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Sven Peters, profile picture
Uploaded bySven Peters
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Getting Git Right

The document discusses the benefits and intricacies of using Git as a version control system, emphasizing improved developer happiness and productivity through efficient workflows. It highlights the importance of code quality, various merge strategies, and the concept of rebasing in maintaining a clean project history. Additionally, it covers workflows tailored to team needs and encourages best practices for coding and collaboration.

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Related topics:
Insights on Software Development•Continuous Integration•
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Who knows ?
Facts 500 Developers
1000+ Nerds Facts
working on 9 products Facts
or in just 3 words We Software
We SoftwareTeams
they know what’s going on! really small team Let’s do it! Great idea! Productivity++
Productivity? team is growing Let’s do it! Great! Why? Who will do it? Is it done? Have you talked to QA? I have no time for this!
Productivity?? we’re not alone Is it profitable? When is it done?
Devel ping S ftware is a S cial Challenge
happy developers & productive teams Ship software Tools faster & smarter
Ship software faster & smarter happy developers & productive teams
All sorts of teams are on &
All sort of teams
Migrating soon? http://atlassian.com/git/
is just a tool!
Happier Developer with Be a
Time machine without paradoxes?
Why does make you happy? 2 Freedom & Safety Explore & Understand 1 3 Fast & Compact 4 Control and Assemble
But Why? Or How?
A lot of the “Why” can be explained at the Conceptual model
Written in C by Linux kernel and filesystem developers
5 minutes dive into internals
Git is fundamentally a content-addressable filesystem with a VCS user interface written on top of it Pro Git Book, Section: Git Inter nals ” “
cba0a.. commit tree blob content blob content blob content 98ca9.. 92ec2.. 5b1d3.. 911e7.. cba0a.. tree 92ec2.. blob 5b1d3.. blob 911e7.. blob author committer README LICENSE test.rb size size size size size parent data model r34ti..
$> tree .git/objects .git/objects ├── info └── pack 2 directories
git add some-file.txt
$> tree .git/objects .git/objects ├── e4 │ └── 3a6ac59164adadac854d591001bbb10086f37d ├── info └── pack 3 directories, 1 file zlib compressed SHA1
git commit -m "First commit"
$> tree .git/objects .git/objects ├── 13 │ └── 1e360ae1a0c08acd18182c6160af6a83e0d22f ├── 31 │ └── 995f2d03aa31ee97ee2e814c9f0b0ffd814316 ├── e4 │ └── 3a6ac59164adadac854d591001bbb10086f37d ├── info └── pack 5 directories, 3 files Commit Tree Blob
cba0a.. commit tree blob content blob content blob content 98ca9.. 92ec2.. 5b1d3.. 911e7.. cba0a.. tree 92ec2.. blob 5b1d3.. blob 911e7.. blob author committer README LICENSE test.rb size size size size size parent data model r34ti..
data model commit tree c4d.. author message: 1st! tree blob 5b1d3.. blob 911e7.. blob cba0a.. size size READM LICENS test.rb parent … commit tree c4d.. author message: Update! parent 8efc8.. tree blob 5b1d3.. blob 911e7.. blob cba0a.. size size READM LICENS test.rb … commit tree c4d.. author message: More! parent bc5e7.. tree blob 5b1d3.. blob 911e7.. blob cba0a.. size size READM LICENS test.rb … …
echo "// Comment" >> some-file.txt
git add some-file.txt
$> tree .git/objects .git/objects ├── 13 │ └── 1e360ae1a0c08acd18182c6160af6a83e0d22f ├── 31 │ └── 995f2d03aa31ee97ee2e814c9f0b0ffd814316 ├── c1 │ └── 9e6823e34980033917b6427f3e245ce2102e6e ├── e4 │ └── 3a6ac59164adadac854d591001bbb10086f37d 6 directories, 4 files Entirely new BLOB
wat?
