[[PageOutline(2-3)]] = Mercurial Plugin for Trac (#1847) = This a plugin for Trac which enables [http://www.selenic.com/mercurial Mercurial] to be used instead of [http://subversion.tigris.org Subversion] as the VersionControlSystem for Trac. ''The plugin has been marked as experimental for a while, but even if there are still some rough edges here and there, it's gotten quite usable.'' Please take care to use a recent version of the plugin before reporting issues. See the [#Releases version table] below. Detailed Change Logs: * active / supported - log:plugins/0.13/mercurial-plugin - log:plugins/0.12/mercurial-plugin * inactive / unsupported - log:plugins/0.10/mercurial-plugin, see [./@89#Trac0.10 Trac 0.10] and [./@89#Settingupthemercurialplugin setting up the plugin for 0.10] - log:plugins/0.11/mercurial-plugin == Download and Installation == === Trac === Consult the version table [#Releases below] to check which precise version you need for your version of Trac. If you want to get a specific revision, add an `svn up -rxxx` step to the instructions below, after the checkout. ==== Trac 0.11 ==== That version of the Mercurial plugin also supports of the new features added in 0.11 to the TracBrowser: - quickjump to a tag or branch - blame support - custom property renderers ([source:sandbox/property-renderers-tmp], now in 0.11) Installation of the plugin: {{{ svn co http://svn.edgewall.org/repos/trac/plugins/0.11/mercurial-plugin }}} create an "egg" from there: {{{ $ cd mercurial-plugin $ python setup.py bdist_egg $ easy_install dist/TracMercurial-0.11.0.[x]-py2.[x].egg }}} Note that you'll need [http://peak.telecommunity.com/DevCenter/setuptools setuptools] >= 0.6 for that (I used setuptools-0.6a9). ==== Trac 0.12 ==== The latest version of the plugin is at [source:plugins/0.12/mercurial-plugin]. This was merged from [source:plugins/multirepos/mercurial-plugin] as part of the MultipleRepositorySupport branch. Installation of the plugin: {{{ svn co http://svn.edgewall.com/repos/trac/plugins/0.12/mercurial-plugin }}} create an "egg" from there: {{{ $ cd mercurial-plugin $ python setup.py bdist_egg }}} ==== Releases and compatibility matrix ==== #Releases {{{#!table class="listing" ||= '''Version''' =||= mercurial-plugin =||= Trac =||= Compatible with hg =|| |---------------------------------------------------------------------------- || '''0.13.0.4''' || [source:plugins/0.13/mercurial-plugin@10880] || [source:trunk] (0.13dev) || 1.1.x to 1.7.5, tip? || |---------------------------------------------------------------------------- || 0.13.0.3 || [source:plugins/0.13/mercurial-plugin@10620] || [source:trunk] (0.13dev) || 1.1.x to 1.7.5, tip? || |---------------------------------------------------------------------------- || 0.13.0.2 || [source:plugins/0.13/mercurial-plugin@10527] || [source:trunk] (0.13dev) || 1.1.x to 1.7.5, tip? || |---------------------------------------------------------------------------- |||||||| || |---------------------------------------------------------------------------- || '''0.12.0.28''' || [source:plugins/0.12/mercurial-plugin@10878] || \ ||[source:branches/0.12-stable] (0.12.x) || \ || 1.1.x to 1.7.5, tip? || |---------------------------------------------------------------------------- || 0.12.0.27 || [source:plugins/0.12/mercurial-plugin@10619] || \ ||[source:branches/0.12-stable] (0.12.x) || \ || 1.1.x to 1.7.5, tip? || |---------------------------------------------------------------------------- || 0.12.0.26 || [source:plugins/0.12/mercurial-plugin@10524] || \ ||[source:branches/0.12-stable] (0.12.x) || \ || 1.1.x to 1.7.5, tip? || |---------------------------------------------------------------------------- || ''0.12.0.24 \\ (experimental)'' || [source:plugins/0.12/mercurial-plugin@10491] || \ ||[source:trunk@9763] and up (0.12.x) || \ || 1.1.x, 1.2.x, 1.3.x, 1.4, 1.5, 1.6, 1.7, tip? || |---------------------------------------------------------------------------- || 0.12.0.23 || [source:plugins/0.12/mercurial-plugin@9946] || \ ||[source:trunk@9763] and up (0.12.x) || \ || 1.1.x, 1.2.x, 1.3.x, 1.4, 1.5, 1.6, 1.7, tip? || |---------------------------------------------------------------------------- || 0.12.0.22 || [source:plugins/0.12/mercurial-plugin@9811] || \ ||[source:trunk@9763] and up (0.12rc1) || \ || 1.1.x, 1.2.x, 1.3.x, 1.4, 1.5 || |---------------------------------------------------------------------------- || 0.12.0.21 || [source:plugins/0.12/mercurial-plugin@9657] || \ ||[source:trunk@9125] and up (0.12b1) || \ || 1.1.x, 1.2.x, 1.3.x, 1.4, 1.5 || |---------------------------------------------------------------------------- |||||||| || |---------------------------------------------------------------------------- || '''0.11.0.10''' || [source:plugins/0.11/mercurial-plugin@10142] || [milestone:0.11] or [source:branches/0.11-stable] || 1.0.x, 1.1.x, 1.2.x, 1.3.x, 1.4, 1.6, tip? || |---------------------------------------------------------------------------- || 0.11.0.9 || [source:plugins/0.11/mercurial-plugin@9445] || [milestone:0.11] or [source:branches/0.11-stable] || 1.0.x, 1.1.x, 1.2.x, 1.3.x, 1.4 || |---------------------------------------------------------------------------- }}} General Notes: - the 0.12 version of the plugin works as well as the 0.11 one, but requires the source:0.12-stable (i.e. doesn't work with source:trunk) === Mercurial === The plugin for 0.11 takes benefit of some new features introduced after the 0.8.2 release of Mercurial, and therefore needs at least a 0.9 version of Mercurial. Note: as mentioned here [http://groups.google.com/group/trac-users/browse_thread/thread/9b1cd95621c19921/9f829e8acd958a8e] It *does* require mercurial-0.9.5. Mercurial 0.9.3 is confirmed to not work with plugin 0.11. You can download Mercurial itself from [http://www.selenic.com/mercurial/wiki/index.cgi/Download Hg:Download]. On Windows, it looks like it's possible to re-use the Mercurial library coming from the [Mercurial:BinaryPackages installer], see [http://selenic.com/pipermail/mercurial/2007-July/013827.html this mail] (though to my knowledge, it is not possible to achieve this using PYTHONPATH and PATH: it fails with `ImportError: No module named handlers` due to library.zip coming in the sys.path before the standard library). ''Note! '' Mercurial's library.zip contains pyd-files, which normal python import can't use (py2exe uses a special importer that allows that), but if you unzip library.zip somewhere and add that directory, it will work on Windows (tested with tracd). Alternatively you can install the pre-built Mercurial Python modules from http://bitbucket.org/tortoisehg/thg-winbuild/downloads/ == Configuration == The configuration has to be done on the Trac side, there's nothing to do on the Mercurial repository side, except for the fact that the repository should be made accessible as a local repository. Thanks to the distributed nature of Mercurial, that's always possible (if the repository is not already local, simply `hg clone` it). === Setting up the mercurial plugin === The TracMercurial plugin egg should be added to the `plugins` folder of the environment, or it can be globally installed (`python setup.py install` or a `python setup.py develop`). For general instructions about plugins, see also TracPlugins. If you installed the egg globally and you're modifying an existing Trac environment to use the Mercurial backend, then you have to explicitly ''enable'' the plugin in TracIni. Since the version 0.11 of the plugin, the package has been renamed to `tracext`: {{{ [components] tracext.hg.* = enabled }}} === Setting up a Trac environment === You can either reuse an existing Trac environment, or create a brand new one. For general instructions, see TracInstall. Since [milestone:0.10], has now a ''repository type'' argument besides ''repository directory''. When creating a new environment with TracAdmin `initenv` command, - for the ''repository type'', specify `hg` instead of the default `svn`. - for the ''repository directory'', specify the location of the Mercurial repository (without the ending `.hg`). Your [wiki:TracIni /conf/trac.ini] configuration file should have a `[trac]` section similar to the following: {{{ [trac] repository_type = hg repository_dir = /path/to/my/hg/repository }}} There's also a few Mercurial specific settings in TracIni: {{{ [hg] # -- Show revision number in addition to the changeset hash (defaults to yes) show_rev = yes # -- Changeset hash format node_format = short # hex: Show the full SHA1 hash # short: Show a shortened hash for the changesets (default) }}} === Setting up post-commit hooks === For [milestone:0.12] and later: If you want to enable post-commit hook functionality on your repository, add the following to your repository's `.hg/hgrc` file (since [10728]): {{{#!ini [hooks] ; If mercurial-plugin is installed globally commit = python:tracext.hg.hooks.add_changesets changegroup = python:tracext.hg.hooks.add_changesets ; If mercurial-plugin is installed in a Trac plugins directory commit = python:/path/to/hooks.py:add_changesets changegroup = python:/path/to/hooks.py:add_changesets [trac] env = /path/to/env trac-admin = /path/to/trac-admin }}} Remember to change `/path/to/env` and `/path/to/trac-admin` to reflect your environment. If TracMercurial is installed in a Trac `plugins` directory, you will also have to download [source:plugins/0.13/mercurial-plugin/tracext/hg/hooks.py hooks.py] and place it somewhere accessible. You must also enable the CommitTicketUpdater functionality in your `trac.ini` by adding {{{ tracopt.ticket.commit_updater.