Go语言实现权重抽奖系统的项目实践

package main

import (
    "crypto/rand"
    "encoding/json"
    "fmt"
    "math/big"
    "net/http"
    "sync"
)

// 奖品配置
type prize struct {
    id     int    `json:"id"`
    name   string `json:"name"`
    weight int    `json:"weight"` // 权重值（非百分比）
}

// 抽奖系统
type lotterysystem struct {
    prizes       []prize
    totalweight  int
    issuedprizes map[int]bool
    mu           sync.mutex
}

// 初始化抽奖系统
func newlotterysystem(prizes []prize) *lotterysystem {
    total := 0
    for _, p := range prizes {
        total += p.weight
    }
    return &lotterysystem{
        prizes:       prizes,
        totalweight:  total,
        issuedprizes: make(map[int]bool),
    }
}

// 安全随机数生成
func securerandom(max int) (int, error) {
    n, err := rand.int(rand.reader, big.newint(int64(max)))
    if err != nil {
        return 0, err
    }
    return int(n.int64()), nil
}

// 执行抽奖
func (ls *lotterysystem) draw() (*prize, error) {
    ls.mu.lock()
    defer ls.mu.unlock()

    if ls.totalweight == 0 {
        return nil, fmt.errorf("no available prizes")
    }

    // 生成随机数
    randomnum, err := securerandom(ls.totalweight)
    if err != nil {
        return nil, err
    }

    // 权重选择
    current := 0
    for _, p := range ls.prizes {
        current += p.weight
        if randomnum < current {
            if ls.issuedprizes[p.id] {
                continue // 已发放的奖品跳过
            }
            ls.issuedprizes[p.id] = true
            return &p, nil
        }
    }

    return nil, fmt.errorf("draw failed")
}

// http服务
func main() {
    // 初始化奖品池
    prizes := []prize{
        {id: 1, name: "一等奖", weight: 1},
        {id: 2, name: "二等奖", weight: 5},
        {id: 3, name: "三等奖", weight: 20},
        {id: 4, name: "参与奖", weight: 74},
    }

    lottery := newlotterysystem(prizes)

    http.handlefunc("/draw", func(w http.responsewriter, r *http.request) {
        prize, err := lottery.draw()
        if err != nil {
            http.error(w, err.error(), http.statusinternalservererror)
            return
        }

        w.header().set("content-type", "application/json")
        json.newencoder(w).encode(prize)
    })

    fmt.println("抽奖服务已启动，监听端口 8080")
    http.listenandserve(":8080", nil)
}

// 权重选择逻辑
current := 0
for _, p := range ls.prizes {
    current += p.weight
    if randomnum < current {
        return &p
    }
}

// 使用crypto/rand生成安全随机数
func securerandom(max int) (int, error) {
    n, err := rand.int(rand.reader, big.newint(int64(max)))
    // ...
}

var mu sync.mutex

func (ls *lotterysystem) draw() {
    ls.mu.lock()
    defer ls.mu.unlock()
    // ...
}

issuedprizes map[int]bool

// 添加测试端点验证概率分布
http.handlefunc("/test", func(w http.responsewriter, r *http.request) {
    results := make(map[int]int)
    for i := 0; i < 10000; i++ {
        templottery := newlotterysystem(prizes)
        prize, _ := templottery.draw()
        results[prize.id]++
    }
    json.newencoder(w).encode(results)
})

// 使用redis分布式锁
func (ls *lotterysystem) distributeddraw() {
    lock := redis.newlock("lottery_lock")
    err := lock.lock()
    // ...抽奖逻辑...
    lock.unlock()
}

type prize struct {
    // ...
    stock     int // 新增库存字段
}
func (ls *lotterysystem) draw() {
    // 检查库存
    if p.stock <= 0 {
        continue
    }
    // 扣减库存
    p.stock--
}

go run main.go

curl http://localhost:8080/draw
# 示例返回：{"id":3,"name":"三等奖","weight":20}

curl http://localhost:8080/test
# 返回万次抽奖结果分布