Before, -J1 was different than no -J: It makes concurrent-output be used
for display, and it actually can run concurrent jobs in some situations.
Eg, a perform stage and a cleanup stage can both run.
dupState is used in several places, and changes NonConcurrent to
Concurrent 1. My concern is that this might, in some case, enable
that concurrent behavior. And in particular, that it might get enabled in
--batch mode, when the user is not expecting concurrent output because
they did not pass -J.
While I don't have a test case where that happens and causes out of
order output, it looks like it could, and so prudent to make this change.
--batch combined with -J now runs batch requests concurrently for many
commands. Before, the combination was accepted, but did not enable
concurrency. Since the output of batch requests can be in any order, --json
with the new "input" field is recommended to be used, to determine which
batch request each response corresponds to.
If --json is not used, batch mode still runs concurrently, using the usual
concurrent-output. That will not be very useful for most batch mode users,
probably, but who knows.
If a program was using --batch -J before, and was parsing non-json output,
this could break it. But, it was relying on git-annex not supporting
concurrency despite it being enabled, so it should have expected concurrent
output. So, I think that's ok.
annex.jobs does not enable concurrency in --batch mode, because that would
confuse programs that use --batch but don't expect concurrency.
This is prep for making batchCommandAction use commandAction,
which will enable concurrency for batch mode. Since commandAction can't
return anything, have to handle the case of a CommandStart that chooses
to do nothing in a different way.
The use case of this field is mostly to support -J combined with --json.
When that is implemented, a user will be able to look at the field to
determine which of the requests they have sent it corresponds to.
The field typically has a single value in its list, but in some cases
mutliple values (eg 2 command-line params) are combined together and the
list will have more.
Note that json parsing was already non-strict, so old git-annex metadata
--json --batch can be fed json produced by the new git-annex and will
not stumble over the new field.
No behavior changes (hopefully), just adding SeekInput and plumbing it
through to the JSON display code for later use.
Over the course of 2 grueling days.
withFilesNotInGit reimplemented in terms of seekHelper
should be the only possible behavior change. It seems to test as
behaving the same.
Note that seekHelper dummies up the SeekInput in the case where
segmentPaths' gives up on sorting the expanded paths because there are
too many input paths. When SeekInput later gets exposed as a json field,
that will result in it being a little bit wrong in the case where
100 or more paths are passed to a git-annex command. I think this is a
subtle enough problem to not matter. If it does turn out to be a
problem, fixing it would require splitting up the input
parameters into groups of < 100, which would make git ls-files run
perhaps more than is necessary. May want to revisit this, because that
fix seems fairly low-impact.
Potentially fixes https://git-annex.branchable.com/bugs/concurrent_git-annex-copy_to_s3_special_remote_fails/
although I don't know if it does.
My thinking is, ResourceT may allocate a resource and then free it,
and a unforced thunk to that resource could result in reading memory
that has since been overwritten by something else, or in a SEGV,
depending. While that seems kind of like a bug in ResourceT to me, if it
is what's happening, this will avoid it. If it's not, this doesn't
really hurt much since the values are all smallish.
This commit was sponsored by Graham Spencer on Patreon.
