From 4f0c3850ba5906449b6408426206177c8a559d38 Mon Sep 17 00:00:00 2001
From: Alexander Morozov <lk4d4@docker.com>
Date: Fri, 18 Dec 2015 12:17:53 -0800
Subject: [PATCH] Use chanotify in supervisor

Signed-off-by: Alexander Morozov <lk4d4@docker.com>
---
 supervisor/oom.go        | 80 ----------------------------------------
 supervisor/supervisor.go | 15 +++++++-
 2 files changed, 13 insertions(+), 82 deletions(-)
 delete mode 100644 supervisor/oom.go

diff --git a/supervisor/oom.go b/supervisor/oom.go
deleted file mode 100644
index 1455b35..0000000
--- a/supervisor/oom.go
+++ /dev/null
@@ -1,80 +0,0 @@
-package supervisor
-
-import (
-	"reflect"
-	"sync"
-)
-
-func newNotifier(s *Supervisor) *notifier {
-	n := &notifier{
-		s:          s,
-		channels:   make(map[<-chan struct{}]string),
-		controller: make(chan struct{}),
-	}
-	go n.start()
-	return n
-}
-
-type notifier struct {
-	m          sync.Mutex
-	channels   map[<-chan struct{}]string
-	controller chan struct{}
-	s          *Supervisor
-}
-
-func (n *notifier) start() {
-	for {
-		c := n.createCase()
-		i, _, ok := reflect.Select(c)
-		if i == 0 {
-			continue
-		}
-		if ok {
-			ch := c[i].Chan.Interface().(<-chan struct{})
-			id := n.channels[ch]
-			e := NewEvent(OOMEventType)
-			e.ID = id
-			n.s.SendEvent(e)
-			continue
-		}
-		// the channel was closed and we should remove it
-		ch := c[i].Chan.Interface().(<-chan struct{})
-		n.removeChan(ch)
-	}
-}
-
-func (n *notifier) Add(ch <-chan struct{}, id string) {
-	n.m.Lock()
-	n.channels[ch] = id
-	n.m.Unlock()
-	// signal the main loop to break and add the new
-	// channels
-	n.controller <- struct{}{}
-}
-
-func (n *notifier) createCase() []reflect.SelectCase {
-	var out []reflect.SelectCase
-	// add controller chan so that we can signal when we need to make
-	// changes in the select.  The controller chan will always be at
-	// index 0 in the slice
-	out = append(out, reflect.SelectCase{
-		Dir:  reflect.SelectRecv,
-		Chan: reflect.ValueOf(n.controller),
-	})
-	n.m.Lock()
-	for ch := range n.channels {
-		v := reflect.ValueOf(ch)
-		out = append(out, reflect.SelectCase{
-			Dir:  reflect.SelectRecv,
-			Chan: v,
-		})
-	}
-	n.m.Unlock()
-	return out
-}
-
-func (n *notifier) removeChan(ch <-chan struct{}) {
-	n.m.Lock()
-	delete(n.channels, ch)
-	n.m.Unlock()
-}
diff --git a/supervisor/supervisor.go b/supervisor/supervisor.go
index df8bcfc..11fbd53 100644
--- a/supervisor/supervisor.go
+++ b/supervisor/supervisor.go
@@ -9,6 +9,7 @@ import (
 	"time"
 
 	"github.com/Sirupsen/logrus"
+	"github.com/docker/containerd/chanotify"
 	"github.com/docker/containerd/eventloop"
 	"github.com/docker/containerd/runtime"
 	"github.com/opencontainers/runc/libcontainer"
@@ -45,7 +46,14 @@ func New(id, stateDir string, tasks chan *StartTask, oom bool) (*Supervisor, err
 		el:             eventloop.NewChanLoop(defaultBufferSize),
 	}
 	if oom {
-		s.notifier = newNotifier(s)
+		s.notifier = chanotify.New()
+		go func() {
+			for id := range s.notifier.Chan() {
+				e := NewEvent(OOMEventType)
+				e.ID = id
+				s.SendEvent(e)
+			}
+		}()
 	}
 	// register default event handlers
 	s.handlers = map[EventType]Handler{
@@ -88,7 +96,7 @@ type Supervisor struct {
 	machine        Machine
 	containerGroup sync.WaitGroup
 	statsCollector *statsCollector
-	notifier       *notifier
+	notifier       *chanotify.Notifier
 	el             eventloop.EventLoop
 }
 
@@ -124,6 +132,9 @@ func (s *Supervisor) Stop(sig chan os.Signal) {
 		logrus.Debug("waiting for containers to exit")
 		s.containerGroup.Wait()
 		logrus.Debug("all containers exited")
+		if s.notifier != nil {
+			s.notifier.Close()
+		}
 		// stop receiving signals and close the channel
 		signal.Stop(sig)
 		close(sig)