Add retry delay on topic subscription failures

Author: pennam

src/AIoTC_Config.h

@@ -142,6 +142,8 @@
 
 #define AIOT_CONFIG_RECONNECTION_RETRY_DELAY_ms      (1000UL)
 #define AIOT_CONFIG_MAX_RECONNECTION_RETRY_DELAY_ms (32000UL)
+#define AIOT_CONFIG_SUBSCRIBE_RETRY_DELAY_ms         (1000UL)
+#define AIOT_CONFIG_SUBSCRIBE_MAX_RETRY_CNT            (10UL)
 #define AIOT_CONFIG_TIMEOUT_FOR_LASTVALUES_SYNC_ms  (30000UL)
 #define AIOT_CONFIG_LASTVALUES_SYNC_MAX_RETRY_CNT      (10UL)
 

src/ArduinoIoTCloudTCP.cpp

@@ -79,6 +79,8 @@ ArduinoIoTCloudTCP::ArduinoIoTCloudTCP()
 , _last_connection_attempt_cnt{0}
 , _last_sync_request_tick{0}
 , _last_sync_request_cnt{0}
+, _last_subscribe_request_tick{0}
+, _last_subscribe_request_cnt{0}
 , _mqtt_data_buf{0}
 , _mqtt_data_len{0}
 , _mqtt_data_request_retransmit{false}
@@ -404,34 +406,58 @@ ArduinoIoTCloudTCP::State ArduinoIoTCloudTCP::handle_SubscribeMqttTopics()
     return State::ConnectPhy;
   }
 
-  if (!_mqttClient.subscribe(_dataTopicIn))
+  unsigned long const now = millis();
+  bool const is_subscribe_retry_delay_expired = (now - _last_subscribe_request_tick) > AIOT_CONFIG_SUBSCRIBE_RETRY_DELAY_ms;
+  bool const is_first_subscribe_request = (_last_subscribe_request_cnt == 0);
+  if (is_first_subscribe_request || is_subscribe_retry_delay_expired)
   {
-    DEBUG_ERROR("ArduinoIoTCloudTCP::%s could not subscribe to %s", __FUNCTION__, _dataTopicIn.c_str());
-#if !defined(__AVR__)
-    DEBUG_ERROR("Check your thing configuration, and press the reset button on your board.");
-#endif
-    return State::SubscribeMqttTopics;
-  }
+    if (_last_subscribe_request_cnt > AIOT_CONFIG_SUBSCRIBE_MAX_RETRY_CNT)
+    {
+      _last_subscribe_request_cnt = 0;
+      _last_subscribe_request_tick = 0;
+      _mqttClient.stop();
+      execCloudEventCallback(ArduinoIoTCloudEvent::DISCONNECT);
+      return State::ConnectPhy;
+    }
 
-  if (_shadowTopicIn != "")
-  {
-    if (!_mqttClient.subscribe(_shadowTopicIn))
+    _last_subscribe_request_tick = now;
+    _last_subscribe_request_cnt++;
+
+    if (!_mqttClient.subscribe(_dataTopicIn))
     {
-      DEBUG_ERROR("ArduinoIoTCloudTCP::%s could not subscribe to %s", __FUNCTION__, _shadowTopicIn.c_str());
+      DEBUG_ERROR("ArduinoIoTCloudTCP::%s could not subscribe to %s", __FUNCTION__, _dataTopicIn.c_str());
 #if !defined(__AVR__)
       DEBUG_ERROR("Check your thing configuration, and press the reset button on your board.");
 #endif
       return State::SubscribeMqttTopics;
     }
-  }
 
-  DEBUG_INFO("Connected to Arduino IoT Cloud");
-  execCloudEventCallback(ArduinoIoTCloudEvent::CONNECT);
+    if (_shadowTopicIn != "")
+    {
+      if (!_mqttClient.subscribe(_shadowTopicIn))
+      {
+        DEBUG_ERROR("ArduinoIoTCloudTCP::%s could not subscribe to %s", __FUNCTION__, _shadowTopicIn.c_str());
+#if !defined(__AVR__)
+        DEBUG_ERROR("Check your thing configuration, and press the reset button on your board.");
+#endif
+        return State::SubscribeMqttTopics;
+      }
+    }
 
-  if (_shadowTopicIn != "")
-    return State::RequestLastValues;
-  else
-    return State::Connected;
+    _last_subscribe_request_cnt = 0;
+    _last_subscribe_request_tick = 0;
+
+    DEBUG_INFO("Connected to Arduino IoT Cloud");
+    execCloudEventCallback(ArduinoIoTCloudEvent::CONNECT);
+
+    if (_shadowTopicIn != "")
+      return State::RequestLastValues;
+    else
+      return State::Connected;
+
+  }
+
+  return State::SubscribeMqttTopics;
 }
 
 ArduinoIoTCloudTCP::State ArduinoIoTCloudTCP::handle_RequestLastValues()

src/ArduinoIoTCloudTCP.h

@@ -116,6 +116,8 @@ class ArduinoIoTCloudTCP: public ArduinoIoTCloudClass
     unsigned int _last_connection_attempt_cnt;
     unsigned long _last_sync_request_tick;
     unsigned int _last_sync_request_cnt;
+    unsigned long _last_subscribe_request_tick;
+    unsigned int  _last_subscribe_request_cnt;
     String _brokerAddress;
     uint16_t _brokerPort;
     uint8_t _mqtt_data_buf[MQTT_TRANSMIT_BUFFER_SIZE];