When pointer files need to be restaged, they're first written to the
log, and then when the restage operation runs, it reads the log. This
way, if the git-annex process is interrupted before it can do the
restaging, a later git-annex process can do it.
Currently, this lets a git-annex get/drop command be interrupted and
then re-ran, and as long as it gets/drops additional files, it will
clean up after the interrupted command. But more changes are
needed to make it easier to restage after an interrupted process.
Kept using the git queue to run the restage action, even though the
list of files that it builds up for that action is not actually used by
the action. This could perhaps be simplified to make restaging a cleanup
action that gets registered, rather than using the git queue for it. But
I wasn't sure if that would cause visible behavior changes, when eg
dropping a large number of files, currently the git queue flushes
periodically, and so it restages incrementally, rather than all at the
end.
In restagePointerFiles, it reads the restage log twice, once to get
the number of files and size, and a second time to process it.
This seemed better than reading the whole file into memory, since
potentially a huge number of files could be in there. Probably the OS
will cache the file in memory and there will not be much performance
impact. It might be better to keep running tallies in another file
though. But updating that atomically with the log seems hard.
Also note that it's possible for calcRestageLog to see a different file
than streamRestageLog does. More files may be added to the log in
between. That is ok, it will only cause the filterprocessfaster heuristic to
operate with slightly out of date information, so it may make the wrong
choice for the files that got added and be a little slower than ideal.
Sponsored-by: Dartmouth College's DANDI project
WIP: This is mostly complete, but there is a problem: createDirectoryUnder
throws an error when annex.dbdir is set to outside the git repo.
annex.dbdir is a workaround for filesystems where sqlite does not work,
due to eg, the filesystem not properly supporting locking.
It's intended to be set before initializing the repository. Changing it
in an existing repository can be done, but would be the same as making a
new repository and moving all the annexed objects into it. While the
databases get recreated from the git-annex branch in that situation, any
information that is in the databases but not stored in the branch gets
lost. It may be that no information ever gets stored in the databases
that cannot be reconstructed from the branch, but I have not verified
that.
Sponsored-by: Dartmouth College's Datalad project
Implemented by making Git.Queue have a FlushAction, which can accumulate
along with another action on files, and runs only once the other action has
run.
This lets git-annex unlock queue up git update-index actions, without
conflicting with the restagePointerFiles FlushActions.
In a repository with filter-process enabled, git-annex unlock will
often not take any more time than before, though it may when the files are
large. Either way, it should always slow down less than git-annex status
speeds up.
When filter-process is not enabled, git-annex unlock will slow down as much
as git status speeds up.
Sponsored-by: Jochen Bartl on Patreon
So that eg, addurl of several large files that take time to download will
update the index for each file, rather than deferring the index updates to
the end.
In cases like an add of many smallish files, where a new file is being
added every few seconds. In that case, the queue will still build up a
lot of changes which are flushed at once, for best performance. Since
the default queue size is 10240, often it only gets flushed once at the
end, same as before. (Notice that updateQueue updated _lastchanged
when adding a new item to the queue without flushing it; that is
necessary to avoid it flushing the queue every 5 minutes in this case.)
But, when it takes more than a 5 minutes to add a file, the overhead of
updating the index immediately is probably small, so do it after each
file. This avoids git-annex potentially taking a very very long time
indeed to stage newly added files, which can be annoying to the user who
would like to get on with doing something with the files it's already
added, eg using git mv to rename them to a better name.
This is only likely to cause a problem if it takes say, 30 seconds to
update the index; doing an extra 30 seconds of work after every 5
minute file add would be less optimal. Normally, updating the index takes
significantly less time than that. On a SSD with 100k files it takes
less than 1 second, and the index write time is bound by disk read and
write so is not too much worse on a hard drive. So I hope this will not
impact users, although if it does turn out to, the time limit could be
made configurable.
A perhaps better way to do it would be to have a background worker
thread that wakes up every 60 seconds or so and flushes the queue.
That is made somewhat difficult because the queue can contain Annex
actions and so this would add a new source of concurrency issues.
So I'm trying to avoid that approach if possible.
Sponsored-by: Erik Bjäreholt on Patreon
Based on my earlier benchmark, I have a rough cost model for how
expensive it is for git-annex smudge to be run on a file, vs
how expensive it is for a gigabyte of a file's content to be read and
piped through to filter-process.
So, using that cost model, it can decide if using filter-process will
be more or less expensive than running the smudge filter on the files to
be restaged.
It turned out to be *really* annoying to temporarily disable
filter-process. I did find a way, but urk, this is horrible. Notice
that, if it's interrupted with it disabled, it will remain disabled
until the next time restagePointerFile runs. Which could be some time
later. If the user runs `git add` or `git checkout` on a lot of small
files before that, they will see slower than expected performance.
