Boost asio udp socket using asio null_buffers

Question

I want to receive data from an UDP socket asynchronously using Boost ASIO library. I don't want to use a fixed length buffer while receiving data using async_receive_from.

The following code is how I used boost asio::null_buffers to determine the incoming packet size and create buffer accordingly.

socket.async_receive_from(boost::asio::null_buffers(),
                           remote_endpoint,
                           [&](boost::system::error_code ec, std::size_t bytes) {
  unsigned int readbytes = socket.available();
  if (readbytes > buffer_size) {
    //reallocate buffer
  }
  std::size_t recvbytes = socket.receive_from(
      boost::asio::buffer(buffer, buffer_size), remote_endpoint, 0, error);

Everything works as expected, however, I want to know if boost null_buffer allocates an internal buffer to keep a copy of the UDP packet received and copies to the given buffer when socket.receive_from() is called.

Also I want to know what is the impact of using null_buffer on performance and memory usage while using a UDP socket.

sehe sehe · Accepted Answer · 2018-04-10T16:32:32

What RichardHodges said.

In addition, Boost 1.66.0 has the new interface where null_buffers are obsolete and reactor-style integration can be dones using the async_wait operations on your socket:

See e.g. the docs here https://www.boost.org/doc/libs/1_66_0/doc/html/boost_asio/reference/basic_socket/wait/overload1.html

Boost asio udp socket using asio null_buffers

2 Answers