Allow self-referential members in default pickling.

Cython/Compiler/ParseTreeTransforms.py

@@ -1639,8 +1639,10 @@ if VALUE is not None:
 
             pickle_func = TreeFragment(u"""
                 def __reduce_cython__(self):
-                    raise TypeError("%s")
-                """ % msg,
+                    raise TypeError("%(msg)s")
+                def __setstate_cython__(self, __pyx_state):
+                    raise TypeError("%(msg)s")
+                """ % {'msg': msg},
                 level='c_class', pipeline=[NormalizeTree(None)]).substitute({})
             pickle_func.analyse_declarations(node.scope)
             self.visit(pickle_func)
@@ -1658,28 +1660,28 @@ if VALUE is not None:
             # TODO(robertwb): Move the state into the third argument
             # so it can be pickled *after* self is memoized.
             unpickle_func = TreeFragment(u"""
-                def %(unpickle_func_name)s(__pyx_type, long __pyx_checksum, __pyx_state, %(args)s):
+                def %(unpickle_func_name)s(__pyx_type, long __pyx_checksum, __pyx_state):
                     if __pyx_checksum != %(checksum)s:
                         from pickle import PickleError
                         raise PickleError("Incompatible checksums (%%s vs %(checksum)s = (%(members)s))" %% __pyx_checksum)
-                    cdef %(class_name)s result
                     result = %(class_name)s.__new__(__pyx_type)
-                    %(assignments)s
-                    if hasattr(result, '__setstate__'):
-                        result.__setstate__(__pyx_state)
-                    elif hasattr(result, '__dict__'):
-                        result.__dict__.update(__pyx_state)
-                    elif __pyx_state is not None:
-                        from pickle import PickleError
-                        raise PickleError("Unexpected state: %%s" %% __pyx_state)
+                    if __pyx_state is not None:
+                        %(unpickle_func_name)s__set_state(<%(class_name)s> result, __pyx_state)
                     return result
+
+                cdef %(unpickle_func_name)s__set_state(%(class_name)s result, tuple __pyx_state):
+                    %(assignments)s
+                    if hasattr(result, '__dict__'):
+                        result.__dict__.update(__pyx_state[%(num_members)s])
                 """ % {
                     'unpickle_func_name': unpickle_func_name,
                     'checksum': checksum,
                     'members': ', '.join(all_members_names),
                     'class_name': node.class_name,
-                    'assignments': '; '.join('result.%s = __pyx_arg_%s' % (v, v) for v in all_members_names),
-                    'args': ','.join('__pyx_arg_%s' % v for v in all_members_names),
+                    'assignments': '; '.join(
+                        'result.%s = __pyx_state[%s]' % (v, ix)
+                        for ix, v in enumerate(all_members_names)),
+                    'num_members': len(all_members_names),
                 }, level='module', pipeline=[NormalizeTree(None)]).substitute({})
             unpickle_func.analyse_declarations(node.entry.scope)
             self.visit(unpickle_func)
@@ -1687,14 +1689,28 @@ if VALUE is not None:
 
             pickle_func = TreeFragment(u"""
                 def __reduce_cython__(self):
-                    if hasattr(self, '__getstate__'):
-                        state = self.__getstate__()
-                    elif hasattr(self, '__dict__'):
-                        state = self.__dict__
+                    cdef bint use_setstate
+                    state = (%(members)s)
+                    _dict = getattr(self, '__dict__', None)
+                    if _dict is not None:
+                        state += _dict,
+                        use_setstate = True
                     else:
-                        state = None
-                    return %s, (type(self), %s, state, %s)
-                """ % (unpickle_func_name, checksum, ', '.join('self.%s' % v for v in all_members_names)),
+                        use_setstate = %(any_notnone_members)s
+                    if use_setstate:
+                        return %(unpickle_func_name)s, (type(self), %(checksum)s, None), state
+                    else:
+                        return %(unpickle_func_name)s, (type(self), %(checksum)s, state)
+
+                def __setstate_cython__(self, __pyx_state):
+                    %(unpickle_func_name)s__set_state(self, __pyx_state)
+                """ % {
+                    'unpickle_func_name': unpickle_func_name,
+                    'checksum': checksum,
+                    'members': ', '.join('self.%s' % v for v in all_members_names) + (',' if len(all_members_names) == 1 else ''),
+                    # Even better, we could check PyType_IS_GC.
+                    'any_notnone_members' : ' or '.join(['self.%s is not None' % e.name for e in all_members if e.type.is_pyobject] or ['False']),
+                },
                 level='c_class', pipeline=[NormalizeTree(None)]).substitute({})
             pickle_func.analyse_declarations(node.scope)
             self.visit(pickle_func)

