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.
Run the same code git-annex used to get the sha, including its sanity
checking. Much better than old grep. Should detect FreeBSD systems with
sha commands that output in stange format.
This after fielding a bug where git-annex was built with a sha256 program
whose output checked out, but was then run with one that output lines
like:
SHA256 (file) = <sha here>
Which it then parsed as having a SHA256 of "SHA256"!
Now the output of the command is required to be of the right length,
and contain only the right characters.
It's possible for files in indirect mode to have a direct mode mapping
file. Probably from when they were in direct mode. In this case,
toDirectGen tried to copy the content from the direct mode file that the
mapping said had it. But, being in indirect mode, it didn't really have the
content. So it did nothing. This fix makes it always move the content from
.git/annex/objects/ when it's there.
Observed that the pushed refs were received, but not merged into master.
The merger never saw an add event for these refs. Either git is not writing
to a new file and renaming it into place, or the inotify code didn't notice
that. Changed it to also watch for modify events and that seems to have
fixed it!
Note that the note on df88c51334 turned out
to be wrong. Multiple repository pairing over XMPP does work, because the
annex-uuid of the xmpp remote is updated to the uuid of the new repo
when pairing takes place. So the push from it is accepted. (And the other
UUIDs are listed in uuid.log, so pushes from those repositories also are
accepted of course.)
The root of the problem is that toInodeCache sees a non-symlink, and so
goes on and generates a new inode cache for the dummy symlink.
Any place that toInodeCache, or sameFileStatus, or genInodeCache are called
may need to deal with this case. Although many of them are ok. For example,
prepSendAnnex calls sameInodeCache, which calls genInodeCache.. but if
the file content is not present, the InodeCache generated for its standin
file is appropriately not the same, and so it returns Nothing.
I've audited some, but have to say I'm not happy with this; it should be
handled at the type level somehow, or a toInodeCache wrapper be used that
is aware of dummy symlinks.
(The Watcher already dealt with it, via the guardSymlinkStandin function.)
