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Issue #18112: PEP 442 implementation (safe object finalization).

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This commit is contained in:
Antoine Pitrou 2013-07-30 19:59:21 +02:00
parent c5d95b17ac
commit 796564c27b
25 changed files with 1254 additions and 321 deletions
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70
Objects/object.c
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@ -255,6 +255,72 @@ _PyObject_NewVar(PyTypeObject *tp, Py_ssize_t nitems)
return PyObject_INIT_VAR(op, tp, nitems);
}
void
PyObject_CallFinalizer(PyObject *self)
{
PyTypeObject *tp = Py_TYPE(self);
/* The former could happen on heaptypes created from the C API, e.g.
PyType_FromSpec(). */
if (!PyType_HasFeature(tp, Py_TPFLAGS_HAVE_FINALIZE) ||
tp->tp_finalize == NULL)
return;
/* tp_finalize should only be called once. */
if (PyType_IS_GC(tp) && _PyGC_FINALIZED(self))
return;
tp->tp_finalize(self);
if (PyType_IS_GC(tp))
_PyGC_SET_FINALIZED(self, 1);
}
int
PyObject_CallFinalizerFromDealloc(PyObject *self)
{
Py_ssize_t refcnt;
/* Temporarily resurrect the object. */
if (self->ob_refcnt != 0) {
Py_FatalError("PyObject_CallFinalizerFromDealloc called on "
"object with a non-zero refcount");
}
self->ob_refcnt = 1;
PyObject_CallFinalizer(self);
/* Undo the temporary resurrection; can't use DECREF here, it would
* cause a recursive call.
*/
assert(self->ob_refcnt > 0);
if (--self->ob_refcnt == 0)
return 0; /* this is the normal path out */
/* tp_finalize resurrected it! Make it look like the original Py_DECREF
* never happened.
*/
refcnt = self->ob_refcnt;
_Py_NewReference(self);
self->ob_refcnt = refcnt;
if (PyType_IS_GC(Py_TYPE(self))) {
assert(_PyGC_REFS(self) != _PyGC_REFS_UNTRACKED);
}
/* If Py_REF_DEBUG, _Py_NewReference bumped _Py_RefTotal, so
* we need to undo that. */
_Py_DEC_REFTOTAL;
/* If Py_TRACE_REFS, _Py_NewReference re-added self to the object
* chain, so no more to do there.
* If COUNT_ALLOCS, the original decref bumped tp_frees, and
* _Py_NewReference bumped tp_allocs: both of those need to be
* undone.
*/
#ifdef COUNT_ALLOCS
--Py_TYPE(self)->tp_frees;
--Py_TYPE(self)->tp_allocs;
#endif
return -1;
}
int
PyObject_Print(PyObject *op, FILE *fp, int flags)
{
@ -1981,7 +2047,7 @@ void
_PyTrash_deposit_object(PyObject *op)
{
assert(PyObject_IS_GC(op));
assert(_Py_AS_GC(op)->gc.gc_refs == _PyGC_REFS_UNTRACKED);
assert(_PyGC_REFS(op) == _PyGC_REFS_UNTRACKED);
assert(op->ob_refcnt == 0);
_Py_AS_GC(op)->gc.gc_prev = (PyGC_Head *)_PyTrash_delete_later;
_PyTrash_delete_later = op;
@ -1993,7 +2059,7 @@ _PyTrash_thread_deposit_object(PyObject *op)
{
PyThreadState *tstate = PyThreadState_GET();
assert(PyObject_IS_GC(op));
assert(_Py_AS_GC(op)->gc.gc_refs == _PyGC_REFS_UNTRACKED);
assert(_PyGC_REFS(op) == _PyGC_REFS_UNTRACKED);
assert(op->ob_refcnt == 0);
_Py_AS_GC(op)->gc.gc_prev = (PyGC_Head *) tstate->trash_delete_later;
tstate->trash_delete_later = op;