Using Git in Eclipse - Eclipse Summit Europe 2010-11-03

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Using Git in Eclipse - Eclipse Summit Europe 2010-11-03

  1. 1. Using Git in Eclipse http://eclipse.org/egit Matthias Sohn (SAP) matthias.sohn@sap.com + = Chris Aniszczyk (Red Hat) zx@redhat.com
  2. 2. Learning Git – There's no free lunch! Using Git in Eclipse | © 2010 by C. Aniszczyk and M. Sohn … the purpose of this presentation isn't to teach you Git, you have to do that yourself!
  3. 3. Git Resources http://git-scm.com/documentation is your friend Watch Linus' talk at Google http://www.youtube.com/watch?v=4XpnKHJAok8 Read the Pro Git book - http://progit.org/book/ Using Git in Eclipse | © 2010 by C. Aniszczyk and M. Sohn
  4. 4. Git, EGit and JGit - Demo and Tour of EGit Code Review at Eclipse Gerrit - Demo of Gerrit Conclusion Outline Using Git in Eclipse | © 2010 by C. Aniszczyk and M. Sohn
  5. 5. Git … a distributed revision control system built by the Linux project to automate patch workflow Distributed means no central repository •No central authority! •Easy offline usage •Easy to fork a project •Protected against manipulation by cryptographic hashes Really good at merging •Coordination only needed "after the fact” •Easier to rejoin (or refresh) forked projects Structured around commits (i.e. patches) •Integrates with email channel •Tools for identifying problem commits (git bisect) •Tools for restructuring branches w/ specific commits Using Git in Eclipse | © 2010 by C. Aniszczyk and M. Sohn
  6. 6. Projects using Git … Git is widely used and is the most popular distributed version control system Git Linux Perl Gnome Qt Ruby on Rails Android PostgreSQL Wine Fedora Debian X.org and so on... Using Git in Eclipse | © 2010 by C. Aniszczyk and M. Sohn
  7. 7. Git at Eclipse Eclipse defined a roadmap to move to Git in 2009 CVS is deprecated; SVN will be deprecated in the future EGit is an Eclipse Team provider for Git http://www.eclipse.org/egit/ JGit is a lightweight Java library implementing Git http://www.eclipse.org/jgit/ The goal is to build an Eclipse community around Git EGit and JGit are still beta and we want to establish a feedback loop to improve the tooling Using Git in Eclipse | © 2010 by C. Aniszczyk and M. Sohn
  8. 8. Git at Eclipse EGit and JGit developed at http://egit.eclipse.org http://git.eclipse.org/ hosts live Eclipse Git repos Virgo, Mylyn Review, ECF, SWTBot … http://dev.eclipse.org/git/index.html git mirrors for CVS Read-only copies kept up-to-date Can clone with git:// or http:// Using Git in Eclipse | © 2010 by C. Aniszczyk and M. Sohn
  9. 9. History of JGit and EGit 2005 Linus Torvalds starts Git 2006 Shawn Pearce starts JGit 2009 Eclipse decides for Git Roadmap JGit/EGit move to eclipse.org SAP joins JGit/EGit 3/2010 Released 0.7 (first release at Eclipse) Diff/Merge Algorithms, Automatic IP Logs 6/2010 Released 0.8 (Helios) Usability Improvements, Git Repositories View, Tagging 9/2010 Released 0.9 (Helios SR1) Merge, Synchronize View, .gitignore Planned: 12/2010 0.10 (Helios SR2) 3/2011 0.11 6/2011 1.0 (Indigo) Using Git in Eclipse | © 2010 by C. Aniszczyk and M. Sohn
  10. 10. Features EGit 0.10 git-add git-format-patch git-shortlog git-relink git-rev-parse git-am git-gc git-show git-remote git-show-branch git-archive git-grep git-stash git-repack git-verify-tag git-bisect git-init git-status git-replace git-whatchanged git-branch git-log git-submodule git-annotate git-bundle * git-merge * git-tag * git-blame .gitignore git-checkout git-mv git-config git-cherry git daemon git-cherry-pick git-notes git-fast-export git-count-objects Visual merge tool git-clean  git-pull git-fast-import git-difftool ** HTTP support git-clone git-push git-filter-branch git-fsck * Mylyn integration git-commit ** git-rebase git-mergetool git-get-tar-commit-id * Staging View git-describe git-reset git-pack-refs git-help * Synchronize View git-diff git-revert git-prune git-merge-tree History View git-fetch git-rm git-reflog git-rerere Repositories View ** planned for 0.10, * planned for 0.11 supported, partial, missing, irrelevant for EGit
  11. 11. Demo: A tour of EGit Using Git in Eclipse | © 2010 by C. Aniszczyk and M. Sohn
  12. 12. Git, EGit and JGit Code Review and Eclipse Gerrit Conclusion Outline Using Git in Eclipse | © 2010 by C. Aniszczyk and M. Sohn
  13. 13. What is Peer Code Review? When one developer writes code, another developer is asked to review that code A careful line-by-line critique Happens in a non-threatening context Goal is cooperation, not fault-finding Often an integral part of coding process Debugging someone else's broken code – Involuntary code review: Not so good; emotions may flare Guido van Rossum [1] [1] http://code.google.com/p/rietveld/downloads/detail?name=Mondrian2006.pdf Using Git in Eclipse | © 2010 by C. Aniszczyk and M. Sohn
  14. 14. Code Review – Benefits Four eyes catch more bugs  Catch bugs early to save hours of debugging Enforce coding standards  Keep overall readability & code quality high Mentoring of new developers  Learn from mistakes without breaking stuff Establish trust relationships  Prepare for more delegation Good alternative to pair programming  asynchronous and across locations Guido van Rossum [1] [1] http://code.google.com/p/rietveld/downloads/detail?name=Mondrian2006.pdf Using Git in Eclipse | © 2010 by C. Aniszczyk and M. Sohn
