Add freeze state to output

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

control.go

@@ -89,6 +89,16 @@ type Hierarchy func() ([]Subsystem, error)
 
 type Path func(subsystem Name) string
 
+type State string
+
+const (
+	Unknown  State = ""
+	Thawed   State = "thawed"
+	Frozen   State = "frozen"
+	Freezing State = "freezing"
+	Deleted  State = "deleted"
+)
+
 // Cgroup handles interactions with the individual groups to perform
 // actions on them as them main interface to this cgroup package
 type Cgroup interface {
@@ -100,4 +110,5 @@ type Cgroup interface {
 	Freeze() error
 	Thaw() error
 	OOMEventFD() (uintptr, error)
+	State() State
 }

freezer.go

@@ -7,13 +7,6 @@ import (
 	"time"
 )
 
-type freezerState string
-
-const (
-	frozen freezerState = "FROZEN"
-	thawed freezerState = "THAWED"
-)
-
 func NewFreezer(root string) *FreezerController {
 	return &FreezerController{
 		root: filepath.Join(root, string(Freezer)),
@@ -33,35 +26,42 @@ func (f *FreezerController) Path(path string) string {
 }
 
 func (f *FreezerController) Freeze(path string) error {
-	if err := f.changeState(path, frozen); err != nil {
+	if err := f.changeState(path, Frozen); err != nil {
 		return err
 	}
-	return f.waitState(path, frozen)
+	return f.waitState(path, Frozen)
 }
 
 func (f *FreezerController) Thaw(path string) error {
-	if err := f.changeState(path, thawed); err != nil {
+	if err := f.changeState(path, Thawed); err != nil {
 		return err
 	}
-	return f.waitState(path, thawed)
+	return f.waitState(path, Thawed)
 }
 
-func (f *FreezerController) changeState(path string, state freezerState) error {
+func (f *FreezerController) changeState(path string, state State) error {
 	return ioutil.WriteFile(
 		filepath.Join(f.root, path, "freezer.state"),
-		[]byte(state),
+		[]byte(strings.ToUpper(string(state))),
 		defaultFilePerm,
 	)
 }
 
-func (f *FreezerController) waitState(path string, state freezerState) error {
-	file := filepath.Join(f.root, path, "freezer.state")
+func (f *FreezerController) state(path string) (State, error) {
+	current, err := ioutil.ReadFile(filepath.Join(f.root, path, "freezer.state"))
+	if err != nil {
+		return "", err
+	}
+	return State(strings.ToLower(strings.TrimSpace(string(current)))), nil
+}
+
+func (f *FreezerController) waitState(path string, state State) error {
 	for {
-		current, err := ioutil.ReadFile(file)
+		current, err := f.state(path)
 		if err != nil {
 			return err
 		}
-		if freezerState(strings.TrimSpace(string(current))) == state {
+		if current == state {
 			return nil
 		}
 		time.Sleep(1 * time.Millisecond)

v1.go

@@ -242,6 +242,23 @@ func (c *v1) OOMEventFD() (uintptr, error) {
 	return s.(*MemoryController).OOMEventFD(c.path(Memory))
 }
 
+func (c *v1) State() State {
+	c.mu.Lock()
+	defer c.mu.Unlock()
+	if c.err != nil && c.err == ErrCgroupDeleted {
+		return Deleted
+	}
+	s := c.getSubsystem(Freezer)
+	if s == nil {
+		return Thawed
+	}
+	state, err := s.(*FreezerController).state(c.path(Freezer))
+	if err != nil {
+		return Unknown
+	}
+	return state
+}
+
 func (c *v1) getSubsystem(n Name) Subsystem {
 	for _, s := range c.subsystems {
 		if s.Name() == n {