Do not sync with a faster remote that was not specified.
That old behavior was only documented in the changelog, and was certianly
surprising. It also meant adding --fast made it slower..
readonly=true is used to make an external special remote that does not
need the external program to be installed. It was stored in the
remote.log by default, and so every time it was specified in an
enableremote or initremote, whatever value was used became the new
default for subsequent enableremotes of that remote.
That was surprising, and I consider it to be a bug.
It does not make much sense to pass it to initremote because then how
would you populate that remote with anything? You would have to
enableremote elsewhere, and store content there. I'm assuming nobody
used it that way.
Someone might rely on passing it to enableremote once, and then that
being inherited in other clones. But that is not how it's documented to
be used. It is barely documented in git-annex at all, only in the
external special remote protocol, and the documentation there says to
"Document that this external special remote can be used in readonly
mode." (by the user of it passing readonly=true to enableremote). The
one external special remote that I know of that does document that is
<https://github.com/bgilbert/gcsannex> (the one that motivated adding
it). That one's docs do say to pass it to enableremote.
So, it seemed safe to make this behavior change. If someone was in fact
relying on one of those behaviors, all their current repos will still
work as they configured them (although they will need to deal
with the related change in 9f3c2dfeda).
In new clones, they will find enableremote fails, complaining the
external program is not in path. An easy enough problem to recover from.
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.
I doubt that warning has ever been right, but I'm sure it is not right
now.
For there to be a risk of git gc deleting objects that are in the annex
index, journal files would have to be staged into it, and deleted, but
the index not committed to the git-annex branch. And AFAICS, there is no
code path where that actually happens. I considered adding one recently,
but didn't.
The way it actually works is, as long as the user has annex.alwayscommit=false
the data lives in the journal, where it's safe from git gc. Then when
git-annex is run w/o that config, the journal is staged into the index,
which is immediately committed to the branch. There's no window where
git gc could delete the objects, because git gc only deletes objects
after some time (2 weeks by default).
Now, if git-annex gets suspended at just the wrong time, or interrupted,
then yes, it's possible. But doesn't matter whether that config was ever
set or not. And many uses of git-annex also recover from that situation
by committing to the git-annex branch.
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.
