bpo-42972: Fully implement GC protocol for sqlite3 heap types (GH-26104)

(cherry picked from commit d3c277a)

Co-authored-by: Erlend Egeberg Aasland <erlend.aasland@innova.no>

Author: miss-islington

Modules/_sqlite/cache.c

@@ -44,14 +44,29 @@ pysqlite_new_node(PyObject *key, PyObject *data)
     return node;
 }
 
+static int
+node_traverse(pysqlite_Node *self, visitproc visit, void *arg)
+{
+    Py_VISIT(self->key);
+    Py_VISIT(self->data);
+    Py_VISIT(Py_TYPE(self));
+    return 0;
+}
+
+static int
+node_clear(pysqlite_Node *self)
+{
+    Py_CLEAR(self->key);
+    Py_CLEAR(self->data);
+    return 0;
+}
+
 static void
 pysqlite_node_dealloc(pysqlite_Node *self)
 {
     PyTypeObject *tp = Py_TYPE(self);
-
-    Py_DECREF(self->key);
-    Py_DECREF(self->data);
-
+    PyObject_GC_UnTrack(self);
+    tp->tp_clear((PyObject *)self);
     tp->tp_free(self);
     Py_DECREF(tp);
 }
@@ -88,31 +103,51 @@ pysqlite_cache_init(pysqlite_Cache *self, PyObject *args, PyObject *kwargs)
     return 0;
 }
 
-static void
-pysqlite_cache_dealloc(pysqlite_Cache *self)
+static int
+cache_traverse(pysqlite_Cache *self, visitproc visit, void *arg)
 {
-    PyTypeObject *tp = Py_TYPE(self);
-    pysqlite_Node* node;
-    pysqlite_Node* delete_node;
-
-    if (!self->factory) {
-        /* constructor failed, just get out of here */
-        return;
+    pysqlite_Node *node = self->first;
+    while (node) {
+        Py_VISIT(node);
+        node = node->next;
+    }
+    Py_VISIT(self->mapping);
+    if (self->decref_factory) {
+        Py_VISIT(self->factory);
     }
+    Py_VISIT(Py_TYPE(self));
+    return 0;
+}
 
+static int
+cache_clear(pysqlite_Cache *self)
+{
     /* iterate over all nodes and deallocate them */
-    node = self->first;
+    pysqlite_Node *node = self->first;
+    self->first = NULL;
     while (node) {
-        delete_node = node;
+        pysqlite_Node *delete_node = node;
         node = node->next;
-        Py_DECREF(delete_node);
+        Py_CLEAR(delete_node);
     }
-
     if (self->decref_factory) {
-        Py_DECREF(self->factory);
+        Py_CLEAR(self->factory);
+    }
+    Py_CLEAR(self->mapping);
+    return 0;
+}
+
+static void
+pysqlite_cache_dealloc(pysqlite_Cache *self)
+{
+    if (!self->factory) {
+        /* constructor failed, just get out of here */
+        return;
     }
-    Py_DECREF(self->mapping);
 
+    PyObject_GC_UnTrack(self);
+    PyTypeObject *tp = Py_TYPE(self);
+    tp->tp_clear((PyObject *)self);
     tp->tp_free(self);
     Py_DECREF(tp);
 }
@@ -260,14 +295,15 @@ pysqlite_cache_display(pysqlite_Cache *self, PyObject *args)
 
 static PyType_Slot node_slots[] = {
     {Py_tp_dealloc, pysqlite_node_dealloc},
-    {Py_tp_new, PyType_GenericNew},
+    {Py_tp_traverse, node_traverse},
+    {Py_tp_clear, node_clear},
     {0, NULL},
 };
 
 static PyType_Spec node_spec = {
     .name = MODULE_NAME ".Node",
     .basicsize = sizeof(pysqlite_Node),
-    .flags = Py_TPFLAGS_DEFAULT | Py_TPFLAGS_BASETYPE,
+    .flags = Py_TPFLAGS_DEFAULT | Py_TPFLAGS_BASETYPE | Py_TPFLAGS_HAVE_GC,
     .slots = node_slots,
 };
 PyTypeObject *pysqlite_NodeType = NULL;
@@ -283,15 +319,16 @@ static PyMethodDef cache_methods[] = {
 static PyType_Slot cache_slots[] = {
     {Py_tp_dealloc, pysqlite_cache_dealloc},
     {Py_tp_methods, cache_methods},
-    {Py_tp_new, PyType_GenericNew},
     {Py_tp_init, pysqlite_cache_init},
+    {Py_tp_traverse, cache_traverse},
+    {Py_tp_clear, cache_clear},
     {0, NULL},
 };
 
 static PyType_Spec cache_spec = {
     .name = MODULE_NAME ".Cache",
     .basicsize = sizeof(pysqlite_Cache),
-    .flags = Py_TPFLAGS_DEFAULT | Py_TPFLAGS_BASETYPE,
+    .flags = Py_TPFLAGS_DEFAULT | Py_TPFLAGS_BASETYPE | Py_TPFLAGS_HAVE_GC,
     .slots = cache_slots,
 };
 PyTypeObject *pysqlite_CacheType = NULL;

