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Version Control - Tips, tricks & good citizenship

Tess Barnes
February 18, 2016

Version Control - Tips, tricks & good citizenship

Are you nervous of version control even if you don't admit it? Have things got harder since your team expanded? Don’t panic! you’re not on your own. I've put together a run down of some of my tricks, tips and ‘good citizen’ techniques to avoid the worst kinds of conflicts and deal with the remaining ones as efficiently as possible. Join me on a journey through some of the causes of version control pain after which we will visit some social and technical solutions. I'll lead you via branching policies, basic conflict resolution, to more tricky conflict management. We will spend time with some of the lesser known features of version control and command line hacks to stay in charge of multiple branches. As a bonus we will discover how version control can be integrated with other tools having many positive knock on effects for your team and wider business: How forcing commit message formats and automating your change log can help your release process or apps to streamline code reviews can avoid some unnecessary context switching. Triggered notification of interested parties helps keep everyone in the loop especially for breaking changes.

Tess Barnes

February 18, 2016
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  1. Tess Barnes February 2016 CC BY-ND 4.0
    Version Control
    Tips, tricks & good citizenship

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  2. Tess Barnes CC BY-ND 4.0
    February 2016
    Tess Barnes
    • first website in html3
    • multi language developer
    • agile advocate
    • works for Fasthosts
    • newbie speaker

    https://joind.in/talk/ac52d
    • @crataegustess

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  3. Tess Barnes CC BY-ND 4.0
    February 2016
    Basic levels
    • text conflicts
    • tree conflicts
    • avoiding conflicts
    • more complex codebases

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  4. Tess Barnes CC BY-ND 4.0
    February 2016
    Bonus levels
    • keep it secret, keep it safe
    • collaboration and review
    • clean code and standards
    • change logs for the lazy
    • keeping everyone in the loop
    • triggering other automatons

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  5. Tess Barnes February 2016 CC BY-ND 4.0
    Minor conflicts
    straight forward; not scary

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  6. Tess Barnes CC BY-ND 4.0
    February 2016
    Minor conflict resolution
    • know your tools
    ✦ command line
    ✦ gui, shortcut menus, visual diff
    • know your code
    • talk to your colleagues

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  7. Tess Barnes February 2016 CC BY-ND 4.0
    Interleaving changes
    slightly more complex to solve

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  8. Tess Barnes CC BY-ND 4.0
    February 2016
    Interleaved causes
    • two developers work on the same file at the same time
    • both replace the same old method
    • “badly” scheduled work
    • “no” design
    • “lack of” communication

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  9. Tess Barnes CC BY-ND 4.0
    February 2016
    which signature?

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  10. Tess Barnes CC BY-ND 4.0
    February 2016
    just theirs

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  11. Tess Barnes CC BY-ND 4.0
    February 2016
    manual edit - ready to save

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  12. Tess Barnes CC BY-ND 4.0
    February 2016
    actual changes to merge back down

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  13. Tess Barnes February 2016 CC BY-ND 4.0
    Tree conflicts
    this is when the fun starts

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  14. Tess Barnes CC BY-ND 4.0
    February 2016
    recognise that face?…
    [1]

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  15. Tess Barnes CC BY-ND 4.0
    February 2016
    Missing
    Delete
    Add

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  16. Tess Barnes CC BY-ND 4.0
    February 2016
    Add conflicts
    trying to add a file that already exists
    Add

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  17. Tess Barnes CC BY-ND 4.0
    February 2016
    these are cleavers
    [2]
    Cleaver.php
    Properties:
    isSharp
    weightInGram
    bladeLengthInInch
    Methods:
    sharpen($on){}
    cut($something){}

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  18. Tess Barnes February 2016 CC BY-ND 4.0
    Mac:wcAdd2 tess$ vi addThis.php
    Mac:wcAdd2 tess$ svn add *
    A Cleavers.php
    Mac:wcAdd2 tess$ svn update
    Updating '.':
    Conflict discovered in '/Repos/svnTest/Add2/Cleavers.php'.
    Select: (p) postpone, (df) diff-full, (e) edit,
    (mc) mine-conflict, (tc) theirs-conflict,
    (s) show all options:
    Add conflicts

