__frozendict__ hack

Author: vstinner

Include/internal/pycore_object.h

@@ -863,8 +863,7 @@ static inline Py_hash_t
 _PyObject_HashFast(PyObject *op)
 {
     if (PyUnicode_CheckExact(op)) {
-        Py_hash_t hash = FT_ATOMIC_LOAD_SSIZE_RELAXED(
-                             _PyASCIIObject_CAST(op)->hash);
+        Py_hash_t hash = PyUnstable_Unicode_GET_CACHED_HASH(op);
         if (hash != -1) {
             return hash;
         }

Lib/importlib/_bootstrap_external.py

@@ -761,6 +761,8 @@ def exec_module(self, module):
             raise ImportError(f'cannot load module {module.__name__!r} when '
                               'get_code() returns None')
         _bootstrap._call_with_frames_removed(exec, code, module.__dict__)
+        if module.__dict__.get('__frozendict__', False):
+            module.frozendict()
 
     def load_module(self, fullname):
         """This method is deprecated."""

Objects/dictobject.c

@@ -6925,6 +6925,11 @@ _PyObject_MaterializeManagedDict(PyObject *obj)
 int
 _PyDict_SetItem_LockHeld(PyDictObject *dict, PyObject *name, PyObject *value)
 {
+    if (!PyDict_Check(dict)) {
+        PyErr_BadInternalCall();
+        return -1;
+    }
+
     if (value == NULL) {
         Py_hash_t hash = _PyObject_HashFast(name);
         if (hash == -1) {

Objects/moduleobject.c

@@ -1266,9 +1266,27 @@ module_dir(PyObject *self, PyObject *args)
     return result;
 }
 
+
+static PyObject *
+module_frozendict(PyObject *self, PyObject *Py_UNUSED(args))
+{
+    PyModuleObject *mod = _PyModule_CAST(self);
+
+    PyObject *frozendict;
+    frozendict = PyObject_CallOneArg((PyObject*)&PyFrozenDict_Type, mod->md_dict);
+    if (frozendict == NULL) {
+        return NULL;
+    }
+
+    Py_SETREF(mod->md_dict, frozendict);
+
+    Py_RETURN_NONE;
+}
+
 static PyMethodDef module_methods[] = {
     {"__dir__", module_dir, METH_NOARGS,
      PyDoc_STR("__dir__() -> list\nspecialized dir() implementation")},
+    {"frozendict", module_frozendict, METH_NOARGS, NULL},
     {0}
 };
 

Objects/typeobject.c

@@ -3988,7 +3988,7 @@ subtype_dict(PyObject *obj, void *context)
 int
 _PyObject_SetDict(PyObject *obj, PyObject *value)
 {
-    if (value != NULL && !PyDict_Check(value)) {
+    if (value != NULL && !_PyAnyDict_Check(value)) {
         PyErr_Format(PyExc_TypeError,
                      "__dict__ must be set to a dictionary, "
                      "not a '%.200s'", Py_TYPE(value)->tp_name);
@@ -4891,6 +4891,37 @@ type_new_init(type_new_ctx *ctx)
 }
 
 
+static int
+type_new_frozendict(PyTypeObject *type)
+{
+    PyObject *__frozendict__;
+    if (PyDict_GetItemStringRef(type->tp_dict, "__frozendict__",
+                                &__frozendict__) < 0) {
+        return -1;
+    }
+    if (__frozendict__ == NULL) {
+        return 0;
+    }
+    int is_true = PyObject_IsTrue(__frozendict__);
+    Py_DECREF(__frozendict__);
+    if (is_true < 0) {
+        return -1;
+    }
+    if (!is_true) {
+        return 0;
+    }
+
+    PyObject *frozendict;
+    frozendict = PyObject_CallOneArg((PyObject*)&PyFrozenDict_Type, type->tp_dict);
+    if (frozendict == NULL) {
+        return -1;
+    }
+
+    Py_SETREF(type->tp_dict, frozendict);
+    return 0;
+}
+
+
 static PyObject*
 type_new_impl(type_new_ctx *ctx)
 {
@@ -4930,6 +4961,10 @@ type_new_impl(type_new_ctx *ctx)
         goto error;
     }
 
+    if (type_new_frozendict(type) < 0) {
+        goto error;
+    }
+
     assert(_PyType_CheckConsistency(type));
 #if defined(Py_GIL_DISABLED) && defined(Py_DEBUG) && SIZEOF_VOID_P > 4
     // After this point, other threads can potentally use this type.
@@ -5977,7 +6012,7 @@ find_name_in_mro(PyTypeObject *type, PyObject *name, int *error)
     for (Py_ssize_t i = 0; i < n; i++) {
         PyObject *base = PyTuple_GET_ITEM(mro, i);
         PyObject *dict = lookup_tp_dict(_PyType_CAST(base));
-        assert(dict && PyDict_Check(dict));
+        assert(dict && _PyAnyDict_Check(dict));
         if (_PyDict_GetItemRef_KnownHash((PyDictObject *)dict, name, hash, &res) < 0) {
             *error = -1;
             goto done;