embracing distributed version control
DESCRIPTION
TRANSCRIPT
Embracing Distributed Version Control
How to Drastically Improve Collaboration, Experimentation,
Productivity, Freedom, Flexibility, Data Integrity and take two strokes off
of your golf game
Lets Talk About It
Open Forum • Ask questions• Ask for demonstrations • Add opinions• Share experiences• Try it yourself
What's the Big Deal?
• Tools should mold to your process• Projects have lots of independent features• Feature isolation • "Major Milestone" vs. "Release Often"• "Only commit when its done" is limiting
The Basics
Centralized Version Control Systems• One centralized server with the revision database
o single point of failure• Clients checkout a working copy to their machine• Most operations happen on the server• Checkouts/Updates happen one directory at a time• Linear revision history (merges squash commits)• Every directory contains a "special folder"
Distributed Version Control Systems• Every client has a full revision history locally
o # backups == # clients o no need to be online
• All operations are local (except sharing)• Non-linear revision history• Network operations are compressed into packed
downloads • Working copy is independent of versioning system
Different to the Core
How Did We Get Here Again?
There Can Only Be One... or maybe two• Everyone has their own opinions• In the end choose what system fits best
o but whatever you do, choose a DVCS (at least for your local development)
• Today we will compare SVN and GIT
Lets Take a Walk... Side by SideSVN GIT
Obtain Code svn checkout <url> git clone <url>
Add Files svn add file1.php *.css git add file1.php *.css
Status svn status git status
Differences svn diff | less git diff
Restore File svn revert <path> git checkout <path>
Commit All Changes svn commit git commit -a
Get Latest Updates svn update git pull
Share Latest Edits git push
Branching
I've Branched Before... So What?
• With CVCS branching is used to separate major releases
• Branching is always followed by merging• Both tasks need to be easy and inexpensive
Branching is Hard... Or is it?
Tasks1.Obtain the source code– Create Branch– Switch Branch– Merge Branch
Branching is Hard... Or is it?
REPO=http://svn.php.net/repository/php/php-src/1. svn checkout $REPO/trunk (10 minutes)– svn copy $REPO/branches/PHP_5_3 $REPO/branches/PHP_5_5 (4
minutes)– svn switch $REPO/branches/PHP_5_5 (50 seconds)– svn merge -r 20:HEAD $REPO/branches/PHP_5_3 (claw your eyes out)
Total Time: ~15 minutes + clawing your eyes out Total Time Branching: ~5 minutes
Branching is Hard... Or is it?
1.git clone git://github.com/php/php-src.git (3
minutes) – git branch PHP_5_5 origin/PHP_5_3 (5
milliseconds)– git checkout PHP_5_5 (2 seconds)– git merge origin/PHP_5_3 (1 second) Total Time: ~3 minutesTotal Time Branching: ~3 seconds
OK. So Branching Is Easy... Now What?• Cheap and easy branching fundamentally changes
the way you approach development• Everything is done on a branch• Issue isolation is now a reality
Every Change Has Its Place in a BranchYou can use any branching style you choose. Here's an example:• master
o also referred to as trunk• hotfix-X
o quick fixes to master • develop
o integration point for all completed feature branches
• feature-Yo every discreet issue is worked on in a feature
branch
complete walk-through: http://nvie.com/git-model
Workflow
Your Centralized Workflow
With Centralized Version Control Systems, your workflow will always look like this.
image source: http://whygitisbetterthanx.com
Chose Your Own Adventure WorkflowWith Distributed Version Control Systems you can morph your workflow to meet your needs. You can do it the same...
image source: http://whygitisbetterthanx.com
Or It Can Work Like This...
Integration Manager Approach• Useful for small to large teams• Integration manager merges all feature branches
into mainline
Or It Can Work Like This...
Dictator and Lieutenants• Useful for large teams• Team Leaders curate new feature branches into
production ready state • Dictator has final say and merged into mainline
Migration & Integration
Dipping Your Toes in the Water
• Use your favorite DVCS with most other VCS repositories
• Push and Pull changes between systems
Diving in Head First
• Import entire history/branches from legacy systems• Rinse & repeat: make you have everything before
you switch
References
GIT • http://git-scm.com/course/svn.html• http://whygitisbetterthanx.com/• http://nvie.com/git-model/ • http://progit.org/book/ • http://gitref.org/ • http://gitready.com/
Mercurial • http://hginit.com/
Get In Touch
Nowell Strite• Twitter: nowells• Email: [email protected]
Matthew Weier O'Phinney• Twitter: weierophinney• Email: [email protected]