On Sun, Nov 13, 2011 at 12:11:31AM +0800, Tay Ray Chuan wrote:
> One thing I'm not comfortable with is the "flexibility" allowed in
> bundle fetching - servers are allowed to send bundles if they see fit,
> and we have to detect it when they do (if I'm reading the "surprised"
> scenario in patch 9 correctly).
Right.
> Perhaps we can expose bundle fetching through /objects/info/bundles?
But what if the server you are hitting doesn't have a git repo at all?
In the simplest case, a bundle provider should just be able to put a
file somewhere http-ccessible, without having any special directory
structure or other meta files.
Which means that we have to be prepared for the URL the user gave us to
be a bundle, not a git repo that contains bundles.
> It could possibly contain information about what bundles are available
> and what revs they contain. If bundles are found, fetch them;
> otherwise, go through the usual ref advertisement and other steps of
> the pack protocol.
This is "step 2" of my plan: hitting a git repo will provide a way of
redirecting to other, static storage. But I think it's important that
the other storage not just be a path in the existing repo, for two
reasons:
1. You might want to redirect the client off-server to a
higher-bandwidth static service like S3, or something backed by a
CDN.
2. The client might not be hitting you through http, so you can't
expect them to look at arbitrary repo files (like
objects/info/bundles). We need to provide the information over the
git protocol (my plan is to use a special ref name, like
"refs/mirrors" to encode the information).
> That way, we take out the "surprise" factor in the fetching protocol.
I don't think it's that big a deal. It influenced the way that patches 9
and 10 were written (patch 9 handles "surprise" bundles when fetching
info/refs, and then patch 10 falls back to fetching $URL without
info/refs). But even if we didn't have the "surprise" case, most of the
code in patch 9 would have just ended up in patch 10. That is, the
surprise case doesn't take much code, and doesn't have a negative impact
on the non-surprise case (i.e., until we see a bundle header, the
behavior is identical, just putting the refs into a memory buffer).
-Peff
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