Bazaar

Bazaar

 




Wiki Tools

  • Find Page
  • Recent Changes
  • Page History
  • Attachments

Differences between revisions 57 and 58
Revision 57 as of 2006-07-04 20:18:33
Size: 5765
Comment:
Revision 58 as of 2006-07-05 13:41:12
Size: 6372
Comment: Update future enhancements.
Deletions are marked like this. Additions are marked like this.
Line 11: Line 11:
alpha. ( alpha.
Line 47: Line 47:
 * Handles complex operations in Subversion: committing to two branches at once, upgrading directories to branches,
   copies from early revisions, ...
Line 62: Line 65:
   This might require also storing 'bzr:inventory' and 'bzr:revision' properties in order to make
   sure the sha1's for a revision keep matching.
Line 64: Line 70:
 * Performance. Network-wise (both bandwidth and roundtrips), the plugin is currently pretty much as efficient as it can be. However, it is currently quite CPU-intensive for no good reason and I hope to make a couple of improvements in that area.  * Proper Windows support. Most of the code depends on '/' being the path separator at the moment.
Line 66: Line 72:
 * Creating and updating native Subversion working copies. This would mostly be supported for completeness, there are not a lot of advantages in supporting it.  * Performance. Network-wise (both bandwidth and roundtrips), the plugin is in good shape. However, it is currently quite CPU-intensive for no good reason and I hope to make a couple of improvements in that area.

    * Keep on-disk cache of file-ids to path mappings

    * Override implementation of get_revision_delta(). Will speed up 'bzr log -v'

    * use svn_ra_replay() on systems that have Subversion 1.4. Saves a couple of roundtrips when fetching history.

    * implement svn_ra_get_dir_revs() in Subversion to fetch the properties set on a specific directory all at once.

 * Creating native Subversion working copies. This would mostly be supported for completeness' sake, there are not a lot of advantages in supporting it.
Line 72: Line 88:
 * `svn:externals'. Externals should be mapped to Bazaar 'by-reference' nested branches and the other way around. This can't be implemented until Bazaars nested branch support lands. AaronBentley's work in progress is at http://code.aaronbentley.com/bzr/bzrrepo/nested-trees/.  * `svn:externals'. Externals should be mapped to Bazaar 'by-reference' nested branches and the other way around. This can't be implemented until Bazaars nested branch support lands. AaronBentley's work in progress is at http://code.aaronbentley.com/bzr/bzrrepo/nested-trees/. Has been delayed until after 0.9 because of required
repository format changes.

 * Horizon revision history. Most of the existing Subversion repositories are quite large and it would therefore be nice to be able to limit the amount of history that needs to be retrieved during checkouts. Subversion supports horizon history fine.
Line 76: Line 95:
 * Showing SVN merges as merges in Bazaar. This requires support for partial merges in Bazaar. Another option would be storing full merge information in Subversion, something which the Subversion folks are working on at the moment (see https://svn.collab.net/repos/svn/branches/merge-tracking).
Line 80: Line 97:
   It might be possible to get rid of the need to retrieve the full log if Bazaar supported file id aliases and if Branch.revision_history() would use iterators. Features held back by Subversion:
Line 82: Line 99:
   The log output can be cached though and only takes a few minutes on large repositories anyway.

   (needs more thought)

 * Horizon revision history. Most of the existing Subversion repositories are quite large and it would therefore be nice to be able to limit the amount of history that needs to be retrieved during checkouts.
 * Showing SVN merges as merges in Bazaar. This requires full merge information in Subversion, something which the Subversion folks are working on at the moment (see https://svn.collab.net/repos/svn/branches/merge-tracking). However, this seems to require support for cherry-picking.

Introduction

This plugin provides a mapping between Bazaar and Subversion revisions unambiguous so to people that run Bazaar on a Subversion branch end up with exactly the same branch and can pull changes from each other.

The plugin can at the moment be used to commit to, pull from, merge from, push to and view logs of Subversion branches from Bazaar.

It is fully functional, _BUT_ has only been tested on a few different Subversion branches, so should be considered alpha.

Screenshots

Features

The following features are currently present:

  • Connecting to remote Subversion repositories over all protocols supported by Subversion itself (at present: svn://, svn+ssh://, http:// (webdav), file://) as well as dump files. Checkouts, lightweight checkouts and branching works.

