Method memoryEventNonBlockFD

cgroup2/manager.go:810–835

memoryEventNonBlockFD returns a non-blocking inotify file descriptor monitoring memory.events. NOTE: Block FD is expensive because unix.Read will block that thread once there is available data to read. In high scale scenarios, it will create a lot of threads.

()

// NOTE: Block FD is expensive because unix.Read will block that thread once there is
// available data to read. In high scale scenarios, it will create a lot of threads.
func (c *Manager) memoryEventNonBlockFD() (_ *os.File, retErr error) {

	rawFd, err := unix.InotifyInit1(unix.IN_CLOEXEC | unix.IN_NONBLOCK)
	if err != nil {
		return nil, fmt.Errorf("failed to create inotify fd: %w", err)
	}

	fd := os.NewFile(uintptr(rawFd), "inotifyfd")
	defer func() {
		if retErr != nil {
			fd.Close()
		}
	}()

	fpath := filepath.Join(c.path, "memory.events")
	if _, err := unix.InotifyAddWatch(rawFd, fpath, unix.IN_MODIFY); err != nil {
		return nil, fmt.Errorf("failed to add inotify watch for %q: %w", fpath, err)
	}

	// monitor to detect process exit/cgroup deletion
	evpath := filepath.Join(c.path, "cgroup.events")
	if _, err = unix.InotifyAddWatch(rawFd, evpath, unix.IN_MODIFY); err != nil {
		return nil, fmt.Errorf("failed to add inotify watch for %q: %w", evpath, err)
	}
	return fd, nil
}

func (c *Manager) EventChan() (<-chan Event, <-chan error) {
	ec := make(chan Event, 1)