[Windows] Stop silently dropping TCP_NODELAY - #3707
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`BaseSocket.setOption` refuses to set `TCP_NODELAY` on sockets whose protocol family is not IP, because doing so fails on UNIX domain sockets. It determined the family from `try? self.localAddress().protocol`, treating a failure to answer as "not an IP socket" and returning without setting anything. On Windows that discards the option every time. Winsock fails `getsockname` for a socket that has not been bound yet, where POSIX reports the wildcard address, and channel options are applied before the socket is bound or connected. Both `ClientBootstrap` and `ServerBootstrap` enable `TCP_NODELAY` by default, so in practice Nagle's algorithm stayed on for every NIO TCP channel on Windows. Ask the socket for its address family instead of deriving it from an address it may not have yet: Winsock reports it in the `WSAPROTOCOL_INFOW` returned by `SO_PROTOCOL_INFOW`. Other platforms keep using the local address exactly as before. This fixes `ChannelTests.testTCP_NODELAYisOnByDefaultForInetSockets` and `testTCP_NODELAYisOnByDefaultForInet6Sockets`, which observed the option reading back as 0 on Windows.
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BaseSocket.setOptiondid not setTCP_NODELAYon Windows, because it determines the socket family usinglocalAddress().protocol, which fails for unbound Winsock sockets becausegetsocknamerequires the socket to be bound.Since NIO applies options before bind/connect, the option was silently dropped.
This PR changes it to get the socket family directly from
SO_PROTOCOL_INFOW/WSAPROTOCOL_INFOWso thatTCP_NODELAYis correctly applied on Windows. (Other platforms continue using the local address, so behavior is unchanged)ChannelTests.testTCP_NODELAYisOnByDefaultForInetSocketsandtestTCP_NODELAYisOnByDefaultForInet6Socketsare now fixed.