where refactoring meets big $$$
TRANSCRIPT
1CONFIDENTIAL
Where refactoring meetsBig $$$
First steps
2CONFIDENTIAL
RULES ;)
REFACTORING
3CONFIDENTIALBy The U.S. Army
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WHO REFACTORS CODE
QUESTION
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ON A DAILY BASIS ☺
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WHO PLANS REFACTORINGS?
QUESTION
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ACADEMIA TIME
REFACTORING
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What is refactoringWhat is refactoring
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==
Meanwhile in perfect worldMeanwhile in perfect world
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• It’s hard to maintain
• Changes in domain are coming
– New requirements are impossible to implement
• There are no tests (sic!)
• Development of new features is so slow
• System is slow
• You just don’t want to go to work anymore
– (nor your colleagues)
Why to refactorWhy to refactor
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EVERYDAY REFACTORINGS
REFACTORING TYPES
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Everyday refactoring :: DefinitionEveryday refactoring :: Definition
• Rename variable / method / class names
• Extract class / method / variable / parameter
• Move code around
• Removing duplication (DRY)
• Removing dead code
• Cleaning up comments
• Improving encapsulation
• etc
http://www.infoq.com/articles/natural-course-refactoring
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• Increases readability of code
• Enables understanding of code
• Introduces patterns
• Simplifies/allows testing
• Cleans up potential, simple, programming mistakes
• Fully supported by IDE in any language
• Is fast, does not need to be planned
• Does not require process, can be done on a go
• Is safe and non-intrusive
– But not always!
Everyday refactoring :: ProsEveryday refactoring :: Pros
By MazeNL77
15CONFIDENTIAL
• In big ball of mud is not always safe!
– Watch out for reflection!
• Without tests and tools (IDE) can be very dangerous
• May be source of funky bugs
• No process, not all developers will adapt
• If backed with restrictive tools, can be counterproductive
– Pre-hooks anyone?
Everyday refactoring :: ConsEveryday refactoring :: Cons
By Indi Samarajiva
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BIG BANG
REFACTORING TYPES
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Big Bang :: DefinitionBig Bang :: Definition
By Xtraterestrial
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• Allows for a fresh start
– New technology stack
– Clean architecture
– Better domain model
• Can be a serious contributor for finding a new job ;)
ProsPros
By MazeNL77
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ConsCons
By Indi Samarajiva
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ConsCons
• We don’t deliver anything for many, many sprints
• World moves forward, our application does not
• Business is unhappy
• Success of the new project is not guaranteed
By Indi Samarajiva
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ConsCons
By Indi Samarajiva
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Big Bang :: When to do itBig Bang :: When to do it
By Wayne Ray
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SPROUTING
REFACTORING TYPES
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• Proposed by Michael Feathers in
“Working Effectively with Legacy Code”
– To refactor methods
– And classes
• Can be used with whole packages, modules,
components, applications
Sprouting :: DefinitionSprouting :: Definition
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• Introducing new code in testable manner
• Separate abstractions
• Prevents rooting of new functionalities
• Enables change of architecture
• Allows to update technology stack
• Allows to build independent modules and applications
ProsPros
By MazeNL77
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• Requires much more work, people and resources than
standard feature release
• May add serious latency to functions and slow down the
whole system
• Adds more abstraction layers to the project
ConsCons
By Indi Samarajiva
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GET PERMISSION
REFACTORING
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Decide what to measureDecide what to measure
• How many commits / sprint
• How many commits / file (how often it changes)
– By different users/ In one sprint
• Cyclomatic complexity
• Code coverage
• LOC per sprint
• Findbugs issues
• Requests / second
• Resource (Memory/CPU) usage
• Lead time (how long its on board)
By Martinvl
29CONFIDENTIAL
Measure!Measure!
• Velocity
• Build time
• Number of failing builds
• Number of merges
– +time of each merge
• ROI / sprint
• Code quality
• Freeze time
• Response time
• Maximum load
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HOW TO MEASURE
REFACTORING
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QA and SupportQA and Support
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Show & discussShow & discuss
• Business like numbers
– Even if they don’t understand them
• Setup goals / milestones
• Try to use work time
• Setup day / sprint of excellence
• Organize hackathon / code retreat
• Share knowledge and train colleagues
• Set standards
– And enforce them with pre-commit hooks ;)
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Read list :: Build a book clubRead list :: Build a book club
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EXAMPLES
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• Quarter of development followed by phase 2 with up to 6 months of work for team
– And short break between them
• Funky structure of domain model
– TreeMap<Integer, Map<TabelType, Map<RecordType, List<TableId>>>>
• Only creator understood the design
Everyday refactoring :: Example -> Planned refactoringsEveryday refactoring :: Example -> Planned refactorings
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• ~5 year old system
• Build on top of 5+ year old code base
• Sudden plan to change business model without consulting with developers
– Business seen that as a simple change (we have everything)
– Development seen a lot of dependencies
– Unable to do as a simple change request
Big Bang :: Real world example -> Domain changeBig Bang :: Real world example -> Domain change
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Sprouting :: Real world exampleSprouting :: Real world example
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Sprouting :: Real world exampleSprouting :: Real world example
By Crochetbug
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Sprouting :: Real world exampleSprouting :: Real world example
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QA SupportQA Support
Case:
Releases are done each week, a lot of DB changes are tangled in, QA has to support each release.
Developers get often issues with not building app, due to DB schema differences. They ask QA for support to get new
schema after each release. A lot of people time is being wasted.
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Case:
Product did not have versioning in first place. It was build
by ant only with some hacks to introduce new build tool:
Maven. Whole thing was in one version, always.
One of hacks involved adding qualifier to allow testing on
different environments.
versioningversioning
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• Don’t allow that to happen
• Refactoring is everyone business
• Small group of experts
• Not everyone care about code quality
• You may end up with huge rotation
• Ideas are not evenly distributed between teams
Antipattern – refactoring teamAntipattern – refactoring team
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• Happens on regular basis
• Everyone participate
• Enables the everyday refactorings
• Does not have to be only about TODOs (duh ;))
TODO huntingTODO hunting
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I love your feedback! ☺I love your feedback! ☺
@michalgruca
www.rits.pl