Expose setsockopt in public API

[standy66]

This would be useful for setting up TCP keepalive and TCP_NODELAY flags. Right now the only option is to assume every SocketStream is anyio._networking.SocketStream and obtain raw socket via _socket._raw_socket

[agronholm]

Are you intent on disabling TCP_NODELAY for your sockets?

[standy66]

I want to be able to execute code similar to the following:

socket.setsockopt(socket.SOL_SOCKET, socket.SO_KEEPALIVE, 1)
if hasattr(socket, "TCP_KEEPIDLE"):
    socket.setsockopt(socket.IPPROTO_TCP, socket.TCP_KEEPIDLE, 300)
elif is_darwin():
    # Darwin specific option
    # Value extracted from XNU source code
    # https://github.com/apple/darwin-xnu/blob/a449c6a3b8014d9406c2ddbdc81795da24aa7443/bsd/netinet/tcp.h#L207
    TCP_KEEPALIVE = 16
    socket.setsockopt(socket.IPPROTO_TCP, TCP_KEEPALIVE, 300)
socket.setsockopt(socket.IPPROTO_TCP, socket.TCP_KEEPINTVL, 30)
socket.setsockopt(socket.IPPROTO_TCP, socket.TCP_KEEPCNT, 5)
socket.setsockopt(socket.IPPROTO_TCP, socket.TCP_NODELAY, 1)

[agronholm]

Yes, I get the use case for setsockopt(). I was merely wondering whether or not you knew that TCP_NODELAY is set for socket streams by default on anyio.

[agronholm]

I implemented getsockopt() and setsockopt() in SocketStream but now I keep wondering if I should expose the raw socket instead. After all, the socket object has a huge amount of low level functionality but I'm uncertain whether it should be exposed or not.

[standy66]

Did you test it?
I'm getting TypeError: setsockopt() takes exactly 3 arguments (4 given) when calling socket_stream.setsockopt(socket.SOL_SOCKET, socket.SO_KEEPALIVE, 1)

socket.SocketType.setsockopt is a weird built-in method, it does not seem to work when you manually pass optlen=None

[agronholm]

It seems that I only tested getsockopt() but forgot about setsockopt(). I will fix this tomorrow.

[agronholm]

Fixed in b383275.