[tahoe-dev] User Specification of Servers (#467)

[Zooko O'Whielacronx]

Dear Mark:

This sounds like a good Google Summer of Code project. However, it
looks like Leif may already be working on it:

https://github.com/tahoe-lafs/tahoe-lafs/pull/39

Could you folks please cross-link the github and trac
tickets/pull-requests/patches/whatever so that everyone finds out
about everyone else's work?

Now, this Preferred Servers work would probably interact with any
future "Upload Strategy of Happiness" work. That is, if someone is
going to fix the server-selection algorithm so that it achieves the
"Servers of Happiness" fault-tolerance level whenever possible, they
would simultaneously need to *preserve* any server-preference behavior
that the Preferred Servers mechanism implements. I think Kevan
addressed this in his thesis -- there is a step in his Upload Strategy
of Happiness algorithm where you have to pick a server and any one out
of a set of servers will do, and that place is where you could
preferentially pick one of the members of that set which is Preferred.
(That set is, if I understand correctly, the set of servers that don't
already have a share assigned to them in this upload.)

https://tahoe-lafs.org/trac/tahoe-lafs/wiki/GSoCIdeas#UploadStrategyOfHappiness

So anyway, I guess what I'm getting at is that if you wanted to
implement Preferred Servers, and it turned out you couldn't because
Leif already did, then there may well be useful extensions or
generalizations of Preferred Servers that you could still do.

The "Darcs execution failed" error on https://tahoe-lafs.org trac
should be fixed now. Please let me know if it recurs.

Regards,

Zooko