golang之log rotate

操作系统： CentOS 6.9_x64

go语言版本： 1.8.3

问题描述

golang的log模块提供的有写日志功能，示例代码如下：

/*
golang log example
E-Mail : Mike_Zhang@live.com
*/
package main

import (
    "log"
    "os"
)

func main() {
    logFile,err := os.Create("test1.log")
    defer logFile.Close()
    if err != nil {
        log.Fatalln("open file error!")
    }
    logger := log.New(logFile,"[Debug]",log.Ldate | log.Ltime | log.Lshortfile)
    logger.Println("test debug message")
    logger.SetPrefix("[Info]")
    logger.Println("test info message")

}

运行效果：

[root@local t2]# go build logTest1.go
[root@local t2]# ./logTest1
[root@local t2]# cat test1.log
[Debug]2017/06/13 23:18:36 logTest1.go:19: test debug message
[Info]2017/06/13 23:18:36 logTest1.go:21: test info message
[root@local t2]#

go语言的log模块没有提供log rotate接口，但实际开发中我们需要该功能：

我们不希望单个日志过大，否则文本编辑器无法打开，查看比较困难；

更不希望占用太大的存储空间，可以指定最多存多少个日志文件。

解决方案

借助带缓冲的channel来实现。

示例代码如下：

/*
    golang log rotate example
    E-Mail : Mike_Zhang@live.com
*/

package main

import (
    "fmt"
    "log"
    "os"
    "time"
)

const (
    BACKUP_COUNT = 5
    MAX_FILE_BYTES = 2 * 1024
)

func doRotate(fPrefix string) {
    for j := BACKUP_COUNT; j >= 1; j-- {
        curFileName := fmt.Sprintf("%s_%d.log",fPrefix,j)
        k := j-1
        preFileName := fmt.Sprintf("%s_%d.log",fPrefix,k)

        if k == 0 {
            preFileName = fmt.Sprintf("%s.log", fPrefix)
        }
        _,err := os.Stat(curFileName)
        if err == nil {
            os.Remove(curFileName)
            fmt.Println("remove : ", curFileName)
        }
        _,err = os.Stat(preFileName)
        if err  == nil {
            fmt.Println("rename : ", preFileName, " => ", curFileName)
            err = os.Rename(preFileName, curFileName)
            if err != nil {
                fmt.Println(err)
            }
        }
    }
}

func NewLogger(fPrefix string) (*log.Logger, *os.File) {
    var logger *log.Logger
    fileName := fmt.Sprintf("%s.log", fPrefix)
    fmt.Println("fileName :", fileName)
    logFile, err := os.OpenFile(fileName, os.O_RDWR|os.O_CREATE|os.O_APPEND, 0666)

    if err != nil {
        fmt.Println("open file error!")
    } else {
        logger = log.New(logFile, "[Debug]", log.Ldate|log.Ltime|log.Lshortfile)
    }
    return logger, logFile
}

func logWorker(msgQueue <-chan string) {
    fPrefix := "msg"
    logger, logFile := NewLogger(fPrefix)
    for msg := range msgQueue {
        logger.Println(msg)
        fi, err2 := logFile.Stat()
        if err2 == nil {
            if fi.Size() > MAX_FILE_BYTES {
                logFile.Close()
                doRotate(fPrefix)
                logger,logFile = NewLogger(fPrefix)
            }
        }
    }
    logFile.Close()
}

func main() {
    msgQueue := make(chan string, 1000)
    go logWorker(msgQueue)

    for j := 1; j <= 1000; j++ {
        msgQueue <- fmt.Sprintf("msg_%d", j)
        time.Sleep(1 * time.Second)
    }
    close(msgQueue)
    return
}

运行效果如下：

[root@local t2]# ./logRotateTest1
fileName : msg.log
rename :  msg.log  =>  msg_1.log
fileName : msg.log
rename :  msg_1.log  =>  msg_2.log
rename :  msg.log  =>  msg_1.log
fileName : msg.log
rename :  msg_2.log  =>  msg_3.log
rename :  msg_1.log  =>  msg_2.log
rename :  msg.log  =>  msg_1.log
fileName : msg.log
^C