(This commit also deletes where I wrote down the benchmark results
earlier.)
Sponsored-by: Noam Kremen on Patreon
This does not change the overall license of the git-annex program, which
was already AGPL due to a number of sources files being AGPL already.
Legally speaking, I'm adding a new license under which these files are
now available; I already released their current contents under the GPL
license. Now they're dual licensed GPL and AGPL. However, I intend
for all my future changes to these files to only be released under the
AGPL license, and I won't be tracking the dual licensing status, so I'm
simply changing the license statement to say it's AGPL.
(In some cases, others wrote parts of the code of a file and released it
under the GPL; but in all cases I have contributed a significant portion
of the code in each file and it's that code that is getting the AGPL
license; the GPL license of other contributors allows combining with
AGPL code.)
Probably not noticed until now because the queue is large enough that two
threads each filling theirs at the same time and flushing is unlikely to
happen.
Also made explicit that each worker thread gets its own queue.
I think that was the case before, but if something was put in the queue
before worker threads were forked off, they could have each inherited the
same queue.
Could have gone with a single shared queue, but per-worker queues is more
efficient, because a worker can add lots of stuff to its own queue without
any locking.
This commit was sponsored by Ole-Morten Duesund on Patreon.
This would be better if getInternalFiles were
more polymorphic, but I can't see a good
way to accomplish that without messing with Data.Typeable,
which seemed like overkill.
Reverted CommandAction back to the simpler version.
This commit was sponsored by Eric Drechsel on Patreon.
Check just before running update-index if the worktree file's content is
still the same, don't update it when it's been modified. This narrows
the race window a lot, from possibly minutes or hours, to seconds or
less.
(Use replaceFile so that the worktree update happens atomically,
allowing the InodeCache of the new worktree file to itself be gathered
w/o any other race.)
This doesn't eliminate the race; it can still occur in the window before
update-index runs. When annex.queue is large, a lot of files will be
statted by the checks, and so the window may still be large enough to be a
problem.
When only a few files are being processed, the window is as small as it
is in the race where a modification gets overwritten by git-annex when
it updates the worktree. Or maybe as small as whatever race git
checkout/pull/merge may have when the worktree gets modified during it.
Still, I've kept a todo about this race.
This commit was supported by the NSF-funded DataLad project.
The queue could potentially contain changes from before withAltRepo, and
get flushed inside the call, which would apply the changes to the modified
repo.
Or, changes could be queued in withAltRepo that were intended to affect
the modified repo, but don't get flushed until later.
I don't know of any cases where either happens, but better safe than sorry.
Note that this affect withIndexFile, which is used in git-annex branch
updates. So, it potentially makes things slower. Should not be by much;
the overhead consists only of querying the current queue a couple of times,
and potentially flushing changes queued within withAltRepo earlier, that
could have maybe been bundled with other later changes.
Notice in particular that the existing queue is not flushed when calling
withAltRepo. So eg when git annex add needs to stage files in the index,
it will still bundle them together efficiently.
Previously, it only flushed when the queue got larger than 1.
Also, make the queue auto-flush when items are added, rather than needing
to be flushed as a separate step. This simplifies the code and make it more
efficient too, as it avoids needing to read the queue out of the state to
check if it should be flushed.
Now there's a Config type, that's extracted from the git config at startup.
Note that laziness means that individual config values are only looked up
and parsed on demand, and so we get implicit memoization for all of them.
So this is not only prettier and more type safe, it optimises several
places that didn't have explicit memoization before. As well as getting rid
of the ugly explicit memoization code.
Not yet done for annex.<remote>.* configuration settings.
While I was in there, I noticed and fixed a bug in the queue size
calculations. It was never encountered only because Queue.add was
only ever run with 1 file in the list.
This allows the queue to be used in a single process for multiple possibly
conflicting commands, like add and rm, without running them out of order.
This assumes that running the same git subcommand with different parameters
cannot itself conflict.
annex.ssh-options, annex.rsync-options, annex.bup-split-options.
And adjust types to avoid the bugs that broke several config settings
recently. Now "annex." prefixing is enforced at the type level.
A bit tricky to avoid printing it twice in a row when there are queued git
commands to run and journal to stage.
Added a generic way to run an action that may output multiple side
messages, with only the first displayed.
useful when adding hundreds of thousands of files on a system with plenty
of memory.
git add gets quite slow in such a large repository, so if the system has
more than the ~32 mb of memory the queue can use by default, it's a useful
optimisation to increase the queue size, in order to decrease the number
of times git add is run.
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.
