Behavior of SIO_FLUSH

Question

When SIO_FLUSH socket ioctl is used in a Windows environment (in user space), I am confused as to what happens. Does this: (1) completely discard the data from the TCP/IP send queue into a black hole, or (2) push the queued send data across the connection until the buffer is empty, or (3) something else? Thanks!

Answer 1

With Windows, you can never be sure. However, this(search for SIOFLUSH) says it discards the send queue associated with the socket. This is what I also expect when I use SIO_FLUSH