[RFC] Ability to register optimised revision fetchers

[Martin Pool]

On 22 March 2010 08:14, Jelmer Vernooij <jelmer at samba.org> wrote:
> It would be nice if all of the fetchers in Bazaar (native and
> non-native) supported prompting a set of hooks for a faster way to fetch
> particular revisions.
>
> There are a couple of use cases for this:
>
>  * A plugin that keeps a cache of all revisions in a store in ~
> somewhere
>  * A plugin that queries launchpad's vcs-imports when importing from a
> foreign version control system
>  * A plugin that asks other local servers whether they have a copy of a
> revision

That would be nice.  You could probably make it work at the moment by
registering an overriding InterRepository, but it would probably be
more maintainable if there was a specific documented mechanism for
this.

There may be some interesting tradeoffs between fast-to-access vs
being in the right format.  But they may not be very important in
practice, if we assume the fallbacks are all in bzr native current
format, so

 local native
 local caches
 local foreign branches
 {perhaps a remote-but-nearby category here}
 remote native
 remote caches
 remote foreign

-- 
Martin <http://launchpad.net/~mbp/>