From a6727f990db7e8a6f6fb381ddbd7fca30b06942b Mon Sep 17 00:00:00 2001
From: Oleg Ozimok <ozimokoleg@gmail.com>
Date: Sun, 7 Apr 2019 21:03:47 +0300
Subject: [PATCH] add server mux

---
 example/mux/clone.go   | 39 +++++++++++++++++++
 example/mux/handler.go | 87 ++++++++++++++++++++++++++++++++++++++++++
 redcon.go              | 64 +++++++++++++++++++++++++++++++
 3 files changed, 190 insertions(+)
 create mode 100644 example/mux/clone.go
 create mode 100644 example/mux/handler.go

diff --git a/example/mux/clone.go b/example/mux/clone.go
new file mode 100644
index 0000000..bc47d65
--- /dev/null
+++ b/example/mux/clone.go
@@ -0,0 +1,39 @@
+package main
+
+import (
+	"log"
+
+	"github.com/tidwall/redcon"
+)
+
+var addr = ":6380"
+
+func main() {
+	log.Printf("started server at %s", addr)
+
+	handler := NewHandler()
+
+	mux := redcon.NewServeMux()
+	mux.HandleFunc("detach", handler.detach)
+	mux.HandleFunc("ping", handler.ping)
+	mux.HandleFunc("quit", handler.quit)
+	mux.HandleFunc("set", handler.set)
+	mux.HandleFunc("get", handler.get)
+	mux.HandleFunc("del", handler.delete)
+
+	err := redcon.ListenAndServe(addr,
+		mux.ServeRESP,
+		func(conn redcon.Conn) bool {
+			// use this function to accept or deny the connection.
+			// log.Printf("accept: %s", conn.RemoteAddr())
+			return true
+		},
+		func(conn redcon.Conn, err error) {
+			// this is called when the connection has been closed
+			// log.Printf("closed: %s, err: %v", conn.RemoteAddr(), err)
+		},
+	)
+	if err != nil {
+		log.Fatal(err)
+	}
+}
diff --git a/example/mux/handler.go b/example/mux/handler.go
new file mode 100644
index 0000000..dd5e616
--- /dev/null
+++ b/example/mux/handler.go
@@ -0,0 +1,87 @@
+package main
+
+import (
+	"log"
+	"sync"
+
+	"github.com/tidwall/redcon"
+)
+
+type Handler struct {
+	itemsMux sync.RWMutex
+	items    map[string][]byte
+}
+
+func NewHandler() *Handler {
+	return &Handler{
+		items: make(map[string][]byte),
+	}
+}
+
+func (h *Handler) detach(conn redcon.Conn, cmd redcon.Command) {
+	detachedConn := conn.Detach()
+	log.Printf("connection has been detached")
+	go func(c redcon.DetachedConn) {
+		defer c.Close()
+
+		c.WriteString("OK")
+		c.Flush()
+	}(detachedConn)
+}
+
+func (h *Handler) ping(conn redcon.Conn, cmd redcon.Command) {
+	conn.WriteString("PONG")
+}
+
+func (h *Handler) quit(conn redcon.Conn, cmd redcon.Command) {
+	conn.WriteString("OK")
+	conn.Close()
+}
+
+func (h *Handler) set(conn redcon.Conn, cmd redcon.Command) {
+	if len(cmd.Args) != 3 {
+		conn.WriteError("ERR wrong number of arguments for '" + string(cmd.Args[0]) + "' command")
+		return
+	}
+
+	h.itemsMux.Lock()
+	h.items[string(cmd.Args[1])] = cmd.Args[2]
+	h.itemsMux.Unlock()
+
+	conn.WriteString("OK")
+}
+
+func (h *Handler) get(conn redcon.Conn, cmd redcon.Command) {
+	if len(cmd.Args) != 2 {
+		conn.WriteError("ERR wrong number of arguments for '" + string(cmd.Args[0]) + "' command")
+		return
+	}
+
+	h.itemsMux.RLock()
+	val, ok := h.items[string(cmd.Args[1])]
+	h.itemsMux.RUnlock()
+
+	if !ok {
+		conn.WriteNull()
+	} else {
+		conn.WriteBulk(val)
+	}
+}
+
+func (h *Handler) delete(conn redcon.Conn, cmd redcon.Command) {
+	if len(cmd.Args) != 2 {
+		conn.WriteError("ERR wrong number of arguments for '" + string(cmd.Args[0]) + "' command")
+		return
+	}
+
+	h.itemsMux.Lock()
+	_, ok := h.items[string(cmd.Args[1])]
+	delete(h.items, string(cmd.Args[1]))
+	h.itemsMux.Unlock()
+
+	if !ok {
+		conn.WriteInt(0)
+	} else {
+		conn.WriteInt(1)
+	}
+}
diff --git a/redcon.go b/redcon.go
index 3f7c1bb..b6e6ddf 100644
--- a/redcon.go
+++ b/redcon.go
@@ -7,6 +7,7 @@ import (
 	"errors"
 	"io"
 	"net"
+	"strings"
 	"sync"
 )
 
@@ -900,3 +901,66 @@ func Parse(raw []byte) (Command, error) {
 	return cmds[0], nil
 
 }
+
+// A Handler responds to an RESP request.
+type Handler interface {
+	ServeRESP(conn Conn, cmd Command)
+}
+
+// The HandlerFunc type is an adapter to allow the use of
+// ordinary functions as RESP handlers. If f is a function
+// with the appropriate signature, HandlerFunc(f) is a
+// Handler that calls f.
+type HandlerFunc func(conn Conn, cmd Command)
+
+// ServeRESP calls f(w, r)
+func (f HandlerFunc) ServeRESP(conn Conn, cmd Command) {
+	f(conn, cmd)
+}
+
+// ServeMux is an RESP command multiplexer.
+type ServeMux struct {
+	handlers map[string]Handler
+}
+
+// NewServeMux allocates and returns a new ServeMux.
+func NewServeMux() *ServeMux {
+	return &ServeMux{
+		handlers: make(map[string]Handler),
+	}
+}
+
+// HandleFunc registers the handler function for the given command.
+func (m *ServeMux) HandleFunc(command string, handler func(conn Conn, cmd Command)) {
+	if handler == nil {
+		panic("redcon: nil handler")
+	}
+	m.Handle(command, HandlerFunc(handler))
+}
+
+// Handle registers the handler for the given command.
+// If a handler already exists for command, Handle panics.
+func (m *ServeMux) Handle(command string, handler Handler) {
+	if command == "" {
+		panic("redcon: invalid command")
+	}
+	if handler == nil {
+		panic("redcon: nil handler")
+	}
+	if _, exist := m.handlers[command]; exist {
+		panic("redcon: multiple registrations for " + command)
+	}
+
+	m.handlers[command] = handler
+}
+
+// ServeRESP dispatches the command to the handler.
+func (m *ServeMux) ServeRESP(conn Conn, cmd Command) {
+	command := strings.ToLower(string(cmd.Args[0]))
+
+	if handler, ok := m.handlers[command]; ok {
+		handler.ServeRESP(conn, cmd)
+	} else {
+		conn.WriteError("ERR unknown command '" + command + "'")
+	}
+}