package main  import (   "encoding/json"   "fmt"   "io/ioutil"   "log"   "os"   "os/signal"   "sync"   "syscall" )  //用json配置測試 type Config struct {   Test1 string `json:"Test1:`   Test2 int  `json:"Test1:` }  var (   config   *Config   configLock = new(sync.RWMutex) )  func loadConfig() bool {   f, err := ioutil.ReadFile("config.json")   if err != nil {     fmt.Println("load config error: ", err)     return false   }    //不同的配置規則，解析復雜度不同   temp := new(Config)   err = json.Unmarshal(f, &config)   if err != nil {     fmt.Println("Para config failed: ", err)     return false   }    configLock.Lock()   config = temp   configLock.Unlock()   return true }  func GetConfig() *Config {   configLock.RLock()   defer configLock.RUnlock()   return config }  func init() {   if !loadConfig() {     os.Exit(1)   }    //熱更新配置可能有多種觸發方式，這里使用系統信號量sigusr1實現   s := make(chan os.Signal, 1)   signal.Notify(s, syscall.SIGUSR1)   go func() {     for {       <-s       log.Println("Reloaded config:", loadConfig())     }   }() }  func main() {   select {} }