Fix for CONPY-119: Fixed memory leak

When creating a cursor with result set type named_tuple
or dictionary, references were not decremented correctly.

For named tuples we don't use a static variable anymore, instead
of it will be created by PyStructSequence_NewType.

include/mariadb_python.h

@@ -307,7 +307,6 @@ extern PyObject *Mariadb_ProgrammingError;
 extern PyObject *Mariadb_NotSupportedError;
 extern PyObject *Mariadb_Warning;
 
-extern PyObject *Mrdb_Pickle;
 extern PyObject *decimal_module,
                 *decimal_type;
 

mariadb/mariadb.c

@@ -26,7 +26,6 @@
 
 extern int codecs_datetime_init(void);
 
-PyObject *Mrdb_Pickle= NULL;
 PyObject *cnx_pool= NULL;
 PyObject *decimal_module= NULL,
          *decimal_type= NULL;
@@ -165,9 +164,6 @@ PyMODINIT_FUNC PyInit__mariadb(void)
         goto error;
     }
 
-    /* we need pickle for object serialization */
-    Mrdb_Pickle= PyImport_ImportModule("pickle");
-
     Py_TYPE(&MrdbCursor_Type) = &PyType_Type;
     if (PyType_Ready(&MrdbCursor_Type) == -1)
     {

mariadb/mariadb_cursor.c

@@ -438,7 +438,11 @@ void MrdbCursor_clear(MrdbCursor *self, uint8_t new_stmt)
     }
     self->fetched= 0;
 
-    MARIADB_FREE_MEM(self->sequence_fields);
+    if (self->sequence_fields)
+    {
+        MARIADB_FREE_MEM(self->sequence_fields);
+        Py_DECREF((PyObject *)self->sequence_type);
+    }
     self->fields= NULL;
     self->row_count= 0;
     self->affected_rows= 0;
@@ -459,6 +463,7 @@ static void ma_set_result_column_value(MrdbCursor *self, PyObject *row, uint32_t
             break;
         case RESULT_DICTIONARY:
             PyDict_SetItemString(row, self->fields[column].name, self->values[column]); 
+            Py_DECREF(self->values[column]); /* CONPY-119 */
             break;
         default:
             PyTuple_SET_ITEM(row, column, (self)->values[column]);
@@ -561,8 +566,7 @@ static int Mrdb_GetFieldInfo(MrdbCursor *self)
             {
                 self->sequence_fields[i].name= self->fields[i].name;
             }
-            self->sequence_type= PyMem_RawCalloc(1,sizeof(PyTypeObject));
-            PyStructSequence_InitType(self->sequence_type, &self->sequence_desc);
+            self->sequence_type= PyStructSequence_NewType(&self->sequence_desc);
         }
     }
     return 0;