SerDes algorithm in .git folder , after I run git clone - unix1998/technical_notes GitHub Wiki

The serialization and deserialization (SerDes) algorithms and data structures used in Git were primarily designed and implemented by Linus Torvalds when he initially developed Git in 2005. Torvalds created Git as a distributed version control system for managing the Linux kernel's source code, focusing on performance, reliability, and distributed development.

Key Aspects of Git's SerDes Design

  1. Original Design by Linus Torvalds:

    • Data Structures: The core data structures, such as blobs, trees, commits, and tags, were designed by Linus Torvalds. These structures are the building blocks of Git's version history and are serialized into binary formats for efficient storage and retrieval.
    • Serialization Techniques: The methods for serializing these objects into compact binary formats, including the use of SHA-1 hashes to identify objects and ensure data integrity, were also part of Torvalds' original design.

  2. Packfile Format:

    • Delta Compression: Git's packfile format, which uses delta compression to store data efficiently, was introduced early in Git's development. Delta compression involves storing only the differences between objects to save space. This approach, along with zlib compression, helps keep the storage footprint small.
    • Implementation Details: While the core concepts were established by Torvalds, the implementation and optimization of packfile handling and compression techniques have evolved over time, with contributions from many other developers.

  3. Evolution and Contributions:

    • After the initial release by Linus Torvalds, Git has been maintained and extended by a large community of contributors. Key contributors like Junio C Hamano (the current maintainer), Shawn Pearce, and many others have refined and optimized Git's internals, including its SerDes algorithms and data structures.
    • Optimization and Enhancements: Over the years, numerous enhancements and optimizations have been made, such as improvements to the packfile format, delta computation, and object storage. Some of these improvements leverage common algorithms and compression libraries, like zlib, for efficient data handling.

Use of Common Algorithms and Libraries

  • zlib: Git uses the zlib library for data compression. Zlib provides a standard implementation of the DEFLATE compression algorithm, which is widely used for compressing data in various formats (e.g., PNG, HTTP, etc.).
  • SHA-1 Hashing: Git uses SHA-1 cryptographic hashing to generate unique identifiers for objects (blobs, trees, commits). This hash function, while not unique to Git, was chosen for its balance of speed and reliability.

Summary

While Linus Torvalds laid the foundation for Git's SerDes mechanisms, the system has since been extended and optimized by a broad community of developers. Git's use of serialization and compression techniques, such as packfiles and delta compression, was initially developed by Torvalds and has evolved to incorporate best practices and common libraries like zlib. This collaborative development has made Git a robust and efficient version control system.