code review for teams too busy to review code - atlassian summit 2010

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A guide for chronically time-poor developers

Code Review for Busy Teams

Brendan Humphreys, Atlassian

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Who am I?

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• @brendanh•Team Lead, FishEye & Crucible•12+ years experience doing code review•12+ years of trying to do code review better•

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Topics

•Back to basics•How to we got to where we are•Three steps towards code review•Strategies & hurdles•Some tips for better reviews•

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#include <stdio.h>main(t,_,a)char *a;{return!0<t?t<3?main(-79,-13,a+main(-87,1-_,main(-86,0,a+1)+a)):1,t<_?main(t+1,_,a):3,main(-94,-27+t,a)&&t==2?_<13?main(2,_+1,"%s %d %d\n"):9:16:t<0?t<-72?main(_,t,"@n'+,#'/*{}w+/w#cdnr/+,{}r/*de}+,/*{*+,/w{%+,/w#q#n+,/#{l,+,/n{n+,/+#n+,/#\;#q#n+,/+k#;*+,/'r :'d*'3,}{w+K w'K:'+}e#';dq#'l \q#'+d'K#!/+k#;q#'r}eKK#}w'r}eKK{nl]'/#;#q#n'){)#}w'){){nl]'/+#n';d}rw' i;# \){nl]!/n{n#'; r{#w'r nc{nl]'/#{l,+'K {rw' iK{;[{nl]'/w#q#n'wk nw' \iwk{KK{nl]!/w{%'l##w#' i; :{nl]'/*{q#'ld;r'}{nlwb!/*de}'c \;;{nl'-{}rw]'/+,}##'*}#nc,',#nw]'/+kd'+e}+;#'rdq#w! nr'/ ') }+}{rl#'{n' ')# \}'+}##(!!/"):t<-50?_==*a?putchar(31[a]):main(-65,_,a+1):main((*a=='/')+t,_,a+1) :0<t?main(2,2,"%s"):*a=='/'||main(0,main(-61,*a,"!ek;dc i@bK'(q)-[w]*%n+r3#l,{}:\nuwloca-O;m .vpbks,fxntdCeghiry"),a+1);}

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What is it that we do all day?

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Req. Design Coding Testing QA Production

$$$

Relative cost of fixing a bug

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$500 million payload

$8 billionrocket

1 line softwaredefect

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The Rise of Agile

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Machines vs Humans

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blocky:~ brendan$ javac hello.java hello.java:6: cannot find symbolsymbol : variable lengthlocation: class java.lang.String for (int i = 0; i < s.length; i++) { ^1 error

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•Checkstyle, Lint, PMD•Findbugs•Clover

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Smarter Tools

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Continuous Feedback

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Tougher Questions

•Meet requirements? •Architecturally sound?•Futureproof?•Coding idioms correct?•Potential reuse•Domain knowledge

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CodeReview}

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Code Review

•“Systematic review of code by peers”• reduce defects• spread code ownership• mentor developers

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Formal Code InspectionFagan, 1976

Finds Defects Early!

Printed Source code!

Rigid process,Face-to-face meetings!

Very slowImpractical for largecodebases

Great for mentoring, knowledge sharing

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Very effective code review, finds defects early

Great for sharing knowledge,mentoring

Pair Programming

Requires two developers,co-located

Transient discussionPersonalities

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Tool-assisted Code Review

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•Managed workflow and notification•Record of discussion•Asynchronous•Change team culture?

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3 steps towards a code review culture

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•Make activity visible•Make code sharable•Encourage discussions around code

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Making Activity Visible

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FishEye: Unlock your repository

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Making Activity Visible

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•The FishEyeActivity Stream•Web•RSS•Watches• JIRA•

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Making Code Sharable

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•FishEye makes it easy to share code pointers•File revisions•Source Lines•Diffs•ChangeSets•

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EncouragingDiscussionsAround code

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Crucible: Lightweight Code Review

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Crucible: ChangeSet Discussions

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ChangeSet Discussions

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•Simple way to provide ad-hoc feedback•Threaded discussions•ChangeSet author notified•Appear in Activity Stream•Preserved as annotation to ChangeSet•

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Crucible: Snippets

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Snippets•Simple “paste-bin” service•Anyone can comment, reply, raise defect•All participants notified•Appear in activity stream•Durable, sharable

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Crucible: “formal” review

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•Simple workflow• draft, review, summarize, close•Manage review workload• target particular reviewers•Advanced features• Pre-commit, Iterative, create from JIRA

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How to get started

•Go slow•Just the diffs•Review the scariest code!•On demand•On assignment

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Common Hurdles to Adoption

•“It takes too much time”•"Code reviews can get nasty"•"We have to stick to XYZ process"•"I don't want to leave my IDE"

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Four tips for better reviews

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#1:Strive for Ego-Free Reviews

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#1: Ego-Free Reviews

• No personal Pronouns

• No point scoring

• Moderator to police

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#2:Don’t be a

Pedant

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#2: Don’t be a Pedant

•Use tools to enforce coding style, catch common errors

•Look for the forest, not the trees

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#3: Find Problems,

Not Solutions

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#3: Find Problems, Not Solutions

• Except for trivial fixes

• Pair program instead

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#4: Embrace Feedback55

•You will learn from it!

