Function librados_sys::rados_watch2

pub unsafe extern "C" fn rados_watch2(
    io: rados_ioctx_t, 
    o: *const c_char, 
    cookie: *mut uint64_t, 
    watchcb: rados_watchcb2_t, 
    watcherrcb: rados_watcherrcb_t, 
    arg: *mut c_void
) -> c_int