[tahoe-dev] what should we work on at the Boulder Hack Fest?

Brian Warner warner at lothar.com
Thu Mar 29 19:18:58 UTC 2012


On 3/29/12 12:01 PM, Greg Troxel wrote:
> 
> More than that - if we have 1 share of M and all shares of N, for N >
> M, then we really just want to purge (or ignore?) the M share, and not
> molest the N shares.

Ah, good point. We really only need a new version if there are multiple
competing versions with the same sequence number, and if that sequence
number is the highest seen. Repair is tricky in that case anyways, since
at the Tahoe level we can't do an automatic merge, so we're certainly
losing information (if it's just a directory modification, then the
directory.py code can re-apply the modification, so that one case might
be safe).

Hm, ServerMap.needs_merge() is pretty close already, but it only looks
at recoverable versions (it tells you that an update will lose
information that would have been recoverable if you'd read the
individual versions first.. there are alternate cases where it doesn't
matter because the other versions weren't recoverable anyways).

We should add a method to ServerMap that tells us whether a new version
is needed or not.

> The above test is how the pubgrid feels to me, or used to.

Yup, that test looks right.

cheers,
 -Brian



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