RFR 15 8243099: SO_INCOMING_NAPI_ID support

[Alan Bateman]

On 06/05/2020 00:36, Ivanov, Vladimir A wrote:
> I was failed to get non-zero value for the ServerSocket and according to clarification from the network experts:
> " NAPI IDs is not marked on listening sockets. A listening socket can accept multiple connections coming on different queues. So even if we do it, it can keep changing and we don't see a use case for it. Once a connection is accepted, accepted or the child socket will return a valid NAPI id."
>
> So seems the listener sockets will have this as zero.
>
Thanks for checking. Here's a suggestion for paragraph 4 that tweaks it 
to make it clearer that it is only interesting for connecting sockets:

      * <p> The socket option is supported by both stream-oriented 
connecting and
      * datagram-oriented sockets. The value of the socket option is 
{@code 0} when
      * the socket is not bound or a packet has not been received. The 
value is
      * also {@code 0} for stream-oriented listening sockets.

-Alan