[Xenomai] How setup receive-timeout for rt_dev_recvfrom?

[Xenomai] How setup receive-timeout for rt_dev_recvfrom?

[Henri Roosen]

Hi Xenomai-list,

I am using the native API and RTDM to read from a RTNet realtime interface.
This all works, however, I need a timeout on the rt_dev_recvfrom.

As there is no rt_dev_select function, I tried to setup a receive
timeout, similar to how the XDDP examples do:

        {
                struct timeval tv;
                tv.tv_sec = 1;
                tv.tv_usec = 0;
                ret = rt_dev_setsockopt(s, SOL_SOCKET, SO_RCVTIMEO,
                                 &tv, sizeof(tv));
                if (ret)
                        fprintf(stderr, "rt_dev_setsockopt: %s\n",
strerror(-ret));
        }

Unfortunately this results in "No such device".

Does anyone know how to properly setup a receive timeout?

Thanks,
Henri

Re: [Xenomai] How setup receive-timeout for rt_dev_recvfrom?

[Gilles Chanteperdrix]

On 06/28/2012 10:05 AM, Henri Roosen wrote:
> Hi Xenomai-list,
> 
> I am using the native API and RTDM to read from a RTNet realtime interface.
> This all works, however, I need a timeout on the rt_dev_recvfrom.
> 
> As there is no rt_dev_select function, I tried to setup a receive
> timeout, similar to how the XDDP examples do:

The posix skin has select, which can be used by native skin threads. You
have to use the result of socket, and not rt_dev_socket as the fd to put
in the fd_set, but apart from that, it should work.

-- 
					    Gilles.

Re: [Xenomai] How setup receive-timeout for rt_dev_recvfrom?

[Henri Roosen]

On Thu, Jun 28, 2012 at 10:20 AM, Gilles Chanteperdrix
<gilles.chanteperdrix@xenomai.org> wrote:
> On 06/28/2012 10:05 AM, Henri Roosen wrote:
>> Hi Xenomai-list,
>>
>> I am using the native API and RTDM to read from a RTNet realtime interface.
>> This all works, however, I need a timeout on the rt_dev_recvfrom.
>>
>> As there is no rt_dev_select function, I tried to setup a receive
>> timeout, similar to how the XDDP examples do:
>
> The posix skin has select, which can be used by native skin threads. You
> have to use the result of socket, and not rt_dev_socket as the fd to put
> in the fd_set, but apart from that, it should work.

Thanks Gilles for your reply! However, I didn't try your suggestion,
because we cannot easily bind the posix skin to our application.

But I found out that RTNet supports setting a timeout on a socket that
is used by rt_dev_recvfrom(). So for the case that anyone is looking
for how to setup a receive timeout, here is what worked for me:

		#include <rtnet.h>
		nanosecs_rel_t timeout = 1000000000LL;
		...
		ret = rt_dev_ioctl(s, RTNET_RTIOC_TIMEOUT, &timeout);

Thanks,
Henri.

>
> --
>                                             Gilles.

Re: [Xenomai] How setup receive-timeout for rt_dev_recvfrom?

[Gilles Chanteperdrix]

On 07/03/2012 08:08 PM, Henri Roosen wrote:
> On Thu, Jun 28, 2012 at 10:20 AM, Gilles Chanteperdrix
> <gilles.chanteperdrix@xenomai.org> wrote:
>> On 06/28/2012 10:05 AM, Henri Roosen wrote:
>>> Hi Xenomai-list,
>>>
>>> I am using the native API and RTDM to read from a RTNet realtime interface.
>>> This all works, however, I need a timeout on the rt_dev_recvfrom.
>>>
>>> As there is no rt_dev_select function, I tried to setup a receive
>>> timeout, similar to how the XDDP examples do:
>>
>> The posix skin has select, which can be used by native skin threads. You
>> have to use the result of socket, and not rt_dev_socket as the fd to put
>> in the fd_set, but apart from that, it should work.
> 
> Thanks Gilles for your reply! However, I didn't try your suggestion,
> because we cannot easily bind the posix skin to our application.
> 
> But I found out that RTNet supports setting a timeout on a socket that
> is used by rt_dev_recvfrom(). So for the case that anyone is looking
> for how to setup a receive timeout, here is what worked for me:
> 
> 		#include <rtnet.h>
> 		nanosecs_rel_t timeout = 1000000000LL;
> 		...
> 		ret = rt_dev_ioctl(s, RTNET_RTIOC_TIMEOUT, &timeout);

I agree that it is simpler than using select.

But just to answer your remark about the posix skin, you can actually
use xenomai posix skin without the "--wrap" trick, and so avoid the
posix skin functions called without wanting it.

What you have to do is use the xenomai posix skin services you want to
use with the __wrap_ prefix. For instance __wrap_socket, __wrap_select.
The simply link with libpthread_rt.so, and do not use the --wrap flag
provided by xeno-config.

-- 
                                                                Gilles.