[FFmpeg-devel] [PATCH 4/4] avformat/udp: do not use thread cancellation when receiving data

[Matt Oliver]

On Fri, 17 Jan 2020 at 18:44, Hendrik Leppkes <h.leppkes at gmail.com> wrote:

> On Fri, Jan 17, 2020 at 12:30 AM Michael Niedermayer
> <michael at niedermayer.cc> wrote:
> >
> > On Thu, Jan 16, 2020 at 01:20:16AM +0100, Marton Balint wrote:
> > > It is not supported by every threading implementation, and the only
> thing we
> > > gain with it is an immediate shutdown of receiving packets on close and
> > > avoiding the poll call before reading the data.
> > >
> > > I don't think it is a big issue if it takes 0.1 sec of delay to close
> an udp
> > > stream. Back when this was introduced the delay was 1 sec, which was
> indeed
> > > noticable.
> > >
> > > And anybody who needs performance sensitive UDP should not use the
> fifo buffer
> > > in the first place, because the kernel can buffer the data much more
> > > effectively.
> > >
> > > Signed-off-by: Marton Balint <cus at passwd.hu>
> > > ---
> > >  libavformat/udp.c | 57
> +++++++++++++++++++++++++------------------------------
> > >  1 file changed, 26 insertions(+), 31 deletions(-)
> >
> > this breaks build on mingw64
> >
> > src/libavformat/udp.c: In function ‘udp_read’:
> > src/libavformat/udp.c:980:17: error: implicit declaration of function
> ‘pthread_cond_timedwait’ [-Werror=implicit-function-declaration]
> >                  int err = pthread_cond_timedwait(&s->cond, &s->mutex,
> &tv);
> >                  ^
>
> We could add that to our own w32 pthread wrapper, unfortunately
> whoever designed pthread_cond_timedwait was on drugs, the absolute
> timespec is just crazy, instead of a delay in
> (milli|micro|nano)seconds, so we'll practically undo the math that
> same function already does to add its timeout to current time. But oh
> well.
>
> - Hendrik


I had an old patch for adding  pthread_cond_timedwait wrapper for win32.
Haven't checked if it still applies but its attached if it is useful.
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