Multiple Repository Support for 0.12

This branch adds support for accessing multiple repositories inside one Trac project.

For now, there is support for the Mercurial (hg) and Subversion (direct-svnfs) type of repositories.

See:

• log:sandbox/multirepos
• log:sandbox/mercurial-plugin-0.12

Checkpoints:

• r6465: initial "release" of the branch, worksforme
• r6469: a few bug fixes

The approach is quite simple: beyond repository connectors, there's now repository providers (IRepositoryProvider components) which are responsible for make available a list of named repositories. That name can be arbitrary (in particular, it may contain '/' to denote a pseudo-hierarchy) and will be used as a prefix for any repository path. Actually, a more complete description of the approach can be found in this mail: ​One trac env for X repositories ?.

If the only repository known is the default one (i.e. the one defined in TracIni, section [trac] repository_...), then Trac behaves exactly as before. But IRepositoryProvider components can make other repositories available. In particular, the default RepositoryManager itself provides a list of repositories listed in a new [repositories] section in TracIni. See r6447 for more details.

Installation (with mercurial)

A current installation procedure which works is the following:

1. Check out the mercurial plugin:

   svn co http://svn.edgewall.com/repos/trac/sandbox/mercurial-plugin-0.12
   

2. build the mercurial plugin. From within the checked-out directory, build the egg file (it will end up in the dist subdirectory):

   python setup.py bdist_egg
   

3. Check out the multirepos branch:

   svn co http://svn.edgewall.com/repos/trac/sandbox/multirepos
   

4. Install the multirepos version of trac (from within the multirepos directory, as root):

   python setup.py install
   

5. Create your trac environment directory

6. Copy the mercurial plugin egg file to the <trac-env>/plugins directory

7. make sure the following is somewhere in <trac-env>/conf/trac.ini, adding all the desired repositories to the [repositories] section:

   [components]
   tracext.hg.* = enabled
   
   [repositories]
   my_repo_a.dir = <path_to_a_repository>
   my_repo_b.dir = <path_to_another_repository>
   my_repo_c.dir = <path_to_yet_another_repository>
   my_repo_c.type = direct-svnfs
   
   [trac]
   repository_dir = <path_to_default_repository>
   repository_type = hg
   

   Note that when the repository .type is not specified, the value of [trac] repository_type is used.
   In the above example, this means that my_repo_a and my_repo_b are Mercurial (hg) repositories.
   Note also that for now, only the direct-svnfs repository type can be used for Subversion repositories, as the cached repository used by the other type (svn) has not yet been extended to support multiple repositories.
8. Cross your fingers, and hope it works :)
   It really should or it's a bug ;-)

To make links to the non-default repository, just add a slash and the alias name after the revision identifier, for example: "[changeset:cffd9e480266/my_repos_b a changeset]". The default repository can be one of the explicitly named repositories.

TODO

• More IRepositoryProvider components:
  • HgForestRepositoryProvider, for providing forest repositories and all sub-repositories managed by each forest
    • work-in-progress on ​http://hg.trbs.net
    • in trac.conf use:

      [hg-forest]
      jdk7.dir = /path/to/mercurial/root/forest/repository/jdk7
      

  • HgParentDirRepositoryProvider, for listing all the working copies present in a given folder
    • work-in-progress on ​http://hg.trbs.net
    • in trac.conf use:

      [hg-parents]
      bunch.dir = /path/to/parent/directory/somedir
      

  • SvnParentDirRepositoryProvider, for listing all the Subversion repositories present in a given folder
• currently, a default repository needs to be defined, otherwise the versioncontrol modules are disabled
• fix AJAX query in annotate
• extend to cached repositories
• IRepositoryProvider must have a way to signal new content, in order to rebuild the repository name cache
• support the .url repository metadata (#1781)
• small issue: visual glitch in Firefox for the new Rev column, where the changeset icon doesn't align properly to the right (but works fine for every other web browser)
• "normal" feature: it's currently not possible to compare across repositories (the situation is detected, but raises a "not implemented" error). It would be quite useful to be able to do so, and it's doable without much work (only need to compare folders in a backend neutral way, we already do our own diff at the file level)
• major feature (blocker): make the cache work again. In a first step, the existing cache could be adapted to simply handle more than one repository.
  Bonus points if that cache is smart enough to handle multiple scoped repositories without data duplication.
  A second (much) more ambitious step would be to generalize the cache so that it can support other (d)vcs.