simple_read_cb
EV_READ|EV_PERSIST, simple_read_cb, NULL);
event_set(&ev, pair[1], EV_READ, simple_read_cb, &ev);
event_set(&ev, pair[1], EV_READ, simple_read_cb, &ev);
event_set(&ev1, pair[1], EV_READ, simple_read_cb, &ev1);
event_set(&ev1, pair[1], EV_READ, simple_read_cb, &ev1);