Mercurial

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This article is about the revision control software. For the metallic element after which it is named, see Mercury. For the Canadian developer of the Netscape 8.0 web browser, see Mercurial Communications.
Mercurial
Mercurial logo.png
Developer(s) Matt Mackall
Stable release 1.4 / 2009-11-16; 11 days ago
Written in Python and C
Operating system Unix-like, Windows, Mac OS X
Type Revision control
License GPL v2 only[nb 1]
Website mercurial.selenic.com

Mercurial is a cross-platform, distributed revision control tool for software developers. It is mainly implemented using the Python programming language, but includes a binary diff implementation written in C. Mercurial was initially written to run on Linux. It has been ported to Windows, Mac OS X, and most other Unix-like systems. Mercurial is primarily a command line program but graphical user interface extensions are available. All of Mercurial's operations are invoked as keyword options to its driver program hg, a reference to 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.[2] It includes an integrated web interface.

The creator and lead developer of Mercurial is Matt Mackall. The source code is available under the terms of the GNU General Public License version 2[nb 1], qualifying Mercurial as free software.

Contents

[edit] Technical information

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.

[edit] Documentation

A comprehensive reference manual, Mercurial: The Definitive Guide,[3] has been written by Bryan O'Sullivan. The manual is freely available under the terms of the Open Publication License.

[edit] History

Mackall first announced Mercurial on April 19, 2005.[4] 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, started 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).

[edit] Related software

Screenshot of hgk in action
  • TortoiseHg provides a user-friendly, right-click menu interface for Windows and GNOME's Nautilus file manager.
  • GUI interfaces for Mercurial include Hgk (tcl/tk). This is implemented as a Mercurial extension, and is part of the official version. This viewer displays the directed acyclic graph of the changesets of a Mercurial repository. This viewer can be invoked via the command 'hg view', if the extension is enabled. hgk was originally based on a similar tool for git called gitk. There is an hgk replacement named hgview that is written in pure python and provides both gtk and qt interfaces.
  • Related tools for merging include (h)gct (Qt) and Meld.
  • The convert extension allows import from CVS, Darcs, git, GNU Arch, Monotone, Perforce, Bazaar and Subversion repositories.
  • NetBeans supports Mercurial from Version 6.
  • Eclipse supports Mercurial with the MercurialEclipse plugin.

[edit] Adoption

[edit] Source code hosting

See also: Comparison of open source software hosting facilities

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

[edit] Projects using Mercurial

Some projects using the Mercurial distributed RCS:[7]

The developers of the Python programming language have announced that they will transition from Subversion to Mercurial. However, as of September 2009 the timeframe is not fixed because the transition team is waiting for hgsubversion to develop.[16][17]

[edit] Notes

  1. ^ a b switching to "GPL v2 or any later version" is planned[1]

[edit] See also

Free Software Portal Logo.svg Free software portal

[edit] References

  1. ^ http://mercurial.selenic.com/wiki/Relicensing
  2. ^ Matt Mackall, Towards a Better SCM: Revlog and Mercurial, Ottawa Linux Symposium Proceedings, 2006.
  3. ^ Bryan O'Sullivan (2007-01-01). Mercurial: The Definitive Guide. http://hgbook.red-bean.com/. 
  4. ^ Mackall, Matt (2005-04-20). "Mercurial v0.1 - a minimal scalable distributed SCM". Linux kernel mailing list. http://www.ussg.iu.edu/hypermail/linux/kernel/0504.2/0670.html. 
  5. ^ Mackall, Matt (2005-04-29). "Re: Mercurial 0.4b vs git patchbomb benchmark". Linux kernel mailing list. http://lkml.indiana.edu/hypermail/linux/kernel/0504.3/1404.html. 
  6. ^ "Google Code Blog: Mercurial Now Available to All Open Source Projects". 2009-05-28. http://google-code-updates.blogspot.com/2009/05/mercurial-now-available-to-all-open.html. 
  7. ^ Some projects that use Mercurial
  8. ^ J. Paul Reed (2007-04-12). "Version Control System Shootout Redux Redux". http://weblogs.mozillazine.org/preed/2007/04/version_control_system_shootou_1.html. 
  9. ^ James Gosling. Interview with Robert Eckstein. James Gosling on Open Sourcing Sun's Java Platform Implementations, Part 1. October 2006.
  10. ^ "OpenSolaris SCM Project History". 2006-10-05. http://opensolaris.org/os/community/tools/scm/history/. 
  11. ^ "OpenOffice.org development switches to Mercurial". 2009-10-15. http://blogs.sun.com/GullFOSS/entry/openoffice_org_development_switches_to. 
  12. ^ David Wood (2009-04-06). "We decided in the end to use Mercurial rather than Git.". http://blog.symbian.org/2009/04/06/collaboration-at-the-heart/#comment-789. Retrieved 2009-05-07. 
  13. ^ Ian Pratt (2005-07-01). "mercurial now live". Xen-devel mailing list. http://lists.xensource.com/archives/html/xen-devel/2005-07/msg00003.html. 
  14. ^ Timo Sirainen (2007-05-19). "CVS to Mercurial switch". Dovecot-news mailing list. http://www.dovecot.org/list/dovecot-news/2007-May/000044.html. 
  15. ^ "Switch to hg.netbeans.org completed". January 2008. http://www.netbeans.org/servlets/ReadMsg?list=nbdev&msgNo=40342. 
  16. ^ Guido van Rossum (2009-03-30). "And the winner is...". Python-Dev mailing list. http://mail.python.org/pipermail/python-dev/2009-March/087931.html. 
  17. ^ Python PEP 385 with Timeline TBD (As of September 2009

[edit] External links

v • d • e
Revision control software
Years, where available, indicate the date of first stable release. Systems named in grey are no longer maintained or have planned end-of-life dates.
Client-server
CVS (1990) · CVSNT (1998) · Subversion (2000)
ClearCase (1992) · Visual SourceSafe (1994) · Perforce (1995) · Team Foundation Server (2005)
Revision controlled project visualization.svg
Distributed
Free/open-source
GNU arch (2001) · Darcs (2002) · DCVS (2002) · SVK (2003) · Monotone (2003) · Codeville (2005) · Git (2005) · Mercurial (2005) · Bazaar (2005)  · Fossil (2007)
Proprietary
TeamWare (1990s?) · Code Co-op (1997) · BitKeeper · Plastic SCM (2006)
Concepts
Articles
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