gotosocial/vendor/go.uber.org/automaxprocs/internal/cgroups/cgroups2.go

176 lines
4.5 KiB
Go

// Copyright (c) 2022 Uber Technologies, Inc.
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
// THE SOFTWARE.
//go:build linux
// +build linux
package cgroups
import (
"bufio"
"errors"
"fmt"
"io"
"os"
"path"
"strconv"
"strings"
)
const (
// _cgroupv2CPUMax is the file name for the CGroup-V2 CPU max and period
// parameter.
_cgroupv2CPUMax = "cpu.max"
// _cgroupFSType is the Linux CGroup-V2 file system type used in
// `/proc/$PID/mountinfo`.
_cgroupv2FSType = "cgroup2"
_cgroupv2MountPoint = "/sys/fs/cgroup"
_cgroupV2CPUMaxDefaultPeriod = 100000
_cgroupV2CPUMaxQuotaMax = "max"
)
const (
_cgroupv2CPUMaxQuotaIndex = iota
_cgroupv2CPUMaxPeriodIndex
)
// ErrNotV2 indicates that the system is not using cgroups2.
var ErrNotV2 = errors.New("not using cgroups2")
// CGroups2 provides access to cgroups data for systems using cgroups2.
type CGroups2 struct {
mountPoint string
groupPath string
cpuMaxFile string
}
// NewCGroups2ForCurrentProcess builds a CGroups2 for the current process.
//
// This returns ErrNotV2 if the system is not using cgroups2.
func NewCGroups2ForCurrentProcess() (*CGroups2, error) {
return newCGroups2From(_procPathMountInfo, _procPathCGroup)
}
func newCGroups2From(mountInfoPath, procPathCGroup string) (*CGroups2, error) {
isV2, err := isCGroupV2(mountInfoPath)
if err != nil {
return nil, err
}
if !isV2 {
return nil, ErrNotV2
}
subsystems, err := parseCGroupSubsystems(procPathCGroup)
if err != nil {
return nil, err
}
// Find v2 subsystem by looking for the `0` id
var v2subsys *CGroupSubsys
for _, subsys := range subsystems {
if subsys.ID == 0 {
v2subsys = subsys
break
}
}
if v2subsys == nil {
return nil, ErrNotV2
}
return &CGroups2{
mountPoint: _cgroupv2MountPoint,
groupPath: v2subsys.Name,
cpuMaxFile: _cgroupv2CPUMax,
}, nil
}
func isCGroupV2(procPathMountInfo string) (bool, error) {
var (
isV2 bool
newMountPoint = func(mp *MountPoint) error {
isV2 = isV2 || (mp.FSType == _cgroupv2FSType && mp.MountPoint == _cgroupv2MountPoint)
return nil
}
)
if err := parseMountInfo(procPathMountInfo, newMountPoint); err != nil {
return false, err
}
return isV2, nil
}
// CPUQuota returns the CPU quota applied with the CPU cgroup2 controller.
// It is a result of reading cpu quota and period from cpu.max file.
// It will return `cpu.max / cpu.period`. If cpu.max is set to max, it returns
// (-1, false, nil)
func (cg *CGroups2) CPUQuota() (float64, bool, error) {
cpuMaxParams, err := os.Open(path.Join(cg.mountPoint, cg.groupPath, cg.cpuMaxFile))
if err != nil {
if os.IsNotExist(err) {
return -1, false, nil
}
return -1, false, err
}
defer cpuMaxParams.Close()
scanner := bufio.NewScanner(cpuMaxParams)
if scanner.Scan() {
fields := strings.Fields(scanner.Text())
if len(fields) == 0 || len(fields) > 2 {
return -1, false, fmt.Errorf("invalid format")
}
if fields[_cgroupv2CPUMaxQuotaIndex] == _cgroupV2CPUMaxQuotaMax {
return -1, false, nil
}
max, err := strconv.Atoi(fields[_cgroupv2CPUMaxQuotaIndex])
if err != nil {
return -1, false, err
}
var period int
if len(fields) == 1 {
period = _cgroupV2CPUMaxDefaultPeriod
} else {
period, err = strconv.Atoi(fields[_cgroupv2CPUMaxPeriodIndex])
if err != nil {
return -1, false, err
}
if period == 0 {
return -1, false, errors.New("zero value for period is not allowed")
}
}
return float64(max) / float64(period), true, nil
}
if err := scanner.Err(); err != nil {
return -1, false, err
}
return 0, false, io.ErrUnexpectedEOF
}