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A couple of Atlassians who get Git and dig the DAG
Tim PettersenDeveloper Advocate
@kannonboy
Ian BuchananDeveloper Advocate
@devpartisan
Git at Atlassian 10 minHappier Developers 40 min
A bit about Stash 10 mins
Better Teams 40 min
Break 10 min
Who knows
?
Facts
500 Developers
1000+ Nerds
Facts
working on 9 products
Facts
Tools
happy developers & productive teams Ship software
faster & smarter
Ship software faster & smarter
happy developers & productive teams
Migrating soon?http://atlassian.com/git/
is just a tool!
Happier Developerwith
Be a
Explore & Understand
1
3
Fast & Compact
Control & Assemble4
Why does make you happy?
2 Freedom & Safety
5 minutes dive into
internals
Git is fundamentally a content-addressable filesystem with a VCS user interface written on top of it P ro G i t B o o k , S e c t i o n : G i t I n t e r n a l s”
“
$> cd ~/repo-directory !$> ls -A !$> git init Initialized empty Git repository in ~/repo-directory/.git/ !$> ls -A .git
$> 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
Blob
Tree
Commit
cba0a..
committree
contentblob
contentblob
contentblob
98ca9..92ec2..
5b1d3..
911e7..
cba0a..
tree 92ec2..
blob 5b1d3..blob 911e7..blob
authorcommitter
READMELICENSEtest.rb
sizesize
size
size
size
data model
parent e34bf..
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
git gc
$> tree .git/objects .git/objects !"" info $ #"" packs #"" pack !"" pack-7475314b451a882d77b1535d215def8bad0f4306.idx #"" pack-7475314b451a882d77b1535d215def8bad0f4306.pack !2 directories, 3 files
PackfileLoose Objects
• Delta encoded • zlib compressed
Fast & Compact1
Everything is localExcept push & pull
Mostly C, written by Linux kernel and
filesystem developers
But what if my repo is big?
446k lines of code added
1
3
Linux Kernel release has 15+ million LOC
1,339 contributors4
2 12,000 non-merge commits
source lwn.net
2 Freedom & Safety
Branching
git stash is awesomeIt’s a way to temporarily save your
work on a stack
So if your boss comes screaming at your desk
git stash Create a patch without a hassle
stash and branch FTW
Losing work is very hard
very very
Redundancy Every developer has a clone
Chain of “unlosability”
Recover a file
git checkout file-name
Recover a commit
git checkout sha-1
git checkout ref (branch/tag)or
Print file as of branch
git show branch:path/to/file
can be any ref
When all is lost, use the
reflog
What is the reflog?it’s a log of all the places where your HEAD has been
garbage collected every
90 days
Explore & Understand 3
= history superpowers
Hard Questions of git logAsk
-S string in all diffs--after,--before when?--author who did what
Who deleted that file?git log -1 -- [path] lists where a file was deleted
git log --diff-filter=D --summary lists all deleted files
Who deleted that method?
git log -S<string> search through all history
Where is that pattern?
git grep <regexp> compare the speed between this
and regular grep or ack…!you’ll be blown away
Have I merged this?
git branch --no-merged lists branches not merged
git branch --merged lists branches already merged
Control & Assemble4
Time machine without paradoxes?
What is a merge?
M
Merge commit
master
feature
merges keep the context of the feature’s commits
feature
master
tree f362c42032aff677c1a09c3f070454df5b411239
parent 49a906f5722ad446a131778cea52e3fda331b706
parent bd1174cd0f30fe9be9efdd41dcd56256340f230e
author Marcus Bertrand <[email protected]> 1409002123 -0700
committer Marcus Bertrand <[email protected]> 1409002123 -0700
!Merge branch 'foo/mybranch'
.git/objects/36/80d8c8fd182f97cb0e75045e2fed5c7b7613ed
commit
Anatomy of a merge
git knows the ancestry
1
2
The merge is local
powerful merge strategies3
merge is better in git
Let’s talk about merge strategies!git has breadth of choice
to merge changes!
recursiveresolve octopus subtreeours yours?
master
feature
What is a fast-forward merge?
master
It will just shift the HEAD tag
feature
merge strategy: resolve
Mmaster
feature
Three-way merge of the ancestors
Common ancestorMerge commit
3-way merge but climbs the ancestry tree recursively if there are multiple ancestors
merge strategy: recursive
M
M
feature
masterancesto
r 1
ancestor 2
ancestor 3
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
feature
master
What is a rebase?It can be used to keep a feature branch up to date with 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
mostlysome
Explore & Understand
1
3
Fast & Compact
Control & Assemble4
Why does make you happy?
2 Freedom & Safety
Pro tips for the road
Happy DeveloperwithA
Productive TeamwithA
Improving Code Quality
1
2
Efficient Workflows
Git & Your Toolchain3
Why makes a team great!
