Bad Cache Example

Bad Cache.go

var mu sync.Mutex
var cache map[string][]byte

func Handler(w http.Response, r *http.Request) {
  mu.Lock()
  defer mu.Unlock()

  url := r.URL.String()

  p, ok := cache[url]

  if !ok {
    buf := bytes.NewBuffer(nil)
    w := io.MultiWriter(w, buf)
    io.Copy(w, expensiveProcessReader(url))
    cache[url] = buf.Bytes()
  } else {
    w.Write(p)
  }
}