rb_fd_set         353 include/ruby/intern.h #define rb_fd_set(n, f)	FD_SET((n), (f))
rb_fd_set        3488 thread.c       rb_fd_set(int n, rb_fdset_t *fds)
rb_fd_set        3595 thread.c       rb_fd_set(int fd, rb_fdset_t *set)