Cython/Utility/ExtensionTypes.c

@@ -68,6 +68,8 @@ static int __Pyx_setup_reduce(PyObject* type_obj) {
     PyObject *reduce = NULL;
     PyObject *reduce_ex = NULL;
     PyObject *reduce_cython = NULL;
+    PyObject *setstate = NULL;
+    PyObject *setstate_cython = NULL;
 
     if (PyObject_HasAttrString(type_obj, "__getstate__")) goto GOOD;
 
@@ -80,23 +82,36 @@ static int __Pyx_setup_reduce(PyObject* type_obj) {
     __Pyx_setup_reduce_GET_ATTR_OR_BAD(reduce_ex, type_obj, "__reduce_ex__");
     if (reduce_ex == object_reduce_ex) {
         __Pyx_setup_reduce_GET_ATTR_OR_BAD(reduce, type_obj, "__reduce__");
-        __Pyx_setup_reduce_GET_ATTR_OR_BAD(reduce_cython, type_obj, "__reduce_cython__");
         if (object_reduce == reduce
             || (strcmp(reduce->ob_type->tp_name, "method_descriptor") == 0
                 && strcmp(((PyMethodDescrObject*)reduce)->d_method->ml_name, "__reduce_cython__") == 0)) {
+            __Pyx_setup_reduce_GET_ATTR_OR_BAD(reduce_cython, type_obj, "__reduce_cython__");
             ret = PyDict_SetItemString(((PyTypeObject*)type_obj)->tp_dict, "__reduce__", reduce_cython); if (ret < 0) goto BAD;
-            ret = PyDict_DelItemString(((PyTypeObject*)type_obj)->tp_dict, "__reduce_cython__");
+            ret = PyDict_DelItemString(((PyTypeObject*)type_obj)->tp_dict, "__reduce_cython__"); if (ret < 0) goto BAD;
+
+            setstate = PyObject_GetAttrString(type_obj, "__setstate__");
+            if (!setstate) PyErr_Clear();
+            if (!setstate
+                || (strcmp(setstate->ob_type->tp_name, "method_descriptor") == 0
+                    && strcmp(((PyMethodDescrObject*)setstate)->d_method->ml_name, "__setstate_cython__") == 0)) {
+            __Pyx_setup_reduce_GET_ATTR_OR_BAD(setstate_cython, type_obj, "__setstate_cython__");
+                ret = PyDict_SetItemString(((PyTypeObject*)type_obj)->tp_dict, "__setstate__", setstate_cython); if (ret < 0) goto BAD;
+                ret = PyDict_DelItemString(((PyTypeObject*)type_obj)->tp_dict, "__setstate_cython__"); if (ret < 0) goto BAD;
+            }
             PyType_Modified((PyTypeObject*)type_obj);
         }
     }
     goto GOOD;
 
 BAD:
+    if (!PyErr_Occurred()) PyErr_Format(PyExc_RuntimeError, "Unable to initialize pickling for %s", ((PyTypeObject*)type_obj)->tp_name);
     ret = -1;
 GOOD:
     Py_XDECREF(builtin_object);
     Py_XDECREF(reduce);
     Py_XDECREF(reduce_ex);
     Py_XDECREF(reduce_cython);
+    Py_XDECREF(setstate);
+    Py_XDECREF(setstate_cython);
     return ret;
 }

