Building Git

Description

Building Git is a deep dive into the internals of the Git version control system. By rebuilding it in a high-level programming language, we explore the computer science behind this widely used tool. In the process, we gain a deeper understanding of Git itself as well as covering a wide array of broadly applicable programming topics, including: Unix concepts Reading and writing from files, making writes appear atomic, prevent race conditions between processes Launching child processes in the foreground and background, communicating with them concurrently Displaying output in the terminal, including colour formatting, paged output, and interacting with the user’s text editor Parsing various file formats, including Git’s Merkle-tree-based commit model, the index, configuration files and packed object files Data structures How Git stores content on disk to make effective use of space, make the history efficient to search, and make it easy to detect differences between commits Using diffs to efficiently update the contents of the workspace when checking out a new commit Effectively using simple in-memory data structures to solve programming problems Parsing and interpreting a query language for addressing commits Concurrent editing How Git uses branches to model concurrent edits Algorithms for detecting differences between file versions and merging branches back together Why merge conflicts happen, how they can be avoided, and how Git helps users prevent lost updates How merging can be used as the basis for numerous operations to edit the commit history Software engineering Bootstrapping and growing a self-hosting system Test-driven development Refactoring to enable new feature development Crash-only software design that allows programs to be interrupted and resumed Networking Using SSH to bootstrap a network protocol How Git repositories communicate to minimise the data they need to transfer when fetching content How the network protocol uses atomic operations to prevent users overwriting each other’s changes