Digging into Git

Daily Kos Skillshare by Meagan Waller

Transcript

1. Digging into Git Daily Kos Skillshare
2. De-magic-ifying Git Collaborating with a team Handy Git knowledge Objectives 2
3. 3 But first— a quick detour into graph theory.
4. A graph is a structure consisting of a collection of nodes and a collection of edges that connect pairs of nodes. 4
5. A graph is a structure consisting of a collection of nodes and a collection of edges that connect pairs of nodes. 4 Node Node Node Edge Edge Edge
6. 5 Thanks Euler Created the foundation for what we now call graph theory.
7. 6 Seven Bridges of Königsberg Can you walk through the city and cross every bridge exactly once?
8. 7 Seven Bridges of Königsberg Each land mass is a node, and each bridge an edge.
9. 7 Seven Bridges of Königsberg Each land mass is a node, and each bridge an edge.
10. 8 Seven Bridges of Königsberg Each land mass is a node, and each bridge an edge.
11. 8 Seven Bridges of Königsberg Each land mass is a node, and each bridge an edge.
12. 9 A Git Repo is a DAG (Directed Acyclic Graph)
13. 9 A Git Repo is a DAG (Directed Acyclic Graph)
14. 9 A Git Repo is a DAG (Directed Acyclic Graph)
15. 9 A Git Repo is a DAG (Directed Acyclic Graph)
16. 9 A Git Repo is a DAG (Directed Acyclic Graph)
17. 9 A Git Repo is a DAG (Directed Acyclic Graph) Not a DAG.
18. 10 A Git Repo is a DAG (Directed Acyclic Graph)
19. 10 A Git Repo is a DAG (Directed Acyclic Graph)
20. 10 A Git Repo is a DAG (Directed Acyclic Graph) A DAG
21. 11 What can you reach? Reachability is a core concept in Git.
22. 11 What can you reach? Reachability is a core concept in Git.
23. 11 What can you reach? Reachability is a core concept in Git.
24. 12 What can you reach? Reachability is a core concept in Git.
25. 12 What can you reach? Reachability is a core concept in Git.
26. 12 What can you reach? Reachability is a core concept in Git.
27. 13 What can you reach? Reachability is a core concept in Git.
28. 13 What can you reach? Reachability is a core concept in Git.
29. 13 What can you reach? Reachability is a core concept in Git.
30. 14 Git isn’t magic . .. .git
31. $ git init 14 Git isn’t magic git init $ git init ls -a . .. .git
32. Example Project 15
33. The Git directory is made up of Git objects. 16
34. 17 The Blob The contents of the file are stored as blobs. !"❱❱❱ git cat-file -p 2edbc8 # This is the Skillshare README
35. 18 The Tree Directories are stored as trees. Trees are pointers to blobs and other trees. !"❱❱❱ git cat-file -p d31e9 100644 blob 2edbc8 README.md 040000 tree 260449 app A tree stores a text file with the mode, type, sha, and, name of each entry.
36. 19 The Commit The history of these blobs and trees is stored in the commit object. !"❱❱❱ git cat-file -p 237e8d7 tree d31e9e author Meagan Waller committer Meagan Waller Initial commit A commit points to a tree and keeps an author, committer, message, and any parent commits
37. 20 The Commit The history of these blobs and trees is stored in the commit object. !"❱❱❱ git cat-file -p e825ee8 tree b8ba0 parent 045883 author Meagan Waller committer Meagan Waller A commit points to a tree and keeps an author, committer, message, and any parent commits
38. 21 The Commit The history of these blobs and trees is stored in the commit object. !"❱❱❱ git cat-file -p 1e4fb7a tree 5d7bf9 parent 4d9d44 parent 1ecf93 author Meagan Waller A commit points to a tree and keeps an author, committer, message, and any parent commits
39. 22 The Tag Tags are objects that provide a permanent shorthand name for a particular commit. !"❱❱❱ git cat-file -p v1.0 object 237e8d type commit tag v1.0 tagger Meagan Waller version 1.0 They contain an object, type, tagger, and a message. The type is usually a commit and the object is the SHA-1 of the commit you’re tagging.
