Re: [Boost-users] [asio] Sending large packages

Subject: Re: [Boost-users] [asio] Sending large packages
From: Matheus Araújo Aguiar (matheus.pit_at_[hidden])
Date: 2010-01-05 05:59:32

2010/1/5 Matheus Araújo Aguiar <matheus.pit_at_[hidden]>

>
>
> On Tue, Jan 5, 2010 at 8:27 AM, Nicola Michael Gutberlet <
> nicola.gutberlet_at_[hidden]> wrote:
>
>> Dear all,
>>
>> Thank you for your replies. I wanted to tell you the error message thrown
>> when trying to send larger packages but it seems to be solved. I don't
>> know
>> why or how...
>>
>> Anyway, it is sensible to check the maximum message size for the
>> socket/OS/whatever. How do I get the information of the maximum size of
>> messages I can write/read over my TCP socket? I noticed the option
>> mentioned
>> by Jason Felice "SO_MAX_MSG_SIZE" but the TCP socket doesn't support it. I
>> tried to use an own template:
>>
>> boost::asio::detail::socket_option::integer<SOL_SOCKET, SO_MAX_MSG_SIZE>
>> cOptionMaxMessageSize;
>> socket->get_option( cOptionMaxMessageSize );
>>
>> But this also did not work - resulting in the option value -1.
>>
>>
> Hi Nicola,
> Note that in the code you posted, you wrote the option as "SO*L*_SOCKET,
> SO_MAX_MSG_SIZE". You have an extra "L" there which might be causing your
> value -1. Also, remember that as stated
>

Sorry for that, the option is not written wrong, i confused things about
that.

> before, this option goes for microsoft windows. There is no maximum size
> you can send through a socket, although there is a MTU(Maximum Transfer
> Unity) and you should read more about it if you are not familiarized with
> that concept. As said before, TCP being a stream protocol, you have to
> ensure in a way or another (by putting the size in front of data, or using
> an "END OF STREAM" mark) that your read get all the bytes you expect.
>
>
> Hope that helps!
>
>
>> Best regards,
>> Nicola
>>
>> -----Original Message-----
>> From: boost-users-bounces_at_[hidden]
>> [mailto:boost-users-bounces_at_[hidden]] On Behalf Of Oliver Seiler
>> Sent: 04 January 2010 18:05
>> To: boost-users_at_[hidden]
>> Subject: Re: [Boost-users] [asio] Sending large packages
>>
>> On Mon, Jan 4, 2010 at 7:30 AM, Jason Felice <jason.m.felice_at_[hidden]>
>> wrote:
>> > On Mon, Jan 4, 2010 at 5:41 AM, Igor R <boost.lists_at_[hidden]> wrote:
>> >>> Doesn’t anyone have any ideas? Did anyone receive this mail?
>> >>
>> >> I guess it's not an asio limitation, but the OS one - you just
>> >> exceeded the maximum message size for the underlying protocol.
>> >> On windows you can use SO_MAX_MSG_SIZE socket option to get the maximum
>> size.
>> >
>> > [...] All TCP networks
>> > have an MTU, and packets larger than this will be sliced up for
>> > delivery (without affecting the data contained within or the
>> > guaranteed order of delivery).
>>
>> And herein lies what the original poster is hitting. The MTU is way
>> smaller than the ~1MB limit the poster sees, so that isn't likely the
>> problem (and would typically only be an issue if using UDP).
>>
>> My guess is the TCP read/write buffers have been exceeded. Original
>> poster should include more information:
>> - OS that this is on,
>> - The actual error codes being encountered.
>>
>> If you're exceeding the TCP buffer sizes and trying to write in one
>> chunk, you may be hitting an error like ENOBUFS (no_buffer_space in
>> boost:error_code). Just a guess though.
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>
>
>
> --
> Matheus Araújo Aguiar
> Computer Scientist
> matheus.pit_at_[hidden]
>

-- 
Matheus Araújo Aguiar
Computer Scientist
matheus.pit_at_[hidden]