CS 241: Systems Programming Lecture 34. Advanced Git Fall 2019 - - PowerPoint PPT Presentation

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CS 241: Systems Programming Lecture 34. Advanced Git Fall 2019 - - PowerPoint PPT Presentation

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CS 241: Systems Programming Lecture 34. Advanced Git Fall 2019 Prof. Stephen Checkoway 1 Using "branches" Development and release versions Trying out new features Focusing on fixing a bug Simpler to do in Git than other VCS, consider

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CS 241: Systems Programming Lecture 34. Advanced Git

Fall 2019

  • Prof. Stephen Checkoway

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SLIDE 2

Using "branches"

Development and release versions Trying out new features Focusing on fixing a bug Simpler to do in Git than other VCS, consider using more frequently

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Branches

Visualize a project’s development as a “linked list” of commits. When a development track splits, a new branch is created. In Git, branches are actually just a pointer to these commits

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Git branching

List all branches in the project

  • git branch

Create a new branch

  • git branch <branchname>

Switch to a branch

  • git checkout <branchname>

Create and immediately switch

  • git checkout –b <branchname>

Delete a branch

  • git branch –d <branchname>

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Using branches

Create and switch to a branch

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$ git branch working $ git checkout working M README Switched to branch 'working' $ git branch master * working

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Stashing

Working tree should be clean when switching branches Save/hide changes you don't want to commit with git stash

  • Pushes changes onto a stash stack

Recover changes lager with git stash pop

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SLIDE 7

Using branches

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Using branches

Integrate changes back into master

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$ git checkout master Switched to branch 'master' $ git merge working Merge made by the 'recursive' strategy. newfile.txt | 1 + 1 file changed, 1 insertion(+) create mode 100644 newfile.txt

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Before git merge

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After git merge

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Merged history

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* cdd07b2 - (HEAD, master) Merge branch 'working' |\ | * 1ccf9e7 - (working) Added a new file * | 3637a76 - Second change * | cf98d00 - First change |/ * cf31a23 - Updated README to 2.0 * 2a8fc15 - Initial commit

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Rebasing

Like merging, rebasing transfers changes from one branch to another Does not create a new commit Replays changes from current branch onto head of other branch

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Before git rebase

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After git rebase

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’ ’ ’

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git rebase

Powerful tool Can change the commit order Merge/split commits Make fixes in earlier commits

  • DO NOT DO ON PUSHED CHANGES OR PUBLIC BRANCH

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$ git rebase –i master

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Conflicts

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Git conflict markers

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$ cat foo.c <<<<<<< HEAD current content ======= branch content >>>>>>> newbranch $ vim foo.c $ git add foo.c $ git rebase --continue

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Pull requests with Github

Contributing changes to repositories on Github Requests the owner of the code integrate your changes

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SLIDE 19

Setup

GitHub

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Setup

upstream
 (theirs)

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Setup

upstream
 (theirs) fork

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Setup

upstream
 (theirs)

  • rigin


(yours) fork

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Setup

upstream
 (theirs)

  • rigin


(yours) clone fork

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SLIDE 24

Setup

upstream
 (theirs)

  • rigin


(yours) local
 (yours) clone fork

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Setup

upstream
 (theirs)

  • rigin


(yours) local
 (yours)

upstream

clone fork

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Setup

upstream
 (theirs)

  • rigin


(yours) local
 (yours)

  • rigin

upstream

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SLIDE 27

Contribute Changes

upstream
 (theirs)

  • rigin


(yours) local
 (yours)

  • rigin

upstream

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SLIDE 28

Contribute Changes

upstream
 (theirs)

  • rigin


(yours) local
 (yours)

  • rigin

upstream push

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SLIDE 29

Contribute Changes

upstream
 (theirs)

  • rigin


(yours) local
 (yours)

  • rigin

upstream push

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Contribute Changes

upstream
 (theirs)

  • rigin


(yours) local
 (yours)

  • rigin

upstream push pull request

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Contribute Changes

upstream
 (theirs)

  • rigin


(yours) local
 (yours)

  • rigin

upstream push pull request

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Integrate Changes

upstream
 (theirs)