* = enabled }}} to the `[components]` section. == Features == The Mercurial support is pretty basic, but works well. I've tested that on the Mercurial repository itself and the performance is acceptable, even if there's currently ''no'' caching in the database (this is what I'm going to work on next, with a very loose definition of next, see #8417). For those used to Subversion in general and Subversion repository browsing in Trac in particular, there are a few differences worth noting. === Mercurial Changesets === ==== Changeset Navigation ==== In Mercurial, the ''Previous Changeset''/''Next Changeset'' navigation is ''not'' purely sequential, as it is in Subversion. Instead of a ''flat'' history of successive changesets, we actually navigate a DAG of changesets. This means a changeset can have multiple parents (0, 1 or 2) and multiple children as well (0 to n). Therefore, ''Previous Changeset'' is a link to the first parent, and ''Next Changeset'' is a link to the first child. In case there are additional parents or children, these are shown as additional changeset properties (''Parents'' or ''Children''), placed below the ''Author'' property and above the ''Message'' property. [[Image(hg-plugin-changeset.png)]] Another additional changeset property is the list of ''Tags'' that might be associated with a changeset. ==== Wiki syntax ==== The Wiki syntax has been extended a bit, to cope with the hexadecimal notation of hg changesets. E.g. `[8ef2]` would link to the changeset 8ef2ba892518c115170398ec754bd1c27cab271f ... Plain changeset numbers are also recognized, provided they are long enough (12 to 40). Also, it is possible to refer to changesets using the changeset: prefix (or cset: or chgset:, for hgweb compatibility). The tag: prefix can be used to refer to symbolic tags, although this is not a requirement (using. e.g. `cset:tip` would work too). Finally, the branch: prefix has a special meaning, as this will not select the specified revision, but the head which is reachable from that revision. === TracBrowser changes in [milestone:0.11] === The TracBrowser ''View revision'' form has been extended with pulldown menus for jumping to a given tag or branch (in Mercurial, a branch within a repository corresponds to a head, i.e. a changeset without children): ---- [[Image(hg-plugin-browser.png)]] ---- There's also support for visual ''blame'' annotations: ---- [[Image(hg-plugin-annotate.png)]] === Mercurial Queue === Since r6443, the MQ extension is supported. If you happen to have applied mq patches in your repository, Trac will show the corresponding patch names as '''Tags:''' in the changeset view. Also, with the 0.12 branch of the plugin (and the MultipleRepositorySupport branch of Trac), you can browse jointly the main repository and the repository for the associated Mercurial queue, if any (i.e. if you versioned your patch queue using `hg qinit -c` and `hg qcommit`). Furthermore, if you declare such a mercurial repository to be a MQ repository, then all the patches will be correctly rendered as patches, regardless of the patch name (see r6462 for details). == Bugs and Limitations == There are still a lot of things that can be improved. === Features that Trac+svn has but not currently implemented for Trac+hg === * ~~History doesn't follow copy/move operations~~ ''implemented in r8445'' [[br]] Works for files only, which is OK I think, as Mercurial has no notion of directories and detecting copy/move of directories would be pretty hard to implement * No ''path history'' mode (i.e. show all create/delete operations that affected a given path) * ~~Revision log ranges [xxx:yyy]~~ ''implemented in r10427 for Trac [milestone:0.12.2]'' * ~~View arbitrary diffs~~ ''implemented in r6053'' === Multi-repository support === First and foremost, even if Mercurial