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 – AtlassianWhat 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

DisadvantagesAdvantages

1 2

Forks

When to use Forks

• When you don’t 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)

DisadvantagesAdvantages

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

DisadvantagesAdvantages

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)

DisadvantagesAdvantages

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 CaseWork 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 CaseUsing 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 CaseRelease 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!