Mercurial
Mercurial is a distributed revision control tool for software developers. It is supported on Microsoft Windows, Linux, and other Unix-like systems, such as FreeBSD and macOS.
This article is about the software development tool. For the Vera Blue album, see Mercurial (album). For the Shadowrun adventure, see Mercurial (Shadowrun).Developer(s)
Mercurial's major design goals include high performance and scalability, decentralization, fully distributed collaborative development, robust handling of both plain text and binary files, and advanced branching and merging capabilities, while remaining conceptually simple.[5] It includes an integrated web-interface. Mercurial has also taken steps to ease the transition for users of other version control systems, particularly Subversion. Mercurial is primarily a command-line driven program, but graphical user interface extensions are available, e.g. TortoiseHg, and several IDEs offer support for version control with Mercurial. All of Mercurial's operations are invoked as arguments to its driver program hg (a reference to Hg – the chemical symbol of the element mercury).
Olivia Mackall[a] originated Mercurial and served as its lead developer until late 2016. Mercurial is released as free software under the GPL-2.0-or-later license.[7] It is mainly implemented using the Python programming language, but includes a binary diff implementation written in C.
Design[edit]
Mercurial uses SHA-1 hashes to identify revisions. For repository access via a network, Mercurial uses an HTTP-based protocol that seeks to reduce round-trip requests, new connections, and data transferred. Mercurial can also work over SSH where the protocol is very similar to the HTTP-based protocol. By default it uses a 3-way merge before calling external merge tools.
Adoption[edit]
Although Mercurial was not selected to manage the Linux kernel sources, it has been adopted by several organizations, including Facebook,[12] the W3C, and Mozilla. Facebook is using the Rust programming language to write Mononoke,[13][14] a Mercurial server specifically designed to support large multi-project repositories.
In 2013, Facebook adopted Mercurial and began work on scaling it to handle their large, unified code repository.[15]
Google also uses Mercurial client as a front-end on their cloud-based 'Piper' monorepo back-end.[16]
Bitbucket announced that its web-based version control services would end support for Mercurial in June 2020 (then extended to July 2020),[17] explaining that "less than 1% of new projects use it, and developer surveys indicated that 90% of developers use Git".[18]