Re: Writing to multiple descriptors with one system call

[Vlad Galu <dudu%dudu.ro@localhost>]

On Wed, Mar 17, 2010 at 5:22 PM, Sad Clouds
<cryintothebluesky%googlemail.com@localhost> wrote:
> On Wed, 17 Mar 2010 16:01:28 +0000
> Quentin Garnier <cube%cubidou.net@localhost> wrote:
>
>> Do you have a real world use for that?  For instance, I wouldn't call
>> a web server that sends the same data to all its clients *at the same
>> time* realistic.
>>
> Why? Because it never happens? I think it happens quite often. Another
> example is a server that is sending live data, i.e. audio playback,
> video stream, etc. If you can't use multicasting over a WAN, then you
> have a situation where you are streaming the same data to large number
> of clients.

That's almost never practical, since you never fall into the ideal
case when all clients consume the data at the exact same rate.

>
>> What do you do when you get EIO for the first fd, EPIPE for the
>> second, EFBIG for the third, EINTR for the fourth and an undefined
>> return status for the 4996 that follow?  (I guess on a socket you
>> might only get EIO, ENOSPC and EINTR, but you get the idea.)
>>
> There are ways to make it work. You could have an errno as part of each
> file descriptor structure and set it accordingly. But then most of the
> time errors would not occur unless something went really wrong.
>



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