golang实现内存缓存

package mainimport (    "fmt"    "time")type Cache struct {    data     map[string]interface{}    ttl      int64 //过期时间    interval int64 //清理间隔}func NewCache(ttl int64, interval int64) *Cache {    c := &Cache{        data:     make(map[string]interface{}),        ttl:      ttl,        interval: interval,    }    go c.clean()    return c}// 设置数据func (c *Cache) Set(key string, val interface{}) {    c.data[key] = val}// 获取数据func (c *Cache) Get(key string) (interface{}, bool) {    val, ok := c.data[key]    if !ok {        return nil, false    }    // 判断数据是否过期    if time.Now().UnixNano() > val.(int64) {        delete(c.data, key)        return nil, false    }    return val, true}// 清理过期数据func (c *Cache) clean() {    for range time.Tick(time.Duration(c.interval) * time.Second) {        for k, v := range c.data {            if time.Now().UnixNano() > v.(int64) {                delete(c.data, k)            }        }    }}func main() {    cache := NewCache(10, 5)    cache.Set("foo", "bar")    cache.Set("hello", "world")    val, ok := cache.Get("foo")    if ok {        fmt.Println(val) // 输出 bar    }    time.Sleep(11 * time.Second)    _, ok = cache.Get("foo")    if !ok {        fmt.Println("key has deleted") // 输出 key has deleted    }}