Sheriffing/How To/Unified Repos
Contents
Unified Repos
- http://mozilla-version-control-tools.readthedocs.org/en/latest/hgmozilla/unifiedrepo.html
- https://mozilla-version-control-tools.readthedocs.org/en/latest/hgmozilla/firefoxtree.html
Setting up the repo
- Set up your ssh key yourself
- Install Mercurial 4.2 or higher
- Make a copy of your .hgrc file for safekeeping and delete the original
- Use default hg tool to resolve code conflicts:
- Open .hgrc file in home folder.
- Search for line
[ui]
. - Search for line starting with
merge =
between the line above and the next one starting with[
. - Add or update it to match
merge = internal:merge3
- hg clone https://hg.mozilla.org/mozilla-central
- cd mozilla-central
- ./mach mercurial-setup
- On macOS
- Install xcode which is be required for the execution of some commands:
xcode-select --install
This will open an install dialog which might be minimized. Check the list of open applications and confirm the installation.
- Install xcode which is be required for the execution of some commands:
Configure mercurial as desired. At a minimum, you need the following:
- Set your username and email.
- Enable the firefoxtree extension.
- Enable the histedit extension.
The following will pull all (or at least most) of the branches sheriffs need to have on hand:
- hg pull autoland && hg pull beta && hg pull release && hg pull esr52
If you need other branches, you can find their names in the firefoxtree extension source.
You should now have everything set up for proper use!
If you want, you can rename the mozilla-central folder to something like "unified", since it is more than just mozilla-central at this point.
The `hg fxheads` command should list references to each of the relevant branch names, and the current revision and commit message for each.
To pull in newly landed changes, you can use one of the following commands:
- hg pull fxtrees # this will pull from all branches listed with the fxheads command
- hg pull treename # this will pull only from the tree with the name "treename"
Merges
This assumes you have your unified repo all set up so that `hg fxheads` lists each of central and autoland.
To merge a specific non-tip <revision> from autoland to mozilla-central:
- hg pull central
- hg up central
- hg merge -r <revision>
- hg commit -m "Merge autoland to mozilla-central a=merge"
- hg push -r . central
To merge mozilla-central into autoland:
- hg pull central
- hg pull autoland
- hg up autoand
- hg merge central
- hg commit -m "Merge mozilla-central to autoland. CLOSED TREE"
- hg push -r . autoland
- If the `hg merge central` command results in "abort: nothing to merge", you should instead use `hg update -r <mozilla-central's tip revision>` to do a non-merging update, then you can do `hg push -r . autoland` to push it as usual.
Uplifts
If branch-specific patches are posted, follow import the patches onto the relevant branch.
If you're uplifting directly from an mozilla-central checkin to mozilla-beta:
Pull and update to prepare for the uplifts:
- hg pull central
- hg pull aurora
- hg up aurora
Graft the mc commit and bring up the editor to edit the commit message, adding "a=foo" as needed:
- hg graft --edit -r <revision>
Repeat the previous step as needed for all uplifts as needed. Verify the outgoing changes and push:
- hg out -r . aurora
- hg push -r . aurora
You can graft a range of commits at once if that's easier:
- hg graft -r <toprevision>::<bottomrevision>
Read the documentation for graft for further help.
Backouts
Better tools are coming:
- https://bugzilla.mozilla.org/show_bug.cgi?id=1117632
- https://bugzilla.mozilla.org/show_bug.cgi?id=1121211
The standard backout command makes backing out revisions more difficult than it should, as it won't pre-fill the backout commit message with a bug number:
- Copy backout <revision> from treeherder, note the bug <number>, and remember the <reason>
- hg backout -r <revision>
- This should open up your editor with a completely empty commit message. Type in the backout message like "Backout revision <revision> (bug <number>) for <reason>" (possibly with "CLOSED TREE" in there to get around a closure hook).
