gh-76785: Simplify Channels XID Types (gh-116318)

I had added an extra cleanup abstraction a while back that has turned out to be unnecessary.

Modules/_xxinterpchannelsmodule.c

@@ -93,38 +93,6 @@ API..  The module does not create any objects that are shared globally.
     PyMem_RawFree(VAR)
 
 
-struct xid_class_registry {
-    size_t count;
-#define MAX_XID_CLASSES 5
-    struct {
-        PyTypeObject *cls;
-    } added[MAX_XID_CLASSES];
-};
-
-static int
-register_xid_class(PyTypeObject *cls, crossinterpdatafunc shared,
-                   struct xid_class_registry *classes)
-{
-    int res = ensure_xid_class(cls, shared);
-    if (res == 0) {
-        assert(classes->count < MAX_XID_CLASSES);
-        // The class has refs elsewhere, so we need to incref here.
-        classes->added[classes->count].cls = cls;
-        classes->count += 1;
-    }
-    return res;
-}
-
-static void
-clear_xid_class_registry(struct xid_class_registry *classes)
-{
-    while (classes->count > 0) {
-        classes->count -= 1;
-        PyTypeObject *cls = classes->added[classes->count].cls;
-        _PyCrossInterpreterData_UnregisterClass(cls);
-    }
-}
-
 #define XID_IGNORE_EXC 1
 #define XID_FREE 2
 
@@ -223,28 +191,6 @@ add_new_exception(PyObject *mod, const char *name, PyObject *base)
 #define ADD_NEW_EXCEPTION(MOD, NAME, BASE) \
     add_new_exception(MOD, MODULE_NAME_STR "." Py_STRINGIFY(NAME), BASE)
 
-static PyTypeObject *
-add_new_type(PyObject *mod, PyType_Spec *spec, crossinterpdatafunc shared,
-             struct xid_class_registry *classes)
-{
-    PyTypeObject *cls = (PyTypeObject *)PyType_FromModuleAndSpec(
-                mod, spec, NULL);
-    if (cls == NULL) {
-        return NULL;
-    }
-    if (PyModule_AddType(mod, cls) < 0) {
-        Py_DECREF(cls);
-        return NULL;
-    }
-    if (shared != NULL) {
-        if (register_xid_class(cls, shared, classes)) {
-            Py_DECREF(cls);
-            return NULL;
-        }
-    }
-    return cls;
-}
-
 static int
 wait_for_lock(PyThread_type_lock mutex, PY_TIMEOUT_T timeout)
 {
@@ -269,8 +215,6 @@ wait_for_lock(PyThread_type_lock mutex, PY_TIMEOUT_T timeout)
 /* module state *************************************************************/
 
 typedef struct {
-    struct xid_class_registry xid_classes;
-
     /* Added at runtime by interpreters module. */
     PyTypeObject *send_channel_type;
     PyTypeObject *recv_channel_type;
@@ -332,19 +276,33 @@ traverse_module_state(module_state *state, visitproc visit, void *arg)
     return 0;
 }
 
+static void
+clear_xid_types(module_state *state)
+{
+    /* external types */
+    if (state->send_channel_type != NULL) {
+        (void)_PyCrossInterpreterData_UnregisterClass(state->send_channel_type);
+        Py_CLEAR(state->send_channel_type);
+    }
+    if (state->recv_channel_type != NULL) {
+        (void)_PyCrossInterpreterData_UnregisterClass(state->recv_channel_type);
+        Py_CLEAR(state->recv_channel_type);
+    }
+
+    /* heap types */
+    if (state->ChannelIDType != NULL) {
+        (void)_PyCrossInterpreterData_UnregisterClass(state->ChannelIDType);
+        Py_CLEAR(state->ChannelIDType);
+    }
+}
+
 static int
 clear_module_state(module_state *state)
 {
-    /* external types */
+    clear_xid_types(state);
-    Py_CLEAR(state->send_channel_type);
-    Py_CLEAR(state->recv_channel_type);
 
