[RFC] Alternative to current push/pull semantics [use weave.join]

[Goffredo Baroncelli]

On Friday 16 December 2005 18:59, John Arbash Meinel wrote:
[...]
> What I was thinking is that we probably could cheat, and instead of just
> adding each text, just do a weave.join().

weave.join( ) does so: it extracts every text not present, then adds it to the
target repository.
However I think that for non merge revision ( == revision with only one parent )
it is possible to merge to a weave without extraction then addition...
I need some time to write the code.

[...]

> But it would change the current semantics to:
> 	download the remote weave header
> 	see that it is missing the revision we want
> 	download the full remote weave
> 	read the local weave
> 	weave.join()
> 	save the remote weave


> After that, even if we don't cache what weaves have what revisions,
> future steps would just be:
> 	download the remote weave header
> 	see it has the revision we care about
> 	no upload needed
> 
> Now right now we can't just download the header. I think we really can,
> but since our buffer size (32k) is greater than the average file size
> (8k), it doesn't gain us much. 

In order to know which revision are in the weave it should be sufficient to inspect
the history weave: in this file are recorded both the file id and the
revision id.
If you want to know which revision id of the README file are in the repository:

$ ./bzr inventory --show-ids | grep ^README
README                                             README-20050309040720-8f368abf9f346b9d

$ grep README-20050309040720-8f368abf9f346b9d .bzr/inventory.weave  | \
	sed -e 's/^.*revision="//' -e 's/".*//' | sort | uniq
mbp at sourcefrog.net-20050309040815-13242001617e4a06
mbp at sourcefrog.net-20050314025438-d52099f915fe65fc
mbp at sourcefrog.net-20050314030104-0116680aba6499b6
mbp at sourcefrog.net-20050314070724-ba6c85db7d96c508
mbp at sourcefrog.net-20050319235021-a4a900883ea8e2d8
mbp at sourcefrog.net-20050326030328-350bb37fb45b5eb4
mbp at sourcefrog.net-20050429004334-bbb9dc81ce0d9de3
mbp at sourcefrog.net-20050509012317-a503ae2eed842146
mbp at sourcefrog.net-20050510082309-92b2ba534866314e
mbp at sourcefrog.net-20050510083156-166057e03c21c713
mbp at sourcefrog.net-20050511010322-54654b917bbce05f
mbp at sourcefrog.net-20050722233200-ccdeca985093a9fb
mbp at sourcefrog.net-20051019070401-0536bd80d1282c7f
mbp at sourcefrog.net-20051101215717-fce2860f5195075a
mbp at sourcefrog.net-20051118081007-80523bf145eb319b
robertc at robertcollins.net-20050919060519-f582f62146b0b458

Goffredo

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