Git. Christoph Matthies Software Engineering II WS 2018/19. Enterprise Platform and Integration Concepts group

Transcription

1 Git Software Engineering II WS 2018/19 Christoph Matthies Enterprise Platform and Integration Concepts group

2 Outline 1. Basics 2. Local 3. Collaboration November 16,

3 Centralized vs Distributed VCS Central Repository Central Repository Commit Checkout Update Push User A? User B? User C VS. User A Pull Pull User C Pull User B Commit Diff November 16,

4 Centralized vs Distributed VCS Distributed VCS are mostly used like centralized VCS Same features (branches, tags, merging) Local commits are a blessing and a curse Commits can be made while offline Higher chances of code diverging Pull-Requests are better than patch files November 16,

5 Git Objects Blob Content of a file Nothing else Tree File structure References Blobs Commit References Tree object Metadata 0..* parent commits Tag Reference to other object November 16,

6 Commit Blob Hello World a ca03f7cccb3c6b6f474f88 f8e9a3bb5b Tree hello.txt world.txt A ca03f7cc... A431253jhfdkagfj... 97b49d4c943e3715fe30f141cc6f27a8548cee0e msg: tree initial 97b49d4c943e3715f... a ca03f7cccb3c6b6f474f88f8e9a3bb5b November 16,

7 Local Operations November 16,

8 File Status Lifecycle November 16,

9 Commit Parent msg: Initial msg: v 2.0 msg: v 2.1 $ git commit -m v 2.1 November 16,

10 Branches & Tags msg: Initial msg: v 2.0 msg: v 2.1 Tag: v2.0 $ git commit -m v 2.1 November 16,

11 Head HEAD msg: Initial msg: v 2.0 msg: v 2.1 Tag: v2.0 November 16,

12 Detached Head $ git checkout v2.0 HEAD msg: Initial msg: v 2.0 msg: v 2.1 Tag: v2.0 November 16,

13 Detached Head $ git checkout v2.0 $ git commit -m v 2.x HEAD msg: v 2.x msg: Initial msg: v 2.0 msg: v 2.1 Tag: v2.0 November 16,

14 Detached Head $ git checkout v2.0 $ git commit -m v 2.x $ git checkout msg: v 2.x HEAD msg: Initial msg: v 2.0 msg: v 2.1 Tag: v2.0 November 16,

15 Fast-forward $ git merge branch_b HEAD msg: Initial msg: Fix A msg: Fix b branch_b November 16,

16 Merge $ git merge branch_b HEAD msg: Initial msg: Fix A msg: merge branch_b msg: Fix b branch_b November 16,

17 Collaboration origin alice bob November 16,

18 Push origin alice$ git push origin alice bob commit b November 16,

19 Fetch origin commit b bob$ git fetch Unreferenced commit alice bob commit b origin/ November 16,

20 Pull origin commit b bob$ git fetch bob$ git merge origin/ Unreferenced commit alice bob commit b origin/ commit b Unreferenced commit November 16,

21 Push with Conflicts origin Feature 2 alice$ git push origin! [rejected] -> (non-fast-forward) alice bob Feature 1 Feature 2 November 16,

22 Push --force origin Feature 2 alice$ git push --f origin Never EVER push --force alice bob Feature 1 Feature 2 November 16,

23 Commit Pull Push origin Feature 2 alice$ git pull origin alice Merge bob Feature 1 Feature 2 November 16,

24 Branching Many ways to structure branches Some helpful tips: Never merge in or release branches Never break build in shared branches November 16,

25 What happened? git log git diff git blame November 16,

26 Summary 1. Basics Objects 2. Local Checkout Add Commit 3. Collaboration Pull Push November 16,

27 Image Credits "Olive tree Karystos". Licensed under Public domain via Wikimedia Commons - live_tree_karystos.jpg November 16,