     /* heap types */
     Py_CLEAR(state->ChannelInfoType);
-    if (state->ChannelIDType != NULL) {
-        (void)_PyCrossInterpreterData_UnregisterClass(state->ChannelIDType);
-    }
-    Py_CLEAR(state->ChannelIDType);
 
     /* exceptions */
     Py_CLEAR(state->ChannelError);
@@ -2614,6 +2572,25 @@ static PyType_Spec channelid_typespec = {
     .slots = channelid_typeslots,
 };
 
+static PyTypeObject *
+add_channelid_type(PyObject *mod)
+{
+    PyTypeObject *cls = (PyTypeObject *)PyType_FromModuleAndSpec(
+                mod, &channelid_typespec, NULL);
+    if (cls == NULL) {
+        return NULL;
+    }
+    if (PyModule_AddType(mod, cls) < 0) {
+        Py_DECREF(cls);
+        return NULL;
+    }
+    if (ensure_xid_class(cls, _channelid_shared) < 0) {
+        Py_DECREF(cls);
+        return NULL;
+    }
+    return cls;
+}
+
 
 /* SendChannel and RecvChannel classes */
 
@@ -2697,7 +2674,6 @@ set_channelend_types(PyObject *mod, PyTypeObject *send, PyTypeObject *recv)
     if (state == NULL) {
         return -1;
     }
-    struct xid_class_registry *xid_classes = &state->xid_classes;
 
     if (state->send_channel_type != NULL
         || state->recv_channel_type != NULL)
@@ -2707,11 +2683,15 @@ set_channelend_types(PyObject *mod, PyTypeObject *send, PyTypeObject *recv)
     }
     state->send_channel_type = (PyTypeObject *)Py_NewRef(send);
     state->recv_channel_type = (PyTypeObject *)Py_NewRef(recv);
-
+    if (ensure_xid_class(send, _channelend_shared) < 0) {
-    if (register_xid_class(send, _channelend_shared, xid_classes)) {
+        Py_CLEAR(state->send_channel_type);
+        Py_CLEAR(state->recv_channel_type);
         return -1;
     }
-    if (register_xid_class(recv, _channelend_shared, xid_classes)) {
+    if (ensure_xid_class(recv, _channelend_shared) < 0) {
+        (void)_PyCrossInterpreterData_UnregisterClass(state->send_channel_type);
+        Py_CLEAR(state->send_channel_type);
+        Py_CLEAR(state->recv_channel_type);
         return -1;
     }
 
@@ -3294,13 +3274,11 @@ module_exec(PyObject *mod)
     if (_globals_init() != 0) {
         return -1;
     }
-    struct xid_class_registry *xid_classes = NULL;
 
     module_state *state = get_module_state(mod);
     if (state == NULL) {
         goto error;
     }
-    xid_classes = &state->xid_classes;
 
     /* Add exception types */
     if (exceptions_init(mod) != 0) {
@@ -3319,8 +3297,7 @@ module_exec(PyObject *mod)
     }
 
     // ChannelID
-    state->ChannelIDType = add_new_type(
+    state->ChannelIDType = add_channelid_type(mod);
-            mod, &channelid_typespec, _channelid_shared, xid_classes);
     if (state->ChannelIDType == NULL) {
         goto error;
     }
@@ -3332,8 +3309,8 @@ module_exec(PyObject *mod)
     return 0;
 
 error:
-    if (xid_classes != NULL) {
+    if (state != NULL) {
-        clear_xid_class_registry(xid_classes);
+        clear_xid_types(state);
     }
     _globals_fini();
     return -1;
@@ -3360,9 +3337,6 @@ module_clear(PyObject *mod)
     module_state *state = get_module_state(mod);
     assert(state != NULL);
 
-    // Before clearing anything, we unregister the various XID types. */
-    clear_xid_class_registry(&state->xid_classes);
-
     // Now we clear the module state.
     clear_module_state(state);
     return 0;
@@ -3374,9 +3348,6 @@ module_free(void *mod)
     module_state *state = get_module_state(mod);
     assert(state != NULL);
 
-    // Before clearing anything, we unregister the various XID types. */
-    clear_xid_class_registry(&state->xid_classes);
-
     // Now we clear the module state.
     clear_module_state(state);