Move cgroups package into libcontainer

Docker-DCO-1.1-Signed-off-by: Michael Crosby <michael@crosbymichael.com> (github: crosbymichael)

libcontainer/cgroups/fs/apply_raw.go

@@ -0,0 +1,155 @@
+package fs
+
+import (
+	"fmt"
+	"io/ioutil"
+	"os"
+	"path/filepath"
+	"strconv"
+
+	"github.com/dotcloud/docker/pkg/libcontainer/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) parent(subsystem string) (string, error) {
+	initPath, err := cgroups.GetInitCgroupDir(subsystem)
+	if err != nil {
+		return "", err
+	}
+	return filepath.Join(raw.root, subsystem, initPath), nil
+}
+
+func (raw *data) path(subsystem string) (string, error) {
+	parent, err := raw.parent(subsystem)
+	if err != nil {
+		return "", err
+	}
+	return filepath.Join(parent, 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
+}