shared request

shared_request.go

package main

import (
	"net/http"
	"sync"
)

type Response struct {
}
type Request struct {
	from     string
	to       string
	waitChan chan struct{}
	response Response
}

func NewRequest(from, to string) *Request {
	r := Request{from: from, to: to, waitChan: make(chan struct{})}
	go r.Call()
	return &r
}

func (r *Request) Call() {
	_, _ = http.Get("http://service.com")
	r.response = Response{}
	close(r.waitChan)
}
func (r *Request) WaitResponse() Response {
	<-r.waitChan
	return r.response
}

type Key struct {
	From string
	To   string
}

type Requester struct {
	mu       sync.RWMutex
	requests map[Key]*Request
}

func (r *Requester) Request(from, to string) Response {
	key := Key{From: from, To: to}
	r.mu.RLock()
	req, ok := r.requests[key]
	r.mu.RUnlock()
	if !ok {
		req := NewRequest(from, to)
		r.mu.Lock()
		r.requests[key] = req
		r.mu.Unlock()
	}
	response := req.WaitResponse()
	r.mu.Lock()
	delete(r.requests, key)
	r.mu.Unlock()
	return response
}

func NewRequester() *Requester {
	return &Requester{
		requests: make(map[Key]*Request),
	}
}

func main() {

	r := NewRequester()
	http.HandleFunc("/", func(writer http.ResponseWriter, request *http.Request) {
		response := r.Request("A", "B")
	})
}