When dropping an unlocked file, preserve its mtime, which avoids git status
unncessarily running the clean filter on the file.
If the index file has close to the same mtime as a work tree file, git will
not trust the index to be up-to-date, and re-runs the clean filter
unncessarily. Preserving the mtime when depopulating a pointer file avoids
git status doing a little (or maybe a lot) of unncessary work.
There are other places that the mtime could be preserved, including other
places where pointer files are written perhaps, but also
populatePointerFile. But, I don't know of cases where those lead to git
status doing unncessary work, so I just fixed the one I'm aware of for now.
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.)
If a pointer file is being populated and something modifies it at the
same time, there was a race there the modified file's InodeCache
could get added into the keys database.
Note that replaceFile normally renames the temp file into place, so the
inode cache caculated for the temp file will still be good. If it has to
fall back to a copy, the worktree file won't be put in the inode cache.
This has the same result as if the worktree file gets touched, and will
be handled the same way. Eg, when dropping, isUnmodified will do an
expensive comparison and notice that the worktree file does have the
same content, and so drop it.
This commit was supported by the NSF-funded DataLad project.
