Fix cc_oid_unreferenced() so that it works with a Python debug build.

In the TRACE_REFS version of the code, call _Py_NewReference() instead
of INCREF to bump the refcount from zero to one.

When exiting the function, don't DECREF the object back to zero
refcount, as that will reinvoke the object's deallocation function.
XXX Why did this ever work?

src/Persistence/cPickleCache.c

@@ -88,7 +88,7 @@ process must skip such objects, rather than deactivating them.
 static char cPickleCache_doc_string[] =
 "Defines the PickleCache used by ZODB Connection objects.\n"
 "\n"
-"$Id: cPickleCache.c,v 1.65 2002/05/02 14:03:07 fdrake Exp $\n";
+"$Id: cPickleCache.c,v 1.66 2002/06/10 22:35:08 jeremy Exp $\n";
 
 #define ASSIGN(V,E) {PyObject *__e; __e=(E); Py_XDECREF(V); (V)=__e;}
 #define UNLESS(E) if(!(E))
@@ -427,9 +427,9 @@ cc_invalidate(ccobject *self, PyObject *args)
   PyObject *inv, *key, *v;
   int i;
 
-  /* XXX The code supports invalidation of all objects, but I don't
-     think it's possible for a Connection object to pass None.  If
-     this is correct, the code could be simplied.
+  /* XXX The code supports invalidation of all objects, but it's
+     impossible for a Connection object to pass None.  The code could be
+     simplied.
   */
 
   if (PyArg_ParseTuple(args, "O!", &PyDict_Type, &inv)) {
@@ -604,22 +604,26 @@ cc_oid_unreferenced(ccobject *self, PyObject *oid)
     */
 
 #ifdef Py_TRACE_REFS
-#error "this code path has not been tested - Toby Dickenson"
-    /* not tested, but it should still work. I would appreciate
-       reports of success */
+    /* This is called from the deallocation function after the
+       interpreter has untracked the reference.  Track it again.
+     */
     _Py_NewReference(v);
-    /* it may be a problem that v->ob_type is still NULL? */
+    /* XXX it may be a problem that v->ob_type is still NULL? 
+       I don't understand what this comment means.  --jeremy */
+    assert(v->ob_type);
 #else
     Py_INCREF(v);
 #endif
+    assert(v->ob_refcnt == 1);
     /* Incremement the refcount again, because delitem is going to
        DECREF it.  If it's refcount reached zero again, we'd call back to
        the dealloc function that called us.
     */
     Py_INCREF(v);
 
-    /* XXX what if this fails? */
-    PyDict_DelItem(self->data, oid);
+    /* XXX Should we call _Py_ForgetReference() on error exit? */
+    if (PyDict_DelItem(self->data, oid) < 0)
+	return -1;
 
     if (v->ob_refcnt != 1) {
         PyErr_SetString(PyExc_ValueError,
@@ -627,12 +631,12 @@ cc_oid_unreferenced(ccobject *self, PyObject *oid)
         return -1;
     }
 
-    /* undo the temporary resurrection */
-#ifdef Py_TRACE_REFS
+    /* Undo the temporary resurrection.
+       Don't DECREF the object, because this function is called from
+       the object's dealloc function. If the refcnt reaches zero, it
+       will all be invoked recursively.
+     */
     _Py_ForgetReference(v);
-#else
-    v->ob_refcnt = 0;
-#endif
 
     return 0;
 }

src/ZODB/cPickleCache.c

@@ -88,7 +88,7 @@ process must skip such objects, rather than deactivating them.
 static char cPickleCache_doc_string[] =
 "Defines the PickleCache used by ZODB Connection objects.\n"
 "\n"
-"$Id: cPickleCache.c,v 1.65 2002/05/02 14:03:07 fdrake Exp $\n";
+"$Id: cPickleCache.c,v 1.66 2002/06/10 22:35:08 jeremy Exp $\n";
 
 #define ASSIGN(V,E) {PyObject *__e; __e=(E); Py_XDECREF(V); (V)=__e;}
 #define UNLESS(E) if(!(E))
@@ -427,9 +427,9 @@ cc_invalidate(ccobject *self, PyObject *args)
   PyObject *inv, *key, *v;
   int i;
 
-  /* XXX The code supports invalidation of all objects, but I don't
-     think it's possible for a Connection object to pass None.  If
-     this is correct, the code could be simplied.
+  /* XXX The code supports invalidation of all objects, but it's
+     impossible for a Connection object to pass None.  The code could be
+     simplied.
   */
 
   if (PyArg_ParseTuple(args, "O!", &PyDict_Type, &inv)) {
@@ -604,22 +604,26 @@ cc_oid_unreferenced(ccobject *self, PyObject *oid)
     */
 
