Ignore and retry Connect() for non-registered clients with an option

client.go

@@ -214,14 +214,16 @@ func (c *client) Connect() Token {
 	c.ibound = make(chan packets.ControlPacket)
 
 	go func() {
-		c.persist.Open()
 
 		c.setConnected(connecting)
 		c.errors = make(chan error, 1)
 		c.stop = make(chan struct{})
 
 		var rc byte
 		protocolVersion := c.options.ProtocolVersion
+	RECONN:
+
+		c.persist.Open()
 
 		if len(c.options.Servers) == 0 {
 			t.setError(fmt.Errorf("No servers defined to connect to"))
@@ -284,6 +286,13 @@ func (c *client) Connect() Token {
 
 		if c.conn == nil {
 			ERROR.Println(CLI, "Failed to connect to a broker")
+			if c.options.ConnectionRetry {
+				time.Sleep(5 * time.Second)
+				c.setConnected(reconnecting)
+				c.persist.Close()
+				goto RECONN
+			}
+
 			c.setConnected(disconnected)
 			c.persist.Close()
 			t.returnCode = rc
@@ -554,7 +563,7 @@ func (c *client) Publish(topic string, qos byte, retained bool, payload interfac
 	token := newToken(packets.Publish).(*PublishToken)
 	DEBUG.Println(CLI, "enter Publish")
 	switch {
-	case !c.IsConnected():
+	case !c.IsConnected() && !c.options.ConnectionRetry:
 		token.err = ErrNotConnected
 		token.flowComplete()
 		return token
@@ -578,13 +587,17 @@ func (c *client) Publish(topic string, qos byte, retained bool, payload interfac
 	}
 
 	if pub.Qos != 0 && pub.MessageID == 0 {
-		pub.MessageID = c.getID(token)
+		if !c.options.CleanSession && c.options.ConnectionRetry {
+			pub.MessageID = c.getAsyncID(token, uint16(len(c.persist.All())+1))
+		} else {
+			pub.MessageID = c.getID(token)
+		}
 		token.messageID = pub.MessageID
 	}
 	persistOutbound(c.persist, pub)
 	if c.connectionStatus() == reconnecting {
 		DEBUG.Println(CLI, "storing publish message (reconnecting), topic:", topic)
-	} else {
+	} else if c.IsConnected() {
 		DEBUG.Println(CLI, "sending publish message, topic:", topic)
 		c.obound <- &PacketAndToken{p: pub, t: token}
 	}

messageids.go

@@ -85,6 +85,18 @@ func (mids *messageIds) getID(t tokenCompletor) uint16 {
 	return 0
 }
 
+func (mids *messageIds) getAsyncID(t tokenCompletor, min uint16) uint16 {
+	mids.Lock()
+	defer mids.Unlock()
+	for i := min; i < midMax; i++ {
+		if _, ok := mids.index[i]; !ok {
+			mids.index[i] = t
+			return i
+		}
+	}
+	return 0
+}
+
 func (mids *messageIds) getToken(id uint16) tokenCompletor {
 	mids.RLock()
 	defer mids.RUnlock()

options.go

@@ -74,6 +74,7 @@ type ClientOptions struct {
 	MessageChannelDepth     uint
 	ResumeSubs              bool
 	HTTPHeaders             http.Header
+	ConnectionRetry         bool
 }
 
 // NewClientOptions will create a new ClientClientOptions type with some
@@ -112,6 +113,7 @@ func NewClientOptions() *ClientOptions {
 		MessageChannelDepth:     100,
 		ResumeSubs:              false,
 		HTTPHeaders:             make(map[string][]string),
+		ConnectionRetry:         false,
 	}
 	return o
 }
@@ -338,3 +340,9 @@ func (o *ClientOptions) SetHTTPHeaders(h http.Header) *ClientOptions {
 	o.HTTPHeaders = h
 	return o
 }
+
+// SetConnectionRetry retries the Connect() call until the client registers the token.
+func (o *ClientOptions) SetConnectionRetry(retry bool) *ClientOptions {
+	o.ConnectionRetry = retry
+	return o
+}

trace.go

@@ -27,7 +27,7 @@ type (
 	NOOPLogger struct{}
 )
 
-func (NOOPLogger) Println(v ...interface{}) {}
+func (NOOPLogger) Println(v ...interface{})               {}
 func (NOOPLogger) Printf(format string, v ...interface{}) {}
 
 // Internal levels of library output that are initialised to not print

unit_client_test.go

@@ -104,4 +104,4 @@ func Test_isConnectionOpenNegative(t *testing.T) {
 	if c.IsConnectionOpen() {
 		t.Fail()
 	}
-}
+}