package fs import ( "fmt" "io/ioutil" "os" "path/filepath" "strconv" "github.com/dotcloud/docker/pkg/cgroups" ) var ( subsystems = map[string]subsystem{ "devices": &devicesGroup{}, "memory": &memoryGroup{}, "cpu": &cpuGroup{}, "cpuset": &cpusetGroup{}, "cpuacct": &cpuacctGroup{}, "blkio": &blkioGroup{}, "perf_event": &perfEventGroup{}, "freezer": &freezerGroup{}, } ) type subsystem interface { Set(*data) error Remove(*data) error Stats(*data) (map[string]float64, error) } type data struct { root string cgroup string c *cgroups.Cgroup pid int } func Apply(c *cgroups.Cgroup, pid int) (cgroups.ActiveCgroup, error) { // We have two implementation of cgroups support, one is based on // systemd and the dbus api, and one is based on raw cgroup fs operations // following the pre-single-writer model docs at: // http://www.freedesktop.org/wiki/Software/systemd/PaxControlGroups/ // // we can pick any subsystem to find the root cgroupRoot, err := cgroups.FindCgroupMountpoint("cpu") if err != nil { return nil, err } cgroupRoot = filepath.Dir(cgroupRoot) if _, err := os.Stat(cgroupRoot); err != nil { return nil, fmt.Errorf("cgroups fs not found") } cgroup := c.Name if c.Parent != "" { cgroup = filepath.Join(c.Parent, cgroup) } d := &data{ root: cgroupRoot, cgroup: cgroup, c: c, pid: pid, } for _, sys := range subsystems { if err := sys.Set(d); err != nil { d.Cleanup() return nil, err } } return d, nil } func GetStats(c *cgroups.Cgroup, subsystem string, pid int) (map[string]float64, error) { cgroupRoot, err := cgroups.FindCgroupMountpoint("cpu") if err != nil { return nil, err } cgroupRoot = filepath.Dir(cgroupRoot) if _, err := os.Stat(cgroupRoot); err != nil { return nil, fmt.Errorf("cgroups fs not found") } cgroup := c.Name if c.Parent != "" { cgroup = filepath.Join(c.Parent, cgroup) } d := &data{ root: cgroupRoot, cgroup: cgroup, c: c, pid: pid, } sys, exists := subsystems[subsystem] if !exists { return nil, fmt.Errorf("subsystem %s does not exist", subsystem) } return sys.Stats(d) } func (raw *data) path(subsystem string) (string, error) { initPath, err := cgroups.GetInitCgroupDir(subsystem) if err != nil { return "", err } return filepath.Join(raw.root, subsystem, initPath, raw.cgroup), nil } func (raw *data) join(subsystem string) (string, error) { path, err := raw.path(subsystem) if err != nil { return "", err } if err := os.MkdirAll(path, 0755); err != nil && !os.IsExist(err) { return "", err } if err := writeFile(path, "cgroup.procs", strconv.Itoa(raw.pid)); err != nil { return "", err } return path, nil } func (raw *data) Cleanup() error { for _, sys := range subsystems { sys.Remove(raw) } return nil } func writeFile(dir, file, data string) error { return ioutil.WriteFile(filepath.Join(dir, file), []byte(data), 0700) } func removePath(p string, err error) error { if err != nil { return err } if p != "" { return os.RemoveAll(p) } return nil }