SiteCache cannot work as middleware ?

I thought SiteCache was a middleware, and when I used it, it didn't work.
I saw the source code as following, I noted:

func SiteCache(store persistence.CacheStore, expire time.Duration) gin.HandlerFunc {
	return func(c *gin.Context) {
		var cache responseCache
		url := c.Request.URL
		key := CreateKey(url.RequestURI())
		if err := store.Get(key, &cache); err != nil {
			c.Next() // just call the next handler, why not saving the response ? like other Decorator 
		} else {
			fmt.Println("cache hited: ", string(cache.Data))
			c.Writer.WriteHeader(cache.Status)
			for k, vals := range cache.Header {
				for _, v := range vals {
					c.Writer.Header().Set(k, v)
				}
			}
			c.Writer.Write(cache.Data)
		}
	}
}

then I changed code as following, and it worked as what i want:

func SiteCache(store persistence.CacheStore, expire time.Duration) gin.HandlerFunc {
	return func(c *gin.Context) {
		var cache responseCache
		url := c.Request.URL
		key := CreateKey(url.RequestURI())
		if err := store.Get(key, &cache); err != nil {

			if err != persistence.ErrCacheMiss {
				log.Println(err.Error())
			}
			// replace writer
			writer := newCachedWriter(store, expire, c.Writer, key)
			c.Writer = writer
			c.Next()
			// Drop caches of aborted contexts
			if c.IsAborted() {
				store.Delete(key)
			}

		} else {
			c.Writer.WriteHeader(cache.Status)
			for k, vals := range cache.Header {
				for _, v := range vals {
					c.Writer.Header().Set(k, v)
				}
			}
			c.Writer.Write(cache.Data)
			c.Abort()
		}
	}
}

so, what is the SiteCache designd for ? A middleware or not ? I'm confused ~
waiting for your answer

Start at SiteCache and trace both the cache-hit and cache-miss paths, including c.Next, responseCache, newCachedWriter, and persistence.CacheStore. No file or test is named, so first determine the intended middleware contract and whether a cache miss should capture the downstream response. Done means the behavior is clarified and verified for both paths.