.. Allowing it to be used by things in constant space!
Random statistics: git annex status has gone from taking 239 mb
of memory and 26 seconds in a repo, to 8 mb and 13 seconds.
The trick here is the unsafeInterleaveIO, and the form of the function's
recursion, which I cribbed heavily from System.IO.HVFS.Utils.recurseDirStat.
The difference is, this one goes to a limited depth and avoids statting
everything.
Before, it leaked space due to caching lists of keys. Now all necessary
data about keys is calculated as they stream in.
The "nearly constant" is due to getKeysPresent, which builds up a lot
of [] thunks as it traverses .git/annex/objects/. Will deal with it later.
Now changes are staged into the branch's index, but not committed,
which avoids growing a large journal. And sync and merge always
explicitly commit, ensuring that even when they do nothing else,
they commit the staged changes.
Added a flag file to indicate that the branch's journal contains
uncommitted changes. (Could use git ls-files, but don't want to run
that every time.)
In the future, this ability to have uncommitted changes staged in the
journal might be used on remotes after a series of oneshot commands.
To avoid commits of data to the git-annex branch after each command
is run, set annex.alwayscommit=false. Its data will then be committed
less frequently, when a merge or sync is done.
I was able to reproduce this on linux using the kernel's nfs server and
mounting localhost:/. Determined that removing the directory fails when
the just-deleted file in it was locked. Considered dropping the lock
before removing the directory, but this would complicate parts of the code
that should not need to worry about locking. So instead, ignore the failure
to remove the directory in this case.
While I was at it, made it attempt to remove both levels of hash
directories, in case they're empty.
Done by adding a oneshot mode, in which location log changes are written to
the journal, but not committed. Taking advantage of git-annex's existing
ability to recover in this situation.
This is used by git-annex-shell and other places where changes are made to
a remote's location log.
For a local git remote, can symlink the file.
For a git remote using rsync, can preseed any local content.
There are a few reasons to use fsck --from on a normal git remote.
One is if it's using gitosis or similar, and you don't have shell access
to run git annex locally. Another reason could be if you just want to
fsck certian files of a bare remote.
This way, the build log will indicate whether StatFS can be relied on.
I've tested all the failing architectures now, and on all of them,
the StatFS code now returns Nothing, rather than Just nonsense.
Also, if annex.diskreserve is set on a platform where StatFS is not
working, git-annex will complain.
Also, the Makefile was missing the sources target used when building with
cabal.
Supporting multiple directory hash types will allow converting to a
different one, without a flag day.
gitAnnexLocation now checks which of the possible locations have a file.
This means more statting of files. Several places currently use
gitAnnexLocation and immediately check if the returned file exists;
those need to be optimised.
The only fully supported thing is to have the main repository on one disk,
and .git/annex on another. Only commands that move data in/out of the annex
will need to copy it across devices.
There is only partial support for putting arbitrary subdirectories of
.git/annex on different devices. For one thing, but this can require more
copies to be done. For example, when .git/annex/tmp is on one device, and
.git/annex/journal on another, every journal write involves a call to
mv(1). Also, there are a few places that make hard links between various
subdirectories of .git/annex with createLink, that are not handled.
In the common case without cross-device, the new moveFile is actually
faster than renameFile, avoiding an unncessary stat to check that a file
(not a directory) is being moved. Of course if a cross-device move is
needed, it is as slow as mv(1) of the data.
git-annex-shell inannex now returns always 0, 1, or 100 (the last when
it's unclear if content is currently in the index due to it currently being
moved or dropped).
(Actual locking code still not yet written.)
The lock will only persist during the perform stage, so the content must
be removed from the annex then, rather than in the cleanup stage.
(No lock is actually taken yet.)
Many functions took the repo as their first parameter. Changing it
consistently to be the last parameter allows doing some useful things with
currying, that reduce boilerplate.
In particular, g <- gitRepo is almost never needed now, instead
use inRepo to run an IO action in the repo, and fromRepo to get
a value from the repo.
This also provides more opportunities to use monadic and applicative
combinators.
