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Miss Islington (bot)
bb5bf24226
gh-118789: Restore hidden `_PyWeakref_ClearRef` (GH-118797)
_PyWeakref_ClearRef was previously exposed in the public C-API, although
it begins with an underscore and is not documented. It's used by a few
C-API extensions. There is currently no alternative public API that can
replace its use.
_PyWeakref_ClearWeakRefsExceptCallbacks is the only thread-safe way to
use _PyWeakref_ClearRef in the free-threaded build. This exposes the C
symbol, but does not make the API public.
(cherry picked from commit db5af7da09)
Co-authored-by: Sam Gross <colesbury@gmail.com>
64 lines
2.2 KiB
C
64 lines
2.2 KiB
C
#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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#ifdef Py_GIL_DISABLED
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/* Pointer to the lock used when clearing in free-threaded builds.
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* Normally this can be derived from wr_object, but in some cases we need
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* to lock after wr_object has been set to Py_None.
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*/
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struct _PyMutex *weakrefs_lock;
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#endif
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};
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PyAPI_FUNC(void) _PyWeakref_ClearRef(PyWeakReference *self);
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Py_DEPRECATED(3.13) static inline PyObject* PyWeakref_GET_OBJECT(PyObject *ref_obj)
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{
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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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#define PyWeakref_GET_OBJECT(ref) PyWeakref_GET_OBJECT(_PyObject_CAST(ref))
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