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daemon.go
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daemon.go
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/*
* Copyright (c) 2022, MegaEase
* All rights reserved.
*
* 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:https://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 daemon
import (
"fmt"
"os"
"path/filepath"
"strconv"
"strings"
"github.com/megaease/easeprobe/global"
)
// Config is the daemon config
type Config struct {
PidFile string
pidFd *os.File
}
// NewPIDFile create a new pid file
func NewPIDFile() (*Config, error) {
c := &Config{}
c.PidFile = filepath.Join(global.GetWorkDir(), global.DefaultPIDFile)
_, err := c.CheckPIDFile()
if err != nil {
return nil, err
}
if err := os.MkdirAll(filepath.Dir(c.PidFile), 0755); err != nil {
return nil, err
}
pidstr := fmt.Sprintf("%d", os.Getpid())
if err := os.WriteFile(c.PidFile, []byte(pidstr), 0600); err != nil {
return nil, err
}
c.pidFd, _ = os.OpenFile(c.PidFile, os.O_APPEND|os.O_EXCL, 0600)
return c, nil
}
// CheckPIDFile check if the pid file exists
// if the PID file exists, return the PID of the process
// if the PID file does not exist, return -1
func (c *Config) CheckPIDFile() (int, error) {
buf, err := os.ReadFile(c.PidFile)
if err != nil {
return -1, nil
}
pidstr := strings.TrimSpace(string(buf))
pid, err := strconv.Atoi(pidstr)
if err != nil {
return -1, nil
}
if processExists(pid) {
return pid, fmt.Errorf("pid file(%s) found, ensure %s(%d) is not running", c.PidFile, global.Prog, pid)
}
return -1, nil
}
// RemovePIDFile remove the pid file
func (c *Config) RemovePIDFile() error {
c.pidFd.Close()
return os.Remove(c.PidFile)
}