•You will learn to love it!

#4: Embrace Feedback

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#include <stdio.h>main(t,_,a)char *a;{return!0<t?t<3?main(-79,-13,a+main(-87,1-_,main(-86,0,a+1)+a)):1,t<_?main(t+1,_,a):3,main(-94,-27+t,a)&&t==2?_<13?main(2,_+1,"%s %d %d\n"):9:16:t<0?t<-72?main(_,t,"@n'+,#'/*{}w+/w#cdnr/+,{}r/*de}+,/*{*+,/w{%+,/w#q#n+,/#{l,+,/n{n+,/+#n+,/#\;#q#n+,/+k#;*+,/'r :'d*'3,}{w+K w'K:'+}e#';dq#'l \q#'+d'K#!/+k#;q#'r}eKK#}w'r}eKK{nl]'/#;#q#n'){)#}w'){){nl]'/+#n';d}rw' i;# \){nl]!/n{n#'; r{#w'r nc{nl]'/#{l,+'K {rw' iK{;[{nl]'/w#q#n'wk nw' \iwk{KK{nl]!/w{%'l##w#' i; :{nl]'/*{q#'ld;r'}{nlwb!/*de}'c \;;{nl'-{}rw]'/+,}##'*}#nc,',#nw]'/+kd'+e}+;#'rdq#w! nr'/ ') }+}{rl#'{n' ')# \}'+}##(!!/"):t<-50?_==*a?putchar(31[a]):main(-65,_,a+1):main((*a=='/')+t,_,a+1) :0<t?main(2,2,"%s"):*a=='/'||main(0,main(-61,*a,"!ek;dc i@bK'(q)-[w]*%n+r3#l,{}:\nuwloca-O;m .vpbks,fxntdCeghiry"),a+1);}

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blocky:~ brendan$ ./a.outOn the first day of Christmas my true love gave to mea partridge in a pear tree.

On the second day of Christmas my true love gave to metwo turtle dovesand a partridge in a pear tree.

On the third day of Christmas my true love gave to methree french hens, two turtle dovesand a partridge in a pear tree.

On the fourth day of Christmas my true love gave to mefour calling birds, three french hens, two turtle dovesand a partridge in a pear tree.

On the fifth day of Christmas my true love gave to mefive gold rings;four calling birds, three french hens, two turtle dovesand a partridge in a pear tree.

On the sixth day of Christmas my true love gave to mesix geese a-laying, five gold rings;four calling birds, three french hens, two turtle dovesand a partridge in a pear tree.

On the seventh day of Christmas my true love gave to meseven swans a-swimming,six geese a-laying, five gold rings;four calling birds, three french hens, two turtle dovesand a partridge in a pear tree.

On the eighth day of Christmas my true love gave to meeight maids a-milking, seven swans a-swimming,six geese a-laying, five gold rings;four calling birds, three french hens, two turtle dovesand a partridge in a pear tree.

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#include <stdio.h>main(t,_,a)char *a;{return!0<t?t<3?main(-79,-13,a+main(-87,1-_,main(-86,0,a+1)+a)):1,t<_?main(t+1,_,a):3,main(-94,-27+t,a)&&t==2?_<13?main(2,_+1,"%s %d %d\n"):9:16:t<0?t<-72?main(_,t,"@n'+,#'/*{}w+/w#cdnr/+,{}r/*de}+,/*{*+,/w{%+,/w#q#n+,/#{l,+,/n{n+,/+#n+,/#\;#q#n+,/+k#;*+,/'r :'d*'3,}{w+K w'K:'+}e#';dq#'l \q#'+d'K#!/+k#;q#'r}eKK#}w'r}eKK{nl]'/#;#q#n'){)#}w'){){nl]'/+#n';d}rw' i;# \){nl]!/n{n#'; r{#w'r nc{nl]'/#{l,+'K {rw' iK{;[{nl]'/w#q#n'wk nw' \iwk{KK{nl]!/w{%'l##w#' i; :{nl]'/*{q#'ld;r'}{nlwb!/*de}'c \;;{nl'-{}rw]'/+,}##'*}#nc,',#nw]'/+kd'+e}+;#'rdq#w! nr'/ ') }+}{rl#'{n' ')# \}'+}##(!!/"):t<-50?_==*a?putchar(31[a]):main(-65,_,a+1):main((*a=='/')+t,_,a+1) :0<t?main(2,2,"%s"):*a=='/'||main(0,main(-61,*a,"!ek;dc i@bK'(q)-[w]*%n+r3#l,{}:\nuwloca-O;m .vpbks,fxntdCeghiry"),a+1);}

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