有意思的代码--利用系统信号切换日志模式

// SetupSignalHandler listens to signals and toggles the log level to DEBUG
// mode when it received a SIGUSR2 signal. Another SIGUSR2 toggles the log
// level back to the old level.
func (k *Kite) SetupSignalHandler() {
    c := make(chan os.Signal, 1)

    signal.Notify(c, syscall.SIGUSR2)
    go func() {
        for s := range c {
            k.Log.Info("Got signal: %s", s)

            if debugMode {
                // toogle back to old settings.
                k.Log.Info("Disabling debug mode")
                if k.SetLogLevel == nil {
                    k.Log.Error("SetLogLevel is not defined")
                    continue
                }

                k.SetLogLevel(getLogLevel())
                debugMode = false
            } else {
                k.Log.Info("Enabling debug mode")
                if k.SetLogLevel == nil {
                    k.Log.Error("SetLogLevel is not defined")
                    continue
                }

                k.SetLogLevel(DEBUG)
                debugMode = true
            }
        }
    }()
}