Note that this does not yet use SecureMem. It would probably make sense for
the Password part of a CredPair to use SecureMem, and making that change
is better than passing in a String and having it converted to SecureMem in
this code.
a ssh remote, and pulls.
XMPP is no longer needed in this configuration!
Requires the remote server have git-annex-shell with notifychanges support.
(untested)
This commit was sponsored by Geog Wechslberger.
So that remotes that use a persistent network connection are restarted.
A remote might keep open a long duration network connection, and could
fail to deal well with losing the connection. This is particularly a
concern now that we have external special reotes. An external
special remote that is implemented naively might open the connection only
when PREPARE is sent, and if it loses connection, throw errors on each
request that is made.
(Note that the ssh connection caching should not have this problem; if the
long-duration ssh process loses connection, the named pipe is disconnected
and the next ssh attempt will reconnect. Also, XMPP already deals with
disconnection robustly in its own way.)
There's no way for git-annex to know if a lost network connection actually
affects a given remote, which might have a transfer in process. It does not
make sense to force kill the transferkeys process every time the NetWatcher
detects a change. (Especially because the NetWatcher sometimes polls 1
change per hour.)
In any case, the NetWatcher only detects connection to a network, not
disconnection. So if a transfer is in progress over the network, and the
network goes down, that will need to time out on its own.
An alternate approch that was considered is to use a separate transferkeys
process for each remote, and detect when a request fails, and assume that
means that process is in a failing state and restart it. The problem with
that approach is that if a resource is not available and a remote fails
every time, it degrades to starting a new transferkeys process for every
file transfer, which is too expensive.
Instead, this commit only handles the network reconnection case, and restarts
transferkeys only once the network has reconnected and another transfer needs
to be made. So, a transferkeys process will be reused for 1 hour, or until the
next network connection.
----
The NotificationBroadcaster was rewritten to use TMVars rather than MSampleVars,
to allow checking without blocking if a notification has been received.
----
This commit was sponsored by Tobias Brunner.
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.
As seen in this bug report, the lifted exception handling using the StateT
monad throws away state changes when an action throws an exception.
http://git-annex.branchable.com/bugs/git_annex_fork_bombs_on_gpg_file/
.. Which can result in cached values being redundantly calculated, or other
possibly worse bugs when the annex state gets out of sync with reality.
This switches from a StateT AnnexState to a ReaderT (MVar AnnexState).
All changes to the state go via the MVar. So when an Annex action is
running inside an exception handler, and it makes some changes, they
immediately go into affect in the MVar. If it then throws an exception
(or even crashes its thread!), the state changes are still in effect.
The MonadCatchIO-transformers change is actually only incidental.
I could have kept on using lifted-base for the exception handling.
However, I'd have needed to write a new instance of MonadBaseControl
for the new monad.. and I didn't write the old instance.. I begged Bas
and he kindly sent it to me. Happily, MonadCatchIO-transformers is
able to derive a MonadCatchIO instance for my monad.
This is a deep level change. It passes the test suite! What could it break?
Well.. The most likely breakage would be to code that runs an Annex action
in an exception handler, and *wants* state changes to be thrown away.
Perhaps the state changes leaves the state inconsistent, or wrong. Since
there are relatively few places in git-annex that catch exceptions in the
Annex monad, and the AnnexState is generally just used to cache calculated
data, this is unlikely to be a problem.
Oh yeah, this change also makes Assistant.Types.ThreadedMonad a bit
redundant. It's now entirely possible to run concurrent Annex actions in
different threads, all sharing access to the same state! The ThreadedMonad
just adds some extra work on top of that, with its own MVar, and avoids
such actions possibly stepping on one-another's toes. I have not gotten
rid of it, but might try that later. Being able to run concurrent Annex
actions would simplify parts of the Assistant code.
Currently have three old versions of functions that more reworking is
needed to remove: getDaemonStatusOld, modifyDaemonStatusOld_, and
modifyDaemonStatusOld
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.
