first

main.go

@@ -0,0 +1,143 @@
+package main
+
+import (
+	"fmt"
+	"net"
+	"net/http"
+	"net/rpc"
+	"time"
+)
+
+type GrainServer struct {
+	Host string
+}
+
+type Grain interface {
+	HandleMessage(message *Message, reply *CartGrain) error
+}
+
+func NewServer(hostname string) *GrainServer {
+	return &GrainServer{
+		Host: hostname,
+	}
+}
+
+func (s *GrainServer) Start(port int, instance Grain) (net.Listener, error) {
+	rpc.Register(instance)
+	rpc.HandleHTTP()
+	return net.Listen("tcp", fmt.Sprintf(":%d", port))
+}
+
+type CartGrain struct {
+	Skus []string
+}
+
+type Message struct {
+	Type    string
+	Content string
+}
+
+type Registry interface {
+	Register(address string, id string) error
+	Get(id string) (*string, error)
+}
+
+type MemoryRegistry struct {
+	registry map[string]string
+}
+
+func (r *MemoryRegistry) Register(address string, id string) error {
+	r.registry[id] = address
+	return nil
+}
+
+func (r *MemoryRegistry) Get(id string) (*string, error) {
+	addr, ok := r.registry[id]
+	if !ok {
+		return nil, fmt.Errorf("id not found")
+	}
+	return &addr, nil
+}
+
+func (c *CartGrain) HandleMessage(message *Message, reply *CartGrain) error {
+	fmt.Println("CartGrain received message: ", message)
+	c.Skus = append(c.Skus, message.Content)
+	*reply = *c
+	return nil
+}
+
+type ServerPool interface {
+	GetOrSpawn(id string, ttl time.Time) (*string, error)
+}
+
+type WebServer struct {
+	ServerPool ServerPool
+}
+
+type MemoryServerPool struct {
+	port  int
+	local *GrainServer
+	pool  map[string]*string
+}
+
+func (p *MemoryServerPool) GetOrSpawn(id string, ttl time.Duration) (*string, error) {
+	addr, ok := p.pool[id]
+	if !ok {
+		prt := p.port
+		p.port++
+		s := NewServer("localhost")
+		_, e := s.Start(prt, &CartGrain{})
+		if e != nil {
+			return nil, e
+		}
+		//go http.Serve(l, nil)
+		a := fmt.Sprintf("localhost:%d", prt)
+		p.pool[id] = &a
+		addr = &a
+	}
+	return addr, nil
+}
+
+func main() {
+	// Create a new instance of the server
+	pool := &MemoryServerPool{
+		port:  1337,
+		pool:  make(map[string]*string),
+		local: NewServer("localhost"),
+	}
+
+	mux := http.NewServeMux()
+	mux.HandleFunc("GET /{id}", func(w http.ResponseWriter, r *http.Request) {
+		id := r.PathValue("id")
+		addr, err := pool.GetOrSpawn(id, time.Hour*1)
+		if err != nil {
+			w.WriteHeader(http.StatusNotFound)
+			return
+		}
+		w.WriteHeader(http.StatusOK)
+		w.Write([]byte(*addr))
+	})
+	mux.HandleFunc("GET /add/{id}", func(w http.ResponseWriter, r *http.Request) {
+		id := r.PathValue("id")
+		addr, err := pool.GetOrSpawn(id, time.Hour*1)
+		if err != nil {
+			w.WriteHeader(http.StatusNotFound)
+			return
+		}
+		w.WriteHeader(http.StatusOK)
+		var cart CartGrain
+		client, err := rpc.DialHTTP("tcp", *addr)
+		if err != nil {
+			w.WriteHeader(http.StatusInternalServerError)
+			return
+		}
+		err = client.Call("CartGrain.HandleMessage", &Message{Type: "add", Content: "123"}, &cart)
+		if err != nil {
+			w.WriteHeader(http.StatusInternalServerError)
+			return
+		}
+		w.Write([]byte(fmt.Sprintf("Cart: %v", cart.Skus)))
+	})
+	http.ListenAndServe(":8080", mux)
+
+}