コード例 #1
1
// Create a new inotify poller.
// This creates an inotify handler, and an epoll handler.
func newFdPoller(fd int) (*fdPoller, error) {
	var errno error
	poller := emptyPoller(fd)
	defer func() {
		if errno != nil {
			poller.close()
		}
	}()
	poller.fd = fd

	// Create epoll fd
	poller.epfd, errno = unix.EpollCreate1(0)
	if poller.epfd == -1 {
		return nil, errno
	}
	// Create pipe; pipe[0] is the read end, pipe[1] the write end.
	errno = unix.Pipe2(poller.pipe[:], unix.O_NONBLOCK)
	if errno != nil {
		return nil, errno
	}

	// Register inotify fd with epoll
	event := unix.EpollEvent{
		Fd:     int32(poller.fd),
		Events: unix.EPOLLIN,
	}
	errno = unix.EpollCtl(poller.epfd, unix.EPOLL_CTL_ADD, poller.fd, &event)
	if errno != nil {
		return nil, errno
	}

	// Register pipe fd with epoll
	event = unix.EpollEvent{
		Fd:     int32(poller.pipe[0]),
		Events: unix.EPOLLIN,
	}
	errno = unix.EpollCtl(poller.epfd, unix.EPOLL_CTL_ADD, poller.pipe[0], &event)
	if errno != nil {
		return nil, errno
	}

	return poller, nil
}
コード例 #2
0
ファイル: monitor.go プロジェクト: jochenvg/go-udev
// DeviceChan binds the udev_monitor socket to the event source and spawns a
// goroutine. The goroutine efficiently waits on the monitor socket using epoll.
// Data is received from the udev monitor socket and a new Device is created
// with the data received. Pointers to the device are sent on the returned channel.
// The function takes a done signalling channel as a parameter, which when
// triggered will stop the goroutine and close the device channel.
// Only socket connections with uid=0 are accepted.
func (m *Monitor) DeviceChan(done <-chan struct{}) (<-chan *Device, error) {

	var event unix.EpollEvent
	var events [maxEpollEvents]unix.EpollEvent

	// Lock the context
	m.lock()
	defer m.unlock()

	// Enable receiving
	if C.udev_monitor_enable_receiving(m.ptr) != 0 {
		return nil, errors.New("udev: udev_monitor_enable_receiving failed")
	}

	// Set the fd to non-blocking
	fd := C.udev_monitor_get_fd(m.ptr)
	if e := unix.SetNonblock(int(fd), true); e != nil {
		return nil, errors.New("udev: unix.SetNonblock failed")
	}

	// Create an epoll fd
	epfd, e := unix.EpollCreate1(0)
	if e != nil {
		return nil, errors.New("udev: unix.EpollCreate1 failed")
	}

	// Add the fd to the epoll fd
	event.Events = unix.EPOLLIN | unix.EPOLLET
	event.Fd = int32(fd)
	if e = unix.EpollCtl(epfd, unix.EPOLL_CTL_ADD, int(fd), &event); e != nil {
		return nil, errors.New("udev: unix.EpollCtl failed")
	}

	// Create the channel
	ch := make(chan *Device)

	// Create goroutine to epoll the fd
	go func(done <-chan struct{}, fd int32) {
		// Close the epoll fd when goroutine exits
		defer unix.Close(epfd)
		// Close the channel when goroutine exits
		defer close(ch)
		// Loop forever
		for {
			// Poll the file descriptor
			nevents, e := unix.EpollWait(epfd, events[:], epollTimeout)
			if e != nil {
				return
			}
			// Process events
			for ev := 0; ev < nevents; ev++ {
				if events[ev].Fd == fd {
					if (events[ev].Events & unix.EPOLLIN) != 0 {
						for d := m.receiveDevice(); d != nil; d = m.receiveDevice() {
							ch <- d
						}
					}
				}
			}
			// Check for done signal
			select {
			case <-done:
				return
			default:
			}
		}
	}(done, int32(fd))

	return ch, nil
}