go缓存设计 redis 发布订阅

一般缓存 有内存缓存， 没有就读redis， redis没有就读tidb；如何防止缓存穿透，这里我们用golang.org/x/sync/singleflight解决，还有缓存更新，比如多个节点如何更新，这里借用redis 发布订阅；需要更新redis 就发送一条发布消息， 订阅的所有结点就删除内存缓存

缓存代码如下：

package mainimport ("context""encoding/json""fmt""github.com/patrickmn/go-cache""github.com/redis/go-redis/v9""golang.org/x/sync/singleflight""time"
)var globalCache *cache.Cache
var channelKey = "cache_Channel"
var rdb *redis.Clientfunc init() {globalCache = cache.New(5*time.Minute, 10*time.Minute)rdb = redis.NewClient(&redis.Options{Addr:     "localhost:6379",Password: "", // no password setDB:       0,  // use default DB
    })ctx := context.Background()if _, err := rdb.Ping(ctx).Result(); err != nil {panic(err)}pubSub := rdb.Subscribe(ctx, channelKey)go func() {ch := pubSub.Channel() // 获取一个 channel，用于接收消息for msg := range ch {  // 循环读取消息if key := msg.Payload; len(key) > 0 {rdb.Del(ctx, key).Err()globalCache.Delete(key)fmt.Println(fmt.Sprintf("redis 订阅%s", key))}}}()}func GetCacheData[T any](ctx context.Context, key string, t T, load func() (T, error)) error {val, ok := globalCache.Get(key)if ok {t, ok = val.(T)if ok {fmt.Println(fmt.Sprintf("内存 读取 %s", key))return nil}}client := rdbvar sg singleflight.Groupval, err, _ := sg.Do(key, func() (interface{}, error) {//读取redisstr, err := client.Get(ctx, key).Result()if err == nil && len(str) > 0 {err = json.Unmarshal([]byte(str), &t)if err == nil {globalCache.Set(key, t, time.Minute*1)}fmt.Println(fmt.Sprintf("redis 读取 %s", key))return t, err}if err != nil && err != redis.Nil {return nil, err}t, err = load()if err != nil {return nil, err}fmt.Println(fmt.Sprintf("db 读取 %s", key))jsonByte, err := json.Marshal(t)if err != nil {return nil, err}//设置redis 缓存err = client.Set(ctx, key, string(jsonByte), time.Minute*5).Err()if err != nil {return t, err}return t, nil})if err != nil {return err}t = val.(T)globalCache.Set(key, t, time.Minute*1)return err
}func RemoveCache(ctx context.Context, key string) error {//通知其他节点err := rdb.Publish(ctx, channelKey, key).Err()if err != nil {return err}fmt.Println(fmt.Sprintf("redis 发布 %s", key))return err
}

这里redis 部分 是否需要方法 singleflight.Group 根据实际情况， 但是tidb部分需要放到里面，使用代码

package mainimport ("context""fmt"
)func main() {ctx := context.Background()key := "firstDemo111"p := new(Person)err := GetCacheData[*Person](ctx, key, p, f)//fmt.Println(fmt.Sprintf("%+v", p))err = GetCacheData[*Person](ctx, key, p, f)//	fmt.Println(fmt.Sprintf("%+v", p))RemoveCache(ctx, key)err = GetCacheData[*Person](ctx, key, p, f)//fmt.Println(fmt.Sprintf("%+v", p))err = GetCacheData[*Person](ctx, key, p, f)ch := make(chan int, 1)val := <-chfmt.Println(val)fmt.Println(err)
}type Person struct {Name stringAge  int
}func f() (*Person, error) {return &Person{Name: "demo", Age: 19}, nil
}

　　运行效果 确认，多个节点 redis 订阅 发布可以通信