Refactor into Cgroups Subsystems and Controllers

Signed-off-by: Michael Crosby <[email protected]>

blkio.go

@@ -12,21 +12,21 @@ import (
 	specs "github.com/opencontainers/runtime-spec/specs-go"
 )
 
-func NewBlkio(root string) *Blkio {
-	return &Blkio{
-		root: filepath.Join(root, "blkio"),
+func NewBlkio(root string) *BlkioController {
+	return &BlkioController{
+		root: filepath.Join(root, string(Blkio)),
 	}
 }
 
-type Blkio struct {
+type BlkioController struct {
 	root string
 }
 
-func (b *Blkio) Path(path string) string {
+func (b *BlkioController) Path(path string) string {
 	return filepath.Join(b.root, path)
 }
 
-func (b *Blkio) Create(path string, resources *specs.Resources) error {
+func (b *BlkioController) Create(path string, resources *specs.Resources) error {
 	if err := os.MkdirAll(b.Path(path), defaultDirPerm); err != nil {
 		return err
 	}
@@ -38,7 +38,7 @@ func (b *Blkio) Create(path string, resources *specs.Resources) error {
 			if err := ioutil.WriteFile(
 				filepath.Join(b.Path(path), fmt.Sprintf("blkio.%s", t.name)),
 				t.format(t.value),
-				0,
+				defaultFilePerm,
 			); err != nil {
 				return err
 			}
@@ -47,11 +47,11 @@ func (b *Blkio) Create(path string, resources *specs.Resources) error {
 	return nil
 }
 
-func (b *Blkio) Update(path string, resources *specs.Resources) error {
+func (b *BlkioController) Update(path string, resources *specs.Resources) error {
 	return b.Create(path, resources)
 }
 
-func (b *Blkio) Stat(path string, stats *Stats) error {
+func (b *BlkioController) Stat(path string, stats *Stats) error {
 	stats.Blkio = &BlkioStat{}
 	settings := []blkioStatSettings{
 		{
@@ -108,7 +108,7 @@ func (b *Blkio) Stat(path string, stats *Stats) error {
 	return nil
 }
 
-func (b *Blkio) readEntry(path, name string, entry []BlkioEntry) error {
+func (b *BlkioController) readEntry(path, name string, entry []BlkioEntry) error {
 	f, err := os.Open(filepath.Join(b.Path(path), fmt.Sprintf("blkio.%s", name)))
 	if err != nil {
 		return err

cgroup_test.go

@@ -6,37 +6,50 @@ import (
 	"path/filepath"
 )
 
-func newMock() (*mockHiearchy, error) {
-	dir, err := ioutil.TempDir("", "cgroups")
+func init() {
+	defaultFilePerm = 0666
+}
+
+func newMock() (*mockCgroup, error) {
+	root, err := ioutil.TempDir("", "cgroups")
 	if err != nil {
 		return nil, err
 	}
-	for _, name := range []string{
-		"cpu",
-		"cpuset",
-		"cpuacct",
-		"pids",
-		"memory",
-		"net_cls",
-		"net_prio",
-		"hugetlb",
-		"freezer",
-		"blkio",
-		"perf_event",
-	} {
-		if err := os.MkdirAll(filepath.Join(dir, name), 0600); err != nil {
+	subsystems := make(map[Name]Subsystem)
+	for _, n := range Subsystems() {
+		name := string(n)
+		if err := os.MkdirAll(filepath.Join(root, name), defaultDirPerm); err != nil {
 			return nil, err
 		}
+		subsystems[n] = &mockSubsystem{
+			root: root,
+			name: n,
+		}
 	}
-	return &mockHiearchy{
-		root: dir,
+	return &mockCgroup{
+		root:       root,
+		subsystems: subsystems,
 	}, nil
 }
 
-type mockHiearchy struct {
-	root string
+type mockCgroup struct {
+	root       string
+	subsystems map[Name]Subsystem
 }
 
-func (m *mockHiearchy) remove() error {
+func (m *mockCgroup) delete() error {
 	return os.RemoveAll(m.root)
 }
+
+func (m *mockCgroup) hierarchy() (map[Name]Subsystem, error) {
+	return m.subsystems, nil
+}
+
+type mockSubsystem struct {
+	root string
+	name Name
+}
+
+func (m *mockSubsystem) Path(path string) string {
+	return filepath.Join(m.root, string(m.name), path)
+}

