How Amazon CodeGuru Reviewer helps Gridium maintain a high quality codebase

Gridium creates software that lets people run commercial buildings at a lower cost and with less energy. Currently, half of the world lives in cities. Soon, nearly 70% will, while buildings utilize 40% of the world’s electricity. In the U.S. alone, commercial real estate value tops one trillion dollars. Furthermore, much of this asset class is still run with spreadsheets, clipboards, and outdated software. Gridium’s software platform collects large amounts of operational data from commercial buildings like offices, medical providers, and corporate campuses. Then, our analytics identifies energy savings opportunities that we work with customers to actualize.

Gridium’s Challenge

Data streams from utility companies across the U.S. are an essential input for Gridium’s analytics. This data is processed and visualized so that our customers can garner new insights and drive smarter decisions. In order to integrate a new data source into our platform, we often utilize third-party contractors to write tools that ingest data feeds and prepare them for analysis.

Our team firmly emphasizes our codebase quality. We strive for our code to be stylistically consistent, easily testable, swiftly understood, and well-documented. We write code internally by using agreed-upon standards. This makes it easy for us to review and edit internal code using standard collaboration tools.

We work to ensure that code arriving from contractors meets similar standards, but enforcing external code quality can be difficult. Contractor-developed code will be written in the style of each contractor. Furthermore, reviewing and editing code written by contractors introduces new challenges beyond those of working with internal code. We have used tools like PyLint to help stylistically align code, but we wanted a method for uncovering more complex issues without burdening the team and undermining the benefits of outside contractors.

Adopting Amazon CodeGuru Reviewer

We began evaluating Amazon CodeGuru Reviewer in order to provide an additional review layer for code developed by contractors, and to find complex corrections within code that traditional tools might not catch.

Initially, we enabled the service only on external repositories and generated reviews on pull requests. CodeGuru immediately provided us with actionable recommendations for maintaining Gridium’s codebase quality.

The example above demonstrates a useful recurring recommendation related to exception-handling. Strictly speaking, there is nothing wrong with utilizing a general Exception class whenever needed. However, utilizing general Exception classes in production can complicate error-handling functions and generate ambiguity when trying to debug or understand code.

After a few weeks of utilizing CodeGuru Reviewer and witnessing its benefits, we determined that we wanted to use it for our entire codebase. Moreover, CodeGuru provided us with meaningful recommendations on our internal repositories.

This example once again showcases CodeGuru’s ability to highlight subtle issues that aren’t necessarily bugs. Without diving through related libraries and functions, it would be difficult to find any optimizable areas, but CodeGuru found that this function could become problematic due to its dependency on twenty other functions. If any of the dependencies is updated, then it could break the entire function, thereby making debugging the root cause difficult.

The explanations following each code recommendation were essential in our quick adoption of CodeGuru. Simply showing what code to change would make it tough to follow through with a code correction. CodeGuru provided ample context, reasoning, and even metrics in some cases to explain and justify a correction.

Conclusion

Our development team thoroughly appreciates the extra review layer that CodeGuru provides. CodeGuru indicates areas that internal review might otherwise miss, especially in code written by external contractors.

In some cases, CodeGuru highlighted issues never before considered by the team. Examples of these issues include highly coupled functions, ambiguous exceptions, and outdated API calls. Each suggestion is accompanied with its context and reasoning so that our developers can independently judge if an edit should be made. Furthermore, CodeGuru was easily set up with our GitHub repositories. We enabled it within minutes through the console.

After familiarizing ourselves with the CodeGuru workflow, Gridium treats CodeGuru recommendations like suggestions that an internal reviewer would make. Both internal developers and third parties act on recommendations in order to improve code health and quality. Any CodeGuru suggestions not accepted by contractors are verified and implemented by an internal reviewer if necessary.

Over the twelve weeks that we have been utilizing Amazon CodeGuru, we have had 281 automated pull request reviews. These provided 104 recommendations resulting in fifty code corrections that we may not have made otherwise. Our monthly bill for CodeGuru usage is about $10.00. If we make only a single correction to our code over a whole month that we would have missed otherwise, then we can safely say that it was well worth the price!

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