Modules/_sqlite/connection.c

@@ -225,28 +225,51 @@ pysqlite_do_all_statements(pysqlite_Connection *self, int action,
     }
 }
 
+static int
+connection_traverse(pysqlite_Connection *self, visitproc visit, void *arg)
+{
+    Py_VISIT(self->statement_cache);
+    Py_VISIT(self->isolation_level);
+    Py_VISIT(self->function_pinboard_trace_callback);
+    Py_VISIT(self->function_pinboard_progress_handler);
+    Py_VISIT(self->function_pinboard_authorizer_cb);
+    Py_VISIT(self->row_factory);
+    Py_VISIT(self->text_factory);
+    Py_VISIT(self->collations);
+    Py_VISIT(self->statements);
+    Py_VISIT(self->cursors);
+    Py_VISIT(Py_TYPE(self));
+    return 0;
+}
+
+static int
+connection_clear(pysqlite_Connection *self)
+{
+    Py_CLEAR(self->statement_cache);
+    Py_CLEAR(self->isolation_level);
+    Py_CLEAR(self->function_pinboard_trace_callback);
+    Py_CLEAR(self->function_pinboard_progress_handler);
+    Py_CLEAR(self->function_pinboard_authorizer_cb);
+    Py_CLEAR(self->row_factory);
+    Py_CLEAR(self->text_factory);
+    Py_CLEAR(self->collations);
+    Py_CLEAR(self->statements);
+    Py_CLEAR(self->cursors);
+    return 0;
+}
+
 static void
-pysqlite_connection_dealloc(pysqlite_Connection *self)
+connection_dealloc(pysqlite_Connection *self)
 {
     PyTypeObject *tp = Py_TYPE(self);
-
-    Py_XDECREF(self->statement_cache);
+    PyObject_GC_UnTrack(self);
+    tp->tp_clear((PyObject *)self);
 
     /* Clean up if user has not called .close() explicitly. */
     if (self->db) {
         sqlite3_close_v2(self->db);
     }
 
-    Py_XDECREF(self->isolation_level);
-    Py_XDECREF(self->function_pinboard_trace_callback);
-    Py_XDECREF(self->function_pinboard_progress_handler);
-    Py_XDECREF(self->function_pinboard_authorizer_cb);
-    Py_XDECREF(self->row_factory);
-    Py_XDECREF(self->text_factory);
-    Py_XDECREF(self->collations);
-    Py_XDECREF(self->statements);
-    Py_XDECREF(self->cursors);
-
     tp->tp_free(self);
     Py_DECREF(tp);
 }
@@ -1328,7 +1351,7 @@ pysqlite_connection_call(pysqlite_Connection *self, PyObject *args,
 
     _pysqlite_drop_unused_statement_references(self);
 
-    statement = PyObject_New(pysqlite_Statement, pysqlite_StatementType);
+    statement = PyObject_GC_New(pysqlite_Statement, pysqlite_StatementType);
     if (!statement) {
         return NULL;
     }
@@ -1909,21 +1932,22 @@ static struct PyMemberDef connection_members[] =
 };
 
 static PyType_Slot connection_slots[] = {
-    {Py_tp_dealloc, pysqlite_connection_dealloc},
+    {Py_tp_dealloc, connection_dealloc},
     {Py_tp_doc, (void *)connection_doc},
     {Py_tp_methods, connection_methods},
     {Py_tp_members, connection_members},
     {Py_tp_getset, connection_getset},
-    {Py_tp_new, PyType_GenericNew},
     {Py_tp_init, pysqlite_connection_init},
     {Py_tp_call, pysqlite_connection_call},
+    {Py_tp_traverse, connection_traverse},
+    {Py_tp_clear, connection_clear},
     {0, NULL},
 };
 
 static PyType_Spec connection_spec = {
     .name = MODULE_NAME ".Connection",
     .basicsize = sizeof(pysqlite_Connection),
-    .flags = Py_TPFLAGS_DEFAULT | Py_TPFLAGS_BASETYPE,
+    .flags = Py_TPFLAGS_DEFAULT | Py_TPFLAGS_BASETYPE | Py_TPFLAGS_HAVE_GC,
     .slots = connection_slots,
 };
 

Modules/_sqlite/cursor.c

@@ -81,27 +81,46 @@ pysqlite_cursor_init_impl(pysqlite_Cursor *self,
     return 0;
 }
 
