[Boost-users] non-blocking read

Subject: [Boost-users] non-blocking read
From: David Kaplan (davkaplan_at_[hidden])
Date: 2010-02-21 10:20:51

I'm trying to implement a non_blocking read as follows (based on some
code on the net):

void util::net::set_result(optional<boost::system::error_code>* a,
boost::system::error_code b)
{
  a->reset(b);
}

template <typename MutableBufferSequence>
optional<boost::system::error_code>
util::net::read_non_blocking(ip::tcp::socket *sock, const
MutableBufferSequence& buffers, int timeoutSec)
{
 optional<boost::system::error_code> timer_result;
 deadline_timer timer(sock->io_service());
 timer.expires_from_now(boost::posix_time::seconds(timeoutSec));
 timer.async_wait(boost::bind(set_result, &timer_result, _1));

 optional<boost::system::error_code> read_result;
 async_read(*sock, buffers,
     boost::bind(set_result, &read_result, _1));

 sock->io_service().reset();
 while (sock->io_service().run_one())
 {
   if (read_result)
     timer.cancel();
   else if (timer_result) {
     sock->cancel();
     throw system_error(boost::system::error_code(errc::timed_out,
get_generic_category()));
   }
 }

 return read_result;
}

I call the code as follows:

 util::net::read_non_blocking(Module::_socket, buffer(buf, 4), 1);

(_socket is a ptr of type tcp::socket)

However I'm having problems linking:

undefined reference to `boost::optional<boost::system::error_code>
util::net::read_non_blocking<boost::asio::mutable_buffers_1>(boost::asio::basic_stream_socket<boost::asio::ip::tcp,
boost::asio::stream_socket_service<boost::asio::ip::tcp> >*,
boost::asio::mutable_buffers_1 const&, int)

Also, what will this code return exacty?