This is similar to the pusher thread, but a separate thread because git
pushes can be done in parallel with exports, and updating a big export
should not prevent other git pushes going out in the meantime.
The exportThread only runs at most every 30 seconds, since updating an
export is more expensive than pushing. This may need to be tuned.
Added a separate channel for export commits; the committer records a
commit in that channel.
Also, reconnectRemotes records a dummy commit, to make the exporter
thread wake up and make sure all exports are up-to-date. So,
connecting a drive with a directory special remote export will
immediately update it, and getting online will automatically
update S3 and WebDAV exports.
The transfer queue is not involved in exports. Instead, failed
exports are retried much like failed pushes.
This commit was sponsored by Ewen McNeill.
I've long considered the XMPP support in git-annex a wart.
It's nice to remove it.
(This also removes the NetMessager, which was only used for XMPP, and the
daemonstatus's desynced list (likewise).)
Existing XMPP remotes should be ignored by git-annex.
This commit was sponsored by Brock Spratlen on Patreon.
Added a RemoteChecker thread, that waits for problems to be reported with
remotes, and checks if their git repository is in need of repair.
Currently, only failures to sync with the remote cause a problem to be
reported. This seems enough, but we'll see.
Plugging in a removable drive with a repository on it that is corrupted
does automatically repair the repository, as long as the corruption causes
git push or git pull to fail. Some types of corruption do not, eg
missing/corrupt objects for blobs that git push doesn't need to look at.
So, this is not really a replacement for scheduled git repository fscking.
But it does make the assistant more robust.
This commit is sponsored by Fernando Jimenez.
Converted several threads to run in the monad.
Added a lot of useful combinators for working with the monad.
Now the monad includes the name of the thread.
Some debugging messages are disabled pending converting other threads.
I now have this topology working:
assistant ---> {bare repo, special remote} <--- assistant
And, I think, also this one:
+----------- bare repo --------+
v v
assistant ---> special remote <--- assistant
While before with assistant <---> assistant connections, both sides got
location info updated after a transfer, in this topology, the bare repo
*might* get its location info updated, but the other assistant has no way to
know that it did. And a special remote doesn't record location info,
so transfers to it won't propigate out location log changes at all.
So, for these to work, after a transfer succeeds, the git-annex branch
needs to be pushed. This is done by recording a synthetic commit has
occurred, which lets the pusher handle pushing out the change (which will
include actually committing any still journalled changes to the git-annex
branch).
Of course, this means rather a lot more syncing action than happened
before. At least the pusher bundles together very close together pushes,
somewhat. Currently it just waits 2 seconds between each push.
Hooked up everything that needs to notify on pushes. Note that
syncNewRemote does not notify. This is probably ok, and I'd need to thread
more state through to make it do so.
This is only set up to support a single push notification method; I didn't
use a NotificationBroadcaster. Partly because I don't yet know what info
about pushes needs to be communicated, so my data types are only
preliminary.
Currently only the web special remote is readonly, but it'd be possible to
also have readonly drives, or other remotes. These are handled in the
assistant by only downloading from them, and never trying to upload to
them.
I've convinced myself that nothing in DaemonStatus can deadlock,
as it always keepts the TMVar full. That was the only reason it was in the
Annex monad.
Added knownRemotes to DaemonStatus. This list is not entirely trivial to
calculate, and having it here should make it easier to add/remove remotes
on the fly later on. It did require plumbing the daemonstatus through to
some more threads.
SampleMVar won't work; between getting the current value and changing
it, another thread could made a change, which would get lost.
TMVar works well; this update situation is handled by atomic transactions.
