Function rustler_sys::rustler_sys_api::enif_select

pub unsafe fn enif_select(
    env: *mut ErlNifEnv,
    e: ErlNifEvent,
    flags: ErlNifSelectFlags,
    obj: *const c_void,
    pid: *const ErlNifPid,
    eref: ERL_NIF_TERM
) -> c_int

See enif_select in the Erlang docs.