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  19. Tess Barnes CC BY-ND 4.0
    February 2016
    Fixing add conflicts
    • pre-empt; check the svn log before you update
    • postpone; many tools treat this as a text conflict
    • check the meaning; rename your file
    • collaborate; this could be a duplicate

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  20. Tess Barnes February 2016 CC BY-ND 4.0
    Should you fix?
    just because you can doesn’t always mean you should
    (on your own)

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  21. Tess Barnes CC BY-ND 4.0
    February 2016
    these are cleavers…

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  22. Tess Barnes CC BY-ND 4.0
    February 2016
    these are cleavers…
    … meat cleavers
    these are also cleavers…
    … following a cause

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  23. Tess Barnes CC BY-ND 4.0
    February 2016

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  24. Tess Barnes CC BY-ND 4.0
    February 2016
    Delete conflicts
    trying to edit a deleted file or delete an edited file
    Delete

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  25. Tess Barnes February 2016 CC BY-ND 4.0
    Mac:wcDel1 tess$ vi deletedFile.py
    Mac:wcDel1 tess$ svn update
    {…}
    Mac:wcDel1 tess$ svn status
    A + C deletedFile.py
    > local edit, incoming delete upon update
    Summary of conflicts:
    Tree conflicts: 1
    ———————————————————————
    D C editedFile.py
    > local delete, incoming edit upon update
    delete conflicts

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  26. Tess Barnes CC BY-ND 4.0
    February 2016
    Fixing delete conflicts
    • someone has deleted that nice file you fixed so beautifully…
    ✦ so find them and talk - it could be just a rename!
    ✦ renames can sometimes be solved by patch file
    ✦ massive refactors? talk, collaborate, hand copy
    ✦ feature removal? don't get frustrated, get coffee

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  27. Tess Barnes CC BY-ND 4.0
    February 2016
    Missing files
    trying to apply change to non existent file
    Missing

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  28. Tess Barnes CC BY-ND 4.0
    February 2016
    when did it get added?

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  29. Tess Barnes CC BY-ND 4.0
    February 2016
    Avoiding missing files
    • depends on branching / merging strategy
    • always merge up to clean working copy
    • useful commit messages please
    • merging back down becomes so much easier
    • … and so do code reviews!

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  30. Tess Barnes CC BY-ND 4.0
    February 2016
    why so many
    conflicts?

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  31. Tess Barnes CC BY-ND 4.0
    February 2016
    here’s why
    • lots of developers
    • lots of overlapping work
    • context swapping
    • impossible to talk 

    all the time
    • we refactor a lot
    that’s me in the dotty scarf [4]

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  32. Tess Barnes CC BY-ND 4.0
    February 2016
    Get out of jail free
    • patch files
    • multiple checkouts
    • stash your work in progress
    • cherry pick commits
    • use a standard e.g. PSR2, PSR3

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  33. Tess Barnes CC BY-ND 4.0
    February 2016
    Why just fix?
    • clean up your code base: 

    be a good code scout
    • be prepared
    • solve root causes
    • have a strategy
    • get the most out of your

    chosen tools

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  34. Tess Barnes CC BY-ND 4.0
    February 2016
    VC tree bonsai
    • principles
    • branching strategies
    • complexity
    keep it looking beautiful [5]

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  35. Tess Barnes CC BY-ND 4.0
    February 2016
    Principles
    • it’s a tree!
    • check out 

    only what you need
    • meaningful names
    • keep it clean
    • keep it current

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  36. Tess Barnes CC BY-ND 4.0
    February 2016
    Branching strategy
    • how do components interact? what is common?
    • how do we code review?
    • what do we test? where and when?
    • how do we release?
    • apocalypse plan (hot fix management)

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  37. Tess Barnes CC BY-ND 4.0
    February 2016
    Coping with complexity
    One script to rule them all
    • quick, efficient, lazy - what’s not to like?
    • handle complex project checkouts
    • fewer missed changes on check in
    • look ahead _before_ updating

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  38. Tess Barnes February 2016 CC BY-ND 4.0
    Checkout (parameterise for branches) + use for update:
    svn co http://your.repository/component/trunk C:\WCopy
    \Component
    svn co http://your.repository/common/dependent1/trunk \
    C:\WCopy\lib\dependent1
    Check Modifications:
    svn status C:\WCopy\Component
    svn status C:\WCopy\lib\dependent1
    View commit history:
    svn log --limit 10 C:\WCopy\Component
    svn log -l 10 C:\WCopy\lib\dependent1
    Script Examples

