Setup

The following must be executed within the Skia source repository.

This command sets up a Git commit-message hook to add a unique Change-Id to each commit. Gerrit only accepts changes with a Change-Id and uses it to identify which review a change applies to.

experimental/tools/set-change-id-hook

If you acquired Skia from a mirror (such as GitHub), you need to change the origin remote to point to point to googlesource. Advanced uses will note that there is nothing special about the string origin and that you could call this remote anything you want, as long as you use that name for get push.

git remote set-url origin 'https://skia.googlesource.com/skia.git'

Authentication

Go to skia.googlesource.com/new-password and follow the instructions.

Creating a Change

Create a topic branch
```
git checkout -b TOPIC
```
You may want to set a tracking branch at this time with:
```
git checkout -b TOPIC -t origin/main
```
Make a commit.
```
echo FOO >> whitespace.txt
git commit --all --message 'Change Foo'
git log -1
```
git log should show that a Change-Id line has been added you your commit message.
If You have multiple commits in your branch, Gerrit will think you want multiple changes that depend on each other. If this is not what you want, you need to squash the commits.
Push to Gerrit
```
git push origin @:refs/for/main
```
@ is shorthand for HEAD, introduced in git v1.8.5.

If you want to target a branch other than main, that can be specified here, too. For example:
```
git push origin @:refs/for/chrome/m57
```
Gerrit Upload Documentation

Open in web browser:

bin/sysopen https://skia-review.googlesource.com/c/skia/+/$(bin/gerrit-number @)

Updating a Change

Edit your commits more.
```
echo BAR >> whitespace.txt
git commit --all --amend
```
Changes to the commit message will be sent with the push as well.
Re-squash if needed. (Not needed if you only amended your original commit.)
Push to Gerrit.
```
git push origin @:refs/for/main
```
If you want to set a comment message for this patch set, do this instead:
```
M=$(experimental/tools/gerrit_percent_encode 'This is the patch set comment message!')
git push origin @:refs/for/main%m=$M
```
The title of this patch set will be "This is the patch set comment message!".

Triggering Commit-Queue Dry Run when you upload a patch

M=$(experimental/tools/gerrit_percent_encode 'This is the patch set comment message!')
git push origin @:refs/for/main%l=Commit-Queue+1,m=$M

Using <tt>git cl try</tt>

On your current branch, after uploading to gerrit:

git cl issue $(bin/gerrit-number @)

Now git cl try and bin/try will work correctly.

Scripting

You may want to make git aliases for common tasks:

git config alias.gerrit-push 'push origin @:refs/for/main'

The following alias amends the head without editing the commit message:

git config alias.amend-head 'commit --all --amend --reuse-message=@'

Set the CL issue numnber:

git config alias.setcl '!git-cl issue $(bin/gerrit-number @)'

The following shell script will squash all commits on the current branch, assuming that the branch has an upstream topic branch.

squash_git_branch() {
    local MESSAGE="$(git log --format=%B ^@{upstream} @)"
    git reset --soft $(git merge-base @ @{upstream})
    git commit -m "$MESSAGE" -e
}

This shell script pushes to gerrit and adds a message to a patchset:

gerrit_push_with_message() {
    local REMOTE='origin'
    local REMOTE_BRANCH='main'
    local MESSAGE="$(echo $*|sed 's/[^A-Za-z0-9]/_/g')"
    git push "$REMOTE" "@:refs/for/${REMOTE_BRANCH}%m=${MESSAGE}"
}

These shell scripts can be turned into Git aliases with a little hack:

git config alias.squash-branch '!M="$(git log --format=%B ^@{u} @)";git reset --soft $(git merge-base @ @{u});git commit -m "$M" -e'

git config alias.gerrit-push-message '!f(){ git push origin @:refs/for/main%m=$(echo $*|sed "s/[^A-Za-z0-9]/_/g");};f'

If your branch's upstream branch (set with git branch --set-upstream-to=...) is set, you can use that to automatically push to that branch:

gerrit_push_upstream() {
    local UPSTREAM_FULL="$(git rev-parse --symbolic-full-name @{upstream})"
    case "$UPSTREAM_FULL" in
        (refs/remotes/*);;
        (*) echo "Set your remote upstream branch."; return 2;;
    esac
    local UPSTREAM="${UPSTREAM_FULL#refs/remotes/}"
    local REMOTE="${UPSTREAM%%/*}"
    local REMOTE_BRANCH="${UPSTREAM#*/}"
    local MESSAGE="$(echo $*|sed 's/[^A-Za-z0-9]/_/g')"
    echo git push $REMOTE @:refs/for/${REMOTE_BRANCH}%m=${MESSAGE}
    git push "$REMOTE" "@:refs/for/${REMOTE_BRANCH}%m=${MESSAGE}"
}

As a Git alias:

git config alias.gerrit-push '!f()(F="$(git rev-parse --symbolic-full-name @{u})";case "$F" in (refs/remotes/*);;(*)echo "Set your remote upstream branch.";return 2;;esac;U="${F#refs/remotes/}";R="${U%%/*}";B="${U#*/}";M="$(echo $*|sed 's/[^A-Za-z0-9]/_/g')";echo git push $R @:refs/for/${B}%m=$M;git push "$R" "@:refs/for/${B}%m=$M");f'