> There is some overlap, yes. TCP_CORK is a mode however. It's silly to introduce the complexity of extra state when a single method call (flushHint()) would suffice.

It is a single call. Note that last sentence from the man page entry: "setting this option forces an explicit flush of pending output, even if TCP_CORK is currently set."

When TCP_CORK is on (turn it on once at socket creation time), the following code is the implementation of your flushHint function:

    int flushHint(int fd) {
        return setsockopt(fd, IPPROTO_TCP, TCP_NODELAY, &(int){ 1 }, sizeof(int))
    }