Optimise database to further speed up importing large trees from special
remotes.
See comment for details of why the other index didn't help cid queries.
It would probably be better to manually create an index on only cid, rather
than adding a second uniqueness constraint that is a larger index. But
persitent does not support creating indexes, and an attempt to manually add
it to the migration failed.
Sponsored-by: Nicholas Golder-Manning on Patreon
This avoids bottlenecking on git check-ignore in a particular situation.
Also, there may have been a correctness issue with it not having updated it.
When the exportdb is already up-to-date, this is not expensive. And the
exportdb is updated elsewhere, so usually it is up-to-date.
Sponsored-by: Joshua Antonishen on Patreon
Speeds up eg git-annex sync --content by up to 50%. When it does not need
to transfer or drop anything, it now noops a lot more quickly.
I didn't see anything else in sync --content noop loop that could really
be sped up. It has to cat git objects to keys, stat object files, etc.
Sponsored-by: unqueued on Patreon
Speed up importing trees from special remotes somewhat by avoiding
redundant writes to sqlite database.
Before, import would write to both the git-annex branch and also to the
sqlite database. But then the next time it was run, needsUpdateFromLog
would see the branch had changed, so run updateFromLog, which would make
the same writes to the sqlite database a second time.
Now import writes only to the git-annex branch. The next time it's run,
needsUpdateFromLog sees that the branch has changed and so calls
updateFromLog, which updates the sqlite database.
Why defer the write to the sqlite database like this? It seems that it
could write to the database as it goes, and at the end call
recordAnnexBranchTree to indicate that the information in the git-annex
branch has all been written to the cidsdb. That would avoid the second
import doing extra work.
But, there could be other processes running at the same time, and one of
them may update the git-annex branch, eg merging a remote git-annex branch
into it. Any cids logs on that merged git-annex branch would not be
reflected in the cidsdb yet. If the import then called
recordAnnexBranchTree, the cidsdb would never get updated with that merged
information.
I don't think there's a good way to prevent, or to detect that situation.
So, it can't call recordAnnexBranchTree at the end. So it might as well
wait until the next run and do updateFromLog then. It could instead do
updateFromLog at the end, but it's going to check needsUpdateFromLog
at the beginning anyway.
Note that the database writes were queued, so there is already a cidmap
that is used to remember changes that the current process has made.
So, omitting database writes can't change the behavior of the current
process.
Also note that thirdpartypopulatedimport uses recordcidkeyindb, which
reflects what it already did. That code path does not use the cidmap,
but does not need to query it either. It might be possible to make that
code path also only update the git-annex branch and not the db, but I
haven't checked.
Sponsored-by: Noam Kremen on Patreon
The obvious way to fix this would be to adapt lines to split on null.
However, it's actually nontrivial to rewrite lines. In particular it has a
weird implementation to avoid a space leak. See:
https://gitlab.haskell.org/ghc/ghc/-/issues/4334
Also, while that is a small amount of code, it's covered by a rather
complex copyright and I'd have to include that copyright in git-annex.
So, I opted to filter out the trailing empty string instead.
Sponsored-by: Dartmouth College's Datalad project