git gc
$> tree .git/objects .git/objects ├── info │ └── packs └── pack ├── pack-7475314b451a882d77b1535d215def8bad0f4306.idx └── pack-7475314b451a882d77b1535d215def8bad0f4306.pack 2 directories, 3 files
Loose Objects Packfile 1. zlib compressed 2. Delta encoded
Fast and Compact
Everything is local Except push & pull
Read: FAST
But what if my repo is big? 2 12,000 non-merge commits 446k lines of code added 1 3 Linux Kernel release has 15+ million LOC 4 1,339 contributors source lwn.net
Control and Assemble
What is a merge? merges keep the context of the feature’s commits M Merge commit feature master feature master
Anatomy of a merge .git/objects/36/80d8c8fd182f97cb0e75045e2fed5c7b7613ed tree f362c42032aff677c1a09c3f070454df5b411239 parent 49a906f5722ad446a131778cea52e3fda331b706 parent bd1174cd0f30fe9be9efdd41dcd56256340f230e author Marcus Bertrand <mbertrand@atlassian.com> 1409002123 -0700 committer Marcus Bertrand <mbertrand@atlassian.com> 1409002123 -0700 Merge branch 'foo/mybranch' commit
merge is better in git git knows the ancestry 1 2 The merge is local 3 powerful merge strategies
Let’s talk about merge strategies! git has breadth of choice on how to merge changes! resolve recursive octopus ours subtree yours?
What is a fast-forward merge? It will just shift the HEAD tag master feature master feature
merge strategy: resolve Three-way merge of the ancestors feature Common ancestor master M Merge commit
merge strategy: recursive 3-way merge but climbs the ancestry tree recursively if there are multiple ancestors M M master feature ancestor 1 ancestor 3 ancestor 2
merge strategy: ours Records a merge but skips incoming changes feature master M IGNORE!
use “ours” to promote more recent branches
merge becomes a non-event
rebase: Rewrite history with safety belts on
What is a rebase? It’s a way to replay commits, one by one, on top of a branch master feature
When you use merge… You pollute your feature branch with non-meaningful merge commits not really part of feature… feature master meaningful merge
What is a rebase? It can be used to keep a feature branch up to date with master feature master
What is an --interactive rebase? Helps you clean up your private branches before publishing them reword fixup pick squash edit exec
CUSTOMARY WARNING! rebase rewrites history! Treat this power with great care. Only rewrite history of local branches or…
So what do I use? merge or rebase?
Merge Commit Rebase (FF) Rebase (Squash) No merge commits Verbose history Easy to read Can be more difficult to trace changes Which should I use? “Ugly” history Full traceability Hard to screw up mostly some
Read more on the topic! bit.do/merge-or-rebase
Pro tips for the road
Everyone has their favorite, but! Liquid prompt is awesome http://bit.do/liquid-prompt
Get all the alias goodness on Bitbucket http://bit.do/git-aliases
Why does make you happy? 2 Freedom & Safety Explore & Understand 1 3 Fast & Compact 4 Control and Assemble
Happy Developerwith A
Productive Teamwith A
Why makes a team great! 2 Improving Code Quality Protect Code 1 3 Efficient Workflows 4 Git & Your Toolchain
Efficient Workflows
Can we still fix a bug for the upcoming Release ? Is the code for that Feature complete? How do we do Hotfix for the current version? Has everyoneReviewed the code for this feature ?
We don’t know! What’s the best Git workflow?
different cultures + different products + different teams = different workflows What’s the best Git workflow?
Design your own Workflows
Issues Code
Issues Code JIRA-123 JIRA-123 JIRA-456 JIRA-456
Can’t be released right now Unfinished features in your trunk / master branch
Branch per issue First: feature/JIRA-30 stable master branch isolated feature work master
Branch per issue First: feature/JIRA-30-user-avatars branch type issue key description
Branch per issue First: bugfix/JIRA-31-oauth-3lo-NPE branch type issue key description
Branch per issue First: hotfix/JIRA-32-broke-ie8-again branch type issue key description
Typos happne! Tool switching sucks
Is the branch green? Branch name pre-populated
Confounding build breakages master
Confounding build breakages bugfix/JRA-1 master
Is the branch green? Branch name pre-populated
SAAS Workflow 1 Atlassian Marketplace Workflow
Simplest Workflow release from here master feature/JIRA-30 feature/JIRA-45
Simplest Workflow release from here master develop feature/JIRA-30 feature/JIRA-45 integrate here
Installable software 2 Atlassian Stash Workflow
Multiple Product Versions v 1.1 v 1.2 master feature/JIRA-30
Multiple Product Versions v 1.1 bugfix/JIRA-41 v 1.2 master