Update vendor

vendor/github.com/docker/containerd/subreaper/reaper.go

@@ -0,0 +1,102 @@
+package subreaper
+
+import (
+	"os"
+	"os/signal"
+	"sync"
+	"syscall"
+
+	"github.com/Sirupsen/logrus"
+	"github.com/docker/containerd/osutils"
+)
+
+var (
+	subscriptions = map[int]*Subscription{}
+	subLock       = sync.Mutex{}
+	counter       = 0
+	once          = sync.Once{}
+)
+
+type Subscription struct {
+	id   int
+	exit osutils.Exit
+	c    chan osutils.Exit
+	wg   sync.WaitGroup
+}
+
+func (s *Subscription) SetPid(pid int) {
+	go func() {
+		for exit := range s.c {
+			if exit.Pid == pid {
+				s.exit = exit
+				s.wg.Done()
+				Unsubscribe(s)
+			}
+		}
+	}()
+}
+
+func (s *Subscription) Wait() int {
+	s.wg.Wait()
+	return s.exit.Status
+}
+
+func Subscribe() *Subscription {
+	subLock.Lock()
+	defer subLock.Unlock()
+
+	Start()
+
+	counter++
+	s := &Subscription{
+		id: counter,
+		c:  make(chan osutils.Exit, 1024),
+	}
+	s.wg.Add(1)
+	subscriptions[s.id] = s
+	return s
+}
+
+func Unsubscribe(sub *Subscription) {
+	subLock.Lock()
+	defer subLock.Unlock()
+
+	delete(subscriptions, sub.id)
+}
+
+func Start() error {
+	var err error
+	once.Do(func() {
+		err = osutils.SetSubreaper(1)
+		if err != nil {
+			return
+		}
+
+		s := make(chan os.Signal, 2048)
+		signal.Notify(s, syscall.SIGCHLD)
+		go childReaper(s)
+	})
+
+	return err
+}
+
+func childReaper(s chan os.Signal) {
+	for range s {
+		exits, err := osutils.Reap()
+		if err == nil {
+			notify(exits)
+		} else {
+			logrus.WithField("error", err).Warn("containerd: reap child processes")
+		}
+	}
+}
+
+func notify(exits []osutils.Exit) {
+	subLock.Lock()
+	for _, exit := range exits {
+		for _, sub := range subscriptions {
+			sub.c <- exit
+		}
+	}
+	subLock.Unlock()
+}