Avoid creating transfer info file before transfer lock is created and
locked.
The wrong order for one thing caused transfer info to be overwritten
when a transfer was already in progress.
But worse, it caused checkTransfer to see the transfer info,
and so lock the transfer lock in order to verify the transfer was not in
progress. Which in a concurrent situation, prevented the transferrer
from locking the transfer lock, so it failed with "transfer already in
progress".
Note that the transferinfo command does not lock the transfer lock
before creating the transfer info. But, that's only run after
recvkey is running, and recvkey does lock the transfer lock, so that
seems more or less ok. (Other than being a super complicated legacy mess
that the P2P code has mostly obsoleted now.)
This commit was supported by the NSF-funded DataLad project.
git grep writeFile finds some more that might also be problems, but
for now I've concentrated on .git/annex/ log files. There are certianly
cases where writeFile is not a problem too.
This commit was sponsored by mo on Patreon.
This avoids all the complication about redundant work discussed in
the previous try at fixing this. At the expense of needing each command
that could have the problem to be patched to simply wrap the action in
onlyActionOn once the key is known. But there do not seem to be many
such commands.
onlyActionOn' should not be used with a CommandStart (or CommandPerform),
although the types do allow it. onlyActionOn handles running the whole
CommandStart chain. I couldn't immediately see a way to avoid mistken
use of onlyActionOn'.
This commit was supported by the NSF-funded DataLad project.
After a false start, I found a fairly non-intrusive way to deal with it.
Although it only handles transfers -- there may be issues with eg
concurrent dropping of the same key, or other operations.
There is no added overhead when -J is not used, other than an added
inAnnex check. When -J is used, it has to maintain and check a small
Set, which should be negligible overhead.
It could output some message saying that the transfer is being done by
another thread. Or it could even display the same progress info for both
files that are being downloaded since they have the same content. But I
opted to keep it simple, since this is rather an edge case, so it just
doesn't say anything about the transfer of the file until the other
thread finishes.
Since the deferred transfer action still runs, actions that do more than
transfer content will still get a chance to do their other work. (An
example of something that needs to do such other work is P2P.Annex,
where the download always needs to receive the content from the peer.)
And, if the first thread fails to complete a transfer, the second thread
can resume it.
But, this unfortunately means that there's a risk of redundant work
being done to transfer a key that just got transferred.
That's not ideal, but should never cause breakage; the same
thing can occur when running two separate git-annex processes.
The get/move/copy/mirror --from commands had extra inAnnex checks added,
inside the download actions. Without those checks, the first thread
downloaded the content, and then the second thread woke up and
downloaded the same content redundantly.
move/copy/mirror --to is left doing redundant uploads for now. It
would need a second checkPresent of the remote inside the upload
to avoid them, which would be expensive. A better way to avoid
redundant work needs to be found..
This commit was supported by the NSF-funded DataLad project.
In my git-annex repos, I found some stale transfer info files
without lock files.
Pass a mode to tryLockExclusive, so it will create the lock file if
not present, and so not fail to clean up such transfer info files.
Normally, transfer info files are accompanied by a lock file.
But, when alwaysRunTransfer is used, the locking can fail
and it will still write the transfer info file. Perhaps there are other
cases too? Note that mkProgressUpdater's meter
writes to the transfer info file too, and it might be possible for
that meter to fire after runTransfer has cleaned up.
This commit was sponsored by andrea rota.
9c4650358c changed the Read instance for
Key.
I've checked all uses of that instance (by removing it and seeing what
breaks), and they're all limited to the webapp, except one.
That is GitAnnexDistribution's Read instance.
So, 9c4650358c would have broken upgrades
of git-annex from downloads.kitenet.net. Once the .info files there got
updated for a new release, old releases would have failed to parse them
and never upgraded.
To fix this, I found a way to make the .info files that contain
GitAnnexDistribution values be readable by the old version of git-annex.
This commit was sponsored by Ewen McNeill.
Turns out that Data.List.Utils.split is slow and makes a lot of
allocations. Here's a much simpler single character splitter that behaves
the same (even in wacky corner cases) while running in half the time and
75% the allocations.
As well as being an optimisation, this helps move toward eliminating use of
missingh.
(Data.List.Split.splitOn is nearly as slow as Data.List.Utils.split and
allocates even more.)
I have not benchmarked the effect on git-annex, but would not be surprised
to see some parsing of eg, large streams from git commands run twice as
fast, and possibly in less memory.
This commit was sponsored by Boyd Stephen Smith Jr. on Patreon.
