Supervisor compiles

Signed-off-by: John Howard <jhoward@microsoft.com>

supervisor/monitor_linux.go

@@ -0,0 +1,88 @@
+package supervisor
+
+import (
+	"sync"
+	"syscall"
+
+	"github.com/Sirupsen/logrus"
+	"github.com/docker/containerd/runtime"
+)
+
+func NewMonitor() (*Monitor, error) {
+	m := &Monitor{
+		processes: make(map[int]runtime.Process),
+		exits:     make(chan runtime.Process, 1024),
+	}
+	fd, err := syscall.EpollCreate1(0)
+	if err != nil {
+		return nil, err
+	}
+	m.epollFd = fd
+	go m.start()
+	return m, nil
+}
+
+type Monitor struct {
+	m         sync.Mutex
+	processes map[int]runtime.Process
+	exits     chan runtime.Process
+	epollFd   int
+}
+
+func (m *Monitor) Exits() chan runtime.Process {
+	return m.exits
+}
+
+func (m *Monitor) Monitor(p runtime.Process) error {
+	m.m.Lock()
+	defer m.m.Unlock()
+	fd := p.ExitFD()
+	event := syscall.EpollEvent{
+		Fd:     int32(fd),
+		Events: syscall.EPOLLHUP,
+	}
+	if err := syscall.EpollCtl(m.epollFd, syscall.EPOLL_CTL_ADD, fd, &event); err != nil {
+		return err
+	}
+	EpollFdCounter.Inc(1)
+	m.processes[fd] = p
+	return nil
+}
+
+func (m *Monitor) Close() error {
+	return syscall.Close(m.epollFd)
+}
+
+func (m *Monitor) start() {
+	var events [128]syscall.EpollEvent
+	for {
+		n, err := syscall.EpollWait(m.epollFd, events[:], -1)
+		if err != nil {
+			if err == syscall.EINTR {
+				continue
+			}
+			logrus.WithField("error", err).Fatal("containerd: epoll wait")
+		}
+		// 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")
+				}
+				EpollFdCounter.Dec(1)
+				if err := proc.Close(); err != nil {
+					logrus.WithField("error", err).Error("containerd: close process IO")
+				}
+				m.m.Unlock()
+				m.exits <- proc
+			}
+		}
+	}
+}