Golang async logger

warn.go

package warn

import (
	"errors"
	"fmt"
	"io"
	"log"
	"os"
	"path/filepath"
	"runtime"
	"runtime/debug"
	"sync/atomic"
	"time"
)

var logFile = os.Stderr
var logFilePath string
var rotateLog uint32

var ch = make(chan []interface{}, 10000)

var pid = os.Getpid()

func Errorln(a ...interface{}) error {
	return errors.New(fmt.Sprintln(a...))
}

func Log(a ...interface{}) {
	//fmt.Fprintln(os.Stderr, a...)
	//return

	select {
	case ch <- a:
	default:
	}
}

func Warn(a ...interface{}) {
	pc, file, line, ok := runtime.Caller(1)
	if ok {
		Log(fmt.Sprintf("%s[%s:%d]", runtime.FuncForPC(pc).Name(), file, line), a)
	} else {
		Log(a)
	}
}

func RunIt() {
	for a := range ch {
		fmt.Fprint(logFile, time.Now().Format("02 Jan 15:04:05.000 "), pid, " ")
		fmt.Fprintln(logFile, a...)

		// переоткрываем лог-файл
		if atomic.LoadUint32(&rotateLog) > 0 {
			atomic.StoreUint32(&rotateLog, 0)

			cleanedPath := filepath.Clean(logFilePath)
			f, err := os.OpenFile(cleanedPath, os.O_WRONLY|os.O_APPEND|os.O_CREATE, 0644)
			if err != nil {
				Fatal(err)
			}
			if logFile != os.Stderr {
				logFile.Close()
			}
			logFile = f // тут race c Close(), но может случиться только при остановке, так что не страшно
		}
	}
}

func Close() {
	close(ch)

	if logFile != os.Stderr {
		logFile.Close()
	}
}

func SetOutput(path string) {
	if path != "" {
		logFilePath = path
		ReopenLog()
	}
}

func ReopenLog() {
	atomic.StoreUint32(&rotateLog, 1)
}

func Fatal(a ...interface{}) {
	fmt.Fprintln(logFile, a...)
	fmt.Fprintln(logFile, string(debug.Stack()))

	time.Sleep(time.Second) // чтобы успело в лог записаться.

	os.Exit(1)
}

type writer struct {
	io.Writer
}

func (w *writer) Write(p []byte) (int, error) {
	Warn(string(p))

	return len(p), nil
}

var w *writer

var logger = log.New(w, "net/http ", 0)

func GetLogger() *log.Logger {
	return logger
}