Detect dropped network connection

Check networkStatus() in mqttStatus() before attempting to reconnect MQTT. Fail quickly to avoid the ~20 seconds for MQTT connect attempts to timeout.

Allow run() to return if the MQTT connection is down, without any other action. The calling sketch can then check network status, etc. to fix the problem. Checking mqttStatus() once per loop() is enough to allow it to retry the MQTT connection when needed.

#99

Author: sellensr

src/AdafruitIO.cpp

@@ -167,8 +167,8 @@ const __FlashStringHelper* AdafruitIO::statusText()
 
 void AdafruitIO::run(uint16_t busywait_ms)
 {
-  // loop until we have a connection
-  while(mqttStatus() != AIO_CONNECTED){}
+  // mqttStatus() will try to reconnect before returning
+  if(mqttStatus() != AIO_CONNECTED) return;
 
   if(busywait_ms > 0)
     _packetread_timeout = busywait_ms;
@@ -239,6 +239,13 @@ aio_status_t AdafruitIO::mqttStatus()
     return _status;
   }
 
+  aio_status_t net_status = networkStatus();
+  // if we aren't connected, return network status -- fail quickly
+  if(net_status != AIO_NET_CONNECTED) {
+    _status = net_status;
+    return _status;
+  }
+  
   if(_mqtt->connected())
     return AIO_CONNECTED;