Add oom support to events

Signed-off-by: Michael Crosby <crosbymichael@gmail.com>

supervisor/monitor_linux.go

@@ -10,8 +10,9 @@ import (
 
 func NewMonitor() (*Monitor, error) {
 	m := &Monitor{
-		processes: make(map[int]runtime.Process),
+		receivers: make(map[int]interface{}),
 		exits:     make(chan runtime.Process, 1024),
+		ooms:      make(chan string, 1024),
 	}
 	fd, err := syscall.EpollCreate1(0)
 	if err != nil {
@@ -24,8 +25,9 @@ func NewMonitor() (*Monitor, error) {
 
 type Monitor struct {
 	m         sync.Mutex
-	processes map[int]runtime.Process
+	receivers map[int]interface{}
 	exits     chan runtime.Process
+	ooms      chan string
 	epollFd   int
 }
 
@@ -33,6 +35,10 @@ func (m *Monitor) Exits() chan runtime.Process {
 	return m.exits
 }
 
+func (m *Monitor) OOMs() chan string {
+	return m.ooms
+}
+
 func (m *Monitor) Monitor(p runtime.Process) error {
 	m.m.Lock()
 	defer m.m.Unlock()
@@ -45,7 +51,27 @@ func (m *Monitor) Monitor(p runtime.Process) error {
 		return err
 	}
 	EpollFdCounter.Inc(1)
-	m.processes[fd] = p
+	m.receivers[fd] = p
+	return nil
+}
+
+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 := syscall.EpollCtl(m.epollFd, syscall.EPOLL_CTL_ADD, fd, &event); err != nil {
+		return err
+	}
+	EpollFdCounter.Inc(1)
+	m.receivers[fd] = o
 	return nil
 }
 
@@ -65,24 +91,38 @@ func (m *Monitor) start() {
 		}
 		// process events
 		for i := 0; i < n; i++ {
-			if events[i].Events == syscall.EPOLLHUP {
-				fd := int(events[i].Fd)
-				m.m.Lock()
-				proc := m.processes[fd]
-				delete(m.processes, fd)
-				if err = syscall.EpollCtl(m.epollFd, syscall.EPOLL_CTL_DEL, fd, &syscall.EpollEvent{
-					Events: syscall.EPOLLHUP,
-					Fd:     int32(fd),
-				}); err != nil {
-					logrus.WithField("error", err).Fatal("containerd: epoll remove fd")
+			fd := int(events[i].Fd)
+			m.m.Lock()
+			r := m.receivers[fd]
+			switch t := r.(type) {
+			case runtime.Process:
+				if events[i].Events == syscall.EPOLLHUP {
+					delete(m.receivers, fd)
+					if err = syscall.EpollCtl(m.epollFd, syscall.EPOLL_CTL_DEL, fd, &syscall.EpollEvent{
+						Events: syscall.EPOLLHUP,
+						Fd:     int32(fd),
+					}); err != nil {
+						logrus.WithField("error", err).Error("containerd: epoll remove fd")
+					}
+					if err := t.Close(); err != nil {
+						logrus.WithField("error", err).Error("containerd: close process IO")
+					}
+					EpollFdCounter.Dec(1)
+					m.exits <- t
 				}
-				EpollFdCounter.Dec(1)
-				if err := proc.Close(); err != nil {
-					logrus.WithField("error", err).Error("containerd: close process IO")
+			case runtime.OOM:
+				// always flush the event fd
+				t.Flush()
+				if t.Removed() {
+					delete(m.receivers, fd)
+					// epoll will remove the fd from its set after it has been closed
+					t.Close()
+					EpollFdCounter.Dec(1)
+				} else {
+					m.ooms <- t.ContainerID()
 				}
-				m.m.Unlock()
-				m.exits <- proc
 			}
+			m.m.Unlock()
 		}
 	}
 }