Move supervisor to it's own package

It allows to keep main namespace cleaner

Signed-off-by: Alexander Morozov <lk4d4@docker.com>

supervisor/stats.go

@@ -0,0 +1,58 @@
+package supervisor
+
+import "github.com/rcrowley/go-metrics"
+
+var (
+	ContainerStartTimer    = metrics.NewTimer()
+	ContainersCounter      = metrics.NewCounter()
+	EventsCounter          = metrics.NewCounter()
+	EventSubscriberCounter = metrics.NewCounter()
+)
+
+func Metrics() map[string]interface{} {
+	return map[string]interface{}{
+		"container-start-time": ContainerStartTimer,
+		"containers":           ContainersCounter,
+		"events":               EventsCounter,
+		"events-subscribers":   EventSubscriberCounter,
+	}
+}
+
+type StatsEvent struct {
+	s *Supervisor
+}
+
+type UnsubscribeStatsEvent struct {
+	s *Supervisor
+}
+
+type StopStatsEvent struct {
+	s *Supervisor
+}
+
+func (h *StatsEvent) Handle(e *Event) error {
+	i, ok := h.s.containers[e.ID]
+	if !ok {
+		return ErrContainerNotFound
+	}
+	e.Stats = h.s.statsCollector.collect(i.container)
+	return nil
+}
+
+func (h *UnsubscribeStatsEvent) Handle(e *Event) error {
+	i, ok := h.s.containers[e.ID]
+	if !ok {
+		return ErrContainerNotFound
+	}
+	h.s.statsCollector.unsubscribe(i.container, e.Stats)
+	return nil
+}
+
+func (h *StopStatsEvent) Handle(e *Event) error {
+	i, ok := h.s.containers[e.ID]
+	if !ok {
+		return ErrContainerNotFound
+	}
+	h.s.statsCollector.stopCollection(i.container)
+	return nil
+}