Work on pub/sub and peer cert setup

socketserver/cmd/socketserver/socketserver.go

@@ -9,8 +9,13 @@ import (
 
 var origin *string = flag.String("origin", "localhost:8001", "Client-visible origin of the socket server")
 var bindAddress *string = flag.String("listen", "", "Address to bind to, if different from origin")
-var certificateFile *string = flag.String("crt", "", "SSL certificate file")
-var privateKeyFile *string = flag.String("key", "", "SSL private key file")
+var usessl *bool = flag.Bool("ssl", false, "Enable the use of SSL for connecting clients and backend connections")
+var certificateFile *string = flag.String("crt", "ssl.crt", "CA-signed SSL certificate file")
+var privateKeyFile *string = flag.String("key", "ssl.key", "SSL private key file")
+var backendRootFile *string = flag.String("peerroot", "backend_issuer.pem", "Root certificate that issued client certificates for backend servers")
+var backendCertFile *string = flag.String("peercrt", "backend_cert.crt", "Backend-trusted certificate, for use as a client certificate")
+var backendKeyFile *string = flag.String("peerkey", "backend_cert.key", "Private key for backend-trusted certificate, for use as a client certificate")
+var basicAuthPwd *string = flag.String("password", "", "Password for HTTP Basic Auth") // TODO
 
 func main() {
 	flag.Parse()
@@ -29,17 +34,24 @@ func main() {
 		SSLKeyFile: *privateKeyFile,
 		SSLCertificateFile: *certificateFile,
 		UseSSL: *certificateFile != "",
+		BackendRootCertFile: *backendRootFile,
+		BackendClientCertFile: *backendCertFile,
+		BackendClientKeyFile: *backendKeyFile,
 
 		SocketOrigin: *origin,
 	}
 
-	server.SetupServerAndHandle(conf)
+	httpServer := &http.Server{
+		Addr: *bindAddress
+	}
+
+	server.SetupServerAndHandle(conf, httpServer.TLSConfig)
 
 	var err error
 	if conf.UseSSL {
-		err = http.ListenAndServeTLS(*bindAddress, *certificateFile, *privateKeyFile, nil)
+		err = httpServer.ListenAndServeTLS(nil, nil)
 	} else {
-		err = http.ListenAndServe(*bindAddress, nil)
+		err = httpServer.ListenAndServe()
 	}
 
 	if err != nil {

socketserver/internal/server/backend.go

@@ -8,16 +8,41 @@ import (
 	"github.com/pmylund/go-cache"
 	"strconv"
 	"io/ioutil"
+	"encoding/json"
+	"crypto/tls"
+	"crypto/x509"
+	"log"
 )
 
-var httpClient http.Client
+var backendHttpClient http.Client
 var backendUrl string
 var responseCache *cache.Cache
 
-func SetupBackend(url string) {
-	httpClient.Timeout = 60 * time.Second
-	backendUrl = url
+var getBacklogUrl string
+
+func SetupBackend(config *Config) {
+	backendHttpClient.Timeout = 60 * time.Second
+	backendUrl = config.BackendUrl
+	if responseCache != nil {
+		responseCache.Flush()
+	}
 	responseCache = cache.New(60 * time.Second, 120 * time.Second)
+
+	getBacklogUrl = fmt.Sprintf("%s/backlog", backendUrl)
+}
+
+func SetupBackendCertificates(config *Config, certPool x509.CertPool) {
+	myCert, err := tls.LoadX509KeyPair(config.BackendClientCertFile, config.BackendClientKeyFile)
+	if err != nil {
+		log.Fatal(err)
+	}
+	tlsConfig := tls.Config{
+		Certificates: []tls.Certificate{myCert},
+		RootCAs: certPool,
+	}
+	tlsConfig.BuildNameToCertificate()
+	transport := &http.Transport{TLSClientConfig: tlsConfig}
+	backendHttpClient.Transport = transport
 }
 
 func getCacheKey(remoteCommand, data string) string {
@@ -33,7 +58,7 @@ func RequestRemoteDataCached(remoteCommand, data string, auth AuthInfo) (string,
 }
 
