Re: [asio-users] scatter/gather (async_receive)

[Craig P. <cperras@u.washington.edu>]

i'll take a look. thanks, daniel.

On Wed, 10 Dec 2008, daniel he wrote:

> Craig,
>
> scatter/gather may not be helpful for your case.  I wrote one small
> project using asio/UDP for video streaming.
> You can find the source code from
> http://ppstreaming.svn.sourceforge.net/viewvc/ppstreaming/trunk/ppstreaming/
>
> Just for your reference, I have not updated it for a long time.
>
> Thank,
>
> Daniel
>
>
> Craig Perras wrote:
>> thanks, Piotr.
>>
>> i'm probably missing something fundamental. i tried using scatter/gather
>> io for udp datagrams (video streaming) to increase performance (say to
>> read multiple datagrams with a single call). but maybe that's not how it's
>> supposed to work? if the datagrams are "packed" into the buffer, then
>> you'll lose the dgram msg boundaries (if they happen to be important).
>> otoh, in practice (on windows and linux), only one dgram is read per call
>> even if, say, 16 buffers are available.
>>
>> any ideas on when scatter/gather io for udp might be useful? i can't think
>> of any (or maybe i'm somehow not coding this right; i'm sending udp
>> packets at ~2e9 bits/second, so they should be buffered).
>>
>> thanks,
>> --craig
>>
>> On Wed, 10 Dec 2008, Piotr Findeisen wrote:
>>
>>
>>> I'd expect that during scatter/gatter read the buffers are filled from first
>>> to last.
>>> As you know the buffers length before the call and know how many bytes are
>>> read in total, you can figure out, which was the last buffer filled and up
>>> to which byte.
>>>
>>> hth,
>>> Piotr
>>>
>>> On Tue, Dec 9, 2008 at 23:27, Craig Perras <cperras@u.washington.edu> wrote:
>>>
>>>
>>>> hi -
>>>>
>>>> i'm trying to use scatter/gather io with udp (async_receive). i can't
>>>> figure out how to get the returned individual buffer lengths, only the
>>>> total bytes read. is it possible to get this information? i'm looking at
>>>> the windows implementation: WSARecv bufs are in/out params, and it looks
>>>> like the returned buffer lengths are discarded.
>>>>
>>>> any help is appreciated.
>>>>
>>>> thanks,
>>>> --craig
>>>>
>>>>
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