A hands-on openstack code refactoring experience report

Abstract

Nowadays, almost everyone uses some kind of cloud infrastructure. As clouds gaining more and more attention, it is now even more important to have stable and reliable cloud systems. Along with stability and reliability comes source code maintainability. Unfortunately, maintainability has no exact definition, there are several definitions both from users’ and developers’ perspective. In this paper, we analyzed two projects of OpenStack, the world’s leading open-source cloud system, using QualityGate, a static software analyzer which can help to determine the maintainability of software. During the analysis we found quality issues that could be fixed by refactoring the code. We have created 47 patches in this two OpenStack projects. We have also analyzed our patches with QualityGate to see whether they increase the maintainability of the system. We found that a single refactoring has a barely noticeable effect on the maintainability of the software, what is more, it can even decrease maintainability. But if we do refactorings regularly, their cumulative effect will probably increase the quality in the mid and long-term. We also experienced that our refactoring commits were very appreciated by the open-source community.