Pushmi

Subversion replication system based on SVK

Chia-liang Kao / 高嘉良 <clkao@clkao.org>

Best Practical Solutions, LLC

Modern Software Development

• Test-driven.

• Geographically distributed.

• Version control is crucial.

Subversion

• Enterprise-standard for distributed development.

• Fixed CVS problems.

• Branch is easy.

• However

  • Centralised.

  • No good merge support.

The Problem

• The Internet isn't as fast as we want it to be

• ... or isn't as reliable as we thought.

• and there can be...

Earthquakes

067.jpg

The Subversion Motto

• Network is expensive

• Disks are cheap

We think

• Network, Disks, CPUs are cheap

• Developers are expensive

Why this matters?

• Developers spent more time on the tools than development == BAD

• Single Point of Failure == BAD

• Developers Unable to Produce == WORSE

The Solution

• Pushmi creates replicas of master repository in branch offices.

• Transparent to the users.

• NO change to existing infrastructure and process.

• Too good to be true?

Conflicts?

FAQ: How do you handle simultaneous commits from different slaves and master?

• We don't.

• The commits are relayed back to the master.

• It's essentially like users are committing directly, without going through replicas.

• And Subversion guards the transaction cleanness for us.

The architecture

diagram-v3.png

Case Study

A leading company in the game industry

• 70 offices around the world

• ... including Beijing, Saigon.

• Some with very limited internet connection.

• Large amount of graphical data.

• Users wait for "svn update" over slow and saturated network.

Case Study (Cont.)

• Eliminated 200ms+ latency for read-only operations from places like Romania

• ... for update, viewing logs, diff, etc.

• Commit performance is only slightly slower.

• When master repository or VPN is down:

  • Developers can still work with read-only operations.

  • along with SVK, can also commits and perform merge later.

Questions?

Thank you

Available on code.bestpractical.com

For support and consultancy, contact sales@bestpractical.com

cpanm Pushmi

perl -MCPAN -e shell
install Pushmi