Function ddsrt_select 

pub unsafe extern "C" fn ddsrt_select(
    nfds: i32,
    readfds: *mut fd_set,
    writefds: *mut fd_set,
    errorfds: *mut fd_set,
    reltime: dds_duration_t,
) -> dds_return_t

@brief Monitor multiple sockets, waiting until one or more become ready.

@param[in] nfds Highest-numbered file descriptor in any of the sets. @param[in] readfds Set of sockets to monitor for read ready status. @param[in] writefds Set of sockets to monitor for write ready status. @param[in] errorfds Set of sockets to monitor for exceptional conditions. @param[in] reltime Interval to block for sockets to become ready.

@returns The number of sockets ready in the sets or a return code.