concurrent_http_cache.go

package main

import (
	"fmt"
	"io"
	"io/ioutil"
	"net/http"
	"os"
	"strings"
	"time"
)

func producer(f *os.File, ch chan struct{}) {
	content := []string{"a", "b", "c", "d", "e"}

	for _, letter := range content {
		time.Sleep(time.Duration(2) * time.Second)
		f.Write([]byte(strings.Repeat(letter, 2000) + "\n\n"))
		f.Sync()
		ch <- struct{}{}
	}
	close(ch)
}

func main() {
	f, err := ioutil.TempFile("", "")
	if err != nil {
		panic(err)
	}

	ch := make(chan struct{})
	fmt.Println("File created %s", f.Name())
	go producer(f, ch)
	http.HandleFunc("/", func(w http.ResponseWriter, r *http.Request) {
		otherF, err := os.Open(f.Name())
		if err != nil {
			panic(err)
		}
		fl := w.(http.Flusher)

		for range ch {
			io.Copy(w, otherF)
			fl.Flush()
		}
	})

	fmt.Println("Server started")
	http.ListenAndServe(":8080", nil)
}