Review your code like a Googler

All change lists must be
reviewed. Period.
“Review your code like a Googler”
2013 Dariusz Łuksza
Dariusz Łuksza, CollabNet
dariusz@luksza.org
@dluksza

Are you Git?
pre-requirements

First rule of Code Review:
Your code is not your wife...
pre-requirements

First rule of Code Review
and OpenSource:
pre-requirements

you can share it!
pre-requirements
First rule of Code Review
and OpenSource:

I'm here for
You!

Next ~47min.
● Code Review & Types
● Post-commit vs pre-commit
● The Gerrit
● EGit + Mylyn Review Gerrit Connector
● Command line→
● Code Review Tips
● Gerrit++
● Q&A
Code reviews with Gerrit
by Mateusz Szczap
@ Marmolana 14:50

Code Review

post-commit review
(formal code review)

Flickr: markcph
post-commit review

Flickr: markcph
post-commit review
Coffee, absolute
must have during
formal code
reviews

Flickr: sebastian_bergmann
post-commit review

Flickr: bike
post-commit review

review on request
(post- or pre-commit)

review on request
(post- or pre-commit)
90 min
later
OK, so where
I was before...
Hi Jeff, could you
review my changes
before I submit
I need a review...
OK, lets go!
Can I interrupt you
for a moment?You already
interrupted me...
Sure you can,
what is it?
this loop iterates
over… mhm... and then
it brakes...
if (req != null) {
for (i = 0; …
if (...) break;
...
I finished my task and need final
code review... would you like
to look on it?
emmmm … OK...
153 min
later
9 min
later
finally I can get
back to my task...
… and then...

asynchronous review
with Gerrit
(pre-commit)

Gerrit Code Review
this loop iterates
over… mhm... and then
it brakes...
if (req != null) {
for (i = 0; …
if (...) break;
...
found it!! HAHAHA
OK, so now,
commit and
push for review!
… step into...
step over...
… step over...
step over...
It's time to check others
review requests
I'm invincible!!
Great! There are requests
from Tom, Sara and Jim...
let me see...

post-commit
vs.
pre-commit

Flickr: bike
post-commit vs. pre-commit
Flickr: sriram
VS.

The Gerrit

The Gerrit
● Created for Android OpenSource project
● Designed to bring Google's code review feeling to
Android community
● Pure Java based
● Has vibrant community
● Used in many OpenSource project's and Enterprise
companies
● Can be used as regular Git server without code review
● Supports branch based permissions
● It is getting more and more extend-able

Who uses Gerrit?

let's play with
Gerrit

Demo Time!
Preconditions:
– You are joining new team with already existing
project
– Somebody already creates yours account in LDAP
– You already generated yours SSH key
– Already have Eclipse Kepler with EGit and Mylyn
Gerrit connector installed

2013 Dariusz Łuksza2013 Dariusz Łuksza
fred
Meet Fred

First login into Gerrit
fred
Insert yours
credentials here

fred
Yours SSH public
key goes here,
remember to
click 'Add'

fred
Finally, click
'Continue'

fred
You are logged in

Configure Mylyn Connector
fred
Add task
repository

fred
If you don't have
Gerrit connector on
the list, use 'Install
More Connectors'
button
Select Gerrit and
click 'Next'

fred
Provide server
data
Validate before
save
Finally, click
'Finish' to save
new connection

fred
Of course I would like to create query for
this connector

fred
Name the query
For our simple use case
'All open changes' will
be enough

fred
After successful configuration you will see
task repository and query in proper
Eclipse views

Cloning project from Gerrit
fred

Clone project from Gerrit
fred

fred
Because in git
repository there is no
Eclipse
configuration file (like
eg. .project) we need
to import it as
'general project'

fred
Now we can import nested Maven projects

Create new feature branch
fred

Create first change
fred
Change something in
repository

Create first change
fred
Remember to
check generation of
'Change-Id' tag
Leave this line as it is,
EGit will generate
'Change-Id' for you

Create first change
fred
Now push yours
changes to Gerrit

Create first change
fred
Provide name of
branch to which
change should
be merged after
successful
review

Create first change
fred

Create first change
fred
After some time
you will see
yours change
on list of open
changes

roman
Meet Roman

Review change
roman

Review change
roman
Double click on
file will open a
compare view

Review change
roman
You can provide
comments directly
for each code line

Review change
roman
As you see Jenkins
already have an
opinion about this
change

Review change
roman
You can publish yours
comments using 'Publish
Comments...' button

Review change
roman
Now you can provide
yours vote and comment
for this change

fred
Switch back to Fred

View incoming comments
fred
You will be
informed about
new comments
on yours reviews

Abandon change
fred
If you push something by
accident you can always
abandon such change

Abandon change
fred

fred
Pushing multiple changes

Push multiple commits
fred
Create two or more
commits in a row
and use standard EGit
'Push to Gerrit...' flow

Push multiple commits
fred
Gerrit will create separate
review requests for each
commit

roman
Switch to Roman

Review connected changes
roman
Of course you will see
two open changes, let's
review last one!

roman
Jenkins already verified
this change, so let's
merge it!

roman

roman
Last step is to push
'Submit' button

roman
Change was submitted,
but it is not merged
because it's parent change
is still under review. It will
be automatically merged
after parent will be
accepted

roman
Let's review
second
change

roman
Of course it was merged
successfully

roman
Of course it was also merged
successfully
Wat is going
with previously
submitted
change?

roman
Roman goes to Bahama
(continue other's work)

Continue other's work
fred
All changes are stored
in Gerrit, you can
fetch each patch set
version when ever
you want to

fred
Provide meaningful
branch name and
click 'Finish'

fred
Done, you have
Roman's changes
locally and can
continue his work

Code Review Tips
● Be constructive, don't hate, always propose or point to
solution
● Don't take comments personally, they are only about
code and how you can improve, code and your skills
● Code review is like refactoring of code that you have
written long time ago … you need to understand
author's intention
● It's like TDD, review code before it hit main repository.
This will guarantee the best application quality
● Do code review on daily basis … remember when you
are not reviewing other's code then application is not
progressing

Dariusz Łuksza, CollabNet
dariusz@luksza.org
@dluksza
“Review your code like a Googler”
Q&A

BTW. Don't forget about DevCrowd
conference in Szczecin in 2014. More
info you can found at:
http://devcrowd.pl

Review your code like a Googler

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