《Software Engineering at Google》摘抄(9)

by kevin 27. 九月 2022 13:56 >

Google’s culture, like that of a lot of software companies, is based on giving engineers wide latitude in how they do their jobs. There is a recognition that strict processes tend not to work well for a dynamic company needing to respond quickly to new technologies, and that bureaucratic rules tend not to work well with creative professionals. Code review, however, is a mandate, one of the few blanket processes in which all software engineers at Google must participate. Google requires code review for almost[^4] every code change to the codebase, no matter how small. This mandate does have a cost and effect on engineering velocity given that it does slow down the introduction of new code into a codebase and can impact time-to-production for any given code change. (Both of these are common complaints by software engineers of strict code review processes.) Why, then, do we require this process? Why do we believe that this is a long-term benefit?(谷歌的文化,就像许多软件公司的文化一样,是基于给工程师们在工作中的自由度。人们认识到,对于需要对新技术做出快速反应的充满活力的公司来说,严格的流程往往不起作用,而官僚主义的规则往往不适合创造性专业人士。然而,代码审查是一项任务,是谷歌所有软件工程师都必须参与的少数全流程之一。谷歌要求对代码库的每一次代码修改都要进行代码审查,无论多么微小。这个任务确实对工程速度有成本和影响,因为它确实减缓了将新代码引入代码库的速度,并可能影响任何特定代码更改的生产时间。(这两点是软件工程师对严格的代码审查过程的常见抱怨)。那么,为什么我们要要求这个过程?为什么我们相信这是一个长期有利的?)


  • 检查代码的正确性
  • 确保其他工程师能够理解代码更改
  • 强化整个代码库的一致性
  • 从心理上促进团队的所有权
  • 实现知识共享
  • 提供代码审查本身的历史记录

Surprisingly enough, checking for code correctness is not the primary benefit Google accrues from the process of code review. Checking for code correctness generally ensures that a change works, but more importance is attached to ensuring that a code change is understandable and makes sense over time and as the codebase itself scales. To evaluate those aspects, we need to look at factors other than whether the code is simply logically “correct” or understood.(令人惊讶的是,检查代码的正确性并不是谷歌从代码审查过程中获得的最大好处。检查代码正确性通常可以确保更改有效,但更重要的是确保代码更改是可以理解的,并且随着时间的推移和代码库本身的扩展而变得有意义。为了评估这些方面,我们需要查看除代码在逻辑上是否“正确”或理解之外的其他因素。)

Code review also has important cultural benefits: it reinforces to software engineers that code is not “theirs” but in fact part of a collective enterprise. Such psychological benefits can be subtle but are still important. Without code review, most engineers would naturally gravitate toward personal style and their own approach to software design. The code review process forces an author to not only let others have input, but to compromise for the sake of the greater good.(代码审查还有重要的文化好处:它向软件工程师强调代码不是“他们的”,而是事实上集体事业的一部分。这种心理上的好处可能很微妙,但仍然很重要。没有代码审查,大多数工程师自然会倾向于个人风格和他们自己的软件设计方法。代码审查过程迫使作者不仅要让别人提出意见,而且要为了更大的利益做出妥协。)

Part of the code review process of feedback and confirmation involves asking questions on why the change is done in a particular way. This exchange of information facilitates knowledge sharing. In fact, many code reviews involve an exchange of information both ways: the authors as well as the reviewers can learn new techniques and patterns from code review. At Google, reviewers may even directly share suggested edits with an author within the code review tool itself.(反馈和确认的代码评审过程的一部分包括询问为什么以特定方式进行更改。这种信息交流有助于知识共享。事实上,许多代码评审都涉及双向信息交换:作者和审查员都可以从代码评审中学习新的技术和模式。在谷歌,审查员甚至可以直接在代码审查工具中与作者分享建议的编辑。)

In general, reviewers should defer to authors on particular approaches and only point out alternatives if the author’s approach is deficient. If an author can demonstrate that several approaches are equally valid, the reviewer should accept the preference of the author. Even in those cases, if defects are found in an approach, consider the review a learning opportunity (for both sides!). All comments should remain strictly professional. Reviewers should be careful about jumping to conclusions based on a code author’s particular approach. It’s better to ask questions on why something was done the way it was before assuming that approach is wrong.(一般来说,审查员应该在特定的方法上听从作者的意见,只有在作者的方法有缺陷时才指出替代方法。如果作者能证明几种方法同样有效,审查员应该接受作者的偏好。即使在这些情况下,如果发现一个方法有缺陷,也要把审查看作是一个学习的机会(对双方都是如此!)。所有的评论都应该严格保持专业性。审查员应该注意不要根据代码作者的特定方法就下结论。在假设该方法是错误的之前,最好先问一下为什么要这样做。)

As much as we expect professionalism on the part of the reviewer, we expect professionalism on the part of the author as well. Remember that you are not your code, and that this change you propose is not “yours” but the team’s. After you check that piece of code into the codebase, it is no longer yours in any case. Be receptive to questions on your approach, and be prepared to explain why you did things in certain ways. Remember that part of the responsibility of an author is to make sure this code is understandable and maintainable for the future.(就像我们期望审查员有专业精神一样,我们也期望作者有专业精神。记住,你不是你的代码,你提出的这个修改不是 "你的",而是团队的。在你把这段代码检查到代码库中后,它无论如何都不再是你的了。要乐于接受关于你的方法的问题,并准备好解释你为什么以某种方式做事情。记住,作者的部分责任是确保这段代码是可以理解的,并且可以为将来维护。)

It’s important to treat each reviewer comment within a code review as a TODO item; a particular comment might not need to be accepted without question, but it should at least be addressed. If you disagree with a reviewer’s comment, let them know, and let them know why and don’t mark a comment as resolved until each side has had a chance to offer alternatives. One common way to keep such debates civil if an author doesn’t agree with a reviewer is to offer an alternative and ask the reviewer to PTAL (please take another look). Remember that code review is a learning opportunity for both the reviewer and the author. That insight often helps to mitigate any chances for disagreement.(重要的是要把代码审查中的每个审查者的评论当作一个TODO项目;一个特定的评论可能不需要被无条件接受,但它至少应该被解决。如果你不同意一个评审员的评论,让他们知道,并让他们知道为什么,在双方都有机会提供替代方案之前,不要把评论标记为已解决。如果作者不同意审查员的意见,保持这种辩论的一个常见方法是提供一个替代方案,并要求评审员PTAL(请再看看)。记住,代码审查对于审查者和作者来说都是一个学习的机会。这种洞察力往往有助于减少任何分歧的场景。)

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