Amarok/Development/Git

Git is a distributed revision control system, and the system currently used by Amarok (since switching from SVN in 2010). Thanks to Ian for the initial git information and for being the resident Git expert.

Initial Setup

User Config (IMPORTANT!!!)

If you plan on ever pushing a commit to main repository, be sure to set your name and e-mail for commit messages:

git config --global user.name "John Doe"
git config --global user.email "[email protected]"

The above two commands will set your name and e-mail in Git (globally). This will allow Git to automatically tag all of your commits with your name and e-mail address.

Getting Amarok

To view the revision history and the source tree, go to http://quickgit.kde.org/?p=amarok.git or projects.kde.org Amarok page. To checkout a copy of the most current source tree, run:

git clone git://anongit.kde.org/amarok.git
cd amarok
git remote set-url --push origin [email protected]:amarok.git

This will create a local copy of the repository under the directory amarok/ in the directory in which the command was executed. The repo will be set to pull from the fast git:// URL and push commits using SSH.

Git Basics

Getting Help

All information on this page is merely an introduction to Git. For more complete information, see

git help

You can also ask the developers on #amarok if you need more help.

Updating Your Repository

To update your local clone of the Amarok repository, please execute

git pull --rebase

This command will run git fetch to download all new commits in the remote branch, and git rebase to add them to your local clone, "replaying" any changes you may have made locally on top of the commits pulled in. To save your time typing --rebase every time when pulling from master, issue

git config branch.master.rebase true

Viewing Commits

To see all of the commits in your current branch, run

git log

For a graphical view of the revision history, you can run

gitk

This program should have been installed with Git, and provides a nice graphical view of the revision history.

Committing Changes

git status     # A summary of which files are changed/new/deleted/etc.
git diff       # Show the actual changes

Check HACKING/commitchecklist.txt

git commit -a  # Commit all current changes

After the last command, Git will open a text editor to allow you to add the commit message. Please write a concise, yet descriptive, summary of the changes included in the commit, then save the file and exit. The option "-a" tells Git to include all changes made to already-existing files. This includes modifications and file deletes. It does not, however, encompass new files. To tell Git to include new files, you have to explicitly run

git add /path/to/new/file1 /path/to/new/file2 ...

before running git commit. To commit only changes made to certain files, you can similarly run git add with the paths of the files whose changes you do want to commit. You can also try either of the following for a more interactive method of adding changes:

git add --interactive
git add --path         # Essentially the same, but jumps directly to the patch subcommand

If you have access to the Amarok repository, you can then run

git push

to push your local changes to the remote Amarok repository, but always check that you're going to push right things before with gitk or a similar tool.

Branching

One of Git's greatest strengths lies in branching. If are planning to make complicated changes to the source code, you can easily create a private branch, track your changes in the branch, and get the changes working before committing the whole thing to the main Amarok Git repository.

Creating a New Branch

By default, your local clone of the Amarok repository lies in the "master" branch. To create a private branch from this one:

git branch NewBranchName    # Create the new branch, with name "NewBranchName"
git checkout NewBranchName  # Switch to the new branch
git checkout master         # Switch back to the master branch

To see a list of all of your branches:

git branch

The branch with an asterisk before it is the one you are currently working in.

Updating a Private Branch

To update your private branch with the latest commits in master,

git rebase master NameOfPrivateBranch

You may need to resolve conflicts between local changes and remote commits at this point. See git-rebase ("git help rebase") for more information.

Merging a Branch into master

To commit changes in a branch to the main Git repository, your should first update your private branch to the latest SVN sources (see above). Then you can merge the private branch into the master branch and commit it to the SVN repository:

git checkout master
git merge --squash MYBRANCH  # merge MYBRANCH into master as a single commit
git commit
git push

After you've merged the changes from a branch into the master, you can delete the branch:

git branch -d MYBRANCH

Conflicts

Work through conflicted files by opening them in your mergetool (opendiff, kdiff3, etc.) and choosing left/right chunks. The merged result is staged for commit.

git mergetool

For binary files or if mergetool won't do, resolve the conflict(s) manually and then do:

git add <file1> [<file2> ...]

Once all conflicts are resolved and staged, commit the pending merge with:

git commit

Using Reviewboard

Amarok uses the KDE Reviewboard for code changes, please see the Techbase article about using Reviewboard with Git

Tricks 'n Tips

Oh Shit: Undo

You've made some changes to a file(s) and you've decided you want to scrap all the work.

git checkout /path/to/file

Abandon everything since your last commit. This command can be DANGEROUS. If merging has resulted in conflicts and you'd like to just forget about the merge use this command.

git reset --hard
 

Undo your most recent successful merge and any changes that occurred after. Useful for forgetting about the merge you just did. If there are conflicts (the merge was not successful), use "git reset --hard" (above) instead.

git reset --hard ORIG_HEAD

Undo your last commit

git reset --soft HEAD^

Ignoring Files/Directories

There are certain folders/files which may not require tracking, and git will say on every checkout and status what these files are, which can be a nuisance. See

man gitignore

Colorize Output

Treat yourself to some color. Add the following to ~/.gitconfig

[color]
   ui = auto
[color "diff"]
   whitespace = red reverse

Further Reading

1. "Git Magic" Tutorial
2. Reference Sheet