 func RequestRemoteData(remoteCommand, data string, auth AuthInfo) (string, error) {
-	destUrl := fmt.Sprintf("%s/%s", backendUrl, remoteCommand)
+	destUrl := fmt.Sprintf("%s/cmd/%s", backendUrl, remoteCommand)
 	var authKey string
 	if auth.UsernameValidated {
 		authKey = "usernameClaimed"
@@ -45,8 +70,11 @@ func RequestRemoteData(remoteCommand, data string, auth AuthInfo) (string, error
 		"clientData": []string{data},
 		authKey: []string{auth.TwitchUsername},
 	}
+	if gconfig.BasicAuthPassword != "" {
+		formData["password"] = gconfig.BasicAuthPassword
+	}
 
-	resp, err := httpClient.PostForm(destUrl, 	formData)
+	resp, err := backendHttpClient.PostForm(destUrl, formData)
 	if err != nil {
 		return "", err
 	}
@@ -70,3 +98,23 @@ func RequestRemoteData(remoteCommand, data string, auth AuthInfo) (string, error
 
 	return responseJson, nil
 }
+
+func FetchBacklogData(chatSubs, channelSubs []string) ([]ClientMessage, error) {
+	formData := url.Values{
+		"chatSubs": chatSubs,
+		"channelSubs": channelSubs,
+	}
+
+	resp, err := backendHttpClient.PostForm(getBacklogUrl, formData)
+	if err != nil {
+		return nil, err
+	}
+	dec := json.NewDecoder(resp.Body)
+	var messages []ClientMessage
+	err = dec.Decode(messages)
+	if err != nil {
+		return nil, err
+	}
+
+	return messages, nil
+}

socketserver/internal/server/commands.go

@@ -6,11 +6,14 @@ import (
 	"log"
 	"sync"
 	"strconv"
+	"time"
 )
 
 var ResponseSuccess = ClientMessage{Command: SuccessCommand}
 var ResponseFailure = ClientMessage{Command: "False"}
 
+const ChannelInfoDelay = 2 * time.Second
+
 func HandleCommand(conn *websocket.Conn, client *ClientInfo, msg ClientMessage) {
 	handler, ok := CommandHandlers[msg.Command]
 	if !ok {
@@ -22,9 +25,7 @@ func HandleCommand(conn *websocket.Conn, client *ClientInfo, msg ClientMessage)
 
 	log.Println(conn.RemoteAddr(), msg.MessageID, msg.Command, msg.Arguments)
 
-	client.Mutex.Lock()
 	response, err := CallHandler(handler, conn, client, msg)
-	client.Mutex.Unlock()
 
 	if err == nil {
 		response.MessageID = msg.MessageID
@@ -64,8 +65,10 @@ func HandleSetUser(conn *websocket.Conn, client *ClientInfo, msg ClientMessage)
 		return
 	}
 
+	client.Mutex.Lock()
 	client.TwitchUsername = username
 	client.UsernameValidated = false
+	client.Mutex.Unlock()
 
 	return ResponseSuccess, nil
 }
@@ -73,9 +76,22 @@ func HandleSetUser(conn *websocket.Conn, client *ClientInfo, msg ClientMessage)
 func HandleSub(conn *websocket.Conn, client *ClientInfo, msg ClientMessage) (rmsg ClientMessage, err error) {
 	channel, err := msg.ArgumentsAsString()
 
-	AddToSliceS(&client.CurrentChannels, channel)
+	client.Mutex.Lock()
 
-	// TODO - get backlog
+	AddToSliceS(&client.CurrentChannels, channel)
+	client.PendingChatBacklogs = append(client.PendingChatBacklogs, channel)
+
+	if client.MakePendingRequests == nil {
+		client.MakePendingRequests = time.AfterFunc(ChannelInfoDelay, GetSubscriptionBacklogFor(conn, client))
+	} else {
+		if !client.MakePendingRequests.Reset(ChannelInfoDelay) {
+			client.MakePendingRequests = time.AfterFunc(ChannelInfoDelay, GetSubscriptionBacklogFor(conn, client))
+		}
+	}
+
+	client.Mutex.Unlock()
+
+	// note - pub/sub updating happens in GetSubscriptionBacklog
 
 	return ResponseSuccess, nil
 }
@@ -83,7 +99,11 @@ func HandleSub(conn *websocket.Conn, client *ClientInfo, msg ClientMessage) (rms
 func HandleUnsub(conn *websocket.Conn, client *ClientInfo, msg ClientMessage) (rmsg ClientMessage, err error) {
 	channel, err := msg.ArgumentsAsString()
 
