Merge pull request #97 from arduino-libraries/fix-dont-loose-message-on-failed-transmit

Fix - Don't loose messages when MQTT connection was broken on message send

Author: aentinger

src/ArduinoIoTCloud.h

@@ -78,7 +78,7 @@ class ArduinoIoTCloudClass {
 
     virtual int connected() = 0;
 
-    virtual void connectionCheck() = 0;
+    virtual ArduinoIoTConnectionStatus connectionCheck() = 0;
 
     virtual void printDebugInfo() = 0;
 

src/ArduinoIoTCloudLPWAN.cpp

@@ -60,11 +60,7 @@ void ArduinoIoTCloudLPWAN::update() {
   // Check if a primitive property wrapper is locally changed
   Thing.updateTimestampOnLocallyChangedProperties();
 
-  connectionCheck();
-
-  if (_iotStatus != ArduinoIoTConnectionStatus::CONNECTED) {
-    return;
-  }
+  if(connectionCheck() != ArduinoIoTConnectionStatus::CONNECTED) return;
 
   if (_connection->available()) {
     uint8_t msgBuf[DEFAULT_CBOR_LORA_MSG_SIZE];
@@ -86,7 +82,7 @@ void ArduinoIoTCloudLPWAN::update() {
 
 }
 
-void ArduinoIoTCloudLPWAN::connectionCheck() {
+ArduinoIoTConnectionStatus ArduinoIoTCloudLPWAN::connectionCheck() {
   if (_connection != NULL) {
 
     _connection->check();
@@ -96,7 +92,7 @@ void ArduinoIoTCloudLPWAN::connectionCheck() {
         _iotStatus = ArduinoIoTConnectionStatus::DISCONNECTED;
         printConnectionStatus(_iotStatus);
       }
-      return;
+      return _iotStatus;
     }
   }
 
@@ -147,6 +143,8 @@ void ArduinoIoTCloudLPWAN::connectionCheck() {
       }
       break;
   }
+
+  return _iotStatus;
 }
 
 void ArduinoIoTCloudLPWAN::printDebugInfo() {

src/ArduinoIoTCloudLPWAN.h

@@ -31,7 +31,7 @@ class ArduinoIoTCloudLPWAN : public ArduinoIoTCloudClass {
     bool disconnect();
     int connected();
     void update();
-    void connectionCheck();
+    ArduinoIoTConnectionStatus connectionCheck();
     void printDebugInfo();
     int begin(LPWANConnectionHandler& connection, bool retry = false);
     inline LPWANConnectionHandler* getConnection() {

src/ArduinoIoTCloudTCP.cpp

@@ -44,7 +44,9 @@ static unsigned long getTime() {
 
 ArduinoIoTCloudTCP::ArduinoIoTCloudTCP():
   _connection(NULL),
-
+  _mqtt_data_buf{0},
+  _mqtt_data_len{0},
+  _mqtt_data_request_retransmit{false},
   _sslClient(NULL),
   #ifdef BOARD_ESP
   _password(""),
@@ -182,7 +184,6 @@ int ArduinoIoTCloudTCP::connect() {
     if (_mqttClient->subscribe(_shadowTopicIn) == 0) {
       return CONNECT_FAILURE_SUBSCRIBE;
     }
-
     _syncStatus = ArduinoIoTSynchronizationStatus::SYNC_STATUS_WAIT_FOR_CLOUD_VALUES;
     _lastSyncRequestTickTime = 0;
   }
@@ -201,10 +202,11 @@ void ArduinoIoTCloudTCP::update() {
   // Check if a primitive property wrapper is locally changed
   Thing.updateTimestampOnLocallyChangedProperties();
 
-  connectionCheck();
+  if(connectionCheck() != ArduinoIoTConnectionStatus::CONNECTED) return;
 
-  if (_iotStatus != ArduinoIoTConnectionStatus::CONNECTED) {
-    return;
+  if(_mqtt_data_request_retransmit && (_mqtt_data_len > 0)) {
+    writeProperties(_mqtt_data_buf, _mqtt_data_len);
+    _mqtt_data_request_retransmit = false;
   }
 
   // MTTQClient connected!, poll() used to retrieve data from MQTT broker
@@ -235,8 +237,15 @@ void ArduinoIoTCloudTCP::update() {
 void ArduinoIoTCloudTCP::sendPropertiesToCloud() {
   uint8_t data[MQTT_TRANSMIT_BUFFER_SIZE];
   int const length = Thing.encode(data, sizeof(data));
-  if (length > 0) {
-    writeProperties(data, length);
+  if (length > 0)
+  {
+    /* If properties have been encoded store them in the back-up buffer
+     * in order to allow retransmission in case of failure.
+     */
+    _mqtt_data_len = length;
+    memcpy(_mqtt_data_buf, data, _mqtt_data_len);
+    /* Transmit the properties to the MQTT broker */
+    writeProperties(_mqtt_data_buf, _mqtt_data_len);
   }
 }
 
@@ -337,7 +346,7 @@ void ArduinoIoTCloudTCP::requestLastValue() {
   writeShadowOut(CBOR_REQUEST_LAST_VALUE_MSG, sizeof(CBOR_REQUEST_LAST_VALUE_MSG));
 }
 
-void ArduinoIoTCloudTCP::connectionCheck() {
+ArduinoIoTConnectionStatus ArduinoIoTCloudTCP::connectionCheck() {
 
   if (_connection != NULL) {
 
@@ -348,7 +357,7 @@ void ArduinoIoTCloudTCP::connectionCheck() {
         _iotStatus = ArduinoIoTConnectionStatus::DISCONNECTED;
         printConnectionStatus(_iotStatus);
       }
-      return;
+      return _iotStatus;
     }
   }
 
@@ -366,6 +375,7 @@ void ArduinoIoTCloudTCP::connectionCheck() {
     case ArduinoIoTConnectionStatus::CONNECTED: {
         if (!_mqttClient->connected()) {
           _iotStatus = ArduinoIoTConnectionStatus::DISCONNECTED;
+          _mqtt_data_request_retransmit = true;
           printConnectionStatus(_iotStatus);
           execCloudEventCallback(_on_disconnect_event_callback, 0 /* callback_arg - e.g. could be error code casted to void * */);
         }
@@ -403,6 +413,8 @@ void ArduinoIoTCloudTCP::connectionCheck() {
       }
       break;
   }
+
+  return _iotStatus;
 }
 
 void ArduinoIoTCloudTCP::printDebugInfo() {

src/ArduinoIoTCloudTCP.h

@@ -44,7 +44,7 @@ class ArduinoIoTCloudTCP: public ArduinoIoTCloudClass {
     bool disconnect();
     int connected();
     void update();
-    void connectionCheck();
+    ArduinoIoTConnectionStatus connectionCheck();
     void printDebugInfo();
     #ifdef BOARD_HAS_ECCX08
     int begin(TcpIpConnectionHandler & connection, String brokerAddress = DEFAULT_BROKER_ADDRESS_SECURE_AUTH, uint16_t brokerPort = DEFAULT_BROKER_PORT_SECURE_AUTH);
@@ -95,6 +95,9 @@ class ArduinoIoTCloudTCP: public ArduinoIoTCloudClass {
     TcpIpConnectionHandler * _connection;
     String _brokerAddress;
     uint16_t _brokerPort;
+    uint8_t _mqtt_data_buf[MQTT_TRANSMIT_BUFFER_SIZE];
+    int _mqtt_data_len;
+    bool _mqtt_data_request_retransmit;
 
     #ifdef BOARD_HAS_ECCX08
     BearSSLClient* _sslClient;