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libct/cgroups/fs: code cleanups #2498

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merged 4 commits into from
Jul 9, 2020
Merged

libct/cgroups/fs: code cleanups #2498

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11fb949
cgroups/fs: rm Remove method from controllers
kolyshkin May 31, 2020
2e22579
libct/cgroups/fs.GetStats: drop PathExists check
kolyshkin Jul 3, 2020
daf30cb
cgroups/fs: rm getSubsystems
kolyshkin May 31, 2020
2a322e9
cgroupv1: remove subsystemSet.Get()
kolyshkin Jun 3, 2020
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4 changes: 0 additions & 4 deletions libcontainer/cgroups/fs/blkio.go
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Original file line number Diff line number Diff line change
Expand Up @@ -74,10 +74,6 @@ func (s *BlkioGroup) Set(path string, cgroup *configs.Cgroup) error {
return nil
}

func (s *BlkioGroup) Remove(d *cgroupData) error {
return removePath(d.path("blkio"))
}

/*
examples:

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4 changes: 0 additions & 4 deletions libcontainer/cgroups/fs/cpu.go
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Expand Up @@ -96,10 +96,6 @@ func (s *CpuGroup) Set(path string, cgroup *configs.Cgroup) error {
return s.SetRtSched(path, cgroup)
}

func (s *CpuGroup) Remove(d *cgroupData) error {
return removePath(d.path("cpu"))
}

func (s *CpuGroup) GetStats(path string, stats *cgroups.Stats) error {
f, err := os.Open(filepath.Join(path, "cpu.stat"))
if err != nil {
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7 changes: 3 additions & 4 deletions libcontainer/cgroups/fs/cpuacct.go
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Expand Up @@ -53,11 +53,10 @@ func (s *CpuacctGroup) Set(path string, cgroup *configs.Cgroup) error {
return nil
}

func (s *CpuacctGroup) Remove(d *cgroupData) error {
return removePath(d.path("cpuacct"))
}

func (s *CpuacctGroup) GetStats(path string, stats *cgroups.Stats) error {
if !cgroups.PathExists(path) {
return nil
}
userModeUsage, kernelModeUsage, err := getCpuUsageBreakdown(path)
if err != nil {
return err
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4 changes: 0 additions & 4 deletions libcontainer/cgroups/fs/cpuset.go
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Expand Up @@ -45,10 +45,6 @@ func (s *CpusetGroup) Set(path string, cgroup *configs.Cgroup) error {
return nil
}

func (s *CpusetGroup) Remove(d *cgroupData) error {
return removePath(d.path("cpuset"))
}

func (s *CpusetGroup) GetStats(path string, stats *cgroups.Stats) error {
return nil
}
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4 changes: 0 additions & 4 deletions libcontainer/cgroups/fs/devices.go
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Expand Up @@ -106,10 +106,6 @@ func (s *DevicesGroup) Set(path string, cgroup *configs.Cgroup) error {
return nil
}

func (s *DevicesGroup) Remove(d *cgroupData) error {
return removePath(d.path("devices"))
}

func (s *DevicesGroup) GetStats(path string, stats *cgroups.Stats) error {
return nil
}
4 changes: 0 additions & 4 deletions libcontainer/cgroups/fs/freezer.go
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Expand Up @@ -61,10 +61,6 @@ func (s *FreezerGroup) Set(path string, cgroup *configs.Cgroup) error {
return nil
}

func (s *FreezerGroup) Remove(d *cgroupData) error {
return removePath(d.path("freezer"))
}

func (s *FreezerGroup) GetStats(path string, stats *cgroups.Stats) error {
return nil
}
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29 changes: 6 additions & 23 deletions libcontainer/cgroups/fs/fs.go
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Expand Up @@ -18,7 +18,7 @@ import (
)

var (
subsystemsLegacy = subsystemSet{
subsystems = []subsystem{
&CpusetGroup{},
&DevicesGroup{},
&MemoryGroup{},
Expand All @@ -38,24 +38,11 @@ var (

