Doctor Gitlove

...or: How I Learned to Stop Worrying and Love Git Rebase

In this talk Paul Bowsher gives some insight into how Git works under-the-hood, so next time you find yourself in some horrible rebase state it's not so scary; you know where it's actually stuck. He explores the different types of object used within git's database and how they all link together to form your git history.

Find the video of the talk at http://vimeo.com/80789852

Transcript

1. Doctor Gitlove Or how I learned to stop worrying and love git rebase
2. What is Git? • Distributed Object Database • Used for Versioned Source Control
3. Git SVN • Own local repository • SHA commit refs • Commit to local • Push to remote • Branches are references • master • Central repository • Sequential commit #s • Commit to remote ! • Branches are directories • trunk
4. Working copy Files on your filesystem
5. Working copy Files on your filesystem
6. Index Staged changes for your next commit
7. Index Staged changes for your next commit
8. Repository Committed changes
9. Repository Committed changes
10. Stash Temporary pseudo-commit
11. Stash Temporary pseudo-commit
12. Stash Temporary pseudo-commit
13. Stash Temporary pseudo-commit
14. Stash Temporary pseudo-commit
15. Objects • Referred to by SHA-1 of their contents • Blob • Tree • Commit • Tag • Immutable
16. Blobs Every file added to the index is stored as a blob
17. Blobs Blobs can be anywhere in the tree
18. Blobs Deleting files doesn’t automatically remove the blob
19. Trees Store location of blob within working copy Store directory structure
20. Trees Inherently versioned
21. Commits Pointers to a tree and parent commit
22. Commits Pointers to a tree and parent commit http://xkcd.com/1296/
23. Tags “Immutable” pointers to commits
24. Refs Not objects, just shorthand pointers
25. git push git fetch • Synchronises object database • blobs, trees, commits, tags • Synchronises remote references • fetch namespaces: origin/master • push fast-forwards •git push --tags
26. Push Uploads missing objects Fast-forwards remote refs
27. Fetch Downloads missing objects Doesn’t touch local refs or working copy
28. Merge New commit with two parents
29. Merge New commit with two parents
30. Rebase Reset local to remote, replay your commits
31. Rebase Reset local to remote, replay your commits
32. Reset Point your ref at a different commit
33. Reset Point your ref at a different commit
34. Reset •--hard • Resets all including working copy •--mixed (default) • Resets all excluding working copy •--soft (git commit --amend) • Resets commit only
35. Pull Some of the above
36. git up $ gem install git-up 1. Stash 2. Fetch 3. Rebase all branches 4. Unstash
37. Feature Branches
38. Integration Branches
39. Rebasing Integration Branches
40. Rebase versus Merge • Rebase • Deal with merge conflicts for each commit that gets replayed • Cleaner history • Requires a force-push, replacing history • Merge • One big merge conflict • Many merge commits into your branch
41. Common gitfalls
42. Collaborator has force- pushed your branch
43. Collaborator has force- pushed your branch • Don’t rebase if your collaborator is still working directly on the branch • Rebase of feature branch onto integration branch is still easy*
44. Rebased then pulled
45. Rebased then pulled
46. Resources Atlassian Git tutorial - https://www.atlassian.com/git/tutorial Try Git - https://try.github.io PeepCode Git Internals PDF - https://github.com/pluralsight/git- internals-pdf/releases Pro Git book - http://git-scm.com/book Git website - http://git-scm.com/