control.go

@@ -1,16 +1,61 @@
 package cgroups
 
-import specs "github.com/opencontainers/runtime-spec/specs-go"
+import (
+	"os"
+
+	specs "github.com/opencontainers/runtime-spec/specs-go"
+)
+
+type Name string
+
+const (
+	Devices   Name = "devices"
+	Hugetlb   Name = "hugetlb"
+	Freezer   Name = "freezer"
+	Pids      Name = "pids"
+	NetCLS    Name = "net_cls"
+	NetPrio   Name = "net_prio"
+	PerfEvent Name = "perf_event"
+	Cpuset    Name = "cpuset"
+	Cpu       Name = "cpu"
+	Cpuacct   Name = "cpuacct"
+	Memory    Name = "memory"
+	Blkio     Name = "blkio"
+)
+
+// Subsystems returns a complete list of the default cgroups
+// avaliable on most linux systems
+func Subsystems() []Name {
+	return []Name{
+		Devices,
+		Hugetlb,
+		Freezer,
+		Pids,
+		NetCLS,
+		NetPrio,
+		PerfEvent,
+		Cpuset,
+		Cpu,
+		Cpuacct,
+		Memory,
+		Blkio,
+	}
+}
 
 const (
-	defaultGroup   = "devices"
-	freezerName    = "freezer"
-	memoryName     = "memory"
 	cgroupProcs    = "cgroup.procs"
-	defaultDirPerm = 0600
+	defaultGroup   = Devices
+	defaultDirPerm = 0755
 )
 
-type Group interface {
+// defaultFilePerm is a var so that the test framework can change the filemode
+// of all files created when the tests are running.  The difference between the
+// tests and real world use is that files like "cgroup.procs" will exist when writing
+// to a read cgroup filesystem and do not exist prior when running in the tests.
+// this is set to a non 0 value in the test code
+var defaultFilePerm = os.FileMode(0)
+
+type Subsystem interface {
 	Path(path string) string
 }
 
@@ -27,13 +72,13 @@ type Updater interface {
 }
 
 // Hierarchy enableds both unified and split hierarchy for cgroups
-type Hierarchy func() (map[string]Group, error)
+type Hierarchy func() (map[Name]Subsystem, error)
 
-type Path func(subsystem string) string
+type Path func(subsystem Name) string
 
-// Control handles interactions with the individual groups to perform
+// Cgroup handles interactions with the individual groups to perform
 // actions on them as them main interface to this cgroup package
-type Control interface {
+type Cgroup interface {
 	Add(pid int) error
 	Delete() error
 	Stat(ignoreNotExist bool) (*Stats, error)

cpu.go

@@ -11,21 +11,21 @@ import (
 	specs "github.com/opencontainers/runtime-spec/specs-go"
 )
 
-func NewCpu(root string) *Cpu {
-	return &Cpu{
-		root: filepath.Join(root, "cpu"),
+func NewCpu(root string) *CpuController {
+	return &CpuController{
+		root: filepath.Join(root, string(Cpu)),
 	}
 }
 
-type Cpu struct {
+type CpuController struct {
 	root string
 }
 
-func (c *Cpu) Path(path string) string {
+func (c *CpuController) Path(path string) string {
 	return filepath.Join(c.root, path)
 }
 
-func (c *Cpu) Create(path string, resources *specs.Resources) error {
+func (c *CpuController) Create(path string, resources *specs.Resources) error {
 	if err := os.MkdirAll(c.Path(path), defaultDirPerm); err != nil {
 		return err
 	}
@@ -59,7 +59,7 @@ func (c *Cpu) Create(path string, resources *specs.Resources) error {
 				if err := ioutil.WriteFile(
 					filepath.Join(c.Path(path), fmt.Sprintf("cpu.%s", t.name)),
 					[]byte(strconv.FormatUint(*t.value, 10)),
-					0,
+					defaultFilePerm,
 				); err != nil {
 					return err
 				}
@@ -70,11 +70,11 @@ func (c *Cpu) Create(path string, resources *specs.Resources) error {
 	return nil
 }
 
-func (c *Cpu) Update(path string, resources *specs.Resources) error {
+func (c *CpuController) Update(path string, resources *specs.Resources) error {
 	return c.Create(path, resources)
 }
 
-func (c *Cpu) Stat(path string, stats *Stats) error {
+func (c *CpuController) Stat(path string, stats *Stats) error {
 	f, err := os.Open(filepath.Join(c.Path(path), "cpu.stat"))
 	if err != nil {
 		return err

cpuacct.go

@@ -14,21 +14,21 @@ const nanosecondsInSecond = 1000000000
 
 var clockTicks = uint64(system.GetClockTicks())
 
-func NewCpuacct(root string) *Cpuacct {
-	return &Cpuacct{
-		root: filepath.Join(root, "cpuacct"),
+func NewCpuacct(root string) *CpuacctController {
+	return &CpuacctController{
+		root: filepath.Join(root, string(Cpuacct)),
 	}
 }
 
