golang golang create / get captchas

Posted 2021-05-24

package main

import (
	"bytes"
	"fmt"
	"log"
	"net/http"
	"time"

	"github.com/dchest/captcha"
	"github.com/go-redis/redis"
	"github.com/labstack/echo/v4"
	"github.com/labstack/echo/v4/middleware"
)

var redisStore *RedisStore
var RedisClient *redis.Client

type RedisStore struct {
	Expire time.Duration
}

func (rs *RedisStore) Set(id string, digits []byte) {
	RedisClient.Set(id, string(digits), rs.Expire)
}

func (rs *RedisStore) Get(id string, clear bool) (digits []byte) {
	bs, err := RedisClient.Get(id).Bytes()
	if err != nil {
		log.Println(err)
	}

	return bs
}

type genCaptchasResp struct {
	URL string `json:"url"`
	ID  string `json:"id"`
}

func main() {
	if err := NewRedisClient(); err != nil {
		log.Println(err)
		return
	}

	redisStore = &RedisStore{Expire: 2 * time.Minute}
	captcha.SetCustomStore(redisStore)

	s := echo.New()
	s.Use(middleware.CORS())

	s.POST("/api/captchas", genCaptchas)
	s.GET("/captchas/:captcha_id", getCaptcha)

	if err := s.Start(":8899"); err != nil {
		log.Println(err)
		return
	}
}

func NewRedisClient() error {
	readTimeout := 2 * time.Second
	writeTimeout := 2 * time.Second

	RedisClient = redis.NewClient(&redis.Options{
		Network:      "tcp",
		Addr:         "localhost:6379",
		DB:           0,
		ReadTimeout:  readTimeout,
		WriteTimeout: writeTimeout,
	})

	_, err := RedisClient.Ping().Result()
	return err
}

func genCaptchas(ctx echo.Context) (err error) {
	id := captcha.NewLen(6)
	return ctx.JSON(http.StatusOK, &genCaptchasResp{
		URL: fmt.Sprintf("/captchas/%s", id),
		ID:  id,
	})
}

func getCaptcha(ctx echo.Context) (err error) {
	id := ctx.Param("captcha_id")
	w := ctx.Response()
	w.Header().Set("Cache-Control", "no-cache, no-store, must-revalidate")
	w.Header().Set("Pragma", "no-cache")
	w.Header().Set("Expires", "0")
	w.Header().Set("Content-Type", "image/png")

	var content bytes.Buffer
	if err := captcha.WriteImage(&content, id, captcha.StdWidth, captcha.StdHeight); err != nil {
		return ctx.String(http.StatusBadRequest, err.Error())
	}

	r := ctx.Request()
	http.ServeContent(w, r, id, time.Time{}, bytes.NewReader(content.Bytes()))
	return nil
}

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 : [email protected]
*/
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：

[[email protected] t2]# go build logTest1.go
[[email protected] t2]# ./logTest1
[[email protected] 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
[[email protected] 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 : [email protected]
*/

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：

[[email protected] 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

讨论

这里只是个简单的示例代码，实现了log rotate，更多功能需自行开发。

好，就这些了，希望对你有帮助。

本文github地址：

https://github.com/mike-zhang/mikeBlogEssays/blob/master/2017/20170614_golang之logRotate.rst

欢迎补充