Modern version control systems for Debian packaging

Introduction

• Distributed VCS are hip
• However, reason for being hip is not the "distributed" feature
• Let's clean up the mess:
  • snapshot- vs. commit-based
  • centralised vs. distributed

Evolution of version control

CVS-like version control systems

• (conceptually) snapshot-based, a revision corresponds to the state of the tree at a given time
• can be represented changeset-centric (CVS vs. SVN)
• merging consists of computing diffs and applying patches
• a commit (changeset or snapshot) has only a log message as meta information

Modern version control systems

• commit-based, there is no snapshot of a tree at a given time
• a tree is identified by the set of commits it contains
• merging consists of identifying the set difference and applying the commits in the reduced set
• every commit is identified by a unique hash

Commit-based version control

Centralised version control

Example of commit-based version control

Features of distributed VCS relevant to Debian

• branching and merging are trivial
• can be run centralised on alioth
• everyone can clone the repository and start hacking with real VCS backing
• no need to keep track of what has been merged where

Demonstration

Let's see git in action before Manoj demonstrates his workflow

Licence

These slides, their design, and the content are © martin f. krafft and released under the terms of the CC by-nc-sa 2.5 licence.

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