-type Cpuacct struct {
+type CpuacctController struct {
 	root string
 }
 
-func (c *Cpuacct) Path(path string) string {
+func (c *CpuacctController) Path(path string) string {
 	return filepath.Join(c.root, path)
 }
 
-func (c *Cpuacct) Stat(path string, stats *Stats) error {
+func (c *CpuacctController) Stat(path string, stats *Stats) error {
 	user, kernel, err := c.getUsage(path)
 	if err != nil {
 		return err
@@ -55,7 +55,7 @@ func (c *Cpuacct) Stat(path string, stats *Stats) error {
 	return nil
 }
 
-func (c *Cpuacct) percpuUsage(path string) ([]uint64, error) {
+func (c *CpuacctController) percpuUsage(path string) ([]uint64, error) {
 	var usage []uint64
 	data, err := ioutil.ReadFile(filepath.Join(c.Path(path), "cpuacct.usage_percpu"))
 	if err != nil {
@@ -71,7 +71,7 @@ func (c *Cpuacct) percpuUsage(path string) ([]uint64, error) {
 	return usage, nil
 }
 
-func (c *Cpuacct) getUsage(path string) (user uint64, kernel uint64, err error) {
+func (c *CpuacctController) getUsage(path string) (user uint64, kernel uint64, err error) {
 	statPath := filepath.Join(c.Path(path), "cpuacct.stat")
 	data, err := ioutil.ReadFile(statPath)
 	if err != nil {

cpuset.go

@@ -11,21 +11,21 @@ import (
 	specs "github.com/opencontainers/runtime-spec/specs-go"
 )
 
-func NewCputset(root string) *Cpuset {
-	return &Cpuset{
-		root: filepath.Join(root, "cpuset"),
+func NewCputset(root string) *CpusetController {
+	return &CpusetController{
+		root: filepath.Join(root, string(Cpuset)),
 	}
 }
 
-type Cpuset struct {
+type CpusetController struct {
 	root string
 }
 
-func (c *Cpuset) Path(path string) string {
+func (c *CpusetController) Path(path string) string {
 	return filepath.Join(c.root, path)
 }
 
-func (c *Cpuset) Create(path string, resources *specs.Resources) error {
+func (c *CpusetController) Create(path string, resources *specs.Resources) error {
 	if err := c.ensureParent(c.Path(path), c.root); err != nil {
 		return err
 	}
@@ -53,7 +53,7 @@ func (c *Cpuset) Create(path string, resources *specs.Resources) error {
 				if err := ioutil.WriteFile(
 					filepath.Join(c.Path(path), fmt.Sprintf("cpuset.%s", t.name)),
 					[]byte(*t.value),
-					0,
+					defaultFilePerm,
 				); err != nil {
 					return err
 				}
@@ -63,7 +63,7 @@ func (c *Cpuset) Create(path string, resources *specs.Resources) error {
 	return nil
 }
 
-func (c *Cpuset) getValues(path string) (cpus []byte, mems []byte, err error) {
+func (c *CpusetController) getValues(path string) (cpus []byte, mems []byte, err error) {
 	if cpus, err = ioutil.ReadFile(filepath.Join(path, "cpuset.cpus")); err != nil {
 		return
 	}
@@ -76,7 +76,7 @@ func (c *Cpuset) getValues(path string) (cpus []byte, mems []byte, err error) {
 // ensureParent makes sure that the parent directory of current is created
 // and populated with the proper cpus and mems files copied from
 // it's parent.
-func (c *Cpuset) ensureParent(current, root string) error {
+func (c *CpusetController) ensureParent(current, root string) error {
 	parent := filepath.Dir(current)
 	if _, err := filepath.Rel(root, parent); err != nil {
 		return nil
@@ -99,7 +99,7 @@ func (c *Cpuset) ensureParent(current, root string) error {
 
 // copyIfNeeded copies the cpuset.cpus and cpuset.mems from the parent
 // directory to the current directory if the file's contents are 0
-func (c *Cpuset) copyIfNeeded(current, parent string) error {
+func (c *CpusetController) copyIfNeeded(current, parent string) error {
 	var (
 		err                      error
 		currentCpus, currentMems []byte
@@ -115,7 +115,7 @@ func (c *Cpuset) copyIfNeeded(current, parent string) error {
 		if err := ioutil.WriteFile(
 			filepath.Join(current, "cpuset.cpus"),
 			parentCpus,
-			0,
+			defaultFilePerm,
 		); err != nil {
 			return err
 		}
@@ -124,7 +124,7 @@ func (c *Cpuset) copyIfNeeded(current, parent string) error {
 		if err := ioutil.WriteFile(
 			filepath.Join(current, "cpuset.mems"),
 			parentMems,
-			0,
+			defaultFilePerm,
 		); err != nil {
 			return err
 		}