40. Visualizing the Git Repo 23 !"❱❱❱ git log 4786ce0 (HEAD -> master) Merge branch ‘new-feature' 240106a (hotfix) Does the even cooler thing 78d44a3 (new-feature) Adds the amazing feature 830b929 Adds to the README 237e8d7 (tag: v1.0) Initial commit
41. Visualizing the Git Repo 24 Commits are nodes in the graph
42. Visualizing the Git Repo 24 Commits are nodes in the graph
43. Visualizing the Git Repo 24 Commits are nodes in the graph
44. Visualizing the Git Repo 24 Commits are nodes in the graph
45. Visualizing the Git Repo 24 Commits are nodes in the graph
46. Visualizing the Git Repo 24 Commits are nodes in the graph
47. Visualizing the Git Repo 25 Commits are nodes in the graph
48. Visualizing the Git Repo 25 Commits are nodes in the graph
49. Visualizing the Git Repo 25 Commits are nodes in the graph Parent commits are edges in the graph
50. Visualizing the Git Repo 26 Commits are nodes in the graph Parent commits are edges in the graph
51. Visualizing the Git Repo 27 Commits are nodes in the graph Parent commits are edges in the graph
52. Branch & Branch Often 28 Git stores a series of snapshots. A commit is a pointer to the snapshot of the content we staged and some metadata. A branch is a moveable, lightweight pointer to a commit. master is no different than any other branch
53. Creating a branch 29 A new pointer is created. !"❱❱❱ git branch new-feature Creating a branch is writing 40 bytes to disk.
54. Creating a branch 30 !"❱❱❱ git checkout new-feature
55. Creating a branch 31 !"❱❱❱ git checkout master
56. When history diverges 32 Commits point to their parents, Git leverages this to automatically merge.
57. When history diverges 33 1. Work on our application 2. Create a branch for a new story 3. Do work in that branch
58. When history diverges 33 1. Work on our application 2. Create a branch for a new story 3. Do work in that branch Critical issue requires a hot fix ASAP
59. When history diverges 33 1. Work on our application 2. Create a branch for a new story 3. Do work in that branch Critical issue requires a hot fix ASAP 1. Switch to production branch 2. Create a hot fix branch 3. After testing, merge branch and push to production 4. Switch back to original story and continue working
60. When history diverges 34 The hot fix merge is fast-forwarded
61. When history diverges 34 The hot fix merge is fast-forwarded No merge commit will be made
62. When history diverges 34 The hot fix merge is fast-forwarded No merge commit will be made Commit pointed to by hotfix branch directly ahead of commit pointed to by master
63. When history diverges 34 The hot fix merge is fast-forwarded No merge commit will be made Commit pointed to by hotfix branch directly ahead of commit pointed to by master Git only had to move the pointer forward.
64. When history diverges 35 Ready to merge new-feature into master.
65. When history diverges 35 Ready to merge new-feature into master. The merge is made by the recursive strategy.
66. When history diverges 35 Ready to merge new-feature into master. The merge is made by the recursive strategy. Our histories have diverged, master had hotfix merged into it.
67. When history diverges 35 Ready to merge new-feature into master. The merge is made by the recursive strategy. Git performs a three-way merge Our histories have diverged, master had hotfix merged into it.
68. When history diverges 35 Ready to merge new-feature into master. The merge is made by the recursive strategy. Git performs a three-way merge 1. Finds a common ancestor of master and the feature branch Our histories have diverged, master had hotfix merged into it.
69. When history diverges 35 Ready to merge new-feature into master. The merge is made by the recursive strategy. Git performs a three-way merge 1. Finds a common ancestor of master and the feature branch 2. Creates a new snapshot, the result of the three-way merge Our histories have diverged, master had hotfix merged into it.
70. When history diverges 35 Ready to merge new-feature into master. The merge is made by the recursive strategy. Git performs a three-way merge 1. Finds a common ancestor of master and the feature branch 2. Creates a new snapshot, the result of the three-way merge 3. Creates a merge commit pointing to the snapshot. This commit will have 2 parents. Our histories have diverged, master had hotfix merged into it.
