I think found it.

Since the UDP object got destructed at the end of every Hook, I was calling

fd_activity->watch(server_->socket_fd_) ;

once in startHook and once again in updateHook. If I do it only once in
updateHook, then I won't get the error anymore... I only had to call the
constructor more times and not the activity watch. Though I am not sure
if it's good practice to call the constructor so many times because I
move from one operation state to another.

Thanks again.

Regards
Keivan

On 24/06/16 12:35, Johannes Meyer wrote:
> Hi Keivan,
>
> I created a simple test package roughly following your example:
> https://github.com/meyerj/file_descriptor_activity_test
>
> I could not reproduce the EBADF (errno 9) errors with this package, at
> least using the most recent toolchain-2.9 version of RTT. Are you sure
> that server->sockfd_ is really a valid file descriptor? It is not
> important how you initialize and bind or connect the socket as long as
> it remains valid while it is being watched by the FileDescriptorActivity.
>
> Regards,
> Johannes
>
>
>
> On Fri, Jun 24, 2016 at 10:53 AM, Keivan Zavari
> <keivan [dot] zavari [..] ... keivan [dot] zavari [..] ...>> wrote:
>
> Dear all,
>
>
> For a project where I use UDP for communication, I thought I start
> very structured and put my UDP send, receive and other definitions
> in a separate class. Hence I simply have an UDP object while send
> and receive are member functions and I define the socket and bind
> to it in the constructor.
>
> Now I am trying to use this class in an orocos component and use
> FileDescriptorActivity to watch the UDP socket. The problem was
> first to figure out how prevent destructing the UDP object. So I
> reset the object with
>
> server_.reset(new UDPServer(comm_addr_, comm_port_));
>
> socket which in constructor is made as:
>
> sockfd_ = socket(AF_INET, SOCK_DGRAM, 0);
>
> is a public member of the class and is defined in the constructor
> of UDPServer.
>
> According to the documentation I define my activity in
> configureHook as:
>
> fd_activity = new RTT::extras::FileDescriptorActivity();
> this->setActivity(fd_activity);
> fd_activity =
> dynamic_cast<RTT::extras::FileDescriptorActivity*>(this->getActivity());
>
>
> and I tell it to watch the socket:
>
> fd_activity->watch(server->sockfd_);
> fd_activity->setTimeout(1000);
>
> I keep getting *error in select() errno 9* which apparently means
> the file descriptor is not valid... Now my question is, what is
> best way to watch the socket? Do I need to implement the whole
> connection and its methods inside the component or is there a
> better way?
>
> Thanks.
>
> Regards
> Keivan
>
>
>
>

Hi Johannes

Thank you for your prompt answer.
I had a look at the example. I made a fork of your example here:

https://github.com/keivanzavari/file_descriptor_activity_test

I configure the component and start the deployer. Then I start the
component.

Then I get errno 9. The problem is I think because the socket is not a
global variable for the component but a property of an object of another
class. Is this correct?
The orocos component works like a charm when I just implement the methods &
properties as functions and variables of it. :)

Regards
Keivan

On 24 June 2016 at 12:35, Johannes Meyer <johannes [..] ...> wrote:

> Hi Keivan,
>
> I created a simple test package roughly following your example:
> https://github.com/meyerj/file_descriptor_activity_test
>
> I could not reproduce the EBADF (errno 9) errors with this package, at
> least using the most recent toolchain-2.9 version of RTT. Are you sure that
> server->sockfd_ is really a valid file descriptor? It is not important how
> you initialize and bind or connect the socket as long as it remains valid
> while it is being watched by the FileDescriptorActivity.
>
> Regards,
> Johannes
>
>
>
> On Fri, Jun 24, 2016 at 10:53 AM, Keivan Zavari <keivan [dot] zavari [..] ...>
> wrote:
>
>> Dear all,
>>
>>
>> For a project where I use UDP for communication, I thought I start very
>> structured and put my UDP send, receive and other definitions in a separate
>> class. Hence I simply have an UDP object while send and receive are member
>> functions and I define the socket and bind to it in the constructor.
>>
>> Now I am trying to use this class in an orocos component and use
>> FileDescriptorActivity to watch the UDP socket. The problem was first to
>> figure out how prevent destructing the UDP object. So I reset the object
>> with
>>
>> server_.reset(new UDPServer(comm_addr_, comm_port_));
>>
>> socket which in constructor is made as:
>>
>> sockfd_ = socket(AF_INET, SOCK_DGRAM, 0);
>>
>> is a public member of the class and is defined in the constructor of
>> UDPServer.
>>
>> According to the documentation I define my activity in configureHook as:
>>
>> fd_activity = new RTT::extras::FileDescriptorActivity();
>> this->setActivity(fd_activity);
>> fd_activity = dynamic_cast<RTT::extras::FileDescriptorActivity*>(this->
>> getActivity());
>>
>> and I tell it to watch the socket:
>>
>> fd_activity->watch(server->sockfd_);
>> fd_activity->setTimeout(1000);
>>
>> I keep getting *error in select() errno 9* which apparently means the
>> file descriptor is not valid... Now my question is, what is best way to
>> watch the socket? Do I need to implement the whole connection and its
>> methods inside the component or is there a better way?
>>
>> Thanks.
>>
>> Regards
>> Keivan
>>
>
>
>
> --
> Johannes Meyer, Roboticist
> +32 468 139828
> Intermodalics - Gaston Geenslaan 9, 3001 Heverlee - BELGIUM
> www.intermodalics.eu
>