Minimise diff

Author: matthiasgoergens

Modules/_collectionsmodule.c

@@ -2118,7 +2118,7 @@ dequereviter_next(PyObject *self)
 static PyObject *
 dequereviter_new(PyTypeObject *type, PyObject *args, PyObject *kwds)
 {
-    Py_ssize_t i, index = 0;
+    Py_ssize_t i, index=0;
     PyObject *deque;
     dequeiterobject *it;
     collections_state *state = get_module_state_by_cls(type);
@@ -2130,18 +2130,24 @@ dequereviter_new(PyTypeObject *type, PyObject *args, PyObject *kwds)
     if (!it)
         return NULL;
     /* consume items from the queue */
-    for (i=0; i < index; i++) {
+    for(i=0; i<index; i++) {
         PyObject *item = dequereviter_next((PyObject *)it);
-        if (item == NULL) {
-            if (PyErr_Occurred()) {
+        if (item) {
+            Py_DECREF(item);
+        } else {
+            /*
+             * It's safe to read directly from it without acquiring the
+             * per-object lock; the iterator isn't visible to any other threads
+             * yet.
+             */
+            if (it->counter) {
                 Py_DECREF(it);
                 return NULL;
-            }
-            break;
+            } else
+                break;
         }
-        Py_DECREF(item);
     }
-    return (PyObject *)it;
+    return (PyObject*)it;
 }
 
 static PyType_Slot dequereviter_slots[] = {