tests/run/reduce_pickle.pyx

@@ -80,6 +80,8 @@ cdef class DefaultReduce(object):
     >>> import pickle
     >>> pickle.loads(pickle.dumps(a))
     DefaultReduce(i=11, s='abc')
+    >>> pickle.loads(pickle.dumps(DefaultReduce(i=11, s=None)))
+    DefaultReduce(i=11, s=None)
     """
 
     cdef readonly int i
@@ -119,6 +121,11 @@ class DefaultReducePySubclass(DefaultReduce):
     >>> import pickle
     >>> pickle.loads(pickle.dumps(a))
     DefaultReducePySubclass(i=11, s='abc', x=1.5)
+
+    >>> a.self_reference = a
+    >>> a2 = pickle.loads(pickle.dumps(a))
+    >>> a2.self_reference is a2
+    True
     """
     def __init__(self, **kwargs):
         self.x = kwargs.pop('x', 0)
@@ -148,3 +155,91 @@ cdef class NoReduceDueToNontrivialCInit(object):
     """
     def __cinit__(self, arg):
         pass
+
+
+cdef class NoMembers(object):
+    """
+    >>> import pickle
+    >>> pickle.loads(pickle.dumps(NoMembers()))
+    NoMembers()
+    """
+    def __repr__(self):
+        return "NoMembers()"
+
+
+cdef struct MyStruct:
+    int i
+    double x
+
+cdef class NoPyMembers(object):
+    """
+    >>> import pickle
+    >>> pickle.loads(pickle.dumps(NoPyMembers(2, 1.75)))
+    NoPyMembers(ii=[2, 4, 8], x=1.75, my_struct=(3, 2.75))
+    """
+    cdef int[3] ii
+    cdef double x
+    cdef MyStruct my_struct
+
+    def __init__(self, i, x):
+        self.ii[0] = i
+        self.ii[1] = i * i
+        self.ii[2] = i * i * i
+        self.x = x
+        self.my_struct = MyStruct(i+1, x+1)
+
+    def __repr__(self):
+        return "NoPyMembers(ii=%s, x=%s, my_struct=(%s, %s))" % (
+            self.ii, self.x, self.my_struct.i, self.my_struct.x)
+
+class NoPyMembersPySubclass(NoPyMembers):
+    """
+    >>> import pickle
+    >>> pickle.loads(pickle.dumps(NoPyMembersPySubclass(2, 1.75, 'xyz')))
+    NoPyMembersPySubclass(ii=[2, 4, 8], x=1.75, my_struct=(3, 2.75), s='xyz')
+    """
+    def __init__(self, i, x, s):
+        super(NoPyMembersPySubclass, self).__init__(i, x)
+        self.s = s
+    def __repr__(self):
+        return super(NoPyMembersPySubclass, self).__repr__().replace(
+            'NoPyMembers', 'NoPyMembersPySubclass')[:-1] + ', s=%r)' % self.s
+
+
+cdef _unset = object()
+
+# Test cyclic references.
+cdef class Wrapper(object):
+  """
+  >>> import pickle
+  >>> w = Wrapper(); w
+  Wrapper(...)
+  >>> w2 = pickle.loads(pickle.dumps(w)); w2
+  Wrapper(...)
+  >>> w2.ref is w2
+  True
+
+  >>> pickle.loads(pickle.dumps(Wrapper(DefaultReduce(1, 'xyz'))))
+  Wrapper(DefaultReduce(i=1, s='xyz'))
+  >>> L = [None]
+  >>> L[0] = L
+  >>> w = Wrapper(L)
+  >>> pickle.loads(pickle.dumps(Wrapper(L)))
+  Wrapper([[...]])
+
+  >>> L[0] = w   # Don't print this one out...
+  >>> w2 = pickle.loads(pickle.dumps(w))
+  >>> w2.ref[0] is w2
+  True
+  """
+  cdef public object ref
+  def __init__(self, ref=_unset):
+      if ref is _unset:
+          self.ref = self
+      else:
+          self.ref = ref
+  def __repr__(self):
+      if self.ref is self:
+          return "Wrapper(...)"
+      else:
+          return "Wrapper(%r)" % self.ref