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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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92
Modules/_io/iobase.c
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@ -196,21 +196,17 @@ iobase_close(PyObject *self, PyObject *args)
/* Finalization and garbage collection support */
int
_PyIOBase_finalize(PyObject *self)
static void
iobase_finalize(PyObject *self)
{
PyObject *res;
PyObject *tp, *v, *tb;
int closed = 1;
int is_zombie;
PyObject *error_type, *error_value, *error_traceback;
int closed;
_Py_IDENTIFIER(_finalizing);
/* Save the current exception, if any. */
PyErr_Fetch(&error_type, &error_value, &error_traceback);
/* If _PyIOBase_finalize() is called from a destructor, we need to
resurrect the object as calling close() can invoke arbitrary code. */
is_zombie = (Py_REFCNT(self) == 0);
if (is_zombie) {
++Py_REFCNT(self);
}
PyErr_Fetch(&tp, &v, &tb);
/* If `closed` doesn't exist or can't be evaluated as bool, then the
object is probably in an unusable state, so ignore. */
res = PyObject_GetAttr(self, _PyIO_str_closed);
@ -223,6 +219,10 @@ _PyIOBase_finalize(PyObject *self)
PyErr_Clear();
}
if (closed == 0) {
/* Signal close() that it was called as part of the object
finalization process. */
if (_PyObject_SetAttrId(self, &PyId__finalizing, Py_True))
PyErr_Clear();
res = PyObject_CallMethodObjArgs((PyObject *) self, _PyIO_str_close,
NULL);
/* Silencing I/O errors is bad, but printing spurious tracebacks is
@ -233,31 +233,25 @@ _PyIOBase_finalize(PyObject *self)
else
Py_DECREF(res);
}
PyErr_Restore(tp, v, tb);
if (is_zombie) {
if (--Py_REFCNT(self) != 0) {
/* The object lives again. The following code is taken from
slot_tp_del in typeobject.c. */
Py_ssize_t refcnt = Py_REFCNT(self);
_Py_NewReference(self);
Py_REFCNT(self) = refcnt;
/* 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;
}
/* Restore the saved exception. */
PyErr_Restore(error_type, error_value, error_traceback);
}
int
_PyIOBase_finalize(PyObject *self)
{
int is_zombie;
/* If _PyIOBase_finalize() is called from a destructor, we need to
resurrect the object as calling close() can invoke arbitrary code. */
is_zombie = (Py_REFCNT(self) == 0);
if (is_zombie)
return PyObject_CallFinalizerFromDealloc(self);
else {
PyObject_CallFinalizer(self);
return 0;
}
return 0;
}
static int
@ -270,8 +264,6 @@ iobase_traverse(iobase *self, visitproc visit, void *arg)
static int
iobase_clear(iobase *self)
{
if (_PyIOBase_finalize((PyObject *) self) < 0)
return -1;
Py_CLEAR(self->dict);
return 0;
}
@ -741,7 +733,7 @@ PyTypeObject PyIOBase_Type = {
0, /*tp_setattro*/
0, /*tp_as_buffer*/
Py_TPFLAGS_DEFAULT | Py_TPFLAGS_BASETYPE
| Py_TPFLAGS_HAVE_GC, /*tp_flags*/
| Py_TPFLAGS_HAVE_GC | Py_TPFLAGS_HAVE_FINALIZE, /*tp_flags*/
iobase_doc, /* tp_doc */
(traverseproc)iobase_traverse, /* tp_traverse */
(inquiry)iobase_clear, /* tp_clear */
@ -760,6 +752,16 @@ PyTypeObject PyIOBase_Type = {
0, /* tp_init */
0, /* tp_alloc */
PyType_GenericNew, /* tp_new */
0, /* tp_free */
0, /* tp_is_gc */
0, /* tp_bases */
0, /* tp_mro */
0, /* tp_cache */
0, /* tp_subclasses */
0, /* tp_weaklist */
0, /* tp_del */
0, /* tp_version_tag */
(destructor)iobase_finalize, /* tp_finalize */
};
@ -905,7 +907,7 @@ PyTypeObject PyRawIOBase_Type = {
0, /*tp_getattro*/
0, /*tp_setattro*/
0, /*tp_as_buffer*/
Py_TPFLAGS_DEFAULT | Py_TPFLAGS_BASETYPE, /*tp_flags*/
Py_TPFLAGS_DEFAULT | Py_TPFLAGS_BASETYPE | Py_TPFLAGS_HAVE_FINALIZE, /*tp_flags*/
rawiobase_doc, /* tp_doc */
0, /* tp_traverse */
0, /* tp_clear */
@ -924,4 +926,14 @@ PyTypeObject PyRawIOBase_Type = {
0, /* tp_init */
0, /* tp_alloc */
0, /* tp_new */
0, /* tp_free */
0, /* tp_is_gc */
0, /* tp_bases */
0, /* tp_mro */
0, /* tp_cache */
0, /* tp_subclasses */
0, /* tp_weaklist */
0, /* tp_del */
0, /* tp_version_tag */
0, /* tp_finalize */
};