I’ve been working with the PKI/Dogtag code for a while. Over the past couple years, I’ve been more and more comfortable with Git. PKI uses SVN as a centralized Repository. Since Git SVN integration is fairly mature, I’ve been using that to manage my coding. On Monday, I gave a presentation to my team on Git SVN.  I’ve taken the outline from the slides and included it here.

This presentation is available on the Dogtag website.

 

Why?

“Saved Games”
Craft Patches
Multitasking
Code Reviews
Lose nothing
Trust

No, really, why?

If I didn’t do this first, I’d spend the whole time in the next presentation explaining what I was doing
But we use Subversion!
SVN is a remote repository
Git for local revision control
Git can work with multiple remotes
To Git, Subversion is just another remote protocol
Is it going to change what I currently do?
Different set of commands, but they have a straightforward mapping to SVN
Different set of tools
Both have large communities with lots of wisdom.
This talk focuses on using git to augment your SVN interactions

How do I get started?

git svn clone \
http://svn.fedorahosted.org/svn/pki \
–prefix svn \
-T trunk -b branches -t tags

-T -b -t are svn specific
–stdlayout
–prefix lets us name the remote repo

You messed up!

My checkout was from:
svn+ssh://admiyo@svn.fedorahosted.org/svn
/pki/trunk/pki

Note the /pki at the end
My git commits won’t get accepted by the above repo
Push to SVN  as “commit cleaning” method
Resort to patches if necessary

That is Slow!  I SVN checkout all the time!

This got the entire history, all branches, all commits
You will do this only once!
Incremental changes are fetched
Git has a really good protocol for ensuring things stay in sync.
Why is there nothing inside the pki directory?
Nothing has been checked out from the local repository
List all branches: git branch -a
List all remote branches: git branch -r
Right now they are the same
To work with Trunk
$  git checkout -b trunk svn/trunk
To work with PKI_8_BRANCH
git checkout -b svn/PKI_8_BRANCH PKI_8_BRANCH
To go back to trunk
git checkout trunk

What did that do?

man git checkout
-b creates a new branch
First unamed param is local branch name
Second unnamed param is the start point
Without -b  and branch point, it uses a local branch

But I only work with one Branch at at time!

Git makes a local repository in  .git/objects
Git branches are Cheap
Git branches are local
You can checkout branches from your local repository and FAST!

I need to make a change for the trunk.

git checkout -b branchname  svn/trunk
Edit code
git add .
git commit -m “commit message”

Uh Oh.  I just messd up

git commit –amend
git reset HEAD~1
–soft : keeps your changes
–hard : clean slate
git reflog

I am not ready to commit it!

Commit goes to local repository
In git terms, you push to a remote repository
git svn dcommit

I need to create a patch for code review.

git format-patch  -M -C –patience –full-index
I have scripted around this to use data out of the .git/config

Someone checked in changes.  How do I merge?

What you want is rebase, not merge.
git svn fetch
git rebase svn/trunk
How would I do a code review?
Commit the changes for what you are working on
Create a branch off of master
Apply the patch to that branch
git am  code_to_review.patch
git difftool HEAD~1 HEAD

I really don’t want to commit, but I don’t want to lose my changes

git stash.
Stack of changes, you can push and pop
When you pop, they will be applied to the current branch where-ever you are
How do I back up my work?
Git works with multiple repositories
Create an external  git repo
git push

ssh://admiyo@fedorapeople.org/home/fedora/admiyo /public_git/pki.git

git push admiyo mywork:mywork

Could be done with Subversion as well

I looked in .git.  What is that stuff?

Files are stored by a hash of their content
objects  think hashtable
Refs: anything named
Tags: tags (Der!)
Remotes: Cached info about remote repositories
Heads:  local branches
HEAD:  what is currently checked out
Logs:  just another series of Hashes
A branch is just the name of a a bunch of files

I can’t remember all this!

http://cheat.errtheblog.com/s/git
http://www.jukie.net/~bart/blog/svn-branches-in-git