+	client.Mutex.Lock()
 	RemoveFromSliceS(&client.CurrentChannels, channel)
+	client.Mutex.Unlock()
+
+	UnsubscribeSingleChat(client, channel)
 
 	return ResponseSuccess, nil
 }
@@ -91,9 +111,22 @@ func HandleUnsub(conn *websocket.Conn, client *ClientInfo, msg ClientMessage) (r
 func HandleSubChannel(conn *websocket.Conn, client *ClientInfo, msg ClientMessage) (rmsg ClientMessage, err error) {
 	channel, err := msg.ArgumentsAsString()
 
-	AddToSliceS(&client.WatchingChannels, channel)
+	client.Mutex.Lock()
 
-	// TODO - get backlog
+	AddToSliceS(&client.WatchingChannels, channel)
+	client.PendingStreamBacklogs = append(client.PendingStreamBacklogs, channel)
+
+	if client.MakePendingRequests == nil {
+		client.MakePendingRequests = time.AfterFunc(ChannelInfoDelay, GetSubscriptionBacklogFor(conn, client))
+	} else {
+		if !client.MakePendingRequests.Reset(ChannelInfoDelay) {
+			client.MakePendingRequests = time.AfterFunc(ChannelInfoDelay, GetSubscriptionBacklogFor(conn, client))
+		}
+	}
+
+	client.Mutex.Unlock()
+
+	// note - pub/sub updating happens in GetSubscriptionBacklog
 
 	return ResponseSuccess, nil
 }
@@ -101,17 +134,88 @@ func HandleSubChannel(conn *websocket.Conn, client *ClientInfo, msg ClientMessag
 func HandleUnsubChannel(conn *websocket.Conn, client *ClientInfo, msg ClientMessage) (rmsg ClientMessage, err error) {
 	channel, err := msg.ArgumentsAsString()
 
+	client.Mutex.Lock()
 	RemoveFromSliceS(&client.WatchingChannels, channel)
+	client.Mutex.Unlock()
+
+	UnsubscribeSingleChannel(client, channel)
 
 	return ResponseSuccess, nil
 }
 
+func GetSubscriptionBacklogFor(conn *websocket.Conn, client *ClientInfo) func() {
+	return func() {
+		GetSubscriptionBacklog(conn, client)
+	}
+}
+
+// On goroutine
+func GetSubscriptionBacklog(conn *websocket.Conn, client *ClientInfo) {
+	var chatSubs, channelSubs []string
+
+	// Lock, grab the data, and reset it
+	client.Mutex.Lock()
+	chatSubs = client.PendingChatBacklogs
+	channelSubs = client.PendingStreamBacklogs
+	client.PendingChatBacklogs = nil
+	client.PendingStreamBacklogs = nil
+	client.MakePendingRequests = nil
+	client.Mutex.Unlock()
+
+	if len(chatSubs) == 0 && len(channelSubs) == 0 {
+		return
+	}
+
+	SubscribeBatch(client, chatSubs, channelSubs)
+
+	messages, err := FetchBacklogData(chatSubs, channelSubs)
+
+	if err != nil {
+		// Oh well.
+		log.Print("error in GetSubscriptionBacklog:", err)
+		return
+	}
+
+	// Deliver to client
+	for _, msg := range messages {
+		client.MessageChannel <- msg
+	}
+}
+
+type SurveySubmission struct {
+	User string
+	Json string
+}
+var SurveySubmissions []SurveySubmission
+var SurveySubmissionLock sync.Mutex
+
 func HandleSurvey(conn *websocket.Conn, client *ClientInfo, msg ClientMessage) (rmsg ClientMessage, err error) {
-	log.Println("Ignoring survey response from", client.ClientID)
+	SurveySubmissionLock.Lock()
+	SurveySubmissions = append(SurveySubmissions, SurveySubmission{client.TwitchUsername, msg.origArguments})
+	SurveySubmissionLock.Unlock()
+
 	return ResponseSuccess, nil
 }
 
