Cleanly remove disconnected clients.

Also fixes a bug where responses for a single client would be sent to
every connected client.

acctmgr.go

@@ -229,8 +229,8 @@ func (am *AccountManager) BlockNotify(bs *wallet.BlockStamp) {
 		// changes, or sending these notifications as the utxos are added.
 		confirmed := a.CalculateBalance(1)
 		unconfirmed := a.CalculateBalance(0) - confirmed
-		NotifyWalletBalance(frontendNotificationMaster, a.name, confirmed)
-		NotifyWalletBalanceUnconfirmed(frontendNotificationMaster, a.name,
+		NotifyWalletBalance(allClients, a.name, confirmed)
+		NotifyWalletBalanceUnconfirmed(allClients, a.name,
 			unconfirmed)
 
 		// If this is the default account, update the block all accounts

cmd.go

@@ -227,7 +227,7 @@ func main() {
 		}
 		updateBtcd <- btcd
 
-		NotifyBtcdConnection(frontendNotificationMaster)
+		NotifyBtcdConnection(allClients)
 		log.Info("Established connection to btcd")
 
 		// Perform handshake.
@@ -246,7 +246,7 @@ func main() {
 
 		// Block goroutine until the connection is lost.
 		<-btcd.closed
-		NotifyBtcdConnection(frontendNotificationMaster)
+		NotifyBtcdConnection(allClients)
 		log.Info("Lost btcd connection")
 	}
 }

ntfns.go

@@ -129,7 +129,7 @@ func NtfnProcessedTx(n btcjson.Cmd) {
 	} else {
 		// Notify frontends of new recv tx and mark as notified.
 		NotifiedRecvTxChans.add <- *recvTxOP
-		NotifyNewTxDetails(frontendNotificationMaster, a.Name(), t.TxInfo(a.Name(),
+		NotifyNewTxDetails(allClients, a.Name(), t.TxInfo(a.Name(),
 			ptn.BlockHeight, a.Wallet.Net())[0])
 	}
 
@@ -151,16 +151,15 @@ func NtfnProcessedTx(n btcjson.Cmd) {
 		// the blockconnected notifiation is processed.
 		if u.Height == -1 {
 			bal := a.CalculateBalance(0) - a.CalculateBalance(1)
-			NotifyWalletBalanceUnconfirmed(frontendNotificationMaster,
-				a.name, bal)
+			NotifyWalletBalanceUnconfirmed(allClients, a.name, bal)
 		}
 	}
 
 	// Notify frontends of new account balance.
 	confirmed := a.CalculateBalance(1)
 	unconfirmed := a.CalculateBalance(0) - confirmed
-	NotifyWalletBalance(frontendNotificationMaster, a.name, confirmed)
-	NotifyWalletBalanceUnconfirmed(frontendNotificationMaster, a.name, unconfirmed)
+	NotifyWalletBalance(allClients, a.name, confirmed)
+	NotifyWalletBalanceUnconfirmed(allClients, a.name, unconfirmed)
 }
 
 // NtfnBlockConnected handles btcd notifications resulting from newly
@@ -208,7 +207,7 @@ func NtfnBlockConnected(n btcjson.Cmd) {
 
 	// Pass notification to frontends too.
 	marshaled, _ := n.MarshalJSON()
-	frontendNotificationMaster <- marshaled
+	allClients <- marshaled
 }
 
 // NtfnBlockDisconnected handles btcd notifications resulting from
@@ -231,7 +230,7 @@ func NtfnBlockDisconnected(n btcjson.Cmd) {
 
 	// Pass notification to frontends too.
 	marshaled, _ := n.MarshalJSON()
-	frontendNotificationMaster <- marshaled
+	allClients <- marshaled
 }
 
 // NtfnTxMined handles btcd notifications resulting from newly

rpcserver.go

@@ -1357,7 +1357,7 @@ func handleSendRawTxReply(icmd btcjson.Cmd, txIDStr string, a *Account, txInfo *
 	bs, err := GetCurBlock()
 	if err == nil {
 		for _, details := range sendtx.TxInfo(a.Name(), bs.Height, a.Net()) {
-			NotifyNewTxDetails(frontendNotificationMaster, a.Name(),
+			NotifyNewTxDetails(allClients, a.Name(),
 				details)
 		}
 	}
@@ -1379,8 +1379,8 @@ func handleSendRawTxReply(icmd btcjson.Cmd, txIDStr string, a *Account, txInfo *
 	// confirmed balance.
 	confirmed := a.CalculateBalance(1)
 	unconfirmed := a.CalculateBalance(0) - confirmed
-	NotifyWalletBalance(frontendNotificationMaster, a.name, confirmed)
-	NotifyWalletBalanceUnconfirmed(frontendNotificationMaster, a.name, unconfirmed)
+	NotifyWalletBalance(allClients, a.name, confirmed)
+	NotifyWalletBalanceUnconfirmed(allClients, a.name, unconfirmed)
 
 	// btcd cannot be trusted to successfully relay the tx to the
 	// Bitcoin network.  Even if this succeeds, the rawtx must be
@@ -1796,7 +1796,7 @@ type AccountNtfn struct {
 func NotifyWalletLockStateChange(account string, locked bool) {
 	ntfn := btcws.NewWalletLockStateNtfn(account, locked)
 	mntfn, _ := ntfn.MarshalJSON()
-	frontendNotificationMaster <- mntfn
+	allClients <- mntfn
 }
 
 // NotifyWalletBalance sends a confirmed account balance notification
@@ -1892,7 +1892,7 @@ func NotifyMinedTxSender(in chan *tx.RecvTx) {
 				recv.BlockHash.String(), recv.BlockHeight,
 				recv.BlockTime, int(recv.BlockIndex))
 			mntfn, _ := ntfn.MarshalJSON()
-			frontendNotificationMaster <- mntfn
+			allClients <- mntfn
 