  • rigin


(yours) local
 (yours)

  • rigin

upstream

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Integrate Changes

upstream
 (theirs)

  • rigin


(yours) local
 (yours)

  • rigin

upstream

fetch

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SLIDE 34

Integrate Changes

upstream
 (theirs)

  • rigin


(yours) local
 (yours)

  • rigin

upstream

fetch

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SLIDE 35

Integrate Changes

upstream
 (theirs)

  • rigin


(yours) local
 (yours)

  • rigin

upstream

push

fetch

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SLIDE 36

Integrate Changes

upstream
 (theirs)

  • rigin


(yours) local
 (yours)

  • rigin

upstream

push

fetch

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You want to contribute code to the Github project fancy/project (fancy is the name of the owner, project is the name of the repo). You fork the repo (producing student/project), commit your changes, and push to student/project. Next, you make a pull request for fancy/project. Which statement is true?

  • A. Your code is now integrated into fancy/project via merging
  • B. Your code is now integrated into fancy/project via rebasing
  • C. You have requested that your code be integrated into fancy/project,

but no changes have been made

  • D. You cannot make any additional commits until the pull request has been

accepted

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  • rigin

upstream local master master master

Branches

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  • rigin

upstream local master master master

$ git checkout -b feature

feature

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  • rigin

upstream local master master master

$ git commit

feature

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  • rigin

upstream local master master master

$ git push -u origin feature

feature feature

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  • rigin

upstream local master master master feature feature

pull request

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  • rigin

upstream local master master master

Great idea, now can you do it more like this?

feature feature

pull request

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  • rigin

upstream local master master master

$ git commit $ git push

feature feature

pull request

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  • rigin

upstream local master master master

Awesome, but please update with new changes in master

feature feature

pull request

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  • rigin

upstream local master master master

$ git remote add upstream https://github.com/… $ git fetch upstream master:master

feature feature

pull request

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  • rigin

upstream local master master master

$ git rebase master

feature feature

pull request WARNING:
 You may have
 to resolve conflicts.

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  • rigin

upstream local master master master

$ git rebase master

feature feature

pull request

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  • rigin

upstream local master master

$ git push -f origin master feature

feature

pull request

master feature

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  • rigin

upstream local master master feature

pull request

master feature

  • Great. Please squash your commits.

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  • rigin

upstream local master master

$ git rebase –i master

feature

pull request

master feature

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  • rigin

upstream local master master

$ git rebase –i master

feature

pull request

master feature

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  • rigin

upstream local master master

$ git rebase –i master

feature

pull request

master feature

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  • rigin

upstream local master master

$ git push -f origin feature

feature

pull request

master feature

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  • rigin

upstream local master master feature

pull request

master feature

Perfect, I accept!

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  • rigin

upstream local master master

Time to Clean Up

feature master feature

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  • rigin

upstream local master master

I accept!

feature master feature

$ git fetch upstream master:master

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  • rigin

upstream local master master

I accept!

feature master feature

$ git push origin master

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  • rigin

upstream local master master

I accept!

master feature

$ git checkout master
 $ git branch -d feature

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  • rigin

upstream local master master

I accept!

master

$ git push origin -d feature

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After a PR is accepted, Github will ask you if you want to delete your feature

  • branch. If you say yes, which branches get deleted?
  • A. feature — the branch named feature in your local repo
  • B. origin/feature — the branch named feature in your remote repo
  • C. upstream/feature — the branch named feature in their remote repo
  • D. feature and origin/feature
  • E. feature, origin/feature, and upstream/feature

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Now that origin/feature has been deleted, how do you delete feature?

  • A. $ git delete feature
  • B. $ git delete -b feature
  • C. $ git branch -d feature
  • D. $ git push origin -d feature
  • E. I would google "delete a git branch" and then click on https://

stackoverflow.com/questions/2003505/how-do-i-delete-a-git-branch- locally-and-remotely like every other programmer

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In-class exercise

https://checkoway.net/teaching/cs241/2019-fall/exercises/Lecture-34.html Grab a laptop and a partner and try to get as much of that done as you can!

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