#include <future>
void
process_connections(connection_set& connections)
{
  while (!done(connections)) {
    for (connection_iterator connection = connections.begin(),
                             end        = connections.end();
         connection != end;
         ++connection) {
      if (connection->has_incoming_data()) {
        data_packet data              = connection->incoming();
        std::promise<payload_type>& p = connection->get_promise(data.id);
        p.set_value(data.payload);
      }
      if (connection->has_outgoing_data()) {
        outgoing_packet data = connection->top_of_outgoing_queue();
        connection->send(data.payload);
        data.promise.set_value(true);
      }
    }
  }
}