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package cgroups
import (
"bufio"
"fmt"
"github.com/dotcloud/docker/pkg/mount"
"io"
"io/ioutil"
"os"
"path/filepath"
"strings"
)
type Cgroup struct {
Name string `json:"name,omitempty"`
Parent string `json:"parent,omitempty"`
DeviceAccess bool `json:"device_access,omitempty"` // name of parent cgroup or slice
Memory int64 `json:"memory,omitempty"` // Memory limit (in bytes)
MemorySwap int64 `json:"memory_swap,omitempty"` // Total memory usage (memory + swap); set `-1' to disable swap
CpuShares int64 `json:"cpu_shares,omitempty"` // CPU shares (relative weight vs. other containers)
CpusetCpus string `json:"cpuset_cpus,omitempty"` // CPU to use
UnitProperties [][2]string `json:"unit_properties,omitempty"` // systemd unit properties
}
type ActiveCgroup interface {
Cleanup() error
}
// https://www.kernel.org/doc/Documentation/cgroups/cgroups.txt
func FindCgroupMountpoint(subsystem string) (string, error) {
mounts, err := mount.GetMounts()
if err != nil {
return "", err
}
for _, mount := range mounts {
if mount.Fstype == "cgroup" {
for _, opt := range strings.Split(mount.VfsOpts, ",") {
if opt == subsystem {
return mount.Mountpoint, nil
}
}
}
}
return "", fmt.Errorf("cgroup mountpoint not found for %s", subsystem)
}
// Returns the relative path to the cgroup docker is running in.
func GetThisCgroupDir(subsystem string) (string, error) {
f, err := os.Open("/proc/self/cgroup")
if err != nil {
return "", err
}
defer f.Close()
return parseCgroupFile(subsystem, f)
}
func GetInitCgroupDir(subsystem string) (string, error) {
f, err := os.Open("/proc/1/cgroup")
if err != nil {
return "", err
}
defer f.Close()
return parseCgroupFile(subsystem, f)
}
func parseCgroupFile(subsystem string, r io.Reader) (string, error) {
s := bufio.NewScanner(r)
for s.Scan() {
if err := s.Err(); err != nil {
return "", err
}
text := s.Text()
parts := strings.Split(text, ":")
for _, subs := range strings.Split(parts[1], ",") {
if subs == subsystem {
return parts[2], nil
}
}
}
return "", fmt.Errorf("cgroup '%s' not found in /proc/self/cgroup", subsystem)
}
func writeFile(dir, file, data string) error {
return ioutil.WriteFile(filepath.Join(dir, file), []byte(data), 0700)
}
func (c *Cgroup) Apply(pid int) (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/
if useSystemd() {
return systemdApply(c, pid)
} else {
return rawApply(c, pid)
}
}
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