+type FollowEvent struct {
+	User string
+	Channel string
+	NowFollowing bool
+	Timestamp time.Time
+}
+var FollowEvents []FollowEvent
+var FollowEventsLock sync.Mutex
+
 func HandleTrackFollow(conn *websocket.Conn, client *ClientInfo, msg ClientMessage) (rmsg ClientMessage, err error) {
+	channel, following, err := msg.ArgumentsAsStringAndBool()
+	if err != nil {
+		return
+	}
+	now := time.Now()
+
+	FollowEventsLock.Lock()
+	FollowEvents = append(FollowEvents, FollowEvent{client.TwitchUsername, channel, following, now})
+	FollowEventsLock.Unlock()
 
 	return ResponseSuccess, nil
 }

socketserver/internal/server/handlecore.go

@@ -4,23 +4,34 @@ import (
 	"net/http"
 	"golang.org/x/net/websocket"
 	"crypto/tls"
-	"log"
 	"strings"
 	"strconv"
 	"errors"
 	"encoding/json"
 	"fmt"
 	"sync"
+	"crypto/x509"
+	"io/ioutil"
 )
 
 const MAX_PACKET_SIZE = 1024
 
 type Config struct {
+	// SSL
 	SSLCertificateFile string
 	SSLKeyFile         string
 	UseSSL             bool
 
+	// CA for client validation (pub/sub commands only)
+	BackendRootCertFile string
+	BackendClientCertFile string
+	BackendClientKeyFile string
+	// Password for client validation (pub/sub commands only)
+	BasicAuthPassword  string
+
+	// Hostname of the socket server
 	SocketOrigin       string
+	// URL to the backend server
 	BackendUrl         string
 }
 
@@ -75,39 +86,58 @@ var ExpectedStringAndInt = errors.New("Error: Expected array of string, int as a
 var ExpectedStringAndBool = errors.New("Error: Expected array of string, bool as arguments.")
 var ExpectedStringAndIntGotFloat = errors.New("Error: Second argument was a float, expected an integer.")
 
+var gconfig *Config
+
 // Create a websocket.Server with the options from the provided Config.
-func SetupServer(config *Config) *websocket.Server {
+func setupServer(config *Config, tlsConfig *tls.Config) *websocket.Server {
+	gconfig = config
 	sockConf, err := websocket.NewConfig("/", config.SocketOrigin)
 	if err != nil {
 		panic(err)
 	}
+
+	SetupBackend(config)
+
 	if config.UseSSL {
 		cert, err := tls.LoadX509KeyPair(config.SSLCertificateFile, config.SSLKeyFile)
 		if err != nil {
 			panic(err)
 		}
-		tlsConf := &tls.Config{
-			Certificates: []tls.Certificate{cert},
-			ServerName: config.SocketOrigin,
+		tlsConfig.Certificates = []tls.Certificate{cert}
+		tlsConfig.ServerName = config.SocketOrigin
+		tlsConfig.BuildNameToCertificate()
+		sockConf.TlsConfig = tlsConfig
+
+		certBytes, err := ioutil.ReadFile(config.BackendRootCertFile)
+		if err != nil {
+			panic(err)
 		}
-		tlsConf.BuildNameToCertificate()
-		sockConf.TlsConfig = tlsConf
+		clientCA, err := x509.ParseCertificate(certBytes)
+		if err != nil {
+			panic(err)
+		}
+		certPool := x509.NewCertPool()
+		certPool.AddCert(clientCA)
+		tlsConfig.ClientCAs = certPool
+		SetupBackendCertificates(config, certPool)
 	}
 
 	sockServer := &websocket.Server{}
 	sockServer.Config = *sockConf
 	sockServer.Handler = HandleSocketConnection
 
-	SetupBackend(config.BackendUrl)
+	go deadChannelReaper()
+
 	return sockServer
 }
 
