We've always, since the introduction of conflicts, had the policy that
deletes lose against any other change, for safety's sake. This is a
problem, however, because it means the sort order of versions is not a
total order.
That is, given two versions `A` and `B` that are currently in conflict,
we will sort them in a given order (let's say `A, B`, so `A < B` for
ordering purposes: we say "A wins over B" or "A is newer than B") and
consider the first in the list the winner. The loser (who has `B` on
disk) will process the conflict at some point and move the file to a
conflict copy and announce `A'` as the resolved conflict. The winner
(with `A` on disk) doesn't do anything.
However, if `A` is deleted the ordering changes. We still have `A < B`
and, of course, `Adel < A` (this is not even a conflict, just linear
order). In most sane systems this would imply the ordering `Adel < A <
B`, however in our case we in fact have `B < Adel` because any version
wins over a deleted one, so there is no logical ordering at all of the
files at this point. `Adel < A < B < Adel ???` In practice the deleted
version may end up at the head or the tail of the list, depending on the
order we do the compares.
Hence, at this point, "whatever" happens and it's not guaranteed to make
any sense. 😬
I propose that we resolve this my simply letting deletes be versions
like anything else and maintain a total ordering based on just version
vectors with the existing tie breakers like always. That means a delete
can win in a conflict situation, and the result should be that the file
is moved to a conflict copy on the losing device. I think this retains
the data safety to almost the same degree as previously, while removing
probably an entire class of strange out of sync bugs...
---
(A potential wrinkle here is that, ideally, we wouldn't even create the
conflict copy when the delete and the losing version represent the same
data -- same as when we handle normal modification conflicts. However,
the deleted FileInfo doesn't carry any information on what the contents
were, so we can't do that right now. A possible future extension would
be to carry the block list hash of the deleted data in the deleted
FileInfo and use that for this purpose, but I don't want to complicate
this PR with that. The block list hash itself also isn't a
protocol-defined thing at the moment, it's something implementation
dependent that we just use locally.)
* main:
docs: link to Docker image, APT, in release notes
build: also create relaysrv and discosrv releases
fix(stupgrades): return latest stable & pre for each major
fix(syncthing): avoid writing panic log to nil fd (#10154)
This changes the default number of connections from one to three (one
metadata + two data connections). This should give some advantages of
multiple connections, while also not being an overwhelming change for
larger installations. (Though those may need to tweak their settings
anyway, as always.)
This adds a file that will be prepended to release notes (tag messages,
GitHub releases, forum posts) for v1 releases. I'd like there to be
something there to flag that things are going to change.
* main:
refactor: use slices package for sorting (#10136)
build: handle multiple general release notes
build: no need to build on the branches that just trigger tags
