Avoid using 100% when using file backend

[PierreF]

The signal watched had a select{} with default clause inside a for{} loop. This cause the default clause to be executed in loop as fast as possible and use 100% CPU.

The following small code show the issue:

package main

import (
	"log"
	"os"
	"time"

	bes "github.com/iegomez/mosquitto-go-auth/backends"
	"github.com/sirupsen/logrus"
)

func main() {
	backend, err := bes.NewFiles(map[string]string{"password_path": "/dev/null"}, logrus.DebugLevel, nil)
	if err != nil {
		log.Fatal(err)
	}

	log.Printf("See me (PID = %d) using 100%% CPU :)", os.Getpid())
	time.Sleep(time.Minute)
        backend.Halt()
}

Using top, you will see that without this PR, the process will use 100% CPU.

[iegomez]

Removing the default clause solves it? I thought having a NO-OP default was the same as having none. TIL.

[iegomez]

BTW, @PierreF, now you are a a collaborator, are you able to merge by yourself after approval?

[PierreF]

Looks like I do :)