Can be used to override the default timestamps used in log files in the
git-annex branch. This is a dangerous environment variable; use with
caution.
Note that this only affects writing to the logs on the git-annex branch.
It is not used for metadata in git commits (other env vars can be set for
that).
There are many other places where timestamps are still used, that don't
get committed to git, but do touch disk. Including regular timestamps
of files, and timestamps embedded in some files in .git/annex/, including
the last fsck timestamp and timestamps in transfer log files.
A good way to find such things in git-annex is to get for getPOSIXTime and
getCurrentTime, although some of the results are of course false positives
that never hit disk (unless git-annex gets swapped out..)
So this commit does NOT necessarily make git-annex comply with some HIPPA
privacy regulations; it's up to the user to determine if they can use it in
a way compliant with such regulations.
Benchmarking: It takes 0.00114 milliseconds to call getEnv
"GIT_ANNEX_VECTOR_CLOCK" when that env var is not set. So, 100 thousand log
files can be written with an added overhead of only 0.114 seconds. That
should be by far swamped by the actual overhead of writing the log files
and making the commit containing them.
This commit was supported by the NSF-funded DataLad project.
This fixes strange displays in some cases, including whereis showing
many duplicate locations, and showing more total copies than actually
exist.
It's unknown if that lead to data loss when eg, dropping. At the moment,
it seems unlikely it could, since the UUID with \r's appended is not the
same as a UUID without, and so no remote matches it.
It's also unknown if \r's can leak in on windows, perhaps when merging the
git-annex branch.
Implemented with no additional overhead of compares etc.
This is safe to do for presence logs because of their locality of change;
a given repo's presence logs are only ever changed in that repo, or in a
repo that has just been actively changing the content of that repo.
So, we don't need to worry about a split-brain situation where there'd
be disagreement about the location of a key in a repo. And so, it's ok to
not update the timestamp when that's the only change that would be made
due to logging presence info.
A dead key is both not present at the location that thinks it has a copy,
and also is assumed to probably not be present anywhere else. Although
there may be lurking disconnected repos that somehow still have a copy.
Suprisingly few changes needed for this! This is because the presence log
code only really concerns itself with keys that are present, and dead keys
are not present.
Note that both the location and web log can be parsed as having a dead key.
I don't see any value to having keys listed as dead in the web log, but
since it doesn't change any behavior, there was no point in not parsing it.
Wrote nice pure transition calculator, and ugly code to stage its results
into the git-annex branch. Also had to split up several Log modules
that Annex.Branch needed to use, but that themselves used Annex.Branch.
The transition calculator is limited to looking at and changing one file at
a time. While this made the implementation relatively easy, it precludes
transitions that do stuff like deleting old url log files for keys that are
being removed because they are no longer present anywhere.
