AtlasCamp 2010: What is DVCS and why it will change the way we work - Jens Schumacher
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Transcript of AtlasCamp 2010: What is DVCS and why it will change the way we work - Jens Schumacher
2010
The Subversion Dilemma !
Check in buggy code and drive everyone else crazy
Avoid checking it in until it’s fully debugged
or
The Subversion Dilemma !
Weeks without Version Control
Jens Schumacher – Atlassian What is DVCS and why it will change the way we work!
2010
Overview!
1. Mercurial vs. Subversion
2. Basic concepts
3. Use cases
Subversion vs Mercurial!
Subversion vs Mercurial!
Merging
Subversion vs Mercurial!
Branching
Subversion vs Mercurial!
Repository Access
Subversion vs Mercurial!
Performance
Subversion vs Mercurial!
Sharing
Subversion vs Mercurial!
Tool Support
Subversion vs Mercurial!
Authentication
Subversion vs Mercurial!
Check Out
Subversion vs Mercurial!
Overview!
1. Mercurial vs. Subversion
2. Basic concepts
3. Use cases
Repository Architecture!
Subversion!
Mercurial!
Subversion!
Revisions
Subversion is always linear
Mercurial!
Changesets
head
Each Changeset can have multiple children
Mercurial!
head
head
Mercurial!
Pull
Merge
Mercurial!
"hg commit" adds a new node
"hg push" and "hg pull" transfer nodes in the graph between two repositories
"hg merge" merge changes in a repository
Branching in Mercurial!
• Forks"• Named Branches"• Bookmarks"• Anonymous Branches"
Forks!
Forks!
• Complete Isolation"• Very easy to discard"
• Forking is slower"
Disadvantages"Advantages"
1 2
Forks!
When to use Forks"
• When you donʼt have commit access"• To experiment"• For a build repository"
Named Branches!
Named Branches!
• Branch Metadata"• Faster than Forking"
• Branch Metadata"• Closing a Branch
(fixed in 1.2)"
Disadvantages"Advantages"
Named Branches!
When to use Named Branches"
• Working in a team on a feature"
Bookmarks!
Bookmarks!
• Lightweight"• Can be deleted"• Similar to git"
• Local (fixed in 1.6) "• Possible loss of context "
Disadvantages"Advantages"
Bookmarks!
When to use Bookmarks"
• Working in a team on a feature"• If you like to way git does branching"• If you use Mercurial 1.6"
Anonymous Branches!
Anonymous Branches!
• Fast "• No name required"• No closing required"
• No description"• Changeset # required
(lookup with hg log)"
Disadvantages"Advantages"
Anonymous Branches!
When to use Anonymous Branches"
• For quick & small fixes"
Overview!
1. Mercurial vs. Subversion
2. Basic concepts
3. Use cases
BitBucket!
Mercurial code hosting"
• Free for 5 users"• Unlimited public collaborators"• Unlimited disk space"
Getting Started!
The Basics!
hg init create a new repositoryhg commit save your changes in the current repositoryhg log see all changes in your repositoryhg pull pull all changes from another repository into yourshg push push your changes into another repositoryhg merge join different lines of history
hg update update the repository's working directoryhg help <command>
Separate Features!
Use Case Work on several features in parallel
Separate Features!
$ hg clone project feature$ cd feature$ (do some changes and commits)
Clone
Separate Features!
$ cd ../project$ hg incoming ../feature
Incoming
Use hg incoming --patch to view the diffs
Separate Features!
$ hg pull ../feature
Pull
The history of feature one is now in your project. However, changes are not yet visible and only stored in the .hg directory
Separate Features!
$ hg merge
Merge
$ hg commit(enter commit message)
Commit
Separate Features!
Changesets
Collaborative Feature Development!
Use Case Using Mercurial to help coordinate the coding
Collaborative Feature Development!
$ hg branch feature(do some changes)$ hg commit(write commit message)
Create a branch
$ hg update feature(do some changes)$ hg commit(write commit message)
Collaborative Feature Development!
$ hg update default$ hg merge feature$ hg commit(write commit message)
Merge the named branch
Named branches stay in history as permanent records after you finished your work.
Collaborative Feature Development!
Changesets
Tagging Revisions!
Use Case Release a plugin
Tagging Revisions!
$ hg tag -r 8 v0.1
Add a tag
$ hg tags
See all tags
$ hg update v0.1
Update to a tagged revision
Tagging Revisions!
Tags"
Overview!
1. Mercurial vs. Subversion
2. Basic concepts
3. Use cases
Try BitBucket!
bitbucket.org"
Links!
• http://mercurial.selenic.com"• http://stevelosh.com/blog/2009/08/a-guide-to-
branching-in-mercurial"• http://hgbook.red-bean.com/"
Thank you!!