Extract cgroups pkg.

Initial move before enhancing cgroups package.

Docker-DCO-1.1-Signed-off-by: Paul Nasrat <pnasrat@gmail.com> (github: pnasrat)
This commit is contained in:
Paul Nasrat 2014-01-20 14:15:44 -05:00
parent 1a380b67aa
commit 13860a3ba9
4 changed files with 135 additions and 1 deletions

1
cgroups/MAINTAINERS Normal file
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Michael Crosby <michael@crosbymichael.com> (@crosbymichael)

106
cgroups/cgroups.go Normal file
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package cgroups
import (
"bufio"
"fmt"
"github.com/dotcloud/docker/pkg/mount"
"io"
"io/ioutil"
"os"
"path/filepath"
"strconv"
"strings"
)
type Values struct {
Memory int64 `json:"memory"`
MemorySwap int64 `json:"memory_swap"`
CpuShares int64 `json:"cpu_shares"`
}
// 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 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, ":")
if parts[1] == subsystem {
return parts[2], nil
}
}
return "", fmt.Errorf("cgroup '%s' not found in /proc/self/cgroup", subsystem)
}
// Returns a list of pids for the given container.
func GetPidsForContainer(id string) ([]int, error) {
pids := []int{}
// memory is chosen randomly, any cgroup used by docker works
subsystem := "memory"
cgroupRoot, err := FindCgroupMountpoint(subsystem)
if err != nil {
return pids, err
}
cgroupDir, err := getThisCgroupDir(subsystem)
if err != nil {
return pids, err
}
filename := filepath.Join(cgroupRoot, cgroupDir, id, "tasks")
if _, err := os.Stat(filename); os.IsNotExist(err) {
// With more recent lxc versions use, cgroup will be in lxc/
filename = filepath.Join(cgroupRoot, cgroupDir, "lxc", id, "tasks")
}
output, err := ioutil.ReadFile(filename)
if err != nil {
return pids, err
}
for _, p := range strings.Split(string(output), "\n") {
if len(p) == 0 {
continue
}
pid, err := strconv.Atoi(p)
if err != nil {
return pids, fmt.Errorf("Invalid pid '%s': %s", p, err)
}
pids = append(pids, pid)
}
return pids, nil
}

27
cgroups/cgroups_test.go Normal file
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package cgroups
import (
"bytes"
"testing"
)
const (
cgroupsContents = `11:hugetlb:/
10:perf_event:/
9:blkio:/
8:net_cls:/
7:freezer:/
6:devices:/
5:memory:/
4:cpuacct,cpu:/
3:cpuset:/
2:name=systemd:/user.slice/user-1000.slice/session-16.scope`
)
func TestParseCgroups(t *testing.T) {
r := bytes.NewBuffer([]byte(cgroupsContents))
_, err := parseCgroupFile("blkio", r)
if err != nil {
t.Fatal(err)
}
}

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@ -1,7 +1,7 @@
package sysinfo
import (
"github.com/dotcloud/docker/cgroups" // FIXME: move cgroups in pkg
"github.com/dotcloud/docker/pkg/cgroups"
"io/ioutil"
"log"
"os"