When contributing code
to Chromium, the last step in the life of a change list is committing it, after which it's closed.
The preferred way of committing changes is via the commit queue
However, in certain circumstances it is acceptable or necessary to directly commit your change, bypassing the commit queue. This is discouraged however, due to not running the tests (hence higher risk of breakage), and requires more supervision on the part of the committer.
Generally directly committing should only be done if the CQ itself is broken, or the CL cannot be processed by the CQ.
If you wish to skip the tree status checks, but otherwise use the CQ, you can use
NOTREECHECKS=true in the Rietveld issue description, though this is obviously strongly discouraged. The primary use case is if the tree is closed due to some breakage, and you wish to commit a change that will fix the breakage.
NOTREECHECKS are flags for the CQ: you still commit by clicking the "Commit" box.
In a nutshell:
- Have the change reviewed per usual process contributing code, with an issue and description on Rietveld, and sufficient LGTMs or TBRs (since presubmit OWNERS approval test isn't run when directly committing).
- Run tests manually, both locally and using the try server for other platforms, to reduce risk of breakage (since try jobs aren't run when directly committing). Try jobs can be run individually via Rietveld, while the standard set can be run from the command line via
- Join the #chromium IRC channel, so that sheriffs can notify you of possible breakages.
- Check that the tree is open (green): Chromium Tree Status :: Blink Tree Status
- Double-check that the tree is open.
- Commit as per below, preferably using
- See if there are any immediate messages on IRC.
- Stay on IRC for an hour or so in case anything happen afterwards.
In case of emergencies, please remember to at least:
- Create a Rietveld issue for description and reference.
- List OWNERS in
TBR (assuming no time for review).
- Join IRC, explain what's happening, and make sure there are no immediate objections.
If the most recent set of changes to the repository breaks the build, we say the tree is red, or closed. You cannot check in your changes until it is green again. You can check the status via apps at Chromium Tree Status
or Blink Tree Status
. More low-level, you can check the BuildBot waterfalls (Chromium
| Chromium OS
) to see that the columns are mostly green before checking in your changes. Otherwise, you will not know if your changes break the build or not.
Good reasons to directly commit code:
Marginal reasons to directly commit code:
- You are reverting at previous change that broke the build (so the tree is closed) and the CQ is down – if the CQ is up, please use
- The change can't be processed by the commit queue (see Build-CommitQueue bugs), such as changing file permissions (Issue 162196).
- A presubmit script is failing.
- If the failure is a false positive, if at all possible, please fix the script instead.
- The change is very big (e.g., large-scale formatting changes or renaming), so by the time it's finished uploading to Rietveld the patch is out of date and won't apply when the CQ tries it.
- If at all possible, try breaking up the patch and landing normally. Even innocuous-looking changes can cause breakages.
Bad reasons to directly commit code:
- The commit queue is too slow (unless the slowness means the change is out of date by the time it is processed) – please be patient.
- The commit queue is down or stalled – please be patient.
- The tree is closed but you want to commit it anyway – please wait for tree to reopen, or use
NOTREECHECKS=true if the CL needs to be committed while the tree is closed.
git cl land (for git repos)
This command commits the current changelist via git directly. You should use this command if you are in a real git repo, such as the chromium repo. You can pass --bypass-hooks if something is wrong with the presubmit hooks or they are blocking an emergency submit.
Committing a patch for a non-committer
- git cl patch <code review issue number>
- This command will download the patch from the code review website, apply the patch, and set the issue number.
- If you work on chrome:
- git cl try # and wait for green bots
- git cl land -c 'Joe Noncommiter <email@example.com>'
- If you work on chromeos:
- git commit --amend -s --author="$AUTHOR_NAME <$AUTHOR_EMAIL>"
- git cl push -c
- You're done!