Note that get --from foo --failed will get things that a previous get --from bar
tried and failed to get, etc. I considered making --failed only retry
transfers from the same remote, but it was easier, and seems more useful,
to not have the same remote requirement.
Noisy due to some refactoring into Types/
The one exception is in Utility.Daemon. As long as a process only
daemonizes once, which seems reasonable, and as long as it avoids calling
checkDaemon once it's already running as a daemon, the fcntl locking
gotchas won't be a problem there.
Annex.LockFile has it's own separate lock pool layer, which has been
renamed to LockCache. This is a persistent cache of locks that persist
until closed.
This is not quite done; lockContent stil needs to be converted.
This is a little optimisation; avoid loading the info file for the
download of the current key when checking for other downloads.
The reversion it fixes is sorta strange.
a812d598ef broke checking for transfers
that were already in progress. Indeed, the transfer lock was not held
after getTransfers was called.
Why? I think it's magic in ghc's handling of getLock and setLock,
although it's hard to tell since those functions are almost entirely
undocumented as to their semantics.
Something, either the RTS (or maybe it's linux?) notices that the
same process has taken a lock and is now calling getLock on a FD attached
to the same file. So, it drops the lock.
So, this optimisation avoids that problematic behavior.
Note that while before checkTransfer this called getLock with WriteLock,
getLockStatus's use of ReadLock will also notice any exclusive locks.
Since transfer info files are only locked exclusively, never shared,
there is no behavior change.
Also, fixes checkLocked to actually return Just False when the file
exists, but is not locked.
Removed old extensible-exceptions, only needed for very old ghc.
Made webdav use Utility.Exception, to work after some changes in DAV's
exception handling.
Removed Annex.Exception. Mostly this was trivial, but note that
tryAnnex is replaced with tryNonAsync and catchAnnex replaced with
catchNonAsync. In theory that could be a behavior change, since the former
caught all exceptions, and the latter don't catch async exceptions.
However, in practice, nothing in the Annex monad uses async exceptions.
Grepping for throwTo and killThread only find stuff in the assistant,
which does not seem related.
Command.Add.undo is changed to accept a SomeException, and things
that use it for rollback now catch non-async exceptions, rather than
only IOExceptions.
Motivation: Hook scripts for nautilus or other file managers
need to provide the user with feedback that a file is being downloaded.
This commit was sponsored by THM Schoemaker.
This allows eg, putting .git/annex/tmp on a ram disk, if the disk IO
of temp object files is too annoying (and if you don't want to keep
partially transferred objects across reboots).
.git/annex/misctmp must be on the same filesystem as the git work tree,
since files are moved to there in a way that will not work cross-device,
as well as symlinked into there.
I first wanted to put the tmp objects in .git/annex/objects/tmp, but
that would pose transition problems on upgrade when partially transferred
objects existed.
git annex info does not currently show the size of .git/annex/misctemp,
since it should stay small. It would also be ok to make something clean it
out, periodically.
Potentially fixes some FD leak if an action on an opened file handle fails
for some reason. There have been some hard to reproduce reports of
git-annex leaking FDs, and this may solve them.
Fixed up a number of things that had worked around there not being a way to
get that.
Most notably, transfer info files on windows now include the process id,
since no locking is currently done. This means the file format varies
between windows and unix.
Windows has a larger (unsigned) PID space, so cannot use the unix CInt
there.
Note that TransferInfo does not yet ever get the TransferPid populated,
as there is missing locking.
This is motivated by a user report that the assistant was repeatedly
retrying transfers of files that had been deleted (in direct mode, so
removing the only copy).
Note that the glacier code retries failed transfers after a while to retry
downloads that have aged long enough to be available. This is ok; if we're
doing a full transfer scan we'll retry on every file that is still in the
git tree.
Also note that this makes the assistant less likely to get every file
referenced by old revs of the git tree. Not something the assistant tries
to ensure anyway, so I feel this is acceptable.
Made fromDirect check that a file in the tree has good content (and is not
a broken symlink either) before copying it to another file that has the
same key.
Made replaceFile clean up the temp file if the action that creates it, or
the file replacement action fails.
Most remotes have meters in their implementations of retrieveKeyFile
already. Simply hooking these up to the transfer log makes that information
available. Easy peasy.
This is particularly valuable information for encrypted remotes, which
otherwise bypass the assistant's polling of temp files, and so don't have
good progress bars yet.
Still some work to do here (see progressbars.mdwn changes), but this
is entirely an improvement from the lack of progress bars for encrypted
downloads.
