Finding somebody who knows how a piece of code works

It can be more efficient to ask somebody how something works than to take weeks to figure it out yourself. Likewise, when making changes, you will need to reach out to someone for review of your code or your designs. So how do you find the best folks to reach out to? Here are some ideas to get you started.

1. Ask your teammates - those who have been on the project longer than you will have a better idea or may have contacts in other areas.
2. Look at theOWNERS files - If you can identify a source file involved in what you want to do, find the lowest levelOWNERS file above it, and email those people. The code review tool can automatedly find relevant owners for your changes, largely based onOWNERS files.
3. Look at theDIR_METADATA file - similar toOWNERS,DIR_METADATA files contain pointers to relevant experts. Look for theteam_email field.
4. Tools -git blame (also available onChromium code search) andChromite Butler can help you find who touched the code last or most extensively. Sometimes not just theauthor butreviewers of a past change will be relevant.
5. Use the Slack channel (link) - while not everybody is listening all the time, you may get a pointer to the right folks to talk to.
6. Use thechromium-dev@chromium.org email alias to ask questions. This is a fairly large email list, so use your judgment about what to post, and it may take awhile to get a reply. If you do this, it helps to ask one crisp question at the top of your mail and then explain in detail instead of rambling and asking many questions.

Sometimes, there isn't one person who knows what you want to find out, but you can find people who know parts of the system. For instance, no one person knows everything about how Chromium starts up or shuts down and can tell you what you did wrong in a shutdown scenario, but you can find people who know some parts of the shutdown to guide you.