I'm wary to add these new primitives when we don't have a clear timeline to adding this support to `librustuv`. Do you have any idea if libuv is intending on supporting this soon? If so, then I think this is ok to put in, but if not, I don't want to let the I/O implementations fall too far out of sync. Right now libnative is playing catch-up, and I don't want to play a perpetual game of "libX needs to catch up to libY".