graphs and the smart server

[Robert Collins]

On Mon, 2007-05-07 at 17:57 +1000, Martin Pool wrote:
> On 5/7/07, Robert Collins <robertc at robertcollins.net> wrote:
> > I propose that we add a __iter__ method to Graph which will allow Graph
> > to be used as the input to various repository methods; then with an
> > InterRepository specialisation for to/from RemoteRepository, we can
> > transparently kick in this remote negotiation logic.
> 
> OK - what would that iterate?  Can you give some pseudocode for how it
> would be used?

So image an API to obtain a bundle from a repository:
def get_bundle(self, revisions):

on RemoteRepository if revisions is a RemoteGraph, it would send a smart
server method:
Repository.get_bundle(repositorypath, serialised_remote_graph)

This assumes the remote graph was previous obtained by doing some graph
difference logic to determine the needed revisions.

A method like fetch (def fetch(self, source, revision_id)) currently
forwards to an InterRepository.

so on InterRemoteAndLocalRepository.fetch:
def fetch(self, revision_id):
    needed_revisions = RemoteGraph(revision_id)
    needed_revisions = self.determine_subgraph(needed_revisions)
    self.target.apply_bundle(self.source.get_bundle(needed_revisions))

Is what I have in mind.

> > Current prototype/demo code is in two parts:
> > remote graph: sftp://bazaar.launchpad.net/~bzr/bzr/remotegraph
> > 'netsim' plugin: http://bazaar.launchpad.net/~lifeless/+junk/bzr-netsim
> 
> That sounds interesting - when posting things like this you might get
> better reviews/conversations if you explained more about what the
> components are.  It looks like netsim measures how many roundtrips and
> bytes would be required to send the graph through this mechanism?

I take your point in general. In this particular case I mailed mainly so
that its not stuck on my laptop idling while I'm at UDS. Theres plenty
of docstrings I think, so people playing with it should pick it up
easily.

netsim is a playground for me to version control experiments without
them cluttering up bzr, and as I figure out the right shape I can write
real code TDD style, with a good object model etc to build up to what
the experiment showed would be nice.

Rob
-- 
GPG key available at: <http://www.robertcollins.net/keys.txt>.
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