  15. 15. Code Review at Eclipse ? Using Git in Eclipse | © 2010 by C. Aniszczyk and M. Sohn
  16. 16. Eclipse - Roles Committer Formally elected Can commit own changes without review Contributor Small changes reviewed by committers Bigger changes also formal IP review by legal team in separate protected Bugzilla (IPZilla) Review Tool patches attached to bug in Bugzilla comments in Bugzilla Using Git in Eclipse | © 2010 by C. Aniszczyk and M. Sohn
  17. 17. Code Review via Bugzilla Using Git in Eclipse | © 2010 by C. Aniszczyk and M. Sohn
  18. 18. Eclipse – Review Process Contributors • create patch using CVS, SVN, Git (since 2009) • attach patch to bug in Bugzilla Committers • do code and IP review • comment, vote in Bugzilla • create CQ for changes needing IP review • commit accepted changes IP Team • does IP review bigger changes from contributors Using Git in Eclipse | © 2010 by C. Aniszczyk and M. Sohn
  19. 19. Eclipse – Review Process Review not done for all changes Each Eclipse.org project does it differently Review tedious for contributors (and also for committers mentoring contributors) Using Git in Eclipse | © 2010 by C. Aniszczyk and M. Sohn
  20. 20. Git, EGit and JGit Code Review and Eclipse Gerrit Conclusion Outline Using Git in Eclipse | © 2010 by C. Aniszczyk and M. Sohn
  21. 21. Gerrit Code Review Gerrit is a Code Review system based on JGit http://code.google.com/p/gerrit/ Also serves as a git server adding access control and workflow Used by • Android https://review.source.android.com/ • JGit, EGit http://egit.eclipse.org/r/ • Google, SAP, … Eclipse wants to use it … Using Git in Eclipse | © 2010 by C. Aniszczyk and M. Sohn
  22. 22. History Gerrit Code Review Gerrit: 4th Generation code review at Google Google started code review with a Linux like review process • patch based • tooling based on Perforce CLI Using Git in Eclipse | © 2010 by C. Aniszczyk and M. Sohn
  23. 23. Google - Web based code review tools Mondrian (Guido van Rossum) • based on Perforce, Google infrastructure • Google proprietary Rietvield (Guido van Rossum) • based on Subversion • Open Source hosted on GoogleApp Engine Gerrit (Shawn Pearce) • started as a fork of Rietvield • based on JGit and GWT • Open Source (Android) • Apache 2 license Using Git in Eclipse | © 2010 by C. Aniszczyk and M. Sohn
  24. 24. One Branch per Feature Master branch contains only reviewed and approved changes • master moves from good to beter state afer each (approved) change Each feature branch is based on the Master branch • stable startng point A change can really be abandoned because • no other approved change can depend on a not yet approved change • Gerrit will automatcally reject a successor change of an abandoned change Using Git in Eclipse | © 2010 by C. Aniszczyk and M. Sohn
  25. 25. Gerrit – Lifecycle of a Change a master topic 1 • create local topic branch • commit change • push it for review • do review • automated verification Using Git in Eclipse | © 2010 by C. Aniszczyk and M. Sohn
  26. 26. Gerrit – Lifecycle of a Change c b a1 2 mastertopic 3 a master topic 1 • create local topic branch • commit change • push it for review • do review • automated verification • refine based on review • push new patchsets until review votes ok Using Git in Eclipse | © 2010 by C. Aniszczyk and M. Sohn
  27. 27. Gerrit – Lifecycle of a Change c b a1 2 mastertopic 3 a master topic 1 • create local topic branch • commit change • push it for review • do review • automated verification • refine based on review • push new patchsets until review votes ok c b a1 2 master topic 3 d • Submit may lead to server-side merge • or merge / rebase before push Using Git in Eclipse | © 2010 by C. Aniszczyk and M. Sohn
  28. 28. Gerrit Workflow Using Git in Eclipse | © 2010 by C. Aniszczyk and M. Sohn
  29. 29. Gerrit http://egit.eclipse.org/r/ - change,825Using Git in Eclipse | © 2010 by C. Aniszczyk and M. Sohn
  30. 30. Code Review – Our Experience Review all changes! Review takes time (1 day … weeks) Implies parallel workflow Every team member should do reviews regularly Authors have to wait for the review to happen Git & Gerrit help a lot here Code Review | © 2010 by M. Sohn
  31. 31. Gerrit Code Review - Outlook Upcoming proposal for Mylyn Gerrit Connector Port from SQL DB to Cassandra Store review comments as git notes for offline review Support for change dependencies across repositories … Using Git in Eclipse | © 2010 by C. Aniszczyk and M. Sohn
  32. 32. Demo: Code Review with Gerrit Using Git in Eclipse | © 2010 by C. Aniszczyk and M. Sohn
  33. 33. Git, EGit and JGit Code Review and Eclipse Gerrit Conclusion Outline Using Git in Eclipse | © 2010 by C. Aniszczyk and M. Sohn
  34. 34. Conclusion EGit and JGit are evolving quickly Gerrit enables a nice code review workflow Git supports convenient branching and merging Git is very fast and scales well Eclipse and major other OS projects are moving to Git Git and Gerrit kick ass! Using Git in Eclipse | © 2010 by C. Aniszczyk and M. Sohn

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