var errSubsystemDoesNotExist = errors.New("cgroup: subsystem does not exist")

type subsystemSet []subsystem

func (s subsystemSet) Get(name string) (subsystem, error) {
for _, ss := range s {
if ss.Name() == name {
return ss, nil
}
}
return nil, errSubsystemDoesNotExist
}

type subsystem interface {
// Name returns the name of the subsystem.
Name() string
// Returns the stats, as 'stats', corresponding to the cgroup under 'path'.
GetStats(path string, stats *cgroups.Stats) error
// Removes the cgroup represented by 'cgroupData'.
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This could be of use to external clients and maybe later on if/when we factor this out into a cgroups library.

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Theoretically, yes.

Practically,

  1. I don't see it being used by kubernetes;
  2. It uses d.path which is expensive, it requires to parse mountinfo (this is actually the main point of it being removed);
  3. Its API is not in line with e.g. Set (which does not use d.path but the path is provided directly).

Also, if needed, it can be trivial to reimplement / re-add, as it doesn't do anything special, so I see no point in keeping it.

Remove(*cgroupData) error
// Creates and joins the cgroup represented by 'cgroupData'.
Apply(*cgroupData) error
// Set the cgroup represented by cgroup.
Expand Down Expand Up @@ -166,10 +153,6 @@ func isIgnorableError(rootless bool, err error) bool {
return false
}

func (m *manager) getSubsystems() subsystemSet {
return subsystemsLegacy
}

func (m *manager) Apply(pid int) (err error) {
if m.cgroups == nil {
return nil
Expand Down Expand Up @@ -199,7 +182,7 @@ func (m *manager) Apply(pid int) (err error) {
return cgroups.EnterPid(m.paths, pid)
}

for _, sys := range m.getSubsystems() {
for _, sys := range subsystems {
p, err := d.path(sys.Name())
if err != nil {
// The non-presence of the devices subsystem is
Expand Down Expand Up @@ -250,9 +233,9 @@ func (m *manager) GetStats() (*cgroups.Stats, error) {
m.mu.Lock()
defer m.mu.Unlock()
stats := cgroups.NewStats()
for name, path := range m.paths {
sys, err := m.getSubsystems().Get(name)
if err == errSubsystemDoesNotExist || !cgroups.PathExists(path) {
for _, sys := range subsystems {
path := m.paths[sys.Name()]
if path == "" {
continue
}
if err := sys.GetStats(path, stats); err != nil {
Expand All @@ -275,7 +258,7 @@ func (m *manager) Set(container *configs.Config) error {

m.mu.Lock()
defer m.mu.Unlock()
for _, sys := range m.getSubsystems() {
for _, sys := range subsystems {
path := m.paths[sys.Name()]
if err := sys.Set(path, container.Cgroups); err != nil {
if m.rootless && sys.Name() == "devices" {
Expand Down
7 changes: 3 additions & 4 deletions libcontainer/cgroups/fs/hugetlb.go
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Expand Up @@ -37,12 +37,11 @@ func (s *HugetlbGroup) Set(path string, cgroup *configs.Cgroup) error {
return nil
}

func (s *HugetlbGroup) Remove(d *cgroupData) error {
return removePath(d.path("hugetlb"))
}

func (s *HugetlbGroup) GetStats(path string, stats *cgroups.Stats) error {
hugetlbStats := cgroups.HugetlbStats{}
if !cgroups.PathExists(path) {
return nil
}
for _, pageSize := range HugePageSizes {
usage := strings.Join([]string{"hugetlb", pageSize, "usage_in_bytes"}, ".")
value, err := fscommon.GetCgroupParamUint(path, usage)
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4 changes: 0 additions & 4 deletions libcontainer/cgroups/fs/memory.go
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Expand Up @@ -165,10 +165,6 @@ func (s *MemoryGroup) Set(path string, cgroup *configs.Cgroup) error {
return nil
}

func (s *MemoryGroup) Remove(d *cgroupData) error {
return removePath(d.path("memory"))
}

