re-added support for ghosts in newformat

[John A Meinel]

Martin Pool wrote:
> Hi,
>
> The upgrade command in the newformat tree now carries across
> references to 'ghost' revision, which are named in a revision
> reference but whose data is not present in the tree.  The main use
> case for these is importing data from bazaar and arch, where trees
> commonly have such things.  They might also be useful in letting
> people store only a subset of history locally.
>
> There is also a test for this, and for upgrade in general, and some
> new test helpers for building trees with given contents.
>
> The test (as they tend to do) discovered a regression in the upgrade
> code, which is (I think) that merging in Transport broke support for
> upgrading from branches whose stores contain a mix of compressed and
> uncompressed files.  That's perhaps a wierd configuration but it does
> happen.  So we should decide whether to make everything compressed
> before upgrading, or perhaps undo the split into CompressedTextStore
> and TextStore.

I don't mind if you want to bring back a mixed store. I removed it
because up to this point, everything I ever encountered was compressed.
And when you are dealing with remote stores, it made sense not to have a
double round trip.

Since the new format prefers an uncompressed revision store, and the
Compressed format is the old format, how about we update
"CompressedTextStore" to handle both compressed and uncompressed (so we
can read the old format), and then we leave the new format as using
TextStore for now, which means that it doesn't need to do the round-trip
stuff.

Anyway, I went ahead and did the work (including tests). You can find
the results here:
http://bzr.arbash-meinel.com/branches/bzr/newformat-compressed-text

Basically, CompressedTextStore is no longer as optimized for pipelined
downloads, etc. But since it is really only used in the "bzr upgrade"
command, I'm not really worried about it.

I also left some comments about how things could be optimized, but I
didn't care to do the work right now.

John
=:->

PS> If people are grabbing some of my old code, I move branches that I'm
not actively maintaining to:
http://bzr.arbash-meinel.com/branches/OLD/

This just helps me keep track of what I'm actively working on, and what
is just historical code.


>
> --
> Martin
>
>

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