Use a single handler (per wallet) for all tx notifications.

cmd.go

@@ -81,6 +81,7 @@ type BtcWallet struct {
 	*wallet.Wallet
 	mtx            sync.RWMutex
 	dirty          bool
+	NewBlockTxSeqN uint64
 	UtxoStore      struct {
 		sync.RWMutex
 		dirty bool
@@ -183,13 +184,35 @@ func OpenWallet(cfg *config, account string) (*BtcWallet, error) {
 }
 
 func (w *BtcWallet) Track() {
+	seq.Lock()
+	n := seq.n
+	seq.n++
+	seq.Unlock()
+
+	// Use goroutines and a WaitGroup to prevent unnecessary waiting for
+	// released locks.
+	var wg sync.WaitGroup
+	wg.Add(2)
+	go func() {
+		defer wg.Done()
 		wallets.Lock()
 		name := w.Name()
 		if wallets.m[name] == nil {
 			wallets.m[name] = w
 		}
 		wallets.Unlock()
+	}()
+	go func() {
+		defer wg.Done()
+		w.mtx.Lock()
+		w.NewBlockTxSeqN = n
+		w.mtx.Unlock()
+	}()
+	wg.Wait()
 
+	replyHandlers.Lock()
+	replyHandlers.m[n] = w.NewBlockTxHandler
+	replyHandlers.Unlock()
 	for _, addr := range w.GetActiveAddresses() {
 		go w.ReqNewTxsForAddress(addr)
 	}
@@ -231,10 +254,9 @@ func (w *BtcWallet) RescanForAddress(addr string, blocks ...int) {
 }
 
 func (w *BtcWallet) ReqNewTxsForAddress(addr string) {
-	seq.Lock()
-	n := seq.n
-	seq.n++
-	seq.Unlock()
+	w.mtx.RLock()
+	n := w.NewBlockTxSeqN
+	w.mtx.RUnlock()
 
 	m := &btcjson.Message{
 		Jsonrpc: "1.0",
@@ -244,8 +266,10 @@ func (w *BtcWallet) ReqNewTxsForAddress(addr string) {
 	}
 	msg, _ := json.Marshal(m)
 
-	replyHandlers.Lock()
-	replyHandlers.m[n] = func(result interface{}) bool {
+	btcdMsgs <- msg
+}
+
+func (w *BtcWallet) NewBlockTxHandler(result interface{}) bool {
 	// TODO(jrick): btcd also sends the block hash in the reply.
 	// Do we want it saved as well?
 	v, ok := result.(map[string]interface{})
@@ -289,7 +313,7 @@ func (w *BtcWallet) ReqNewTxsForAddress(addr string) {
 		return false
 	}
 
-		// btcd sends the tx  hashe as a BE string.  Convert to a
+	// btcd sends the tx hash as a BE string.  Convert to a
 	// LE ShaHash.
 	txhash, err := btcwire.NewShaHashFromStr(txhashBE)
 	if err != nil {
@@ -340,7 +364,3 @@ func (w *BtcWallet) ReqNewTxsForAddress(addr string) {
 	// Never remove this handler.
 	return false
 }
-	replyHandlers.Unlock()
-
-	btcdMsgs <- msg
-}

sockets.go

@@ -319,7 +319,7 @@ func ListenAndServe() error {
 	// requests for each channel in the set.
 	go frontendListenerDuplicator()
 
-	// XXX(jrick): We need some sort of authentication before websocket
+	// TODO(jrick): We need some sort of authentication before websocket
 	// connections are allowed, and perhaps TLS on the server as well.
 	http.Handle("/frontend", websocket.Handler(frontendReqsNotifications))
 	if err := http.ListenAndServe(fmt.Sprintf(":%d", cfg.SvrPort), nil); err != nil {