On 19 February I held a presentation for my colleagues about distributed version control systems (DVCS). My main goal was to inform them on what I think is the next logical step in source control. Also see http://vlent.nl/weblog/2010/02/25/distributed-version-control-systems-presentation

1. Distributed Version
Control Systems
A short introduction
19 February, 2010

2. Outline
• Goals
• What is DVCS anyway?
• What are the disadvantages?
• What are the advantages?
• How do I interface with Subversion?

3. Goals
• Inform about DVCS
• Not trying to force a
change!

4. DVCS in 5 minutes
Flexible workflow

5. DVCS in 5 minutes
Flexible workflow

6. DVCS in 5 minutes
Flexible workflow

7. DVCS in 5 minutes
Flexible workflow

8. DVCS in 5 minutes
Flexible workflow
dev prod

9. DVCS in 5 minutes
• Complete local copy of the repository
• Most common actions don’t need network
• Private branches

10. DVCS in 5 minutes
• Most popular:
• Bazaar
• Git
• Mercurial

11. Disadvantages
• More complex to learn/use
• New or redefined terminology
• No partial clones so one repo per project
• Easier to crawl into a cave

12. Advantages
• Local commits (easier to experiment)
• FAST!
• Cleaner working copy (no .svn dirs)
• Working copy svn same size as full history
• Code review local commits before push

13. Advantages
• Cooperation without commits to central
repo
• Better merging, thus low barrier for
branching
• Commit before merge instead of merge
before commit

14. Cooperation

15. Cooperation

16. Cooperation

17. Branching
“trunk”

18. Branching
“trunk”
branch
feature X

19. Branching
“trunk”
branch
feature X

20. Branching
“trunk”
branch
feature X

21. Branching
“trunk”
branch
branch

22. Branching
“trunk”
branch
branch

23. Branching
“trunk”
branch
feature X

24. Branching
release
“trunk”
branch
branch
bugfix

25. Branching
“trunk”
branch
branch
feature X

26. Merge before commit
remote local
update
run tests; no errors

27. Merge before commit
remote local
update
run tests; no errors
write code
run tests; no errors

28. Merge before commit
remote local
update
run tests; no errors
write code
run tests; no errors
update + solve conflicts

29. Merge before commit
remote local
update
run tests; no errors
write code
error in run tests; no errors
commit?
error in
update + solve conflicts
merge?
run tests; errors

30. Merge before commit
remote local
update
run tests; no errors
write code
error in run tests; no errors
commit?
error in
update + solve conflicts
merge?
run tests; errors
No commit to revert to!

31. Commit before merge
remote local
update
run tests; no errors

32. Commit before merge
remote local
update
run tests; no errors
write code
run tests; no errors
make local commit

33. Commit before merge
remote local
update
run tests; no errors
write code
run tests; no errors
make local commit
update + solve conflicts

34. Commit before merge
remote local
update
run tests; no errors
write code
error in run tests; no errors
commit?
make local commit
error in
update + solve conflicts merge?
run tests; errors

35. Commit before merge
remote local
update
run tests; no errors
write code
Revert to
run tests; no errors
working commit
make local commit and try again

36. How I use git-svn
svn buildout
src
theme
policy

37. How I use git-svn
svn buildout
src
theme
policy
$ git svn clone -s <buildout-url>
git buildout
src
theme
policy

38. How I use git-svn
svn buildout
src
theme svn:external
policy svn:external

39. How I use git-svn
svn buildout
src
theme svn:external
policy svn:external
$ git svn clone -s <buildout-url>
$ git-ext-svn-clone
git buildout
src
theme git
policy git

40. How I use git-svn
svn

41. How I use git-svn
svn
clone
master

42. How I use git-svn
svn
master
branch
feature X

43. How I use git-svn
other commits
svn
master
branch
feature X

44. How I use git-svn
svn
fetch + rebase
master
feature X

45. How I use git-svn
svn
master
rebase
feature X

46. How I use git-svn
svn
master
merge
feature X

47. How I use git-svn
svn
dcommit (push)
master

48. How I use git-svn
• Unsolved problem: how to use git-svn
when buildout uses:
• infrae.subversion ?
• mr.developer ?

49. Questions? Tips?