object.h special-build macro minefield: renamed all the new lexical
helper macros to something saner, and used them appropriately in other
files too, to reduce #ifdef blocks.
classobject.c, instance_dealloc(): One of my worst Python Memories is
trying to fix this routine a few years ago when COUNT_ALLOCS was defined
but Py_TRACE_REFS wasn't. The special-build code here is way too
complicated. Now it's much simpler. Difference: in a Py_TRACE_REFS
build, the instance is no longer in the doubly-linked list of live
objects while its __del__ method is executing, and that may be visible
via sys.getobjects() called from a __del__ method. Tough -- the object
is presumed dead while its __del__ is executing anyway, and not calling
_Py_NewReference() at the start allows enormous code simplification.
typeobject.c, call_finalizer(): The special-build instance_dealloc()
pain apparently spread to here too via cut-'n-paste, and this is much
simpler now too. In addition, I didn't understand why this routine
was calling _PyObject_GC_TRACK() after a resurrection, since there's no
plausible way _PyObject_GC_UNTRACK() could have been called on the
object by this point. I suspect it was left over from pasting the
instance_delloc() code. Instead asserted that the object is still
tracked. Caution: I suspect we don't have a test that actually
exercises the subtype_dealloc() __del__-resurrected-me code.
diff --git a/Objects/typeobject.c b/Objects/typeobject.c
index 2beb3b3..a7afa9b 100644
--- a/Objects/typeobject.c
+++ b/Objects/typeobject.c
@@ -365,22 +365,8 @@
PyObject *error_type, *error_value, *error_traceback;
/* Temporarily resurrect the object. */
-#ifdef Py_TRACE_REFS
-#ifndef Py_REF_DEBUG
-# error "Py_TRACE_REFS defined but Py_REF_DEBUG not."
-#endif
- /* much too complicated if Py_TRACE_REFS defined */
- _Py_NewReference((PyObject *)self);
-#ifdef COUNT_ALLOCS
- /* compensate for boost in _Py_NewReference; note that
- * _Py_RefTotal was also boosted; we'll knock that down later.
- */
- self->ob_type->tp_allocs--;
-#endif
-#else /* !Py_TRACE_REFS */
- /* Py_INCREF boosts _Py_RefTotal if Py_REF_DEBUG is defined */
- Py_INCREF(self);
-#endif /* !Py_TRACE_REFS */
+ assert(self->ob_refcnt == 0);
+ self->ob_refcnt = 1;
/* Save the current exception, if any. */
PyErr_Fetch(&error_type, &error_value, &error_traceback);
@@ -402,28 +388,32 @@
/* Undo the temporary resurrection; can't use DECREF here, it would
* cause a recursive call.
*/
-#ifdef Py_REF_DEBUG
- /* _Py_RefTotal was boosted either by _Py_NewReference or
- * Py_INCREF above.
- */
- _Py_RefTotal--;
-#endif
- if (--self->ob_refcnt > 0) {
-#ifdef COUNT_ALLOCS
- self->ob_type->tp_frees--;
-#endif
- _PyObject_GC_TRACK(self);
- return -1; /* __del__ added a reference; don't delete now */
- }
-#ifdef Py_TRACE_REFS
- _Py_ForgetReference((PyObject *)self);
-#ifdef COUNT_ALLOCS
- /* compensate for increment in _Py_ForgetReference */
- self->ob_type->tp_frees--;
-#endif
-#endif
+ assert(self->ob_refcnt > 0);
+ if (--self->ob_refcnt == 0)
+ return 0; /* this is the normal path out */
- return 0;
+ /* __del__ resurrected it! Make it look like the original Py_DECREF
+ * never happened.
+ */
+ {
+ int refcnt = self->ob_refcnt;
+ _Py_NewReference(self);
+ self->ob_refcnt = refcnt;
+ }
+ assert(_Py_AS_GC(self)->gc.gc_refs != _PyGC_REFS_UNTRACKED);
+ /* If Py_REF_DEBUG, the original decref dropped _Py_RefTotal, but
+ * _Py_NewReference bumped it again, so that's a wash.
+ * If Py_TRACE_REFS, _Py_NewReference re-added self to the object
+ * chain, so no more to do there either.
+ * 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
+ --self->ob_type->tp_frees;
+ --self->ob_type->tp_allocs;
+#endif
+ return -1; /* __del__ added a reference; don't delete now */
}
static void
@@ -1387,13 +1377,13 @@
/* No readable descriptor found yet */
meta_get = NULL;
-
+
/* Look for the attribute in the metatype */
meta_attribute = _PyType_Lookup(metatype, name);
if (meta_attribute != NULL) {
meta_get = meta_attribute->ob_type->tp_descr_get;
-
+
if (meta_get != NULL && PyDescr_IsData(meta_attribute)) {
/* Data descriptors implement tp_descr_set to intercept
* writes. Assume the attribute is not overridden in
@@ -1416,7 +1406,7 @@
return local_get(attribute, (PyObject *)NULL,
(PyObject *)type);
}
-
+
Py_INCREF(attribute);
return attribute;
}