mirror of https://github.com/python/cpython
58 lines
1.6 KiB
C
58 lines
1.6 KiB
C
#ifndef Py_INTERNAL_WEAKREF_H
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#define Py_INTERNAL_WEAKREF_H
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#ifdef __cplusplus
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extern "C" {
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#endif
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#ifndef Py_BUILD_CORE
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# error "this header requires Py_BUILD_CORE define"
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#endif
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static inline PyObject* _PyWeakref_GET_REF(PyObject *ref_obj) {
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assert(PyWeakref_Check(ref_obj));
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PyWeakReference *ref = _Py_CAST(PyWeakReference*, ref_obj);
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PyObject *obj = ref->wr_object;
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if (obj == Py_None) {
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// clear_weakref() was called
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return NULL;
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}
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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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Py_ssize_t refcnt = Py_REFCNT(obj);
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if (refcnt == 0) {
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return NULL;
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}
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assert(refcnt > 0);
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return Py_NewRef(obj);
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}
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static inline int _PyWeakref_IS_DEAD(PyObject *ref_obj) {
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assert(PyWeakref_Check(ref_obj));
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PyWeakReference *ref = _Py_CAST(PyWeakReference*, ref_obj);
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PyObject *obj = ref->wr_object;
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if (obj == Py_None) {
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// clear_weakref() was called
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return 1;
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}
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// See _PyWeakref_GET_REF() for the rationale of this test
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return (Py_REFCNT(obj) == 0);
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}
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extern Py_ssize_t _PyWeakref_GetWeakrefCount(PyWeakReference *head);
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extern void _PyWeakref_ClearRef(PyWeakReference *self);
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#ifdef __cplusplus
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}
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#endif
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#endif /* !Py_INTERNAL_WEAKREF_H */
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