 // Set up a websocket listener and register it on /.
 // (Uses http.DefaultServeMux .)
-func SetupServerAndHandle(config *Config) {
-	sockServer := SetupServer(config)
+func SetupServerAndHandle(config *Config, tlsConfig *tls.Config) {
+	sockServer := setupServer(config, tlsConfig)
 
 	http.HandleFunc("/", sockServer.ServeHTTP)
+	http.HandleFunc("/pub", HandlePublishRequest)
 }
 
 // Handle a new websocket connection from a FFZ client.
@@ -122,17 +152,14 @@ func HandleSocketConnection(conn *websocket.Conn) {
 		})
 	}
 
-	defer func() {
-		closer()
-	}()
-
-	log.Print("! Got a connection from ", conn.RemoteAddr())
+	// Close the connection when we're done.
+	defer closer()
 
 	_clientChan := make(chan ClientMessage)
 	_serverMessageChan := make(chan ClientMessage)
 	_errorChan := make(chan error)
 
-	// Receive goroutine
+	// Launch receiver goroutine
 	go func(errorChan chan <- error, clientChan chan <- ClientMessage) {
 		var msg ClientMessage
 		var err error
@@ -148,13 +175,15 @@ func HandleSocketConnection(conn *websocket.Conn) {
 		// exit
 	}(_errorChan, _clientChan)
 
-	var client ClientInfo
-	client.MessageChannel = _serverMessageChan
-
 	var errorChan <-chan error = _errorChan
 	var clientChan <-chan ClientMessage = _clientChan
 	var serverMessageChan <-chan ClientMessage = _serverMessageChan
 
+	var client ClientInfo
+	client.MessageChannel = _serverMessageChan
+
+	// All set up, now enter the work loop
+
 	RunLoop:
 	for {
 		select {
@@ -180,7 +209,20 @@ func HandleSocketConnection(conn *websocket.Conn) {
 			FFZCodec.Send(conn, smsg)
 		}
 	}
-	// exit
+
+	// Exit
+
+	// Launch message draining goroutine - we aren't out of the pub/sub records
+	go func() {
+		for _ := range _serverMessageChan {}
+	}()
+
+	// Stop getting messages...
+	UnsubscribeAll(&client)
+
+	// And finished.
+	// Close the channel so the draining goroutine can finish, too.
+	close(_serverMessageChan)
 }
 
 func CallHandler(handler CommandHandler, conn *websocket.Conn, client *ClientInfo, cmsg ClientMessage) (rmsg ClientMessage, err error) {

