/
websocket.go
149 lines (130 loc) · 4.25 KB
/
websocket.go
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package main
import (
"code.google.com/p/go.net/websocket"
"encoding/json"
"fmt"
"github.com/garyburd/redigo/redis"
"github.com/gorilla/sessions"
"github.com/joinmytalk/xlog"
"time"
)
// WebsocketHandler handles an incoming WebSocket and dispatches to the correct
// handler based on whether the user is authenticated and whether the session
// he's viewing belongs to him.
func WebsocketHandler(s *websocket.Conn, dbStore *Store, sessionStore sessions.Store, redisAddr string) {
StatCount("websocket", 1)
xlog.Infof("WebsocketHandler: opened connection")
r := s.Request()
session, err := sessionStore.Get(r, SESSIONNAME)
if err != nil {
xlog.Debugf("Getting session failed: %v", err)
StatCount("getting session failed", 1)
return
}
sessionData := struct {
SessionID string `json:"session_id"`
}{}
if err := websocket.JSON.Receive(s, &sessionData); err != nil {
xlog.Errorf("WebsocketHandler: JSON.Receive failed: %v", err)
return
}
owner, sessionID, err := dbStore.GetOwnerForSession(sessionData.SessionID)
if err != nil {
xlog.Errorf("GetOwnerForSession failed: %v", err)
return
}
if session.Values["userID"] == nil {
xlog.Errorf("WebsocketHandler is not authenticated -> slave handler")
slaveHandler(s, sessionID, dbStore, redisAddr)
} else if owner == session.Values["userID"].(int) {
xlog.Infof("WebSocketHandler owner matches -> master handler")
masterHandler(s, sessionID, dbStore, redisAddr)
} else {
xlog.Infof("WebSocketHandler owner doesn't match -> slave handler")
slaveHandler(s, sessionID, dbStore, redisAddr)
}
}
// Command describes a command as sent over WebSockets and as stored in the database.
type Command struct {
ID int `meddler:"id,pk" json:"-"`
Timestamp time.Time `meddler:"timestamp,utctimez" json:"timestamp"`
Cmd string `meddler:"cmd" json:"cmd"`
Page int `meddler:"page" json:"page"`
SessionID int `meddler:"session_id" json:"-"`
Coordinates []float64 `meddler:"coordinates,json" json:"coords"`
Color string `meddler:"color" json:"color"`
Width int `meddler:"width" json:"width"`
CanvasWidth int `meddler:"canvas_width" json:"canvasWidth"`
CanvasHeight int `meddler:"canvas_height" json:"canvasHeight"`
}
func slaveHandler(s *websocket.Conn, sessionID int, dbStore *Store, redisAddr string) {
xlog.Debugf("entering SlaveHandler")
c, err := redis.Dial("tcp", redisAddr)
if err != nil {
xlog.Errorf("redis.Dial failed: %v", err)
return
}
defer c.Close()
psc := redis.PubSubConn{Conn: c}
topic := fmt.Sprintf("session.%d", sessionID)
psc.Subscribe(topic)
defer psc.Unsubscribe(topic)
for {
switch v := psc.Receive().(type) {
case redis.Message:
StatCount("command for slave", 1)
var cmd Command
if err := json.Unmarshal(v.Data, &cmd); err != nil {
break
}
if err := websocket.JSON.Send(s, cmd); err != nil {
xlog.Errorf("slaveHandler: JSON.Send failed: %v", err)
return
}
if cmd.Cmd == "close" {
return
}
case redis.Subscription:
xlog.Debugf("mkay... redis.Subscription received: %#v", v)
}
}
}
func masterHandler(s *websocket.Conn, sessionID int, dbStore *Store, redisAddr string) {
xlog.Debugf("entering MasterHandler")
c, err := redis.Dial("tcp", redisAddr)
if err != nil {
xlog.Errorf("redis.Dial failed: %v", err)
return
}
defer c.Close()
for {
var cmd Command
if err := websocket.JSON.Receive(s, &cmd); err != nil {
xlog.Errorf("masterHandler: JSON.Receive failed: %v", err)
break
}
xlog.Debugf("masterHandler: received command: %#v", cmd)
cmd.SessionID = sessionID
cmd.Timestamp = time.Now()
if cmd.Cmd != "clearSlide" {
if err := dbStore.InsertCommand(&cmd); err != nil {
xlog.Errorf("Inserting command failed: %v", err)
break
}
}
executeCommand(cmd, dbStore)
cmdJSON, _ := json.Marshal(cmd)
c.Send("PUBLISH", fmt.Sprintf("session.%d", sessionID), string(cmdJSON))
c.Flush()
}
xlog.Debugf("masterHandler: closing connection")
}
func executeCommand(cmd Command, dbStore *Store) {
StatCount("command from master", 1)
switch cmd.Cmd {
case "clearSlide":
if err := dbStore.ClearSlide(cmd.SessionID, cmd.Page); err != nil {
xlog.Errorf("clearSlide for %d page %d failed: %v", cmd.SessionID, cmd.Page, err)
}
}
}