 #ifdef Py_TRACE_REFS
-#error "this code path has not been tested - Toby Dickenson"
-    /* not tested, but it should still work. I would appreciate
-       reports of success */
+    /* This is called from the deallocation function after the
+       interpreter has untracked the reference.  Track it again.
+     */
     _Py_NewReference(v);
-    /* it may be a problem that v->ob_type is still NULL? */
+    /* XXX it may be a problem that v->ob_type is still NULL? 
+       I don't understand what this comment means.  --jeremy */
+    assert(v->ob_type);
 #else
     Py_INCREF(v);
 #endif
+    assert(v->ob_refcnt == 1);
     /* Incremement the refcount again, because delitem is going to
        DECREF it.  If it's refcount reached zero again, we'd call back to
        the dealloc function that called us.
     */
     Py_INCREF(v);
 
-    /* XXX what if this fails? */
-    PyDict_DelItem(self->data, oid);
+    /* XXX Should we call _Py_ForgetReference() on error exit? */
+    if (PyDict_DelItem(self->data, oid) < 0)
+	return -1;
 
     if (v->ob_refcnt != 1) {
         PyErr_SetString(PyExc_ValueError,
@@ -627,12 +631,12 @@ cc_oid_unreferenced(ccobject *self, PyObject *oid)
         return -1;
     }
 
-    /* undo the temporary resurrection */
-#ifdef Py_TRACE_REFS
+    /* Undo the temporary resurrection.
+       Don't DECREF the object, because this function is called from
+       the object's dealloc function. If the refcnt reaches zero, it
+       will all be invoked recursively.
+     */
     _Py_ForgetReference(v);
-#else
-    v->ob_refcnt = 0;
-#endif
 
     return 0;
 }

src/persistent/cPickleCache.c

@@ -88,7 +88,7 @@ process must skip such objects, rather than deactivating them.
 static char cPickleCache_doc_string[] =
 "Defines the PickleCache used by ZODB Connection objects.\n"
 "\n"
-"$Id: cPickleCache.c,v 1.65 2002/05/02 14:03:07 fdrake Exp $\n";
+"$Id: cPickleCache.c,v 1.66 2002/06/10 22:35:08 jeremy Exp $\n";
 
 #define ASSIGN(V,E) {PyObject *__e; __e=(E); Py_XDECREF(V); (V)=__e;}
 #define UNLESS(E) if(!(E))
@@ -427,9 +427,9 @@ cc_invalidate(ccobject *self, PyObject *args)
   PyObject *inv, *key, *v;
   int i;
 
-  /* XXX The code supports invalidation of all objects, but I don't
-     think it's possible for a Connection object to pass None.  If
-     this is correct, the code could be simplied.
+  /* XXX The code supports invalidation of all objects, but it's
+     impossible for a Connection object to pass None.  The code could be
+     simplied.
   */
 
   if (PyArg_ParseTuple(args, "O!", &PyDict_Type, &inv)) {
@@ -604,22 +604,26 @@ cc_oid_unreferenced(ccobject *self, PyObject *oid)
     */
 
 #ifdef Py_TRACE_REFS
-#error "this code path has not been tested - Toby Dickenson"
-    /* not tested, but it should still work. I would appreciate
-       reports of success */
+    /* This is called from the deallocation function after the
+       interpreter has untracked the reference.  Track it again.
+     */
     _Py_NewReference(v);
-    /* it may be a problem that v->ob_type is still NULL? */
+    /* XXX it may be a problem that v->ob_type is still NULL? 
+       I don't understand what this comment means.  --jeremy */
+    assert(v->ob_type);
 #else
     Py_INCREF(v);
 #endif
+    assert(v->ob_refcnt == 1);
     /* Incremement the refcount again, because delitem is going to
        DECREF it.  If it's refcount reached zero again, we'd call back to
        the dealloc function that called us.
     */
     Py_INCREF(v);
 
-    /* XXX what if this fails? */
-    PyDict_DelItem(self->data, oid);
+    /* XXX Should we call _Py_ForgetReference() on error exit? */
+    if (PyDict_DelItem(self->data, oid) < 0)
+	return -1;
 
     if (v->ob_refcnt != 1) {
         PyErr_SetString(PyExc_ValueError,
@@ -627,12 +631,12 @@ cc_oid_unreferenced(ccobject *self, PyObject *oid)
         return -1;
     }
 
-    /* undo the temporary resurrection */
-#ifdef Py_TRACE_REFS
+    /* Undo the temporary resurrection.
+       Don't DECREF the object, because this function is called from
+       the object's dealloc function. If the refcnt reaches zero, it
+       will all be invoked recursively.
+     */
     _Py_ForgetReference(v);
-#else
-    v->ob_refcnt = 0;
-#endif
 
     return 0;
 }