Mercurial

This article is about the revision control software. For the unrelated corporation, see Mercurial Communications.
Mercurial
Developer(s) Matt Mackall
Initial release 19 April 2005 (2005-04-19)[1]
Stable release 3.7.3[2] / 29 March 2016 (2016-03-29)
Written in Python and C
Operating system Unix-like, MS Windows, Mac OS X
Type Revision control
License GNU GPL v2+
Website www.mercurial-scm.org

Mercurial, a cross-platform, distributed revision-control tool for software developers, is mainly implemented using the Python programming language, but includes a binary diff implementation written in C. It is supported on MS Windows and Unix-like systems, such as FreeBSD, Mac OS X and Linux. Mercurial is primarily a command-line driven program, but graphical user interface extensions are available. 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).

Mercurial's major design goals include high performance and scalability, decentralized, fully-distributed collaborative development, robust handling of both plain text and binary files, and advanced branching and merging capabilities, while remaining conceptually simple.[3] It includes an integrated web-interface. Mercurial has also taken steps to ease the transition for users of other version control systems, particularly Subversion.

Matt Mackall originated Mercurial and serves as its lead developer. Mercurial is released as free software under the terms of the GNU GPL v2 (or any later version[4]).

History

Mackall first announced Mercurial on 19 April 2005.[1] The impetus for this was the announcement earlier that month by Bitmover that they were withdrawing the free version of BitKeeper.

BitKeeper had been used for the version control requirements of the Linux kernel project. Mackall decided to write a distributed version control system as a replacement for use with the Linux kernel. This project started a few days after another project called Git, initiated by Linus Torvalds with similar aims.[5]

The Linux kernel project decided to use Git rather than Mercurial, but Mercurial is now used by many other projects (see below). "Git vs. Mercurial" has become one of the holy wars of hacker culture.[6]

In an answer on the Mercurial mailing list, Matt Mackall explained how the name "Mercurial" was chosen:[7]

Shortly before the first release, I read an article about the ongoing Bitkeeper debacle that described Larry McVoy as mercurial (in the sense of 'fickle'). Given the multiple meanings, the convenient abbreviation, and the good fit with my pre-existing naming scheme (see my email address), it clicked instantly. Mercurial is thus named in Larry's honor. I do not know if the same is true of Git.

In 2013, Facebook adopted Mercurial and began work on scaling it to handle their large, unified code repository.[8]

Design

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.

Usage

Figure 1 shows some of the most important operations in Mercurial and their relations to Mercurial's concepts.

Figure 1: Some important operations of Mercurial and their relations.

Related software

Screenshot of hgk in action
Screenshot of TortoiseHg client history
TortoiseHg
TortoiseHg is a cross-platform GUI for Mercurial. Most Mercurial operations can be invoked from the graphical interface. It can be used stand-alone on Windows, Mac OS X, or Linux.[9] It can also be integrated with Windows Explorer[10] and GNOME Nautilus.[11] On Windows, the TortoiseHg installer bundles Mercurial and Python.
MacHg
MacHg is a free and fast multithreaded front end for Mac OS X 10.6 and later.[12]
SourceTree
A freeware Mac OS X and Windows GUI client developed by Atlassian that works with both Mercurial and Git.[13]
Hgk
This was the original log viewer for Mercurial. It is implemented as a Mercurial extension with a tcl/tk frontend. It was originally based on a similar tool for Git called gitk. This viewer is now considered an unloved feature.[14] Recommended alternatives are hgview[15] or TortoiseHg.
Murky
A Mac OS X GUI in Objective-C 2.0, runs on Mac OS X 10.5 and later.[16]
MacMercurial
A Mac OS X GUI "not intended to completely replace command line use of Mercurial, only to ease the most common Mercurial operations," for Mac OS X 10.4 or later.[17]
EasyMercurial
A simple user interface for the Mercurial distributed version control system. It's free, open source, and cross-platform.[18]
hgtui
A free TUI client for Linux and Windows (using cygwin).[19]

Adoption

Although Mercurial was not selected to manage the Linux kernel sources, it has been adopted by several organizations, including Facebook,[24] the W3C, and Mozilla.

