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.

Transcript

1. Tess Barnes February 2016 CC BY-ND 4.0 Version Control Tips, tricks & good citizenship
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
3. Tess Barnes CC BY-ND 4.0 February 2016 Basic levels • text conflicts • tree conflicts • avoiding conflicts • more complex codebases
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
5. Tess Barnes February 2016 CC BY-ND 4.0 Minor conflicts straight forward; not scary
7. 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
8. Tess Barnes February 2016 CC BY-ND 4.0 Interleaving changes slightly more complex to solve
10. 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
11. Tess Barnes CC BY-ND 4.0 February 2016 which signature?
12. Tess Barnes CC BY-ND 4.0 February 2016 just theirs
13. Tess Barnes CC BY-ND 4.0 February 2016 manual edit - ready to save
14. Tess Barnes CC BY-ND 4.0 February 2016 actual changes to merge back down
15. Tess Barnes February 2016 CC BY-ND 4.0 Tree conflicts this is when the fun starts
16. Tess Barnes CC BY-ND 4.0 February 2016 recognise that face?… [1]
17. Tess Barnes CC BY-ND 4.0 February 2016 Missing Delete Add
18. Tess Barnes CC BY-ND 4.0 February 2016 Add conflicts trying to add a file that already exists Add
19. Tess Barnes CC BY-ND 4.0 February 2016 these are cleavers [2] Cleaver.php Properties: isSharp weightInGram bladeLengthInInch Methods: sharpen($on){} cut($something){}
20. 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
21. 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
22. 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)
23. Tess Barnes CC BY-ND 4.0 February 2016 these are cleavers…
24. Tess Barnes CC BY-ND 4.0 February 2016 these are cleavers… … meat cleavers these are also cleavers… … following a cause
25. Tess Barnes CC BY-ND 4.0 February 2016
26. Tess Barnes CC BY-ND 4.0 February 2016 Delete conflicts trying to edit a deleted file or delete an edited file Delete
27. 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
28. 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
29. Tess Barnes CC BY-ND 4.0 February 2016 Missing files trying to apply change to non existent file Missing
30. Tess Barnes CC BY-ND 4.0 February 2016 when did it get added?
31. 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!
32. Tess Barnes CC BY-ND 4.0 February 2016 why so many conflicts?
33. 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]
34. 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
35. 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
36. Tess Barnes CC BY-ND 4.0 February 2016 VC tree bonsai • principles • branching strategies • complexity keep it looking beautiful [5]
37. 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
38. 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)
39. 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
40. 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
43. Tess Barnes February 2016 CC BY-ND 4.0 Getting more out of your version control bonus levels…
44. 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
45. 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
46. Tess Barnes CC BY-ND 4.0 February 2016 Get hooked • enforce authorisation • enforce code review • enforce standards • create change logs easily
47. Tess Barnes CC BY-ND 4.0 February 2016 Enforcing authorisation keeping your stuff safe
48. 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?
49. 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
50. 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
51. Tess Barnes CC BY-ND 4.0 February 2016 Enforcing code review two heads are better than one
52. 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
53. 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
54. Tess Barnes CC BY-ND 4.0 February 2016 Getting outside help • handle merge requests ✦ gitlab, bitbucket, git flow, gitlab flow • gateway software ✦ gerrit
55. Tess Barnes CC BY-ND 4.0 February 2016 Enforcing standards making it easier to handle…
56. 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
57. 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
58. 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
59. Tess Barnes CC BY-ND 4.0 February 2016 Creating change logs the lazy way
60. 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
61. 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
62. Tess Barnes February 2016 CC BY-ND 4.0 scrape details from svn log
63. 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?
64. 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
65. Tess Barnes CC BY-ND 4.0 February 2016 Start a revolution • continuous build • deployment 
 to test servers • automated testing
66. 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
68. 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/
69. 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
70. 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
71. Tess Barnes February 2016 CC BY-ND 4.0 Thanks for listening Any Questions? Feedback: https://joind.in/talk/ac52d