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 {} 
}