 			// Mark as sent.
 			m[recv.TxID] = struct{}{}

sockets.go

@@ -52,13 +52,10 @@ var (
 	ErrConnLost = errors.New("connection lost")
 
 	// Adds a frontend listener channel
-	addFrontendListener = make(chan (chan []byte))
-
-	// Removes a frontend listener channel
-	deleteFrontendListener = make(chan (chan []byte))
+	addClient = make(chan clientContext)
 
 	// Messages sent to this channel are sent to each connected frontend.
-	frontendNotificationMaster = make(chan []byte, 100)
+	allClients = make(chan []byte, 100)
 )
 
 // server holds the items the RPC server may need to access (auth,
@@ -69,6 +66,11 @@ type server struct {
 	authsha   [sha256.Size]byte
 }
 
+type clientContext struct {
+	send         chan []byte
+	disconnected chan struct{} // closed on disconnect
+}
+
 // parseListeners splits the list of listen addresses passed in addrs into
 // IPv4 and IPv6 slices and returns them.  This allows easy creation of the
 // listeners on the correct interface "tcp4" and "tcp6".  It also properly
@@ -262,55 +264,26 @@ func (s *server) ServeRPCRequest(w http.ResponseWriter, r *http.Request) {
 	}
 }
 
-// frontendListenerDuplicator listens for new wallet listener channels
-// and duplicates messages sent to frontendNotificationMaster to all
-// connected listeners.
-func frontendListenerDuplicator() {
-	// frontendListeners is a map holding each currently connected frontend
-	// listener as the key.  The value is ignored, as this is only used as
-	// a set.
-	frontendListeners := make(map[chan []byte]bool)
+// clientResponseDuplicator listens for new wallet listener channels
+// and duplicates messages sent to allClients to all connected clients.
+func clientResponseDuplicator() {
+	clients := make(map[clientContext]struct{})
 
-	// Don't want to add or delete a wallet listener while iterating
-	// through each to propigate to every attached wallet.  Use a binary
-	// semaphore to prevent this.
-	sem := make(chan struct{}, 1)
-	sem <- struct{}{}
+	for {
+		select {
+		case cc := <-addClient:
+			clients[cc] = struct{}{}
 
-	// Check for listener channels to add or remove from set.
-	go func() {
-		for {
-			select {
-			case c := <-addFrontendListener:
-				<-sem
-				frontendListeners[c] = true
-				sem <- struct{}{}
-
-				NotifyBtcdConnection(c)
-				bs, err := GetCurBlock()
-				if err == nil {
-					NotifyNewBlockChainHeight(c, bs)
-					NotifyBalances(c)
+		case n := <-allClients:
+			for cc := range clients {
+				select {
+				case <-cc.disconnected:
+					delete(clients, cc)
+				default:
+					cc.send <- n
 				}
-
-			case c := <-deleteFrontendListener:
-				<-sem
-				delete(frontendListeners, c)
-				sem <- struct{}{}
 			}
 		}
-	}()
-
-	// Duplicate all messages sent across frontendNotificationMaster, as
-	// well as internal btcwallet notifications, to each listening wallet.
-	for {
-		ntfn := <-frontendNotificationMaster
-
-		<-sem
-		for c := range frontendListeners {
-			c <- ntfn
-		}
-		sem <- struct{}{}
 	}
 }
 
@@ -331,11 +304,12 @@ func NotifyBtcdConnection(reply chan []byte) {
 func WSSendRecv(ws *websocket.Conn) {
 	// Add frontend notification channel to set so this handler receives
 	// updates.
-	frontendNotification := make(chan []byte)
-	addFrontendListener <- frontendNotification
-	defer func() {
-		deleteFrontendListener <- frontendNotification
-	}()
+	cc := clientContext{
+		send:         make(chan []byte),
+		disconnected: make(chan struct{}),
+	}
+	addClient <- cc
+	defer close(cc.disconnected)
 
 	// jsonMsgs receives JSON messages from the currently connected frontend.
 	jsonMsgs := make(chan []byte)
@@ -363,11 +337,15 @@ func WSSendRecv(ws *websocket.Conn) {
 			// Handle request here.
 			go func(m []byte) {
 				resp := ReplyToFrontend(m, true)
-				frontendNotification <- resp
+
+				select {
+				case cc.send <- resp:
+				case <-cc.disconnected:
+				}
 			}(m)
 
-		case ntfn, _ := <-frontendNotification:
-			if err := websocket.Message.Send(ws, ntfn); err != nil {
+		case m := <-cc.send:
+			if err := websocket.Message.Send(ws, m); err != nil {
 				// Frontend disconnected.
 				return
 			}
@@ -395,7 +373,7 @@ func (s *server) Start() {
 	// requests for each channel in the set.
 	//
 	// Use a sync.Once to insure no extra duplicators run.
-	go duplicateOnce.Do(frontendListenerDuplicator)
+	go duplicateOnce.Do(clientResponseDuplicator)
 
 	log.Trace("Starting RPC server")
 
@@ -554,8 +532,8 @@ func Handshake(rpc ServerConn) error {
 	if err != nil {
 		return fmt.Errorf("cannot get best block: %v", err)
 	}
-	NotifyNewBlockChainHeight(frontendNotificationMaster, bs)
-	NotifyBalances(frontendNotificationMaster)
+	NotifyNewBlockChainHeight(allClients, bs)
+	NotifyBalances(allClients)
 
 	// Get default account.  Only the default account is used to
 	// track recently-seen blocks.