[FFmpeg-devel] [RFC] Event loop

[Lynne]

Feb 19, 2021, 15:52 by george at nsup.org:

> Lynne (12021-02-19):
>
>> File descriptors are reference counted. So if something takes ownership
>> of an FD (completely reasonable, since it may want to clean up, seek, and
>> flush+close it afterwards), then you can just dup() it before giving
>> it to libuv.
>>
>
> You are completely misunderstanding the problem. A foreign protocol is a
> protocol for which we have a read function in a library; if the library
> is not bad, we can have it non-blocking; if the library is good, we can
> have the file descriptor behind for polling.
>
> When we have that, we can integrate it an event loop: add the file
> descriptor to our watch list; when poll() tells us it is readable, call
> the read function of the library.
>
> Many libraries can work like that, including libX11 and libxcb, ALSA,
> and actually, to some extent, libavformat.
>
> Many event loops can work like that, including libev, and Gtk+/GLib.
>
> It seems that libuv cannot work like that: it insists for doing the
> reading itself.
>

That's okay, I'd let it read and call events as they happen on the fds.
I've written several pollin/pollout loops for Wayland FDs before and
if possible I'd rather not have written them at all.


>> Windows is something we explicitly support. So we need something
>> which works on Windows as well, otherwise we still lose a very very
>> large majority of users.
>>
>
> But we are primarily a Unix project, with a Unix culture and Unix-style
> code. If we forget this, we get something that half-way each and all the
> way bad.
>

I'm not even going to respond to this...


>> That's some very prejudiced thinking. Their solutions are ugly because they
>> got paid for it?
>>
>
> No, "throw money at the problem" means bigger hardware because the code
> is needlessly slow and not optimized, because they chose the easy
> solution.
>

Not going to respond to this either.

But I'll say this: maybe it's better that you don't actually get in touch with anyone
from libuv or otherwise, or if you do please don't mention anything about FFmpeg.