Source code hosting

The following websites provide free source code hosting for Mercurial repositories:

Open source projects using Mercurial

Some projects using the Mercurial distributed RCS:[28]

See also

References

  1. 1 2 Mackall, Matt (2005-04-20). "Mercurial v0.1 – a minimal scalable distributed SCM". Linux kernel (Mailing list).
  2. ↑ "What’s new", Mercurial (wiki) (3.7.3 ed.), Selenic.
  3. ↑ Mackall, Matthew ‘Matt’ (2006), "Towards a Better SCM: Revlog and Mercurial" (PDF), Linux Symposium Proceedings (PDF), Ottawa: Selenic.
  4. ↑ "Relicensing", Mercurial (wiki), Selenic.
  5. ↑ Mackall, Matt (2005-04-29). "Re: Mercurial 0.4b vs git patchbomb benchmark". Linux kernel (Mailing list).
  6. ↑ "Managing source code with Mercurial". Mercurial and Git fans are also happy to discuss the learning curve, merits, and usability of each VCS system's command set. Space prevents that discussion here, but a web search on that topic will provide lots of interesting reading material.
  7. ↑ Mackall, Matt (2012-02-15). "Why did Matt choose the name Mercurial?". Mercurial (Mailing list). Retrieved 8 March 2012.
  8. ↑ Goode, Durham; Agarwal, Siddharth. "Scaling Mercurial at Facebook". Facebook Code. Facebook. Retrieved 13 October 2015.
  9. ↑ "Introduction". TortoiseHg Documentation. Retrieved 23 April 2014.
  10. ↑ "Windows Explorer Integration". TortoiseHg Documentation. Retrieved 23 April 2014.
  11. ↑ "GNOME desktop integration". TortoiseHg Documentation. Retrieved 23 April 2014.
  12. ↑ http://jasonfharris.com/machg/
  13. ↑ http://www.sourcetreeapp.com/
  14. ↑ "Hgk Extension". Mercurial Wiki. Retrieved 23 April 2014.
  15. ↑ http://www.logilab.org/project/hgview
  16. ↑ http://bitbucket.org/snej/murky/wiki/Home
  17. ↑ http://www.jwwalker.com/pages/macmerc.html
  18. ↑ http://easyhg.org/
  19. ↑ https://code.google.com/p/hgtui/
  20. ↑ http://meld.sourceforge.net/
  21. ↑ http://visualhg.codeplex.com/
  22. ↑ http://bitbucket.org/zzsergant/hgsccpackage/
  23. ↑ http://www.javaforge.com/project/HGE
  24. ↑ "Scaling Mercurial at Facebook".
  25. ↑ "CodePlex now supporting native Mercurial". CodePlex (Weblog). Microsoft. 2010-01-22.
  26. ↑ "Git, Mercurial & Subversion hosting". Features. Codebase HQ. 2013-03-04.
  27. ↑ "Hosting", Mercurial (wiki), Selenic.
  28. ↑ "Some projects that use Mercurial", Mercurial (wiki), Selenic.
  29. ↑ "Source", Adblock+.
  30. ↑ "Source code repositories migrated from Subversion to Mercurial". Coin3D (news). 2010-02-27.
  31. ↑ "Mercurial Work Flow" (wiki). Illumos. 2011-03-13.
  32. ↑ Reed, J Paul (2007-04-12). "Version Control System Shootout Redux Redux".
  33. ↑ "Switch to hg.netbeans.org completed". Net beans. January 2008.
  34. ↑ "Mercurial". Developers. OGRE – Open Source 3D Graphics Engine. 2010-04-04.
  35. ↑ James Gosling (October 2006). Open Sourcing Sun's Java Platform Implementations, Part 1. Interview with Robert Eckstein. Sun. Archived from the original on 1 March 2009.
  36. ↑ "Source Repositories". OpenIndiana. 2011-03-13.

External links

This article is issued from Wikipedia - version of the Wednesday, May 04, 2016. The text is available under the Creative Commons Attribution/Share Alike but additional terms may apply for the media files.