File server for testing cache performance

test_file_server.go

package main

import (
	"encoding/json"
	"fmt"
	"io/ioutil"
	"log"
	"net/http"
	"strings"

	"github.com/bparli/lfuda-go"
)

var (
	stats Stats
	cache *lfuda.Cache
)

type CacheStats struct {
	Stats  Stats
	Age    float64
	Size   float64
	Length int
}

type Stats struct {
	Hits   int
	Misses int
}

func downloadHandler(w http.ResponseWriter, r *http.Request) {
	fileName := strings.TrimPrefix(r.URL.Path, "/")

	if cache != nil {
		if val, ok := cache.Get(fileName); ok {
			w.Write(val.([]byte))
			stats.Hits++
			return
		}
	}

	stats.Misses++
	bytes, err := ioutil.ReadFile("/tmp/testCache/" + fileName)
	if err != nil {
		fmt.Println("Error reading file", fileName, err)
	}

	if cache != nil {
		go func() {
			if cache.Set(fileName, bytes) {
				fmt.Printf("Setting %s resulted in an eviction\n", fileName)
			}
		}()

	}
	w.Write(bytes)
}

func main() {
	onEvicted := func(k interface{}, v interface{}) {
		if k != v {
			fmt.Printf("Evicted key %v\n", k)
		}
	}

	// 100MB cache
	cache = lfuda.NewGDSFWithEvict(100*1024*1024, onEvicted)

	statsHandler := func(w http.ResponseWriter, _ *http.Request) {
		jsonData := &CacheStats{
			Stats: stats,
		}
		if cache != nil {
			jsonData = &CacheStats{
				Stats:  stats,
				Age:    cache.Age(),
				Size:   cache.Size(),
				Length: cache.Len(),
			}
		}

		data, err := json.Marshal(jsonData)
		if err != nil {
			fmt.Println("Error marshaling the response", err)
		}
		w.Header().Set("Content-Type", "application/json")
		w.Write(data)
	}

	http.HandleFunc("/stats", statsHandler)
	http.HandleFunc("/", downloadHandler)
	log.Fatal(http.ListenAndServe(":8080", nil))

}