fix ref bug with iter, views and istr

CHANGES/1311.bugfix.rst

@@ -0,0 +1,2 @@
+Fixed reference leak in iterators, views and ``istr``
+-- by :user:`Vizonex`.

multidict/_multilib/istr.h

@@ -22,8 +22,11 @@ PyDoc_STRVAR(istr__doc__, "istr class implementation");
 static inline void
 istr_dealloc(istrobject *self)
 {
+    PyTypeObject *tp = Py_TYPE(self);
     Py_XDECREF(self->canonical);
-    PyUnicode_Type.tp_dealloc((PyObject *)self);
+    PyUnicode_Type.tp_dealloc((PyObject *)(&self->str));
+    /* Clear it because sometimes this might appear NULL */
+    Py_CLEAR(tp);
 }
 
 static inline PyObject *

multidict/_multilib/iter.h

@@ -134,9 +134,11 @@ multidict_keys_iter_iternext(MultidictIter *self)
 static inline void
 multidict_iter_dealloc(MultidictIter *self)
 {
+    PyTypeObject *tp = Py_TYPE(self);
     PyObject_GC_UnTrack(self);
     Py_XDECREF(self->md);
-    PyObject_GC_Del(self);
+    tp->tp_free(self);
+    Py_DECREF(tp);
 }
 
 static inline int
@@ -221,6 +223,7 @@ static PyType_Slot multidict_keys_iter_slots[] = {
     {Py_tp_clear, multidict_iter_clear},
     {Py_tp_iter, PyObject_SelfIter},
     {Py_tp_iternext, multidict_keys_iter_iternext},
+    {Py_tp_free, PyObject_GC_Del},
     {0, NULL},
 };
 

multidict/_multilib/views.h

@@ -30,9 +30,11 @@ _init_view(_Multidict_ViewObject *self, MultiDictObject *md)
 static inline void
 multidict_view_dealloc(_Multidict_ViewObject *self)
 {
+    PyTypeObject *tp = Py_TYPE(self);
     PyObject_GC_UnTrack(self);
     Py_XDECREF(self->md);
-    PyObject_GC_Del(self);
+    tp->tp_free(self);
+    Py_DECREF(tp);
 }
 
 static inline int
@@ -1678,6 +1680,7 @@ static PyType_Slot multidict_valuesview_slots[] = {
     {Py_tp_traverse, multidict_view_traverse},
     {Py_tp_clear, multidict_view_clear},
     {Py_tp_iter, multidict_valuesview_iter},
+    {Py_tp_free, PyObject_GC_Del},
     {0, NULL},
 };
 

tests/isolated/multidict_type_leak.py

@@ -0,0 +1,35 @@
+from multidict import MultiDict, istr
+import sys
+
+md = MultiDict([("a", "1"), ("b", "2")])
+
+if __name__ == "__main__":
+    # XXX: Code Coverage misbehaves so do this instead
+    it = iter(md.keys())
+    iter_type = type(it)
+    del it
+    baseline = sys.getrefcount(iter_type)
+    for _ in range(1000):
+        it = iter(md.keys())
+        list(it)
+        del it
+    after = sys.getrefcount(iter_type)
+
+    # NOTE: On Freethreaded Mode this value can be negative
+    assert (after - baseline) <= 0, "iterator type leaked"
+
+    # Test view type leak
+    view_type = type(md.keys())
+    baseline = sys.getrefcount(view_type)
+    for _ in range(1000):
+        v = md.keys()
+        del v
+    after = sys.getrefcount(view_type)
+    assert (after - baseline) <= 0, "view type leaked"
+
+    baseline = sys.getrefcount(istr)
+    for _ in range(1000):
+        s = istr("hello")
+        del s
+    after = sys.getrefcount(istr)
+    assert (after - baseline) <= 0, "istr type leaked"

tests/test_leaks.py

@@ -15,6 +15,7 @@
         "multidict_extend_multidict.py",
         "multidict_extend_tuple.py",
         "multidict_update_multidict.py",
+        "multidict_type_leak.py",
         "multidict_pop.py",
     ),
 )