func (s *apiServer) ListCheckpoint(ctx context.Context, r *types.ListCheckpointRequest) (*types.ListCheckpointResponse, error) {
	e := supervisor.NewEvent(supervisor.GetContainerEventType)
	s.sv.SendEvent(e)
	if err := <-e.Err; err != nil {
		return nil, err
	}
	var container runtime.Container
	for _, c := range e.Containers {
		if c.ID() == r.Id {
			container = c
			break
		}
	}
	if container == nil {
		return nil, grpc.Errorf(codes.NotFound, "no such containers")
	}
	checkpoints, err := container.Checkpoints()
	if err != nil {
		return nil, err
	}
	var out []*types.Checkpoint
	for _, c := range checkpoints {
		out = append(out, &types.Checkpoint{
			Name:        c.Name,
			Tcp:         c.Tcp,
			Shell:       c.Shell,
			UnixSockets: c.UnixSockets,
			// TODO: figure out timestamp
			//Timestamp:   c.Timestamp,
		})
	}
	return &types.ListCheckpointResponse{Checkpoints: out}, nil
}

// stopCollection closes the channels for all subscribers and removes
// the container from metrics collection.
func (s *statsCollector) stopCollection(c runtime.Container) {
	s.m.Lock()
	if publisher, exists := s.publishers[c.ID()]; exists {
		publisher.pub.Close()
		delete(s.publishers, c.ID())
	}
	s.m.Unlock()
}

// unsubscribe removes a specific subscriber from receiving updates for a container's stats.
func (s *statsCollector) unsubscribe(c runtime.Container, ch chan interface{}) {
	s.m.Lock()
	publisher := s.publishers[c.ID()]
	if publisher != nil {
		publisher.pub.Evict(ch)
		if publisher.pub.Len() == 0 {
			delete(s.publishers, c.ID())
		}
	}
	s.m.Unlock()
}

// collect registers the container with the collector and adds it to
// the event loop for collection on the specified interval returning
// a channel for the subscriber to receive on.
func (s *statsCollector) collect(c runtime.Container) chan interface{} {
	s.m.Lock()
	defer s.m.Unlock()
	publisher, exists := s.publishers[c.ID()]
	if !exists {
		pub := pubsub.NewPublisher(100*time.Millisecond, 1024)
		publisher = &statsPair{ct: c, pub: pub}
		s.publishers[c.ID()] = publisher
	}
	return publisher.pub.Subscribe()
}

func (m *Monitor) MonitorOOM(c runtime.Container) error {
	m.m.Lock()
	defer m.m.Unlock()
	o, err := c.OOM()
	if err != nil {
		return err
	}
	fd := o.FD()
	event := syscall.EpollEvent{
		Fd:     int32(fd),
		Events: syscall.EPOLLHUP | syscall.EPOLLIN,
	}
	if err := archutils.EpollCtl(m.epollFd, syscall.EPOLL_CTL_ADD, fd, &event); err != nil {
		return err
	}
	EpollFdCounter.Inc(1)
	m.receivers[fd] = o
	return nil
}

func createAPIContainer(c runtime.Container, getPids bool) (*types.Container, error) {
	processes, err := c.Processes()
	if err != nil {
		return nil, grpc.Errorf(codes.Internal, "get processes for container: "+err.Error())
	}
	var procs []*types.Process
	for _, p := range processes {
		oldProc := p.Spec()
		stdio := p.Stdio()
		appendToProcs := &types.Process{
			Pid:       p.ID(),
			SystemPid: uint32(p.SystemPid()),
			Terminal:  oldProc.Terminal,
			Args:      oldProc.Args,
			Env:       oldProc.Env,
			Cwd:       oldProc.Cwd,
			Stdin:     stdio.Stdin,
			Stdout:    stdio.Stdout,
			Stderr:    stdio.Stderr,
		}
		setUserFieldsInProcess(appendToProcs, oldProc)
		procs = append(procs, appendToProcs)
	}
	var pids []int
	state := c.State()
	if getPids && (state == runtime.Running || state == runtime.Paused) {
		if pids, err = c.Pids(); err != nil {
			return nil, grpc.Errorf(codes.Internal, "get all pids for container: "+err.Error())
		}
	}
	return &types.Container{
		Id:         c.ID(),
		BundlePath: c.Path(),
		Processes:  procs,
		Labels:     c.Labels(),
		Status:     string(state),
		Pids:       toUint32(pids),
		Runtime:    c.Runtime(),
	}, nil
}

func (h *DeleteEvent) deleteContainer(container runtime.Container) error {
	delete(h.s.containers, container.ID())
	return container.Delete()
}

func createAPIContainer(c runtime.Container, getPids bool) (*types.Container, error) {
	processes, err := c.Processes()
	if err != nil {
		return nil, grpc.Errorf(codes.Internal, "get processes for container: "+err.Error())
	}
	var procs []*types.Process
	for _, p := range processes {
		oldProc := p.Spec()
		stdio := p.Stdio()
		proc := &types.Process{
			Pid:       p.ID(),
			SystemPid: uint32(p.SystemPid()),
			Terminal:  oldProc.Terminal,
			Args:      oldProc.Args,
			Env:       oldProc.Env,
			Cwd:       oldProc.Cwd,
			Stdin:     stdio.Stdin,
			Stdout:    stdio.Stdout,
			Stderr:    stdio.Stderr,
		}
		proc.User = &types.User{
			Uid:            oldProc.User.UID,
			Gid:            oldProc.User.GID,
			AdditionalGids: oldProc.User.AdditionalGids,
		}
		proc.Capabilities = oldProc.Capabilities
		proc.ApparmorProfile = oldProc.ApparmorProfile
		proc.SelinuxLabel = oldProc.SelinuxLabel
		proc.NoNewPrivileges = oldProc.NoNewPrivileges
		for _, rl := range oldProc.Rlimits {
			proc.Rlimits = append(proc.Rlimits, &types.Rlimit{
				Type: rl.Type,
				Soft: rl.Soft,
				Hard: rl.Hard,
			})
		}
		procs = append(procs, proc)
	}
	var pids []int
	state := c.State()
	if getPids && (state == runtime.Running || state == runtime.Paused) {
		if pids, err = c.Pids(); err != nil {
			return nil, grpc.Errorf(codes.Internal, "get all pids for container: "+err.Error())
		}
	}
	return &types.Container{
		Id:         c.ID(),
		BundlePath: c.Path(),
		Processes:  procs,
		Labels:     c.Labels(),
		Status:     string(state),
		Pids:       toUint32(pids),
		Runtime:    c.Runtime(),
	}, nil
}

func (s *Supervisor) deleteContainer(container runtime.Container) error {
	delete(s.containers, container.ID())
	return container.Delete()
}