blob: 8946dd5959e4b28b8f35a6ee69e1dbbbb2419777 [file] [log] [blame]
// +build linux
package cgroups
import (
"bufio"
"fmt"
"io"
"io/ioutil"
"os"
"path/filepath"
"strconv"
"strings"
"time"
"github.com/docker/go-units"
)
const (
cgroupNamePrefix = "name="
CgroupProcesses = "cgroup.procs"
)
// https://www.kernel.org/doc/Documentation/cgroup-v1/cgroups.txt
func FindCgroupMountpoint(subsystem string) (string, error) {
// We are not using mount.GetMounts() because it's super-inefficient,
// parsing it directly sped up x10 times because of not using Sscanf.
// It was one of two major performance drawbacks in container start.
if !isSubsystemAvailable(subsystem) {
return "", NewNotFoundError(subsystem)
}
f, err := os.Open("/proc/self/mountinfo")
if err != nil {
return "", err
}
defer f.Close()
scanner := bufio.NewScanner(f)
for scanner.Scan() {
txt := scanner.Text()
fields := strings.Split(txt, " ")
for _, opt := range strings.Split(fields[len(fields)-1], ",") {
if opt == subsystem {
return fields[4], nil
}
}
}
if err := scanner.Err(); err != nil {
return "", err
}
return "", NewNotFoundError(subsystem)
}
func FindCgroupMountpointAndRoot(subsystem string) (string, string, error) {
if !isSubsystemAvailable(subsystem) {
return "", "", NewNotFoundError(subsystem)
}
f, err := os.Open("/proc/self/mountinfo")
if err != nil {
return "", "", err
}
defer f.Close()
scanner := bufio.NewScanner(f)
for scanner.Scan() {
txt := scanner.Text()
fields := strings.Split(txt, " ")
for _, opt := range strings.Split(fields[len(fields)-1], ",") {
if opt == subsystem {
return fields[4], fields[3], nil
}
}
}
if err := scanner.Err(); err != nil {
return "", "", err
}
return "", "", NewNotFoundError(subsystem)
}
func isSubsystemAvailable(subsystem string) bool {
cgroups, err := ParseCgroupFile("/proc/self/cgroup")
if err != nil {
return false
}
_, avail := cgroups[subsystem]
return avail
}
func FindCgroupMountpointDir() (string, error) {
f, err := os.Open("/proc/self/mountinfo")
if err != nil {
return "", err
}
defer f.Close()
scanner := bufio.NewScanner(f)
for scanner.Scan() {
text := scanner.Text()
fields := strings.Split(text, " ")
// Safe as mountinfo encodes mountpoints with spaces as \040.
index := strings.Index(text, " - ")
postSeparatorFields := strings.Fields(text[index+3:])
numPostFields := len(postSeparatorFields)
// This is an error as we can't detect if the mount is for "cgroup"
if numPostFields == 0 {
return "", fmt.Errorf("Found no fields post '-' in %q", text)
}
if postSeparatorFields[0] == "cgroup" {
// Check that the mount is properly formated.
if numPostFields < 3 {
return "", fmt.Errorf("Error found less than 3 fields post '-' in %q", text)
}
return filepath.Dir(fields[4]), nil
}
}
if err := scanner.Err(); err != nil {
return "", err
}
return "", NewNotFoundError("cgroup")
}
type Mount struct {
Mountpoint string
Root string
Subsystems []string
}
func (m Mount) GetThisCgroupDir(cgroups map[string]string) (string, error) {
if len(m.Subsystems) == 0 {
return "", fmt.Errorf("no subsystem for mount")
}
return getControllerPath(m.Subsystems[0], cgroups)
}
func getCgroupMountsHelper(ss map[string]bool, mi io.Reader, all bool) ([]Mount, error) {
res := make([]Mount, 0, len(ss))
scanner := bufio.NewScanner(mi)
numFound := 0
for scanner.Scan() && numFound < len(ss) {
txt := scanner.Text()
sepIdx := strings.Index(txt, " - ")
if sepIdx == -1 {
return nil, fmt.Errorf("invalid mountinfo format")
}
if txt[sepIdx+3:sepIdx+9] != "cgroup" {
continue
}
fields := strings.Split(txt, " ")
m := Mount{
Mountpoint: fields[4],
Root: fields[3],
}
for _, opt := range strings.Split(fields[len(fields)-1], ",") {
if !ss[opt] {
continue
}
if strings.HasPrefix(opt, cgroupNamePrefix) {
m.Subsystems = append(m.Subsystems, opt[len(cgroupNamePrefix):])
} else {
m.Subsystems = append(m.Subsystems, opt)
}
if !all {
numFound++
}
}
res = append(res, m)
}
if err := scanner.Err(); err != nil {
return nil, err
}
return res, nil
}
// GetCgroupMounts returns the mounts for the cgroup subsystems.
// all indicates whether to return just the first instance or all the mounts.
func GetCgroupMounts(all bool) ([]Mount, error) {
f, err := os.Open("/proc/self/mountinfo")
if err != nil {
return nil, err
}
defer f.Close()
allSubsystems, err := ParseCgroupFile("/proc/self/cgroup")
if err != nil {
return nil, err
}
allMap := make(map[string]bool)
for s := range allSubsystems {
allMap[s] = true
}
return getCgroupMountsHelper(allMap, f, all)
}
// GetAllSubsystems returns all the cgroup subsystems supported by the kernel
func GetAllSubsystems() ([]string, error) {
f, err := os.Open("/proc/cgroups")
if err != nil {
return nil, err
}
defer f.Close()
subsystems := []string{}
s := bufio.NewScanner(f)
for s.Scan() {
if err := s.Err(); err != nil {
return nil, err
}
text := s.Text()
if text[0] != '#' {
parts := strings.Fields(text)
if len(parts) >= 4 && parts[3] != "0" {
subsystems = append(subsystems, parts[0])
}
}
}
return subsystems, nil
}
// GetThisCgroupDir returns the relative path to the cgroup docker is running in.
