git-annex/doc/todo/git-remote-annex.mdwn
Joey Hess adcebbae47
clean up git-remote-annex git-annex branch handling
Implemented alternateJournal, which git-remote-annex
uses to avoid any writes to the git-annex branch while setting up
a special remote from an annex:: url.

That prevents the remote.log from being overwritten with the special
remote configuration from the url, which might not be 100% the same as
the existing special remote configuration.

And it prevents an overwrite deleting of other stuff that was
already in the remote.log.

Also, when the branch was created by git-remote-annex, only delete it
at the end if nothing else has been written to it by another command.
This fixes the race condition described in
797f27ab05, where git-remote-annex
set up the branch and git-annex init and other commands were
run at the same time and their writes to the branch were lost.
2024-05-15 17:33:38 -04:00

70 lines
3.3 KiB
Markdown

git-remote-annex will be a program that allows push/pull/clone of a git
repository to many types of git-annex special remote.
This is a redesign and reimplementation of git-remote-datalad-annex.
It will be a safer implementation, will support incremental pushes, and
will be available to users who don't use datalad.
--[[Joey]]
---
This is implememented and working. Remaining todo list for it:
* Test incremental push edge cases involving checkprereq.
* Cloning from an annex:: url with importtree=yes doesn't work
(with or without exporttree=yes). This is because the ContentIdentifier
db is not populated.
* It would be nice if git-annex could generate an annex:: url
for a special remote and show it to the user, eg when
they have set the shorthand "annex::" url, so they know the full url.
`git-annex info $remote` could also display it.
Currently, the user has to remember how the special remote was
configured and replicate it all in the url.
There are some difficulties to doing this, including that
RemoteConfig can have hidden fields that should be omitted.
* initremote/enableremote could have an option that configures the url to a
special remote to a annex:: url. This would make it easier to use
git-remote-annex, since the user would not need to set up the url
themselves. (Also it would then avoid setting `skipFetchAll = true`)
* Improve recovery from interrupted push by using outManifest to clean up
after it. (Requires populating outManifest.)
* See XXX in uploadManifest about recovering from a situation
where the remote is left with a deleted manifest when a push
is interrupted part way through. This should be recoverable
by caching the manifest locally and re-uploading it when
the remote has no manifest or prompting the user to merge and re-push.
* datalad-annex supports cloning from the web special remote,
using an url that contains the result of pushing to eg, a directory
special remote.
`datalad-annex::https://example.com?type=web&url={noquery}`
Supporting something like this would be good.
* Improve behavior in push races. A race can overwrite a change
to the MANIFEST and lose work that was pushed from the other repo.
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. This is probably
okish.
But.. a MANIFEST overwrite will leave bundle files in the remote that
are not listed in the MANIFEST. It seems likely that git-annex could
detect that after the fact and clean it up. Eg, if it caches
the last MANIFEST it uploaded, next time it downloads the MANIFEST
it can check if there are bundle files in the old one that are not
in the new one. If so, it can drop those bundle files from the remote.
* A push 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 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.
Can this be improved?