Efficient Workflows
Git workflow?What’s the best
We don’t know!
+ different teams+ different products
different cultures
= different workflows
Git workflow?What’s the best
DesignWorkflows
your own
Issues Code
Issues Code
JIRA-456
JIRA-123JIRA-123
JIRA-456
Can’t be released right now
Unfinished features in your trunk / master branch
Branch per issueFirst:
feature/JIRA-30
stable master branch
isolated feature work
master
feature/JIRA-30-user-avatars
branch type
issue key
description
Branch per issueFirst:
bugfix/JIRA-31-oauth-3lo-NPE
branch type
issue key
description
Branch per issueFirst:
hotfix/JIRA-32-broke-ie8-again
branch type
issue key
description
Branch per issueFirst:
Typos happne!Tool switching sucks
Is the branch green?
Branch name pre-populated
master
Confounding build breakages
bugfix/JRA-1
master
Confounding build breakages
Is the branch green?
Branch name pre-populated
Atlassian Marketplace1Workflow
SAAS Workflow
Simplest Workflow
release from here
feature/JIRA-30
feature/JIRA-45
master
release from here
feature/JIRA-30
feature/JIRA-45
develop
master
integrate here
Simplest Workflow
Atlassian Stash2Workflow
Installable software
Multiple Product Versions
feature/JIRA-30
master
v 1.2
v 1.1
master
v 1.2
v 1.1
bugfix/JIRA-41
Multiple Product Versions
master
v 1.2
v 1.1
bugfix/JIRA-41
Multiple Product Versions
master
v 1.2
v 1.1
bugfix/JIRA-45
Multiple Product Versions
master
v 1.2
v 1.1
bugfix/JIRA-45
Multiple Product Versions
Multiple Product Versions
master
v 1.2
v 1.1
bugfix/JIRA-45
boring work
Automatic mergeswith Stash
Design your workflow
Nearly everything is possible with
Improving Code Quality
CodeReview
Photo: Yogi (Flickr)
Better Code
Shared Knowledge
Team Ownership
G = 1
R+1
Developer guilt
Team Ownership
Code Reviews
Pull Requests
Pull Requests
do it before merge
Pull Requests
Pull Request Creation
Pull Request Creation
Pull Request Creation
Discuss
Pull Request Creation
Discuss your changes
Side by side diff the choice is yours
Pull Request Merge Checks
Who would be
the best to reviewmy code?
Auto Suggest Reviewers
Free Add On For
committed code to this Pull Request
Suggestions:
contributed files that were modified
Git and your Toolchain
& CI
automatically triggered
Building branches
master
always build master
Every line of code starts with an
Issue
Visualize your development
Issue
Sprint Branch Pull Request
Build
2014 style
Visualize your development
Automatic Issue Transitions
master
IN REVIEW DONEIN PROGRESSOPEN
feature/JIRA-30
master
IN REVIEW DONEIN PROGRESSOPEN
Branch created!
Automatic Issue Transitions
feature/JIRA-30
master
IN REVIEW DONEIN PROGRESSOPEN
Pull Request Created!
Automatic Issue Transitions
feature/JIRA-30
master
IN REVIEW DONEIN PROGRESSOPEN
Pull Request Merged!
Automatic Issue Transitions
See what’s going on
Builds
with
Bots
See what’s going onwith
Pages
Issues Branches Pull Requests etc.
See what’s going onwith
Issues Branches
Pull Requests etc.
See what’s going onwith
Why Git?
Ship software faster & smarter
So now you can answer
Why Git?„ „
Why ?
CommitLog
Git workflows for teams
Extensions &
Integrations
Scalability
Why ?
Git workflow for teams
feature/STASH-123
master
Forking
Branching
vs
feature/STASH-123
master
Git workflow for teams
X reviewers approved? Y builds passed? All tasks complete?
feature/STASH-123
master
Git workflow for teams
Pull request merge checks
Repository hooks
Branch permissions
feature/STASH-123
master
Git workflow for teams
Pull request merge checks
Repository hooks
Branch permissions
Flexible & Extensible
Powerful integrations
Powerful integrations
• Full Java API • Repository Hooks • Merge Checks • User Interface • REST end-points • Filetype renderers • SSH commands
Stash Platform
Branch Permissions REST APIs JIRA
Integration
Source? You betcha!
Plugin APIs
insert /rest/api/latestRESTful APIs
RESTful APIs insert /rest/api/latest
Scalability
Request throttling
Request queuing
Scalability
Response Caching
Scalability
Clustering
Scalability
Git workflows for teams
Extensions &
Integrations
Scalability
Why ?
All sorts of teams are on
&
Ch ee se!want a shirt?
#gettinggitright
win wireless headphones
Fill out the survey
(check your mail)
#gettinggitright
Q & A$10 for up to 10 devs
Free for 5 users Totally free
Free basic version
