_REFCNT(obj) > 0) {
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return obj;
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}
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return Py_None;
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}
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#if !defined(Py_LIMITED_API) || Py_LIMITED_API+0 < 0x030b0000
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# define PyWeakref_GET_OBJECT(ref) PyWeakref_GET_OBJECT(_PyObject_CAST(ref))
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#endif
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