  • Track Bazaar merges in Subversion. Merged revisions show up as ghosts.
  • Subversion working copies. Can be modified, queried (bzr status' on a vanilla working copied created with svn co' works) and committed from.

  • Committing to Subversion from Bazaar.
  • Push Bazaar revisions to Subversion. These revisions will show up in Subversion as a commit with the pushed revision as one of the parents.
  • Follow branch copies. Revision history is not truncated when a branch was copied in Subversion.
  • Efficiently uses network bandwidth.
  • Recognizes file metadata (executable bits, symlinks).
  • 'import-svn' command with functionality similar to svn2bzr.
  • Ability to track merges done with SVK (http://svk.elixus.org/) and write merges from SVK/Svn branches in a format understandable by SVK.

  • Generates consistent file ids and revision ids. Two branches made using this plugin of the same Subversion branch will result in *exactly* the same Bazaar branch.
  • Handles complex operations in Subversion: committing to two branches at once, upgrading directories to branches,
    • copies from early revisions, ...

Future Enhancements

In the future, I also hope to support:

  • Renames. Initial work has been done to support this, but the number of corner cases is wide, so support for this
  • "True" push. This requires storing the Bazaar inventory and revision in Subversion revision properties.
    • Ideally, revision id aliases would have to be used so the revision id that is being 'overriden' can still exist. Once this is implemented, it would also be possible and make sense to store GPG signatures for commits in Subversion branches. This might require also storing 'bzr:inventory' and 'bzr:revision' properties in order to make sure the sha1's for a revision keep matching.
  • Proper read locking, which has basically been ignored for now.
  • Proper Windows support. Most of the code depends on '/' being the path separator at the moment.
  • Performance. Network-wise (both bandwidth and roundtrips), the plugin is in good shape. However, it is currently quite CPU-intensive for no good reason and I hope to make a couple of improvements in that area.
    • Keep on-disk cache of file-ids to path mappings
    • Override implementation of get_revision_delta(). Will speed up 'bzr log -v'
    • use svn_ra_replay() on systems that have Subversion 1.4. Saves a couple of roundtrips when fetching history.
    • implement svn_ra_get_dir_revs() in Subversion to fetch the properties set on a specific directory all at once.
  • Creating native Subversion working copies. This would mostly be supported for completeness' sake, there are not a lot of advantages in supporting it.

Some Subversion properties can currently not be represented in Bazaar and are therefore ignored for the time being:

  • svn:ignore' is not imported. There should be a Repository.get_ignores(revid)' call in Bazaar rather than a magic '.bzrignore' file.

  • `svn:externals'. Externals should be mapped to Bazaar 'by-reference' nested branches and the other way around. This can't be implemented until Bazaars nested branch support lands. AaronBentley's work in progress is at http://code.aaronbentley.com/bzr/bzrrepo/nested-trees/. Has been delayed until after 0.9 because of required

repository format changes.

  • Horizon revision history. Most of the existing Subversion repositories are quite large and it would therefore be nice to be able to limit the amount of history that needs to be retrieved during checkouts. Subversion supports horizon history fine.

Other features currently held back by Bazaars feature set:

  • Branch.revision_history() and generating file ids currently requires retrieving the full `log' of a Subversion repository.

Features held back by Subversion:

  • Showing SVN merges as merges in Bazaar. This requires full merge information in Subversion, something which the Subversion folks are working on at the moment (see https://svn.collab.net/repos/svn/branches/merge-tracking). However, this seems to require support for cherry-picking.

Implementation

http://people.samba.org/bzr/jelmer/bzr-svn/bzr.dev

Installation

The plugin requires a couple of fixes to the Python bindings for Subversion. Debian/Ubuntu packages available at http://samba.org/~jelmer/bzr/. You need the python-subversion and libsvn0 packages. These changes have been submitted to the Ubuntu Subversion package in [https://launchpad.net/products/bzr-svn/+bug/51304 #51304].

You will also need bzr.dev (plus a small fix for workingtrees that I will send in soon).

Simply place this directory in ~/.bazaar/plugins and you should be able to check out branches from Subversion using bzr.

Bugs

Please file bug reports in launchpad. The product URL for bzr-svn is https://launchpad.net/products/bzr-svn/.

License

GNU General Public License, v2 or later.

Unit testing

Simply run 'bzr selftest svn'