71. Merge Conflicts 36 <<<<<<< HEAD:app.rb def initialize(some_arg) ======= def initialize(better_arg_name) >>>>>>> new-feature:app.rb
72. Merge Conflicts 36 <<<<<<< HEAD:app.rb def initialize(some_arg) ======= def initialize(better_arg_name) >>>>>>> new-feature:app.rb Why?
73. Merge Conflicts 37 <<<<<<< HEAD:app.rb def initialize(some_arg) ======= def initialize(better_arg_name) >>>>>>> new-feature:app.rb
74. Merge Conflicts 38 <<<<<<< HEAD:app.rb def initialize(some_arg) ======= def initialize(better_arg_name) >>>>>>> new-feature:app.rb
75. Merge Conflicts 39 <<<<<<< HEAD:app.rb def initialize(some_arg) ======= def initialize(better_arg_name) >>>>>>> new-feature:app.rb
76. Merge Conflicts 40 <<<<<<< HEAD:app.rb def initialize(some_arg) ======= def initialize(better_arg_name) >>>>>>> new-feature:app.rb
77. Rebasing 41 Another way to integrate changes from one branch to another. Takes changes committed on one branch and replays them on another one.
78. Rebasing 42 $ git checkout new-feature $ git rebase master First, rewinding head to replay your work on top of it... Applying: Adds to the README Applying: Adds TODO for specs
79. Golden Rule of Rebasing 43 Never rebase commits that exist outside your repository. C1 master C1 dk/master C2 C3 master DK team remote repository My local repo — I’ve cloned the repo and based work on it.
80. Golden Rule of Rebasing 44 Never rebase commits that exist outside your repository. C1 master DK team remote repository, someone else does work that includes a merge and pushes it up C4 C6 C5
81. Golden Rule of Rebasing 45 Never rebase commits that exist outside your repository. C1 dk/master C2 C3 master My local repo, I’ve fetched and merged into my work. C4 C6 C5 C7
82. Golden Rule of Rebasing 46 Never rebase commits that exist outside your repository. DK Remote Repo, after `git push —force` C1 master C4’ C6 C5 C4
83. Golden Rule of Rebasing 47 Never rebase commits that exist outside your repository. My local repo, after fetching from the server. C1 dk/master C4’ C6 C5 C4 C2 C3 master C7
84. Golden Rule of Rebasing 48 Never rebase commits that exist outside your repository. My local repo, after fetching from the server and merging into my work. C1 dk/master C4’ C6 C5 C4 C2 C3 master C7 C8
85. Golden Rule of Rebasing 49 If this happens, your challenge is to figure out what is yours and what they’re rewritten.
86. Golden Rule of Rebasing 49 If this happens, your challenge is to figure out what is yours and what they’re rewritten. Git calculates another checksum based on the patch introduced with the commit called the patch-id.
87. Golden Rule of Rebasing 50 Never rebase commits that exist outside your repository. My local repo, after merging into my work. C1 dk/master C4’ C6 C5 C4 C2 C3 master C7 C8
88. Golden Rule of Rebasing 51 Run git rebase dk/master 1. What is unique to our branch 2. Which aren’t merge commits 3. Which have not been rewritten into the target branch 4. Apply those commits to the top of dk/master C1 dk/master C4’ C6 C5 C4 C2 C3 master C7
89. Golden Rule of Rebasing 52 Run git rebase dk/master 1. What is unique to our branch 2. Which aren’t merge commits 3. Which have not been rewritten into the target branch 4. Apply those commits to the top of dk/master C1 dk/master C4’ C6 C5 C4 C2 C3 master C7
90. Golden Rule of Rebasing 53 Run git rebase dk/master 1. What is unique to our branch 2. Which aren’t merge commits 3. Which have not been rewritten into the target branch 4. Apply those commits to the top of dk/master C1 dk/master C4’ C6 C5 C4 C2 C3 master C7
91. Golden Rule of Rebasing 54 Run git rebase dk/master 1. What is unique to our branch 2. Which aren’t merge commits 3. Which have not been rewritten into the target branch 4. Apply those commits to the top of dk/master C1 dk/master C4’ C6 C5 C4 C2 C3 master C7
92. Golden Rule of Rebasing 55 Run git rebase dk/master 1. What is unique to our branch 2. Which aren’t merge commits 3. Which have not been rewritten into the target branch 4. Apply those commits to the top of dk/master C1 dk/master C4’ C5 C2’ C3’ master
93. Golden Rule of Rebasing 56 Always use git pull --rebase Set it with: git config --global pull.rebase true Treat rebase as a way to clean-up and work with commits before you push them.