- hg push -r . <tree>
qbackout can still be used, though you will want to use `hg oops` in place of `hg qbackout` (eg if you use `hg share` to get multiple working directories, qbackout and other uses of mq do not play nice with shared repos):
- Copy the backout <revision> from treeherder
- hg oops -e -r <revision>
- This should open up your editor with a prepopulated commit message like "Backed out <revision> (bug <number>)". Add in the <reason> and possibly "CLOSED TREE" to get around a closure hook.
- hg out -r . <tree>
- to double-check what you will be pushing
- hg push -r . <tree>
qbackout can also back out a range of commits in a single backout commit:
- hg oops -e -s -r <toprevision>:<bottomrevision>
- This will open your editor with a prepopulated commit message like "Backed out <toprevision>,<anymiddlerevisions>,<bottomrevision> (bug <number>,any other bug <numbers>)". Add in the <reason> and possibly "CLOSED TREE" to get around a closure hook.
- hg push -r . <tree>
(Omit oops's -s flag to back out each individual revision in the range as a separate commit.)
Revert a backout
- `hg graft`, see https://mozilla-version-control-tools.readthedocs.org/en/latest/hgmozilla/common.html#revive-a-commit-that-was-backed-out
Rebasing after losing a push race
This assumes you have commits you're attempting to push to autoland when you lose a push race with someone. Change `autoland` to the correct branch name as needed.
- hg pull autoland
- hg rebase -d autoland
- hg push -r . autoland
Recovering from mistakes
The histedit subcommand of hg lets you remove, edit and reorder changesets (in addition to other actions):
- hg histedit
If a merge commit needs to be removed:
- hg strip --no-backup -r .
WARNING: The hg strip command below removes any commits that haven't been pushed to the remote repositories, regardless of what branch/label/tag those commits are on. (So if you have local changes as patches for other issues - even based on other trees - they will be removed.) Only do this if you don't care about any of those commits!
- hg strip --no-backup 'not public()'
You may also need to use some combination of the following to get things back to a known-good state:
- hg purge # http://mercurial.selenic.com/wiki/PurgeExtension
- hg up -C .
See what you're about to push
`hg out` without any flags added will show you a LOT of unrelated commits. To see just what you'll be pushing to a given branch, use `hg out -r . <branch>`
- hg out -r . autoland
- This will only display the things you're about to push to the autoland branch
View incoming changes
Since your unified repo will likely have all changesets from the various branches pulled locally, `hg in <somebranch> -r <somerev>` will likely not help you see what would be pulled into your current branch from <somebranch> up to that <somerev>. Instead, you can use the following to print out the equivalent. Say you want to see what would be merged onto mozilla-central from autoland's revision ca142ec8ba0f:
Make sure m-c is fully up to date:
- hg pull central
- hg up central
Get all of autoland's changesets:
- hg pull autoland
Do a preview of the merge without actually performing the merge:
- hg merge -r ca142ec8ba0f -P
This will print out everything on autoland (up to and including revision ca142ec8ba0f) that is not already on mozilla-central.
See the log for a particular branch
- hg log -fr [branch]
Extras
hg aliases
mergetocentral/mergetointegration
I set up the following aliases in my global .hgrc file to make merging things around trunk a little faster:
[alias] # merge tree $1, revision $2 to central, optionally appending $3 (for "CLOSED TREE", etc) mergetocentral = !$HG pull central ; $HG up central ; $HG pull $1 ; $HG merge $2 ; $HG commit -m "Merge $1 to central, a=merge $3" ; $HG push -r . central # merge central tip to tree $1, optionally appending $2 (for "CLOSED TREE", etc) mergetointegration = !$HG pull central ; $HG pull $1 ; $HG up $1 ; $HG merge central ; $HG commit -m "Merge m-c to $1, a=merge $2" ; $HG push -r . $1
With these set up, I can merge autoland's revision 04a3d9130aa0 over to mozilla-central with the following command:
hg mergetocentral autoland 04a3d9130aa0
and then I can merge mozilla-central's tip back to autoland with the following command:
hg mergetointegration autoland
This cuts down on a lot of repetitive typing, saving a bit of time.