 #endif
 
 public final class Selector {
+    private var open: Bool
 #if os(Linux)
     private typealias EventType = epoll_event
     private let eventsCapacity = 2048

        eventfd = try wrapSyscall({ $0 >= 0 }, function: "eventfd") {
            CEventfd.eventfd(0, Int32(EFD_CLOEXEC | EFD_NONBLOCK))
        }

        var ev = epoll_event()
        ev.events = Selector.toEpollEvents(interested: .read)

        fd = try wrapSyscall({ $0 >= 0 }, function: "kqueue") {
            Darwin.kqueue()
        }
        self.open = true

        var event = kevent()
        event.ident = Selector.EvUserIdent
