Dvcs With Mercurial (No Notes)

Notes:	Hide Notes

Slide 1: Distributed Source Control With Mercurial Or, How I Learned to Stop Worrying and Love the Merge Ted Naleid - Lead Developer at Carol.com Slide 2: Overview • • • • • Introduction SVN (centralized VCS) vs DVCS Current Popular DVCS Alternatives Mercurial (hg) examples Hands on with hg Slide 3: checkout add remove update log commit merge ... remote central repos Build Server Centralized VCS (SVN) Slide 4: Alice's repos add remove update log commit diff merge ... push pull push pull push pull Dave's repos Bob's repos build repos Build Server Distributed VCS (Mercurial) Slide 5: SVN Limitations DVCS/Mercurial Strengths Slide 6: Branching is easy, but merging is painful Branching is easy, merging is (relatively) easy Slide 7: Active net connection required to interact If your computer is on, you have access to the repository Slide 8: Unable to share changes with others without sharing with everyone (including the build server) Sharing changes with selected people is easy (hg serve/hg push/hg pull) Slide 9: Fails to merge changes when something is renamed Aware of file history and can merge into renamed file Slide 10: .svn files are littered throughout your source tree Single .hg directory at root of source tree Slide 11: Slow over-the-wire performance Fast performance; you’re working on local filesystem Slide 12: Discourages experimentation Cheap to create/throw away local experimental branch Slide 13: SVN Strengths DVCS/Mercurial Limitations Slide 14: Familiar to most developers Most developers will need to learn to think differently Slide 15: Relatively easy to grasp Better understanding of version control concepts required Slide 16: Everyone knows where the trunk is because there’s only one server Need to define and adhere to convention to know where the trunk is Slide 17: Well established tool support and integration Tool support and integration isn’t quite as far along Slide 18: There is a winner among free, centralized VCS systems: Subversion DVCS systems are still new and a clear winner has not been established Slide 19: Popular 2nd Gen DVCS Systems Git - Bazaar - Mercurial Slide 20: Git Created by Linus Torvalds in 2005 after the BitKeeper “debacle” Slide 21: Git - Website & Hosting • • Website: http://git.or.cz/ Hosting: • • http://github.com http://repo.or.cz Slide 22: Git - Use in the Wild • • • • • Linux Kernel One Laptop Per Child (OLPC) Ruby on Rails Lots of other Ruby stuff Written mostly in C Slide 23: Git - Common Wisdom • • • • • Fastest of the DVCS systems Unfriendly to non-Linux/Unix systems Complex, with ~150 commands added to path Very popular in the Linux/Ruby communities Probably the most “buzz” off all DVCS systems right now Slide 24: Bazaar (bzr) Created by Canonical, Ltd. (creators of Ubuntu) in 2005 Slide 25: Bazaar - Website & Hosting • • Website: http://bazaar-vcs.org/ Hosting: https://launchpad.net/ Slide 26: Bazaar - Use in the Wild • • • Ubuntu Drupal Fairly big in Python community • it’s written mostly in Python Slide 27: Bazaar - Common Wisdom • • • • • Has gone through lots of revisions/changed formats Slowest of the 3 Migration of an existing SVN repository is REALLY slow Made to be friendly, similar to SVN Smallest market share Slide 28: Mercurial (hg) Created by Matt Mackall in 2005 after the BitKeeper “debacle” Slide 29: Mercurial - Website & Hosting • • Website: http://www.selenic.com/mercurial/ Hosting: • • http://freehg.org/ http://sharesource.org/ Slide 30: Mercurial - Use in the Wild • • • • • OpenJDK (Java) OpenSolaris Mozilla NetBeans Many others (largely Java/Python related) • Like Bazaar, it’s mostly written in Python Slide 31: Mercurial - Common Wisdom • • • • • Similar syntax to SVN Slightly slower than Git, but faster than Bazaar Good cross-platform support Getting good support from large Java projects (OpenJDK, NetBeans, etc) Lower maintenance and easier learning curve than Git Slide 32: Why did I choose Mercurial over Git/Bazaar? Slide 33: Similar commands to SVN • • • • • • hg add hg remove hg update hg log hg status It’s like SVN but with the ability to “push” and “pull” Slide 34: Better cross platform support and growing tool integration Slide 35: No “packing” of the repository is necessary Slide 36: Local revision numbers are “friendly” Slide 37: It’s used by a number of big Java projects Slide 38: It’s the first one I tried :) Slide 39: All 3 of these tools look fantastic. Slide 40: Mercurial Usage Examples How do I do X? Slide 41: portal/ local ﬁle system hg init hg addremove hg commit portal/.hg local repos Create a new repository Slide 42: portal/ local ﬁle system creates tip ﬁles on ﬁlesystem portal/.hg http://hg01/repos/portal remote repos local repos hg clone hg clone http://hg01/repos/portal “Checkout” an Existing Repository Slide 43: portal/ local ﬁle system portal/.hg http://hg01/repos/portal hg pull remote repos hg update local repos "hg pull -u" will do this in one command Pull down the latest changes (no conflicts with local changes) Slide 44: local ﬁle changes hg commit local ﬁle system conﬂict! ﬁles unchanged! portal/.hg hg update hg pull local repos http://hg01/repos/portal remote repos hg merge hg commit "hg fetch" will pull->update->merge->commit in one command Pull down the latest changes (conflicts detected with local changes) Slide 45: local ﬁle changes portal/.hg local ﬁle system hg add hg remove hg addremove hg commit http://hg01/repos/portal remote repos hg push local repos Push changes to another repository (by default, push will refuse to run if it would require a merge) Slide 46: portal/.hg local repos hg incoming hg outgoing http://hg01/repos/portal remote repos Do a push/pull dry run Slide 47: portal/.hg Branching is done by simply cloning a repository portal-clone/ local ﬁle system creates tip ﬁles on ﬁlesystem local repos hg clone hg clone portal portal-clone portal-clone/.hg local repos Create a new “branch” (experimenting is cheap and easy) Slide 48: local ﬁle changes portal/.hg local ﬁle system hg diff hg status hg identify local repos Compare file system with repository Slide 49: portal/.hg hg log hg annotate hg cat hg grep hg serve local repos Query repository for info Slide 50: Hands on with Hg Slide 51: Creating new repository Slide 52: Cloning repository/ branching Slide 53: Pushing changes to another repository Slide 54: Merging conflicting changes Slide 55: Creating a tag Slide 56: Searching through history Slide 57: Viewing repository through a web browser Slide 58: A quick way to stick your toes in and try Mercurial out: use it as a “Super Client” for SVN Slide 59: Web Resources • • • • • Choosing a distributed version control system http://www.dribin.org/dave/blog/archives/2007/12/28/dvcs/ Understanding Mercurial http://www.selenic.com/mercurial/wiki/index.cgi/UnderstandingMercurial Version Control and the “80%” (DVCS counterpoint) http://blog.red-bean.com/sussman/?p=79 Mercurial Book http://hgbook.red-bean.com/hgbook.html Video of Bryan O’Sullivan (creator of the Mercurial Book) http://video.google.com/videoplay?docid=-7724296011317502612 Slide 60: Questions?