Using Review Board
The Apache Software Foundation provides an instance of Review Board (RB) for projects to use in code reviews. Here is how RB can be used to support development in the context of the Apache Accumulo bylaws.
Contributors to Accumulo are encouraged to use RB for non-trivial patches and any time feedback is desired. No one is required to use RB, but its ready availability and better interface for feedback can help with reviews. Committers seeking review prior to pushing changes can also benefit similarly. It should be noted that more recently the use of GitHub has been overtaking the use of Review Board for code reviews.
Roles for Review Board
Optional Pre-Commit Review
Accumulo operates under the Commit-Then-Review (CtR) policy, so code review does not need to occur prior to commit. However, a committer may opt to hold a code review before commit for changes that, in their opinion, would benefit from additional attention. RB can be used to conduct such code reviews.
Consensus Approval after a Code Change Veto
Code changes are approved by lazy approval, with consensus approval following a veto (see the Actions section of the bylaws). RB can be used to coordinate a consensus approval vote by providing a convenient view of the code change under consideration. The vote itself must still be held on the developer mailing list.
Guidelines for Posting a Review
- It is best to post a git-generated patch as the basis for a review. RB does
not support patches containing multiple commits, so either squash commits
first, or submit a diff spanning the changeset. The
post-reviewtools generate diffs.
- Strive to make your changes small. Reviewers are less likely to want to trudge through a review with lots of changes, and are more likely to miss problems.
- Begin the summary of the review with a JIRA issue number. A review must always be associated with a JIRA issue. The issue number should also be entered in the “Bugs” field of the review, providing a link to JIRA.
- The “Branch” field should contain the name of the branch that the code change is based on (e.g., the base of your git feature branch).
- Include the “accumulo” user group as reviewers. Also include specific people as individual reviewers, even if they are in the “accumulo” group, if you deem them of primary importance for the review (e.g., you have been working out problems with the review with them, they are expert in the area).
- Use the description to summarize the change under review. Include helpful instructions to the reviewers here.
- Describe any testing done on the change. It is not expected that reviewers will do their own testing, and they may reject the review if you have not done sufficient testing yourself.
- Avoid submitting generated code for review if it can be reproduced by a reviewer.
After the review is published, set the status of the associated JIRA issue to “Patch Available” as a signal to reviewers. Also, link to the review from the issue (More -> Link -> Web Link) to help viewers of the issue find the review and assess its progress.
Guidelines for Reviewing Code
- Try to associate comments with relevant lines of code in the review.
- By default, each comment opens a review issue. If a comment pertains to something that should not block the review from completing successfully, then clear the “Open an issue” checkbox before saving your feedback. Examples that might qualify as non-issues: minor formatting/whitespace issues, spelling mistakes, general background questions.
- If a review looks good, be sure to “Ship It” by either using the “Ship It!” button or by submitting a general review with the “Ship It” checkbox checked.
Guidelines for Completing a Review
These guidelines do not apply to consensus approval votes, since the vote completion depends on the votes registered in the developer mailing list.
- Use your judgement for the number of “Ship It”s you want to receive to consider a review passed. Usually, getting one “Ship It” is enough to proceed with a commit. It is recommended that the “Ship It” be from a committer who is a neutral party not involved in the change under review.
- Use your judgement for the minimum time length you set for the review. Simple changes can be up for just a day, while complex ones should take up to seven.
- Review time should be extended in the face of problems discovered in the review. Update the review with improved code instead of discarding (i.e., closing unsuccessfully) it and beginning a new one.
- A review should not be “submitted” (i.e., closed successfully) unless there are no outstanding issues. Check with reviewers to ensure that their issues are resolved satisfactorily.
- A review should be “discarded” if the code requires major rework or it becomes obvious it should never be committed (due to design changes, becoming overcome by events, being back-burnered, etc.).
- Don’t leave a review open indefinitely. Once you have received sufficient feedback to submit or discard it, do so. If there has been no activity for some time, discard the review. A new one can always be created later.
Once you’ve closed a review as submitted, if you are unable to commit your changes yourself, attach the final version of them to the relevant JIRA issue. They should be in the form of a patch containing a single commit, per the final steps of the contribution process.