re-added support for ghosts in newformat

[John A Meinel]

Robert Collins wrote:
> On Tue, 2005-10-04 at 14:09 -0500, John A Meinel wrote:
>
>
>>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.
>
>
> Another way to do it would be to make the default format that the branch
> wants paramterisable.
>
> i.e. TextStore(transport, compressed_is_default=True)
>
> => tries .gz first then without.
>
> TextStore(transport, compressed_is_default=False)
>
> => tries without .gz, then with.
>
> For a homogenous store, with the right default, this will be optimal.
> For a heterogenous store, or one with the wrong default, you'll pay the
> probe cost.. but bringing in some async stuff will mean you are only
> paying the request cost, not the latency cost, for many operations.

Actually, it is much worse than a simple probe.

The problem is that in my code, I was able to use "has_multi" which
should allow a pipelined check, if you requested 50 files, I could check
for their existence in a single command.

Now, I can actually change the pipelining, so that if you request 50
files, I check for the existence of 100, and then decide what results to
return accordingly.

For a single file, I would probe double.

It would indeed be possible. And if you look at my branch, you will see
that CompressedTextStore has some comments about where that sort of
thing could be done.

Since we are moving away from ever having a compressed store (we either
have a full-text or a weave), I wasn't going to take the time to
implement it.

Do you feel that CompressedText has a future? I thought we only needed
to support it to allow for "bzr upgrade".

John
=:->
>
> Rob
>

-------------- next part --------------
A non-text attachment was scrubbed...
Name: signature.asc
Type: application/pgp-signature
Size: 253 bytes
Desc: OpenPGP digital signature
Url : https://lists.ubuntu.com/archives/bazaar/attachments/20051004/7ab17660/attachment.pgp