patch 3/3 debuginfod client interruptability

[Aaron Merey]

On Fri, Nov 15, 2019 at 11:16 AM Mark Wielaard <mark@klomp.org> wrote:
> On Mon, 2019-11-04 at 16:48 -0500, Frank Ch. Eigler wrote:
> > At the wise counsel of gdb folks such as <tromey> and <simark>:
> >
> >     debuginfod 3/3: client interruptability
> >
> >     For interactive clients such as gdb, interruptibility is important for
> >     usability during longer downloads.  This patchset adds a
> >     download-progress callback function to the debuginfod client library,
> >     with which a caller app can interrupt a download as well as be
> >     notified of its quantitative progress.
>
> I have some concerns about this. It cannot be associated with a
> particular debuginfod-find request.

Good point, maybe we should add a progress function to debuginfo-find,
or include a default progress function with libdebuginfod. Maybe one
that prints the url where the target was found plus the download
completion percentage every few seconds.

> IMHO it should have an extra argument to indicate which build-id
> and request type exec, debug or source (+path) the progress/callback
> was for.

I think we could add this information to the progress function output
without changing the API. But if users would like more control over
how this information gets used in the progress func maybe it's
worth considering.

> Also this one global progress/interruptable hook. Which means it
> cannot be used by e.g. libdw and an application that uses both
> libdw and find-debuginfo directly.

I wonder how often this kind of situation will come up. If it's very
infrequent maybe it's enough to simply flag this issue in the docs
so users know to avoid it.

Aaron