Stacking policy

[Aaron Bentley]

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James Westby wrote:
> Hi Aaron,
> 
> Thanks for bringing this up.
> 
> On Tue, 2008-04-01 at 11:48 -0400, Aaron Bentley wrote:
>> 1. Open containing folders looking for a shared repository or stacking
>>    configuration.  If a shared repository is found, select that shared
>>    repository.  If a stacking configuration is found, select that
>>    policy.
> 
> Do you have any idea how this stacking configuration would look?

I would suggest having a file named .bzr/config that would be an
ini-style config file.  The variable "default_stacking_location" would
provide the location of a branch to stack on.

>> 2. If no policy has been selected, and the branch is being created from
>>    another branch (i.e. bzr branch), and the other branch has the same
>>    URL prefix (including hostname, if applicable), select the other
>>    branch as the stack-on branch.
> 
> This does ok at trying to make sure that the stacked-on branch doesn't
> suddenly disappear. However, what about things like filesystem 
> boundaries.

They're impossible to detect in the common case.  For file locations, we
could disallow stacking on branches which use different filesystems.
But that's only one form of visibility difference.

> If I were to a USB stick to transfer a branch
> 
>   bzr branch bzr.dev /media/usb
> 
> then when I get this usb to the other machine it can no longer find
> the revisions it needs.

But hopefully you'll see a message like "Stacking /media/usb/bzr.dev on
bzr.dev" and realize you need to do something different.

> Is there a reason that you don't want to leave it up to shared-repos
> and points 0 and 1 to do what the user wants?

Bazaar is being perceived as slow because its default mode of operation
is slow.  People don't learn about the extra configuration required to
make it fast, or don't bother doing it, so they get this impression.

I don't think being slow is a good default.  Stacking doesn't require
extra configuration, so it's a way of being fast by default.

Aaron
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