Function pump_until 

fn pump_until(
    conn: &Connection,
    queue: &mut EventQueue<CaptureState>,
    state: &mut CaptureState,
    wake_rd: RawFd,
    timeout: Option<Duration>,
    done: impl Fn(&CaptureState) -> bool,
) -> Result<Pump, String>

Dispatch events until done(state) holds, waiting on the Wayland socket and the wake pipe together so control messages interrupt any capture wait. The predicate is re-checked after every dispatch, so a wait whose condition was satisfied by already-queued events returns without ever blocking.