-static void pysqlite_cursor_dealloc(pysqlite_Cursor* self)
+static int
+cursor_traverse(pysqlite_Cursor *self, visitproc visit, void *arg)
 {
-    PyTypeObject *tp = Py_TYPE(self);
+    Py_VISIT(self->connection);
+    Py_VISIT(self->row_cast_map);
+    Py_VISIT(self->row_factory);
+    Py_VISIT(self->next_row);
+    Py_VISIT(Py_TYPE(self));
+    return 0;
+}
 
+static int
+cursor_clear(pysqlite_Cursor *self)
+{
     /* Reset the statement if the user has not closed the cursor */
     if (self->statement) {
         pysqlite_statement_reset(self->statement);
-        Py_DECREF(self->statement);
+        Py_CLEAR(self->statement);
     }
 
-    Py_XDECREF(self->connection);
-    Py_XDECREF(self->row_cast_map);
-    Py_XDECREF(self->description);
-    Py_XDECREF(self->lastrowid);
-    Py_XDECREF(self->row_factory);
-    Py_XDECREF(self->next_row);
+    Py_CLEAR(self->connection);
+    Py_CLEAR(self->row_cast_map);
+    Py_CLEAR(self->description);
+    Py_CLEAR(self->lastrowid);
+    Py_CLEAR(self->row_factory);
+    Py_CLEAR(self->next_row);
 
     if (self->in_weakreflist != NULL) {
         PyObject_ClearWeakRefs((PyObject*)self);
     }
 
+    return 0;
+}
+
+static void
+cursor_dealloc(PyObject *self)
+{
+    PyTypeObject *tp = Py_TYPE(self);
+    PyObject_GC_UnTrack(self);
+    tp->tp_clear(self);
     tp->tp_free(self);
     Py_DECREF(tp);
 }
@@ -487,7 +506,7 @@ _pysqlite_query_execute(pysqlite_Cursor* self, int multiple, PyObject* operation
 
     if (self->statement->in_use) {
         Py_SETREF(self->statement,
-                  PyObject_New(pysqlite_Statement, pysqlite_StatementType));
+                  PyObject_GC_New(pysqlite_Statement, pysqlite_StatementType));
         if (!self->statement) {
             goto error;
         }
@@ -1006,21 +1025,22 @@ static const char cursor_doc[] =
 PyDoc_STR("SQLite database cursor class.");
 
 static PyType_Slot cursor_slots[] = {
-    {Py_tp_dealloc, pysqlite_cursor_dealloc},
+    {Py_tp_dealloc, cursor_dealloc},
     {Py_tp_doc, (void *)cursor_doc},
     {Py_tp_iter, PyObject_SelfIter},
     {Py_tp_iternext, pysqlite_cursor_iternext},
     {Py_tp_methods, cursor_methods},
     {Py_tp_members, cursor_members},
-    {Py_tp_new, PyType_GenericNew},
     {Py_tp_init, pysqlite_cursor_init},
+    {Py_tp_traverse, cursor_traverse},
+    {Py_tp_clear, cursor_clear},
     {0, NULL},
 };
 
 static PyType_Spec cursor_spec = {
     .name = MODULE_NAME ".Cursor",
     .basicsize = sizeof(pysqlite_Cursor),
-    .flags = Py_TPFLAGS_DEFAULT | Py_TPFLAGS_BASETYPE,
+    .flags = Py_TPFLAGS_DEFAULT | Py_TPFLAGS_BASETYPE | Py_TPFLAGS_HAVE_GC,
     .slots = cursor_slots,
 };
 

Modules/_sqlite/prepare_protocol.c

@@ -30,26 +30,33 @@ pysqlite_prepare_protocol_init(pysqlite_PrepareProtocol *self, PyObject *args,
     return 0;
 }
 
+static int
+pysqlite_prepare_protocol_traverse(PyObject *self, visitproc visit, void *arg)
+{
+    Py_VISIT(Py_TYPE(self));
+    return 0;
+}
+
 static void
 pysqlite_prepare_protocol_dealloc(pysqlite_PrepareProtocol *self)
 {
     PyTypeObject *tp = Py_TYPE(self);
-
+    PyObject_GC_UnTrack(self);
     tp->tp_free(self);
     Py_DECREF(tp);
 }
 
 static PyType_Slot type_slots[] = {
     {Py_tp_dealloc, pysqlite_prepare_protocol_dealloc},
-    {Py_tp_new, PyType_GenericNew},
     {Py_tp_init, pysqlite_prepare_protocol_init},
+    {Py_tp_traverse, pysqlite_prepare_protocol_traverse},
     {0, NULL},
 };
 
 static PyType_Spec type_spec = {
     .name = MODULE_NAME ".PrepareProtocol",
     .basicsize = sizeof(pysqlite_PrepareProtocol),
-    .flags = Py_TPFLAGS_DEFAULT,
+    .flags = Py_TPFLAGS_DEFAULT | Py_TPFLAGS_HAVE_GC,
     .slots = type_slots,
 };