socketserver/internal/server/publisher.go

@@ -0,0 +1,173 @@
+package server
+
+// This is the scariest code I've written yet for the server.
+// If I screwed up the locking, I won't know until it's too late.
+
+import (
+	"sync"
+	"time"
+	"net/http"
+)
+
+type SubscriberList struct {
+	sync.RWMutex
+	Members []chan <- ClientMessage
+}
+
+var ChatSubscriptionInfo map[string]*SubscriberList
+var ChatSubscriptionLock sync.RWMutex
+var WatchingSubscriptionInfo map[string]*SubscriberList
+var WatchingSubscriptionLock sync.RWMutex
+
+func PublishToChat(channel string, msg ClientMessage) {
+	ChatSubscriptionLock.RLock()
+	list := ChatSubscriptionInfo[channel]
+	if list != nil {
+		list.RLock()
+		for _, ch := range list.Members {
+			ch <- msg
+		}
+		list.RUnlock()
+	}
+	ChatSubscriptionLock.RUnlock()
+}
+
+func PublishToWatchers(channel string, msg ClientMessage) {
+	WatchingSubscriptionLock.RLock()
+	list := WatchingSubscriptionInfo[channel]
+	if list != nil {
+		list.RLock()
+		for _, ch := range list.Members {
+			ch <- msg
+		}
+		list.RUnlock()
+	}
+	WatchingSubscriptionLock.RUnlock()
+}
+
+func HandlePublishRequest(w http.ResponseWriter, r *http.Request) {
+	if r.TLS {
+		PeerCertificates
+	}
+}
+
+// Add a channel to the subscriptions while holding a read-lock to the map.
+// Locks:
+//   - ALREADY HOLDING a read-lock to the 'which' top-level map via the rlocker object
+//   - possible write lock to the 'which' top-level map via the wlocker object
+//   - write lock to SubscriptionInfo (if not creating new)
+func _subscribeWhileRlocked(which map[string]*SubscriberList, channelName string, value chan <- ClientMessage, rlocker sync.Locker, wlocker sync.Locker) {
+	list := which[channelName]
+	if list == nil {
+		// Not found, so create it
+		rlocker.Unlock()
+		wlocker.Lock()
+		list = &SubscriberList{}
+		list.Members = &[]chan <- ClientMessage{value} // Create it populated, to avoid reaper
+		which[channelName] = list
+		wlocker.Unlock()
+		rlocker.Lock()
+	} else {
+		list.Lock()
+		AddToSliceC(&list.Members, value)
+		list.Unlock()
+	}
+}
+
+// Locks:
+//   - read lock to top-level maps
+//   - possible write lock to top-level maps
+//   - write lock to SubscriptionInfos
+func SubscribeBatch(client *ClientInfo, chatSubs, channelSubs []string) {
+	mchan := client.MessageChannel
+	if len(chatSubs) > 0 {
+		rlocker := ChatSubscriptionLock.RLocker()
+		rlocker.Lock()
+		for _, v := range chatSubs {
+			_subscribeWhileRlocked(ChatSubscriptionInfo, v, mchan, rlocker, ChatSubscriptionLock)
+		}
+		rlocker.Unlock()
+	}
+	if len(channelSubs) > 0 {
+		rlocker := WatchingSubscriptionLock.RLocker()
+		rlocker.Lock()
+		for _, v := range channelSubs {
+			_subscribeWhileRlocked(WatchingSubscriptionInfo, v, mchan, rlocker, WatchingSubscriptionLock)
+		}
+		rlocker.Unlock()
+	}
+}
+
+// Unsubscribe the client from all channels, AND clear the CurrentChannels / WatchingChannels fields.
+// Locks:
+//   - read lock to top-level maps
+//   - write lock to SubscriptionInfos
+//   - write lock to ClientInfo
+func UnsubscribeAll(client *ClientInfo) {
+	ChatSubscriptionLock.RLock()
+	client.Mutex.Lock()
+	for _, v := range client.CurrentChannels {
+		list := ChatSubscriptionInfo[v]
+		list.Lock()
+		RemoveFromSliceC(&list.Members, client.MessageChannel)
+		list.Unlock()
+	}
+	client.CurrentChannels = nil
+	client.Mutex.Unlock()
+	ChatSubscriptionLock.RUnlock()
+
+	WatchingSubscriptionLock.RLock()
+	client.Mutex.Lock()
+	for _, v := range client.WatchingChannels {
+		list := WatchingSubscriptionInfo[v]
+		list.Lock()
+		RemoveFromSliceC(&list.Members, client.MessageChannel)
+		list.Unlock()
+	}
+	client.WatchingChannels = nil
+	client.Mutex.Unlock()
+	WatchingSubscriptionLock.RUnlock()
+}
+
+func UnsubscribeSingleChat(client *ClientInfo, channelName string) {
+	ChatSubscriptionLock.RLock()
+	list := ChatSubscriptionInfo[channelName]
+	list.Lock()
+	RemoveFromSliceC(&list.Members, client.MessageChannel)
+	list.Unlock()
+	ChatSubscriptionLock.RUnlock()
+}
+
+func UnsubscribeSingleChannel(client *ClientInfo, channelName string) {
+	WatchingSubscriptionLock.RLock()
+	list := WatchingSubscriptionInfo[channelName]
+	list.Lock()
+	RemoveFromSliceC(&list.Members, client.MessageChannel)
+	list.Unlock()
+	WatchingSubscriptionLock.RUnlock()
+}
+
+const ReapingDelay = 120 * time.Minute
+
+// Checks each of ChatSubscriptionInfo / WatchingSubscriptionInfo
+// for entries with no subscribers every ReapingDelay.
+// Started from SetupServer().
+func deadChannelReaper() {
+	for {
+		time.Sleep(ReapingDelay / 2)
+		ChatSubscriptionLock.Lock()
+		for key, val := range ChatSubscriptionInfo {
+			if len(val.Members) == 0 {
+				ChatSubscriptionInfo[key] = nil
+			}
+		}
+		ChatSubscriptionLock.Unlock()
+		time.Sleep(ReapingDelay / 2)
+		WatchingSubscriptionLock.Lock()
+		for key, val := range WatchingSubscriptionInfo {
+			if len(val.Members) == 0 {
+				WatchingSubscriptionInfo[key] = nil
+			}
+		}
+	}
+}

