1 files changed, 82 insertions, 0 deletions
diff --git a/vendor/src/github.com/docker/libcontainer/cgroups/fs/notify_linux.go b/vendor/src/github.com/docker/libcontainer/cgroups/fs/notify_linux.go
new file mode 100644
index 0000000000..d92063bade
--- /dev/null
+++ b/vendor/src/github.com/docker/libcontainer/cgroups/fs/notify_linux.go
@@ -0,0 +1,82 @@
+// +build linux
+
+package fs
+
+import (
+	"fmt"
+	"os"
+	"path/filepath"
+	"syscall"
+
+	"github.com/docker/libcontainer/cgroups"
+)
+
+// NotifyOnOOM sends signals on the returned channel when the cgroup reaches
+// its memory limit. The channel is closed when the cgroup is removed.
+func NotifyOnOOM(c *cgroups.Cgroup) (<-chan struct{}, error) {
+	d, err := getCgroupData(c, 0)
+	if err != nil {
+		return nil, err
+	}
+
+	return notifyOnOOM(d)
+}
+
+func notifyOnOOM(d *data) (<-chan struct{}, error) {
+	dir, err := d.path("memory")
+	if err != nil {
+		return nil, err
+	}
+
+	fd, _, syserr := syscall.RawSyscall(syscall.SYS_EVENTFD2, 0, syscall.FD_CLOEXEC, 0)
+	if syserr != 0 {
+		return nil, syserr
+	}
+
+	eventfd := os.NewFile(fd, "eventfd")
+
+	oomControl, err := os.Open(filepath.Join(dir, "memory.oom_control"))
+	if err != nil {
+		eventfd.Close()
+		return nil, err
+	}
+
+	var (
+		eventControlPath = filepath.Join(dir, "cgroup.event_control")
+		data             = fmt.Sprintf("%d %d", eventfd.Fd(), oomControl.Fd())
+	)
+
+	if err := writeFile(dir, "cgroup.event_control", data); err != nil {
+		eventfd.Close()
+		oomControl.Close()
+		return nil, err
+	}
+
+	ch := make(chan struct{})
+
+	go func() {
+		defer func() {
+			close(ch)
+			eventfd.Close()
+			oomControl.Close()
+		}()
+
+		buf := make([]byte, 8)
+
+		for {
+			if _, err := eventfd.Read(buf); err != nil {
+				return
+			}
+
+			// When a cgroup is destroyed, an event is sent to eventfd.
+			// So if the control path is gone, return instead of notifying.
+			if _, err := os.Lstat(eventControlPath); os.IsNotExist(err) {
+				return
+			}
+
+			ch <- struct{}{}
+		}
+	}()
+
+	return ch, nil
+}