get --from, move --from: When used with a local git remote, these used to
silently skip files that the location log thought were present on the
remote, when the remote actually no longer contained them. Since that
behavior could be surprising, now instead display a warning.
I got very confused when I encountered this behavior, since it was silently
skipping a file I needed that whereis said was on the remote.
get without --from already displayed a "unable to access these remotes"
message, which while a bit misleading in that the remote is likely
accessible, but just doesn't contain the file, at least indicated something
went wrong.
Having get --from display a warning makes it in line with get
w/o --from, so seems certianly ok. It might be there are situations where
move --from is used, on eg a whole directory, and the user only wants to
move whatever is present in the remote, and is perfectly ok with files
that are not present being skipped. So I'm less sure about the new warning
being ok there. OTOH, only local git remotes avoiding displaying a warning
in that case too, so this just brings them into line with other remotes.
(Also note that this makes it a little bit faster when dealing with a lot of
files, since it avoids a redundant stat of the file.)
Avoid running a large number of git cat-file child processes when run with
a large -J value.
This implementation takes care to avoid adding any overhead to git-annex
when run without -J. When run with -J, there is a small bit of added
overhead, to manipulate the resource pool. That optimisation added a
fair bit of complexity.
The journal read optimisation in aeca7c220 later got fixed in eedd73b84
to stage and commit any files that were left in the journal by a
previous git-annex run. That's necessary for the optimisation to work
correctly. But it also meant that alwayscommit=false started committing
the previous git-annex processes journalled changes, which defeated the
purpose of the config setting entirely.
So, disable the optimisation when alwayscommit=false, leaving the
files in the journal and not committing them. See my comments on the bug
report for why this seemed the best approach.
Also fixes a problem when annex.merge-annex-branches=false and there
are changes in the journal. That config indirectly prevents committing
the journal. (Which seems a bit odd given its name, but it always has..)
So, when there were changes in the journal, perhaps left there due to
alwayscommit=false being set before, the optimisation would prevent
git-annex from reading the journal files, and it would operate with out
of date information.
