Use a generator goroutine and chan to create new JSON IDs

cmd.go

@@ -215,11 +215,7 @@ func getCurHeight() (height int64) {
 		return height
 	}
 
-	seq.Lock()
-	n := seq.n
-	seq.n++
-	seq.Unlock()
-
+	n := <-NewJsonID
 	m, err := btcjson.CreateMessageWithId("getblockcount",
 		fmt.Sprintf("btcwallet(%v)", n))
 	if err != nil {
@@ -285,11 +281,7 @@ func (w *BtcWallet) CalculateBalance(confirmations int) float64 {
 // each address stored in a wallet and sets up a new reply handler for
 // these notifications.
 func (w *BtcWallet) Track() {
-	seq.Lock()
-	n := seq.n
-	seq.n++
-	seq.Unlock()
-
+	n := <-NewJsonID
 	w.mtx.Lock()
 	w.NewBlockTxSeqN = n
 	w.mtx.Unlock()
@@ -310,11 +302,7 @@ func (w *BtcWallet) Track() {
 // blocks[0].  If len(blocks) is 2 or greater, the rescan will be
 // performed for the block range blocks[0]...blocks[1] (inclusive).
 func (w *BtcWallet) RescanForAddress(addr string, blocks ...int) {
-	seq.Lock()
-	n := seq.n
-	seq.n++
-	seq.Unlock()
-
+	n := <-NewJsonID
 	params := []interface{}{addr}
 	if len(blocks) > 0 {
 		params = append(params, blocks[0])
@@ -493,6 +481,22 @@ func (w *BtcWallet) newBlockTxHandler(result interface{}, e *btcjson.Error) bool
 	return false
 }
 
+// NewJsonID is used to receive the next unique JSON ID for btcd
+// requests, starting from zero and incrementing by one after each
+// read.
+var NewJsonID = make(chan uint64)
+
+// JsonIDGenerator sends incremental integers across a channel.  This
+// is meant to provide a unique value for the JSON ID field for btcd
+// messages.
+func JsonIDGenerator(c chan uint64) {
+	var n uint64
+	for {
+		c <- n
+		n++
+	}
+}
+
 func main() {
 	tcfg, _, err := loadConfig()
 	if err != nil {
@@ -523,6 +527,9 @@ func main() {
 		}
 	}()
 
+	// Begin generating new IDs for JSON calls.
+	go JsonIDGenerator(NewJsonID)
+
 	for {
 		replies := make(chan error)
 		done := make(chan int)

cmdmgr.go

@@ -23,7 +23,6 @@ import (
 	"github.com/conformal/btcjson"
 	"github.com/conformal/btcwallet/wallet"
 	"github.com/conformal/btcwire"
-	"sync"
 	"time"
 )
 
@@ -127,25 +126,6 @@ var (
 	}
 )
 
-var (
-	// seq holds the btcwallet sequence number for frontend messages
-	// which must be sent to and received from btcd.  A Mutex protects
-	// against concurrent access.
-	seq = struct {
-		sync.Mutex
-		n uint64
-	}{}
-
-	// replyRouter maps uint64 ids to reply channels, so btcd replies can
-	// be routed to the correct frontend.
-	replyRouter = struct {
-		sync.Mutex
-		m map[uint64]chan []byte
-	}{
-		m: make(map[uint64]chan []byte),
-	}
-)
-
 // ProcessFrontendMsg checks the message sent from a frontend.  If the
 // message method is one that must be handled by btcwallet, the request
 // is processed here.  Otherwise, the message is sent to btcd.
@@ -190,11 +170,7 @@ func ProcessFrontendMsg(reply chan []byte, msg []byte) {
 
 	default:
 		// btcwallet does not understand method.  Pass to btcd.
-		seq.Lock()
-		n := seq.n
-		seq.n++
-		seq.Unlock()
-
+		n := <-NewJsonID
 		var id interface{} = fmt.Sprintf("btcwallet(%v)-%v", n,
 			jsonMsg.Id)
 		jsonMsg.Id = &id
@@ -489,11 +465,7 @@ func SendFrom(reply chan []byte, msg *btcjson.Message) {
 	}
 
 	// Send rawtx off to btcd
-	seq.Lock()
-	n := seq.n
-	seq.n++
-	seq.Unlock()
-
+	n := <-NewJsonID
 	var id interface{} = fmt.Sprintf("btcwallet(%v)-%v", n, msg.Id)
 	m, err := btcjson.CreateMessageWithId("sendrawtransaction", id,
 		hex.EncodeToString(rawtx))
@@ -606,11 +578,7 @@ func SendMany(reply chan []byte, msg *btcjson.Message) {
 	}
 
 	// Send rawtx off to btcd
-	seq.Lock()
-	n := seq.n
-	seq.n++
-	seq.Unlock()
-
+	n := <-NewJsonID
 	var id interface{} = fmt.Sprintf("btcwallet(%v)-%v", n, msg.Id)
 	m, err := btcjson.CreateMessageWithId("sendrawtransaction", id,
 		hex.EncodeToString(rawtx))
@@ -734,11 +702,7 @@ func CreateEncryptedWallet(reply chan []byte, msg *btcjson.Message) {
 	}
 
 	// Grab a new unique sequence number for tx notifications in new blocks.
-	seq.Lock()
-	n := seq.n
-	seq.n++
-	seq.Unlock()
-
+	n := <-NewJsonID
 	bw := &BtcWallet{
 		Wallet:         w,
 		name:           wname,

sockets.go

@@ -58,7 +58,7 @@ var (
 	// Messages sent to this channel are sent to each connected frontend.
 	frontendNotificationMaster = make(chan []byte, 100)
 
-	// replyHandlers maps between a sequence number (passed as part of
+	// replyHandlers maps between a unique number (passed as part of
 	// the JSON Id field) and a function to handle a reply or notification
 	// from btcd.  As requests are received, this map is checked for a
 	// handler function to route the reply to.  If the function returns
@@ -69,6 +69,15 @@ var (
 	}{
 		m: make(map[uint64]func(interface{}, *btcjson.Error) bool),
 	}
+
+	// replyRouter maps unique uint64 ids to reply channels, so btcd
+	// replies can be routed to the correct frontend.
+	replyRouter = struct {
+		sync.Mutex
+		m map[uint64]chan []byte
+	}{
+		m: make(map[uint64]chan []byte),
+	}
 )
 
 // frontendListenerDuplicator listens for new wallet listener channels
@@ -484,10 +493,7 @@ func BtcdConnect(reply chan error) {
 // Bitcoin networks).  If the sanity checks pass, all wallets are set to
 // be tracked against chain notifications from this btcd connection.
 func BtcdHandshake(ws *websocket.Conn) {
-	seq.Lock()
-	n := seq.n
-	seq.n++
-	seq.Unlock()
+	n := <-NewJsonID
 	msg := btcjson.Message{
 		Method: "getcurrentnet",
 		Id:     fmt.Sprintf("btcwallet(%v)", n),