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  39. Tess Barnes February 2016 CC BY-ND 4.0
    Getting more out of
    your version control
    bonus levels…

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  40. Tess Barnes CC BY-ND 4.0
    February 2016
    Bonus levels
    • keep it secret, keep it safe
    • collaboration and review
    • clean code and standards
    • change logs for the lazy
    • keeping everyone in the loop
    • triggering other automatons

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  41. Tess Barnes CC BY-ND 4.0
    February 2016
    What is a hook?
    • insertion point for custom code
    ✦ before the commit happens
    ✦ after the commit
    • server side or client side
    • centralised or pseudo-distributed systems

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  42. Tess Barnes CC BY-ND 4.0
    February 2016
    Get hooked
    • enforce authorisation
    • enforce code review
    • enforce standards
    • create change logs easily

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  43. Tess Barnes CC BY-ND 4.0
    February 2016
    Enforcing authorisation
    keeping your stuff safe

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  44. Tess Barnes CC BY-ND 4.0
    February 2016
    Why enforce authorisation
    • do you want the world to read everything?
    • are there more sensitive components?
    • do you want only certain people to commit?
    • how often or urgently will this change?

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  45. Tess Barnes CC BY-ND 4.0
    February 2016
    Authorisation solutions
    ★ apache
    • mod_authz_svn + rules file
    ★ svnserve
    • svnserve.conf entry -> rules file
    both support LDAP

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  46. Tess Barnes CC BY-ND 4.0
    February 2016
    What if you use git?
    ★ git lab
    • Cloud or EE or CE on linux
    ★ bit bucket
    • EE or Cloud or Academic licence
    self serve is compatible with LDAP

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  47. Tess Barnes CC BY-ND 4.0
    February 2016
    Enforcing code review
    two heads are better than one

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  48. Tess Barnes CC BY-ND 4.0
    February 2016
    Why use tools with this?
    • get a window into the code
    ✦ no more switching context
    • visibility of reviews to everyone
    ✦ multiple reviewers
    • protect your master repository

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  49. Tess Barnes CC BY-ND 4.0
    February 2016
    How do we automate?
    • roll your own
    • enforce via repository access
    • automate the basics: compile or run php -f -l
    • use an IDE or at least get good plugins

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  50. Tess Barnes CC BY-ND 4.0
    February 2016
    Getting outside help
    • handle merge requests
    ✦ gitlab, bitbucket, git flow, gitlab flow
    • gateway software
    ✦ gerrit

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  51. Tess Barnes CC BY-ND 4.0
    February 2016
    Enforcing standards
    making it easier to handle…

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  52. Tess Barnes CC BY-ND 4.0
    February 2016
    Enforcing standards
    • php code sniffer / stylecop / python compile
    • execute as client side pre commit hook
    • use built in phpcs-svn-pre-commit for server side hook
    • refuse commit if changes don’t pass
    • give grace with a threshold

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  53. Tess Barnes CC BY-ND 4.0
    February 2016
    TortoiseSVN example
    • php code sniffer

    on working copy
    • check current directory or check changed
    list to be more efficient
    • Not ideal: client side hooks rely on the
    developer environment

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  54. Tess Barnes February 2016 CC BY-ND 4.0
    Why reinvent the wheel? Use php code sniffer’s built in pre commit hook
    script in your own pre commit hook file:
    /path/to/PHP_CodeSniffer/scripts/phpcs-svn-pre-commit \
    --standard=PSR2 "$REPOS" -t "$TXN" >&2 || exit 1
    This builds on svnlook changed and svnlook cat to check the latest version of
    the files, ignoring files being deleted
    To add a tolerance, amend the phpcs-svn-pre-commit file:
    $tolerance = 5;
    $numErrors = $phpcs->process();
    if ($numErrors > $tolerance) {
    exit(1);
    }
    More info: PHP_CodeSniffer - wiki - Using-the-SVN-pre-commit-Hook
    server hook example

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  55. Tess Barnes CC BY-ND 4.0
    February 2016
    Creating change logs
    the lazy way

