Make cgroup1.Load and cgroup2.Load closer

- cgroup1.Load's first parameter could be moved to functional options.
- cgroup2.LoadManager's first parameter could be moved too and Manager
  suffix doesn't make much sense.

Both changes make cgroup1.Load and cgroup2.Load much closer.

Signed-off-by: Kazuyoshi Kato <katokazu@amazon.com>

Author: Kazuyoshi Kato

cgroup1/cgroup.go

@@ -34,14 +34,14 @@ import (
 )
 
 // New returns a new control via the cgroup cgroups interface
-func New(hierarchy Hierarchy, path Path, resources *specs.LinuxResources, opts ...InitOpts) (Cgroup, error) {
+func New(path Path, resources *specs.LinuxResources, opts ...InitOpts) (Cgroup, error) {
 	config := newInitConfig()
 	for _, o := range opts {
 		if err := o(config); err != nil {
 			return nil, err
 		}
 	}
-	subsystems, err := hierarchy()
+	subsystems, err := config.hiearchy()
 	if err != nil {
 		return nil, err
 	}
@@ -71,15 +71,15 @@ func New(hierarchy Hierarchy, path Path, resources *specs.LinuxResources, opts .
 
 // Load will load an existing cgroup and allow it to be controlled
 // All static path should not include `/sys/fs/cgroup/` prefix, it should start with your own cgroups name
-func Load(hierarchy Hierarchy, path Path, opts ...InitOpts) (Cgroup, error) {
+func Load(path Path, opts ...InitOpts) (Cgroup, error) {
 	config := newInitConfig()
 	for _, o := range opts {
 		if err := o(config); err != nil {
 			return nil, err
 		}
 	}
 	var activeSubsystems []Subsystem
-	subsystems, err := hierarchy()
+	subsystems, err := config.hiearchy()
 	if err != nil {
 		return nil, err
 	}

cgroup1/opts.go

@@ -36,11 +36,13 @@ type InitOpts func(*InitConfig) error
 type InitConfig struct {
 	// InitCheck can be used to check initialization errors from the subsystem
 	InitCheck InitCheck
+	hiearchy  Hierarchy
 }
 
 func newInitConfig() *InitConfig {
 	return &InitConfig{
 		InitCheck: RequireDevices,
+		hiearchy:  Default,
 	}
 }
 
@@ -59,3 +61,10 @@ func RequireDevices(s Subsystem, _ Path, _ error) error {
 	}
 	return ErrIgnoreSubsystem
 }
+
+func WithHiearchy(h Hierarchy) InitOpts {
+	return func(c *InitConfig) error {
+		c.hiearchy = h
+		return nil
+	}
+}

cgroup2/manager.go

@@ -196,13 +196,35 @@ func NewManager(mountpoint string, group string, resources *Resources) (*Manager
 	return &m, nil
 }
 
-func LoadManager(mountpoint string, group string) (*Manager, error) {
+type InitConfig struct {
+	mountpoint string
+}
+
+type InitOpts func(c *InitConfig) error
+
+// WithMountpoint sets the unified mountpoint other than /sys/fs/cgroup.
+func WithMountpoint(path string) InitOpts {
+	return func(c *InitConfig) error {
+		c.mountpoint = path
+		return nil
+	}
+}
+
+// Load a cgroup.
+func Load(group string, opts ...InitOpts) (*Manager, error) {
+	c := InitConfig{mountpoint: defaultCgroup2Path}
+	for _, opt := range opts {
+		if err := opt(&c); err != nil {
+			return nil, err
+		}
+	}
+
 	if err := VerifyGroupPath(group); err != nil {
 		return nil, err
 	}
-	path := filepath.Join(mountpoint, group)
+	path := filepath.Join(c.mountpoint, group)
 	return &Manager{
-		unifiedMountpoint: mountpoint,
+		unifiedMountpoint: c.mountpoint,
 		path:              path,
 	}, nil
 }

cmd/cgctl/main.go

@@ -99,7 +99,7 @@ var delCommand = cli.Command{
 	Usage: "delete a cgroup",
 	Action: func(clix *cli.Context) error {
 		path := clix.Args().First()
-		c, err := cgroup2.LoadManager(clix.GlobalString("mountpoint"), path)
+		c, err := cgroup2.Load(path, cgroup2.WithMountpoint(clix.GlobalString("mountpoint")))
 		if err != nil {
 			return err
 		}
@@ -112,7 +112,7 @@ var listCommand = cli.Command{
 	Usage: "list processes in a cgroup",
 	Action: func(clix *cli.Context) error {
 		path := clix.Args().First()
-		c, err := cgroup2.LoadManager(clix.GlobalString("mountpoint"), path)
+		c, err := cgroup2.Load(path, cgroup2.WithMountpoint(clix.GlobalString("mountpoint")))
 		if err != nil {
 			return err
 		}
@@ -132,7 +132,7 @@ var listControllersCommand = cli.Command{
 	Usage: "list controllers in a cgroup",
 	Action: func(clix *cli.Context) error {
 		path := clix.Args().First()
-		c, err := cgroup2.LoadManager(clix.GlobalString("mountpoint"), path)
+		c, err := cgroup2.Load(path, cgroup2.WithMountpoint(clix.GlobalString("mountpoint")))
 		if err != nil {
 			return err
 		}
@@ -152,7 +152,7 @@ var statCommand = cli.Command{
 	Usage: "stat a cgroup",
 	Action: func(clix *cli.Context) error {
 		path := clix.Args().First()
-		c, err := cgroup2.LoadManager(clix.GlobalString("mountpoint"), path)
+		c, err := cgroup2.Load(path, cgroup2.WithMountpoint(clix.GlobalString("mountpoint")))
 		if err != nil {
 			return err
 		}