func GetThisCgroupDir(subsystem string) (string, error) {
cgroups, err := ParseCgroupFile("/proc/self/cgroup")
if err != nil {
return "", err
}
return getControllerPath(subsystem, cgroups)
}
func GetInitCgroupDir(subsystem string) (string, error) {
cgroups, err := ParseCgroupFile("/proc/1/cgroup")
if err != nil {
return "", err
}
return getControllerPath(subsystem, cgroups)
}
func readProcsFile(dir string) ([]int, error) {
f, err := os.Open(filepath.Join(dir, CgroupProcesses))
if err != nil {
return nil, err
}
defer f.Close()
var (
s = bufio.NewScanner(f)
out = []int{}
)
for s.Scan() {
if t := s.Text(); t != "" {
pid, err := strconv.Atoi(t)
if err != nil {
return nil, err
}
out = append(out, pid)
}
}
return out, nil
}
// ParseCgroupFile parses the given cgroup file, typically from
// /proc/<pid>/cgroup, into a map of subgroups to cgroup names.
func ParseCgroupFile(path string) (map[string]string, error) {
f, err := os.Open(path)
if err != nil {
return nil, err
}
defer f.Close()
return parseCgroupFromReader(f)
}
// helper function for ParseCgroupFile to make testing easier
func parseCgroupFromReader(r io.Reader) (map[string]string, error) {
s := bufio.NewScanner(r)
cgroups := make(map[string]string)
for s.Scan() {
if err := s.Err(); err != nil {
return nil, err
}
text := s.Text()
// from cgroups(7):
// /proc/[pid]/cgroup
// ...
// For each cgroup hierarchy ... there is one entry
// containing three colon-separated fields of the form:
// hierarchy-ID:subsystem-list:cgroup-path
parts := strings.SplitN(text, ":", 3)
if len(parts) < 3 {
return nil, fmt.Errorf("invalid cgroup entry: must contain at least two colons: %v", text)
}
for _, subs := range strings.Split(parts[1], ",") {
cgroups[subs] = parts[2]
}
}
return cgroups, nil
}
func getControllerPath(subsystem string, cgroups map[string]string) (string, error) {
if p, ok := cgroups[subsystem]; ok {
return p, nil
}
if p, ok := cgroups[cgroupNamePrefix+subsystem]; ok {
return p, nil
}
return "", NewNotFoundError(subsystem)
}
func PathExists(path string) bool {
if _, err := os.Stat(path); err != nil {
return false
}
return true
}
func EnterPid(cgroupPaths map[string]string, pid int) error {
for _, path := range cgroupPaths {
if PathExists(path) {
if err := WriteCgroupProc(path, pid); err != nil {
return err
}
}
}
return nil
}
// RemovePaths iterates over the provided paths removing them.
// We trying to remove all paths five times with increasing delay between tries.
// If after all there are not removed cgroups - appropriate error will be
// returned.
func RemovePaths(paths map[string]string) (err error) {
delay := 10 * time.Millisecond
for i := 0; i < 5; i++ {
if i != 0 {
time.Sleep(delay)
delay *= 2
}
for s, p := range paths {
os.RemoveAll(p)
// TODO: here probably should be logging
_, err := os.Stat(p)
// We need this strange way of checking cgroups existence because
// RemoveAll almost always returns error, even on already removed
// cgroups
if os.IsNotExist(err) {
delete(paths, s)
}
}
if len(paths) == 0 {
return nil
}
}
return fmt.Errorf("Failed to remove paths: %v", paths)
}
func GetHugePageSize() ([]string, error) {
var pageSizes []string
sizeList := []string{"B", "kB", "MB", "GB", "TB", "PB"}
files, err := ioutil.ReadDir("/sys/kernel/mm/hugepages")
if err != nil {
return pageSizes, err
}
for _, st := range files {
nameArray := strings.Split(st.Name(), "-")
pageSize, err := units.RAMInBytes(nameArray[1])
if err != nil {
return []string{}, err
}
sizeString := units.CustomSize("%g%s", float64(pageSize), 1024.0, sizeList)
pageSizes = append(pageSizes, sizeString)
}
return pageSizes, nil
}
// GetPids returns all pids, that were added to cgroup at path.
func GetPids(path string) ([]int, error) {
return readProcsFile(path)
}
// GetAllPids returns all pids, that were added to cgroup at path and to all its
// subcgroups.
func GetAllPids(path string) ([]int, error) {
var pids []int
// collect pids from all sub-cgroups
err := filepath.Walk(path, func(p string, info os.FileInfo, iErr error) error {
dir, file := filepath.Split(p)
if file != CgroupProcesses {
return nil
}
if iErr != nil {
return iErr
}
cPids, err := readProcsFile(dir)
if err != nil {
return err
}
pids = append(pids, cPids...)
return nil
})
return pids, err
}
// WriteCgroupProc writes the specified pid into the cgroup's cgroup.procs file
func WriteCgroupProc(dir string, pid int) error {
// Normally dir should not be empty, one case is that cgroup subsystem
// is not mounted, we will get empty dir, and we want it fail here.
if dir == "" {
return fmt.Errorf("no such directory for %s", CgroupProcesses)
}
// Dont attach any pid to the cgroup if -1 is specified as a pid
if pid != -1 {
if err := ioutil.WriteFile(filepath.Join(dir, CgroupProcesses), []byte(strconv.Itoa(pid)), 0700); err != nil {
return fmt.Errorf("failed to write %v to %v: %v", pid, CgroupProcesses, err)
}
}
return nil
}