In a situation where there are two repos that are diverged and each pushes
in turn to git-remote-annex, the first to push updates it. Then the second
push fails because it is not a fast-forward. The problem is, before git
push fails with "non-fast-forward", it actually calls git-remote-annex
with push.
So, to the user it appears as if the push failed, but it actually reached
the remote, and overwrote the other push!
The only solution to this seems to be for git-remote-annex push to notice
when a non-force-push would overwrite a ref stored in the remote, and
refuse to push that ref, returning an error to git. This seems strange,
why would git make remote helpers implement that when it later checks the
same thing itself?
With this fix, it's still possible for a race to overwrite a change to
the MANIFEST and lose work that was pushed from the other repo. But that
needs two pushes to be running at the same time. From the user's
perspective, that situation is the same as if one repo pushed new work,
then the other repo did a git push --force, overwriting the first repo's
push. In the first repo, another push will then fail as a non
fast-forward, and the user can recover as usual. But, a MANIFEST
overwrite will leave bundle files in the remote that are not listed in
the MANIFEST. It seems likely that git-annex will eventually be able to
detect that after the fact and clean it up. Eg, it can learn all bundles
that are stored in the remote using the location log, and compare them
to the MANIFEST to find bundles that got lost.
The race can also appear to the user as if they pushed a ref, but then
it got deleted from the remote. This happens when two two pushes are
pushing different ref names. This might be harder for the user to
notice; git fetch does not indicate that a remote ref got deleted.
They would have to use git fetch --prune to notice the deletion.
Once the user does notice, they can re-push their ref to recover.
Sponsored-by: Jack Hill on Patreon
This is a shell script, so not final code, and it does not use git-annex
at all, but it shows how to push to git bundles, listed in a MANIFEST,
the same as the git-remote-annex program will eventually do.
While developing this, I realized that the design needed to be changed
slightly regarding where refs are stored. Since a push can delete a ref
from a remote, storing each newly pushed ref in a bundle won't work,
because deleting a ref would then entail deleting all old bundles and
re-uploading from scratch. So instead, only the refs in the last bundle
listed in the MANIFEST are the active refs. Any refs in prior bundles
are just old refs that were stored previously (a reflog as it were).
That means that, in a situation where two different people are pushing
to the same special remote from different repos, whoever pushes last
wins. Any refs pushed by the other person earlier will be ignored. This
may not be desirable, and git-annex might be able use the git-annex
branch to detect such situations and rescue the refs that got lost. Even
without such a recovery process though, the refs that the other person
thought they pushed will be preserved in their refs/namespaces/mine, so
a pull followed by a push will generally resolve the situation.
Note that the use of refs/namespaces/mine in the bundle is not really
desirable, and it might be worth making a local clone of the repo in
order to set up the refs that will be put in the bundle. Which seems to
be the only way to avoid needing that. But it does need to maintain
the refs/namespaces/mine/ in the git repo in order to remember what refs
have been pushed to the remote before, in order to include them in the
next bundle pushed. A name that includes the remote uuid will be needed
in the final implementation.
Anyway, this shell script seems to fully work, including incremental
pushing, force pushing, and pushes that delete refs.
Sponsored-by: Brett Eisenberg on Patreon
This reverts commit cee12f6a2f.
This commit broke git-annex init run in a repo that was cloned from a
repo with an adjusted branch checked out.
The problem is that findAdjustingCommit was not able to identify the
commit that created the adjusted branch. It seems that there is an extra
"\n" at the end of the commit message that it does not expect.
Since backwards compatability needs to be maintained, cannot just make
findAdjustingCommit accept it with the "\n". Will have to instead
have one commitTree variant that uses the old method, and use it for
adjusted branch committing.
sync, assist, import: Allow -m option to be specified multiple times, to
provide additional paragraphs for the commit message.
The option parser didn't allow multiple -m before, so there is no risk of
behavior change breaking something that was for some reason using multiple
-m already.
Pass through to git commands, so that the method used to assemble the
paragrahs is whatever git does. Which might conceivably change in the
future.
Note that git commit-tree has supported -m since git 1.7.7. commitTree
was probably not using it since it predates that version. Since the
configure script prevents building git-annex with git older than 2.1,
there is no risk that it's not supported now.
Sponsored-by: Nicholas Golder-Manning on Patreon
A recent change made plumbing the backend through fsck unncessary.
Left fsck checking backend and skipping operating on key when it could
not find one. Not checking the backend would be a behavior change.
For example the command git-annex fsck --key FOO--bar does nothing
since FOO is not a known backend. If this were removed it would
instead go on and fsck it and warn that no copies exist of the key.
That behavior change seems like it would be fine, but I also have no
reason to make it.
While redundant concurrent transfers were already prevented in most
cases, it failed to prevent the case where two different repositories were
sending the same content to the same repository. By removing the uuid
from the transfer lock file for Download transfers, one repository
sending content will block the other one from also sending the same
content.
In order to interoperate with old git-annex, the old lock file is still
locked, as well as locking the new one. That added a lot of extra code
and work, and the plan is to eventually stop locking the old lock file,
at some point in time when an old git-annex process is unlikely to be
running at the same time.
Note that in the case of 2 repositories both doing eg
`git-annex copy foo --to origin`
the output is not that great:
copy b (to origin...)
transfer already in progress, or unable to take transfer lock
git-annex: transfer already in progress, or unable to take transfer lock
97% 966.81 MiB 534 GiB/s 0sp2pstdio: 1 failed
Lost connection (fd:14: hPutBuf: resource vanished (Broken pipe))
Transfer failed
Perhaps that output could be cleaned up? Anyway, it's a lot better than letting
the redundant transfer happen and then failing with an obscure error about
a temp file, which is what it did before. And it seems users don't often
try to do this, since nobody ever reported this bug to me before.
(The "97%" there is actually how far along the *other* transfer is.)
Sponsored-by: Joshua Antonishen on Patreon
If the lock file was not able to be exclusivlely locked, don't indicate
locking failed. I'm pretty sure this was a typo. It goes all the way
back to 891c85cd88 where locking was first
introduced on windows, and there's no indication of why it would make
sense to return True here.
Sponsored-by: Leon Schuermann on Patreon
