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82 lines
2.2 KiB
C
82 lines
2.2 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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#include "pycore_critical_section.h" // Py_BEGIN_CRITICAL_SECTION()
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#include "pycore_object.h" // _Py_REF_IS_MERGED()
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static inline int _is_dead(PyObject *obj)
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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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#if defined(Py_GIL_DISABLED)
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Py_ssize_t shared = _Py_atomic_load_ssize_relaxed(&obj->ob_ref_shared);
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return shared == _Py_REF_SHARED(0, _Py_REF_MERGED);
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#else
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return (Py_REFCNT(obj) == 0);
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#endif
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}
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static inline PyObject* _PyWeakref_GET_REF(PyObject *ref_obj)
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{
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assert(PyWeakref_Check(ref_obj));
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PyObject *ret = NULL;
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Py_BEGIN_CRITICAL_SECTION(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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goto end;
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}
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if (_is_dead(obj)) {
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goto end;
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}
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#if !defined(Py_GIL_DISABLED)
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assert(Py_REFCNT(obj) > 0);
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#endif
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ret = Py_NewRef(obj);
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end:
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Py_END_CRITICAL_SECTION();
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return ret;
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}
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static inline int _PyWeakref_IS_DEAD(PyObject *ref_obj)
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{
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assert(PyWeakref_Check(ref_obj));
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int ret = 0;
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Py_BEGIN_CRITICAL_SECTION(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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ret = 1;
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}
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else {
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// See _PyWeakref_GET_REF() for the rationale of this test
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ret = _is_dead(obj);
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}
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Py_END_CRITICAL_SECTION();
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return ret;
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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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