allows intra-repository branching, it strongly supports the use of branching by cloning the full repository. Therefore, it is common to have a lot of hg repositories around, each devoted to the implementation of some particular feature. Trac should support this by the way of multiple repository support within a single environment (see #2086). This is now implemented since Trac [milestone:0.12]. Use the 0.12 version of the plugin. === To cache or not to cache? === Recent versions of the plugin (r7744 for 0.11 or r7757 for 0.12) have a greatly improved browsing speed. It's now possible to navigate on repositories of the size of the Linux kernel repo. However, producing diffs or even gathering the timeline events for repositories of such size is still too slow. For the diffs, we could reduce the amount diffs generated (see #2591, #7975). For the timeline, we should really have a cache, not only for the performance issue but also because the current heuristic for retrieving the changesets in a given period of time doesn't always work (see r5365). === Cool Features === ''Wild ideas'' section... ==== Visualize branches and merges ==== There should be a way to show graphically the branch and merge points within the revision log view. Not something as fancy as `hgk`, but nonetheless something that will make the changeset relationships immediately obvious. ''Starting with Trac [milestone:0.13], we show a graphical overview of the branch graph when viewing the log of the repository root (#1492)'' Also, there is [http://trac-hacks.org/wiki/RevtreePlugin RevtreePlugin]. ==== Search over the source ==== A search provider could do the equivalent of an `hg grep`. ==== Highlight Conflict Resolution ==== While visualizing changeset diffs for merge changesets, we already show the changes relative to both parents, which helps to understand how conflicts (if any) were solved. But this can be improved by specifically highlighting lines that differs from both parents. ==== Repository Management ==== Trac should allow for creating new repositories or clones of existing repositories. Maybe repository deletion and renaming should be supported, too. ==== ~~HG Forest Support~~ Subrepositories support ==== //The forest extension has been superseded by support for [Mercurial:Subrepository nested repositories]. Replace //forest// below by //subrepository//.// (#9704) Support for the Forest extension for Mercurial. Forest extension allows operations on trees with nested Mercurial repositories, called forests. Those to some degree correspond to multi-project CVS/Svn/... repositories. Already got most of it working, expect that it's pretty much hacked in the Trac 0.10.3 version of the mercurial plugin. Since it needs a bit more flexibile templating (in regards with the lookup/url's) this is hacked around node.path at the moment. Some (small/large?) issues remain but most of it is working. ''Note that with the MultipleRepositorySupport branch of Trac, it should be possible to implement an IRepositoryProvider component knowing about the `forest` extension and adding besides the repository for the forest itself, the managed repositories as well.'' ==== ''Add your cool feature here...'' ==== == Troubleshooting == === "unsupported version control system hg" === If you get this message try the following two basic checks first: * From a Python console session try to import the Mercurial module, if all goes well it should not complain: {{{#!pycon >>> from mercurial import ui, hg >>> repo = hg.repository(ui.ui(), '/path/to/a/mercurial/repo') >>> len(repo) 234 }}} You can also look at the `hg.__file__` attribute to verify you're loading the expected Mercurial library. * Log in as an user with `TRAC_ADMIN` permission, and look in the `Admin` pages, `General / Plugins`. Do you see the entry for the !TracMercurial plugin there? If yes, is the !MercurialConnector component enabled? === Known Issues === [[TicketQuery(component=plugin/mercurial,milestone=plugin - mercurial,status=!closed)]] == Implementation Notes == Hacking on Mercurial: - [mercurial:MercurialApi] - [mercurial:ApiChanges] - [mercurial:CommandServer] and [mercurial:PythonHglib] (not yet used - see #10411) I'm interested in feedback concerning the code, in particular concerning Mercurial. I'm pretty sure I did things in a sub-optimal way, as I was discovering the guts of hg while writing the plugin. Therefore, I'll be pleased to get tips for improvements. '' -- ChristianBoos ''