socketserver/internal/server/types.go

@@ -3,19 +3,20 @@ package server
 import (
 	"github.com/satori/go.uuid"
 	"sync"
+	"time"
 )
 
 type ClientMessage struct {
 	// Message ID. Increments by 1 for each message sent from the client.
 	// When replying to a command, the message ID must be echoed.
 	// When sending a server-initiated message, this is -1.
-	MessageID     int
+	MessageID     int `json:_`
 	// The command that the client wants from the server.
 	// When sent from the server, the literal string 'True' indicates success.
 	// Before sending, a blank Command will be converted into SuccessCommand.
-	Command       Command
+	Command       Command `json:cmd`
 	// Result of json.Unmarshal on the third field send from the client
-	Arguments     interface{}
+	Arguments     interface{} `json:data`
 
 	origArguments string
 }
@@ -41,19 +42,35 @@ type ClientInfo struct {
 	// If it seems to be a performance problem, we can split this.
 	Mutex            sync.Mutex
 
+	// TODO(riking) - does this need to be protected cross-thread?
 	AuthInfo
 
 	// Username validation nonce.
 	ValidationNonce  string
 
 	// The list of chats this client is currently in.
-	// Protected by Mutex
+	// Protected by Mutex.
 	CurrentChannels  []string
 
 	// This list of channels this client needs UI updates for.
-	// Protected by Mutex
+	// Protected by Mutex.
 	WatchingChannels []string
 
+	// List of channels that we have not yet checked current chat-related channel info for.
+	// This lets us batch the backlog requests.
+	// Protected by Mutex.
+	PendingChatBacklogs []string
+
+	// List of channels that we have not yet checked current stream-related channel info for.
+	// This lets us batch the backlog requests.
+	// Protected by Mutex.
+	PendingStreamBacklogs []string
+
+	// A timer that, when fired, will make the pending backlog requests.
+	// Usually nil. Protected by Mutex.
+	MakePendingRequests *time.Timer
+
 	// Server-initiated messages should be sent here
+	// Never nil.
 	MessageChannel   chan <- ClientMessage
 }

socketserver/internal/server/utils.go

@@ -3,19 +3,20 @@ package server
 import (
 )
 
-func AddToSliceS(ary *[]string, val string) {
+func AddToSliceS(ary *[]string, val string) bool {
 	slice := *ary
 	for _, v := range slice {
 		if v == val {
-			return
+			return false
 		}
 	}
 
 	slice = append(slice, val)
 	*ary = slice
+	return true
 }
 
-func RemoveFromSliceS(ary *[]string, val string) {
+func RemoveFromSliceS(ary *[]string, val string) bool {
 	slice := *ary
 	var idx int = -1
 	for i, v := range slice {
@@ -25,10 +26,43 @@ func RemoveFromSliceS(ary *[]string, val string) {
 		}
 	}
 	if idx == -1 {
-		return
+		return false
 	}
 
 	slice[idx] = slice[len(slice) - 1]
 	slice = slice[:len(slice) - 1]
 	*ary = slice
+	return true
+}
+
+func AddToSliceC(ary *[]chan <- ClientMessage, val chan <- ClientMessage) bool {
+	slice := *ary
+	for _, v := range slice {
+		if v == val {
+			return false
+		}
+	}
+
+	slice = append(slice, val)
+	*ary = slice
+	return true
+}
+
+func RemoveFromSliceC(ary *[]chan <- ClientMessage, val chan <- ClientMessage) bool {
+	slice := *ary
+	var idx int = -1
+	for i, v := range slice {
+		if v == val {
+			idx = i
+			break
+		}
+	}
+	if idx == -1 {
+		return false
+	}
+
+	slice[idx] = slice[len(slice) - 1]
+	slice = slice[:len(slice) - 1]
+	*ary = slice
+	return true
 }