Files
cloudpods/pkg/lbagent/utils/pidfile.go
2019-11-19 11:06:29 +00:00

107 lines
2.4 KiB
Go

// Copyright 2019 Yunion
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package utils
import (
"fmt"
"io/ioutil"
"os"
"strconv"
"strings"
"syscall"
"yunion.io/x/pkg/errors"
)
const errPidNotRunning = errors.Error("pid not running")
type PidFile struct {
Path string
Comm string
}
func NewPidFile(path, comm string) *PidFile {
pf := &PidFile{
Path: path,
Comm: comm,
}
return pf
}
func (pf *PidFile) findProcess() (*os.Process, error) {
data, err := ioutil.ReadFile(pf.Path)
if err != nil {
return nil, err
}
s := strings.TrimSpace(string(data))
pid, err := strconv.Atoi(s)
if err != nil {
return nil, err
}
proc, err := os.FindProcess(pid)
if err != nil {
return nil, errPidNotRunning
}
if err := proc.Signal(syscall.Signal(0)); err != nil {
return nil, errPidNotRunning
}
return proc, nil
}
func (pf *PidFile) findComm(pid int) (string, error) {
fp := fmt.Sprintf("/proc/%d/comm", pid)
data, err := ioutil.ReadFile(fp)
if err != nil {
return "", err
}
comm := strings.TrimSpace(string(data))
return comm, nil
}
// ConfirmedOrUnlink reads the pidfile, confirm that it's running and comm
// matches pf.Comm
//
// When confirmed is true, proc must be non-nil
func (pf *PidFile) ConfirmOrUnlink() (proc *os.Process, confirmed bool, err error) {
proc, err = pf.findProcess()
if err != nil {
if err == errPidNotRunning {
os.Remove(pf.Path)
}
err = errors.Wrapf(err, "pidfile %s: find process: %v", pf.Path, err)
return
}
comm, err := pf.findComm(proc.Pid)
if err != nil {
err = errors.Wrapf(err, "pidfile %s: find comm: %v", pf.Path, err)
return
}
if pf.Comm == comm {
confirmed = true
return
}
err = os.Remove(pf.Path)
if err != nil {
err = errors.Wrapf(err, "pidfile %s: unlink: %v", pf.Path, err)
}
return
}
func WritePidFile(pid int, pidFile string) error {
data := fmt.Sprintf("%d\n", pid)
err := ioutil.WriteFile(pidFile, []byte(data), FileModeFile)
return err
}