94. Rebase or Merge? 57 Commit history is the story of how your project was made. Rebase Repository’s commit history is a record of what actually happened. Merge
95. Interactive Staging 58 Craft your commits to include only certain combinations and parts of files. !"❱❱❱ git add -i staged unstaged path 1: unchanged +1/-1 README.md 2: unchanged +4/-0 lib/app.rb *** Commands *** 1: status 2: update 3: revert 4: add untracked 5: patch 6: diff 7: quit 8: help What now>
96. Interactive Staging 59 Craft your commits to include only certain combinations and parts of files. What now> 2 staged unstaged path 1: unchanged +1/-1 README.md 2: unchanged +4/-0 lib/app.rb Update>>
97. Interactive Staging 60 Craft your commits to include only certain combinations and parts of files. Update>> 1 staged unstaged path * 1: unchanged +1/-1 README.md 2: unchanged +4/-0 lib/app.rb Update>> updated one path *** Commands *** 1: status 2: update 3: revert 4: add untracked 5: patch 6: diff 7: quit 8: help What now>
98. Interactive Staging 61 Craft your commits to include only certain combinations and parts of files. *** Commands *** 1: status 2: update 3: revert 4: add untracked 5: patch 6: diff 7: quit 8: help What now> 5 staged unstaged path 1: unchanged +1/-1 README.md Patch update>> 1 staged unstaged path * 1: unchanged +1/-1 README.md
99. Interactive Staging 62 Craft your commits to include only certain combinations and parts of files. Patch update>> diff --git a/README.md b/README.md index f8b7956..2a41661 100644 --- a/README.md +++ b/README.md @@ -2,4 +2,4 @@ This is the skillshare README! -Learning Git is fun! +Learning Git is fun. Stage this hunk [y,n,q,a,d,/,e,?]?
100. Interactive Staging 63 Craft your commits to include only certain combinations and parts of files. Stage this hunk [y,n,q,a,d,/,e,?]? ? y - stage this hunk n - do not stage this hunk q - quit; do not stage this hunk or any of the remaining ones a - stage this hunk and all later hunks in the file d - do not stage this hunk or any of the later hunks in the file g - select a hunk to go to / - search for a hunk matching the given regex j - leave this hunk undecided, see next undecided hunk J - leave this hunk undecided, see next hunk k - leave this hunk undecided, see previous undecided hunk K - leave this hunk undecided, see previous hunk s - split the current hunk into smaller hunks e - manually edit the current hunk ? - print help
101. Handy Git Knowledge 64 log --graph --date=short
102. Handy Git Knowledge 65 log --pretty=format:\"%h %cr %cn %Cgreen%s%Creset\" --name-status
103. Handy Git Knowledge 66 log --pretty=format:\"%h %cr %cn %Cgreen%s%Creset\"
104. Handy Git Knowledge 67 https://git-scm.com/ Blog posts http://reinh.com/blog/2009/03/02/a-git-workflow-for-agile-teams.html https://randyfay.com/content/rebase-workflow-git http://unethicalblogger.com/2010/04/02/a-rebase-based-workflow.html http://2ndscale.com/rtomayko/2008/the-thing-about-git https://git-scm.com/ Guides & Tools https://www.atlassian.com/git https://www.git-tower.com/ http://gitready.com/ https://www.khanacademy.org/ computing/computer-science/ algorithms#graph-representation http://rogerdudler.github.io/git-guide/ https://onlywei.github.io/explain-git-with-d3/ https://blog.thoughtram.io/git/2014/11/18/the-anatomy-of- a-git-commit.html
107. Any Questions? 69