Redis优化高并发下的秒杀性能

// main.go
package main

import (
	"fmt"
	"github.com/go-redis/redis"
	_ "github.com/go-sql-driver/mysql"
	"github.com/jinzhu/gorm"
	"log"
	"net/http"
	"strconv"
	"time"
)

type Envelope struct {
	Id        int `gorm:"primary_key"`
	Code      string
	UserId    int
	CreatedAt time.Time
	RewardAt  *time.Time
}

func (Envelope) TableName() string {
	return "envelope"
}

func (p *Envelope) BeforeCreate() error {
	p.CreatedAt = time.Now()
	return nil
}

const (
	QueueEnvelope = "envelope"
	QueueUser     = "user"
)

var (
	db          *gorm.DB
	redisClient *redis.Client
)

func init() {
	var err error
	db, err = gorm.Open("mysql", "root:root@tcp(localhost:3306)/test?charset=utf8&parseTime=True&loc=Local")
	if err != nil {
		log.Fatal(err)
	}
	if err = db.DB().Ping(); err != nil {
		log.Fatal(err)
	}
	db.DB().SetMaxOpenConns(100)
	fmt.Println("database connected. pool size 10")
}

func init() {
	redisClient = redis.NewClient(&redis.Options{
		Addr:     "localhost:6379",
		DB:       0,
		PoolSize: 100,
	})
	if _, err := redisClient.Ping().Result(); err != nil {
		log.Fatal(err)
	}
	fmt.Println("redis connected. pool size 100")
}

// 读取Code写入Queue
func init() {
	envelopes := make([]Envelope, 0, 100)
	if err := db.Debug().Where("user_id=0").Limit(100).Find(&envelopes).Error; err != nil {
		log.Fatal(err)
	}
	if len(envelopes) != 100 {
		log.Fatal("不足100个奖品")
	}
	for i := range envelopes {
		if err := redisClient.LPush(QueueEnvelope, envelopes[i].Code).Err(); err != nil {
			log.Fatal(err)
		}
	}
	fmt.Println("load 100 envelopes")
}

func main() {
	http.HandleFunc("/envelope", func(w http.ResponseWriter, r *http.Request) {
		uid := r.Header.Get("x-user-id")
		if uid == "" {
			w.WriteHeader(401)
			_, _ = fmt.Fprint(w, "UnAuthorized")
			return
		}
		uidValue, err := strconv.Atoi(uid)
		if err != nil {
			w.WriteHeader(400)
			_, _ = fmt.Fprint(w, "Bad Request")
			return
		}
		// 检测用户是否抢过了
		if result, err := redisClient.HIncrBy(QueueUser, uid, 1).Result(); err != nil || result != 1 {
			w.WriteHeader(429)
			_, _ = fmt.Fprint(w, "Too Many Request")
			return
		}
		// 检测是否在队列中
		code, err := redisClient.LPop(QueueEnvelope).Result()
		if err != nil {
			w.WriteHeader(200)
			_, _ = fmt.Fprint(w, "No Envelope")
			return
		}
		// 发放红包
		envelope := &Envelope{}
		err = db.Where("code=?", code).Take(&envelope).Error
		if err == gorm.ErrRecordNotFound {
			w.WriteHeader(200)
			_, _ = fmt.Fprint(w, "No Envelope")
			return
		}
		if err != nil {
			w.WriteHeader(500)
			_, _ = fmt.Fprint(w, err)
			return
		}
		now := time.Now()
		envelope.UserId = uidValue
		envelope.RewardAt = &now
		rowsAffected := db.Where("user_id=0").Save(&envelope).RowsAffected // 添加user_id=0来验证Redis是否真的解决争抢问题
		if rowsAffected == 0 {
			fmt.Printf("发生争抢. id=%d\n", envelope.Id)
			w.WriteHeader(500)
			_, _ = fmt.Fprintf(w, "发生争抢. id=%d\n", envelope.Id)
			return
		}
		_, _ = fmt.Fprint(w, envelope.Code)
	})

	fmt.Println("listen on 8080")
	fmt.Println(http.ListenAndServe(":8080", nil))
}