At this point, private repos should mostly work, except for a few
commands that directly read from the git-annex branch and will not see
the private journal.
Private index not yet implemented.
Fix bug caused by recent optimisations that could make git-annex not see
recently recorded status information when configured with
annex.alwayscommit=false.
This does mean that --all can end up processing the same key more than once,
but before the optimisations that introduced this bug, it used to also behave
that way. So I didn't try to fix that; it's an edge case and anyway git-annex
behaves well when run on the same key repeatedly.
I am not too happy with the use of a MVar to buffer the list of files in the
journal. I guess it doesn't defeat lazy streaming of the list, if that
list is actually generated lazily, and anyway the size of the journal is
normally capped and small, so if configs are changed to make it huge and
this code path fire, git-annex using enough memory to buffer it all is not a
large problem.
Fix bug caused by recent optimisations that could make git-annex not see
recently recorded status information when configured with
annex.alwayscommit=false.
When not using --all, precaching only gets triggered when the
command actually needs location logs, and so there's no speed hit there.
This is a minor speed hit for --all, because it precaches even when the
location log is not actually going to be used, and so checking the journal
is not necessary. It would have been possible to defer checking the journal
until the cache gets used. But that would complicate the usual Branch.get
code path with two different kinds of caches, and the speed hit is really
minimal. A better way to speed up --all, later, would be to avoid
precaching at all when the location log is not going to be used.
This adds a separate journal, which does not currently get committed to
an index, but is planned to be committed to .git/annex/index-private.
Changes that are regarding a UUID that is private will get written to
this journal, and so will not be published into the git-annex branch.
All log writing should have been made to indicate the UUID it's
regarding, though I've not verified this yet.
Currently, no UUIDs are treated as private yet, a way to configure that
is needed.
The implementation is careful to not add any additional IO work when
privateUUIDsKnown is False. It will skip looking at the private journal
at all. So this should be free, or nearly so, unless the feature is
used. When it is used, all branch reads will be about twice as expensive.
It is very lucky -- or very prudent design -- that Annex.Branch.change
and maybeChange are the only ways to change a file on the branch,
and Annex.Branch.set is only internal use. That let Annex.Branch.get
always yield any private information that has been recorded, without
the risk that Annex.Branch.set might be called, with a non-private UUID,
and end up leaking the private information into the git-annex branch.
And, this relies on the way git-annex union merges the git-annex branch.
When reading a file, there can be a public and a private version, and
they are just concacenated together. That will be handled the same as if
there were two diverged git-annex branches that got union merged.