func (s *MemoryGroup) GetStats(path string, stats *cgroups.Stats) error {
// Set stats from memory.stat.
statsFile, err := os.Open(filepath.Join(path, "memory.stat"))
Expand Down
7 changes: 0 additions & 7 deletions libcontainer/cgroups/fs/name.go
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Expand Up @@ -28,13 +28,6 @@ func (s *NameGroup) Set(path string, cgroup *configs.Cgroup) error {
return nil
}

func (s *NameGroup) Remove(d *cgroupData) error {
if s.Join {
removePath(d.path(s.GroupName))
}
return nil
}

func (s *NameGroup) GetStats(path string, stats *cgroups.Stats) error {
return nil
}
4 changes: 0 additions & 4 deletions libcontainer/cgroups/fs/net_cls.go
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Expand Up @@ -35,10 +35,6 @@ func (s *NetClsGroup) Set(path string, cgroup *configs.Cgroup) error {
return nil
}

func (s *NetClsGroup) Remove(d *cgroupData) error {
return removePath(d.path("net_cls"))
}

func (s *NetClsGroup) GetStats(path string, stats *cgroups.Stats) error {
return nil
}
4 changes: 0 additions & 4 deletions libcontainer/cgroups/fs/net_prio.go
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Expand Up @@ -33,10 +33,6 @@ func (s *NetPrioGroup) Set(path string, cgroup *configs.Cgroup) error {
return nil
}

func (s *NetPrioGroup) Remove(d *cgroupData) error {
return removePath(d.path("net_prio"))
}

func (s *NetPrioGroup) GetStats(path string, stats *cgroups.Stats) error {
return nil
}
4 changes: 0 additions & 4 deletions libcontainer/cgroups/fs/perf_event.go
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Expand Up @@ -26,10 +26,6 @@ func (s *PerfEventGroup) Set(path string, cgroup *configs.Cgroup) error {
return nil
}

func (s *PerfEventGroup) Remove(d *cgroupData) error {
return removePath(d.path("perf_event"))
}

func (s *PerfEventGroup) GetStats(path string, stats *cgroups.Stats) error {
return nil
}
7 changes: 3 additions & 4 deletions libcontainer/cgroups/fs/pids.go
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Expand Up @@ -44,11 +44,10 @@ func (s *PidsGroup) Set(path string, cgroup *configs.Cgroup) error {
return nil
}

func (s *PidsGroup) Remove(d *cgroupData) error {
return removePath(d.path("pids"))
}

func (s *PidsGroup) GetStats(path string, stats *cgroups.Stats) error {
if !cgroups.PathExists(path) {
return nil
}
current, err := fscommon.GetCgroupParamUint(path, "pids.current")
if err != nil {
return fmt.Errorf("failed to parse pids.current - %s", err)
Expand Down
19 changes: 4 additions & 15 deletions libcontainer/cgroups/systemd/v1.go
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Expand Up @@ -41,18 +41,7 @@ type subsystem interface {

var errSubsystemDoesNotExist = errors.New("cgroup: subsystem does not exist")

type subsystemSet []subsystem

func (s subsystemSet) Get(name string) (subsystem, error) {
for _, ss := range s {
if ss.Name() == name {
return ss, nil
}
}
return nil, errSubsystemDoesNotExist
}

var legacySubsystems = subsystemSet{
var legacySubsystems = []subsystem{
&fs.CpusetGroup{},
&fs.DevicesGroup{},
&fs.MemoryGroup{},
Expand Down Expand Up @@ -355,9 +344,9 @@ func (m *legacyManager) GetStats() (*cgroups.Stats, error) {
m.mu.Lock()
defer m.mu.Unlock()
stats := cgroups.NewStats()
for name, path := range m.paths {
sys, err := legacySubsystems.Get(name)
if err == errSubsystemDoesNotExist || !cgroups.PathExists(path) {
for _, sys := range legacySubsystems {
path := m.paths[sys.Name()]
if path == "" {
continue
}
if err := sys.GetStats(path, stats); err != nil {
Expand Down