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  56. Tess Barnes CC BY-ND 4.0
    February 2016
    Lazy change logs
    • Pre commit: Enforce commit message patterns
    ✦ makes things clearer for code review
    ✦ encourages user facing comments
    • Post commit: Scrape the log for publishable data
    ✦ allow hot fix & merge to be treated differently
    ✦ combine logs from multiple sources

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  57. Tess Barnes February 2016 CC BY-ND 4.0
    Check min length
    Pattern match
    Validate commit messages
    Allow for special tags:
    3rd party, merge, hotfix

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  58. Tess Barnes February 2016 CC BY-ND 4.0
    scrape details from svn log

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  59. Tess Barnes CC BY-ND 4.0
    February 2016
    Publish those logs
    • only add the latest e.g. by date or last 100
    • on post commit hook or regular cron job
    • ftp upload with rss / atom feed?
    • rabbitMQ / zeroMQ pub sub?
    • email notification?

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  60. Tess Barnes CC BY-ND 4.0
    February 2016
    Keep everyone in the loop
    • can you script it?

    you can post commit it
    • keep it specific
    • avoid duplication
    • keep it relevant
    • beware of performance

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  61. Tess Barnes CC BY-ND 4.0
    February 2016
    Start a revolution
    • continuous build
    • deployment 

    to test servers
    • automated testing

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  62. Tess Barnes CC BY-ND 4.0
    February 2016
    In summary: do…
    • get comfortable with the basics
    • talk to each other
    • care about your code
    • consider how version control fits in
    • get the most out of it

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  63. Tess Barnes CC BY-ND 4.0
    February 2016
    Still hungry?
    If you want to look deeper check out these references for further info…
    ✦ git book: http://git-scm.com/book/en/v2
    ✦ svn book: http://svnbook.red-bean.com/en/1.7/index.html
    ✦ php code scouts: http://phpboyscout.uk/php-scout/
    ✦ php sniffer: https://github.com/squizlabs/PHP_CodeSniffer
    ✦ PSR: http://www.php-fig.org/psr/psr-2/ (the PSR-2 rundown),

    http://code.tutsplus.com/tutorials/psr-huh--net-29314 (older but friendly)
    ✦ useful commit hooks (svn):

    http://blog.grimsy.net/2008/07/a-few-svn-pre-commit-hooks/

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  64. Tess Barnes CC BY-ND 4.0
    February 2016
    Popular links
    For more about tools to do things the easy way…
    ✦ TortoiseSVN: https://tortoisesvn.net
    ✦ GitHub: https://github.com
    ✦ GitLabFlow: http://doc.gitlab.com/ee/workflow/gitlab_flow.html
    ✦ Bitbucket: https://bitbucket.org/product/features
    ✦ Gerrit: https://www.gerritcodereview.com
    ✦ Top ten Sublime plugins (blog): http://neverstopbuilding.com/sublime-plugins-for-php
    ✦ Fossil: http://fossil-scm.org/index.html/doc/trunk/www/index.wiki

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  65. Tess Barnes CC BY-ND 4.0
    February 2016
    Credit where it’s due
    The media in these slides are my own or credited where references can be found.
    [1] photo credit (CC BY 2.0) Evil Erin https://www.flickr.com/photos/evilerin/3078856253
    [2] image from Wikipedia https://en.wikipedia.org/wiki/Cleaver
    [3] image from Old English Hexateuch https://en.wikipedia.org/wiki/Old_English_Hexateuch
    [4] photo credit (CC BY 2.0) JD Hancock https://www.flickr.com/photos/jdhancock/8755184025
    [5] photo credit (CC BY-ND 2.0) Beverly Vealach https://www.flickr.com/photos/cowtools/293244244
    happy kitten - first seen on Dave Paquettes fun article
    zephod (Adam Pope as Zephod) (CC BY 3.0) https://commons.wikimedia.org/wiki/
    File:Adam_Pope_Zaphod_Beeblebrox.JPG
    don’t panic - photo credit (CC BY-SA 2.0) Sarabbit https://www.flickr.com/photos/sarabbit/4549185468
    Please bear this in mind when referencing or reusing any material.
    CC BY-ND 4.0 licence details

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  66. Tess Barnes February 2016 CC BY-ND 4.0
    Thanks for listening
    Any Questions?
    Feedback: https://joind.in/talk/ac52d

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