Changing signature of CBOREncoder::encode to allow the propagation of internal errors to the outside

Author: aentinger

src/ArduinoIoTCloudLPWAN.cpp

@@ -126,11 +126,12 @@ void ArduinoIoTCloudLPWAN::disconnect()
 
 void ArduinoIoTCloudLPWAN::sendPropertiesToCloud()
 {
+  int bytes_encoded = 0;
   uint8_t data[CBOR_LORA_MSG_MAX_SIZE];
-  int const length = CBOREncoder::encode(_property_container, data, sizeof(data), true);
-  if (length > 0) {
-    writeProperties(data, length);
-  }
+
+  if (CBOREncoder::encode(_property_container, data, sizeof(data), bytes_encoded, true) == CborNoError)
+    if (bytes_encoded > 0)
+      writeProperties(data, bytes_encoded);
 }
 
 int ArduinoIoTCloudLPWAN::writeProperties(const byte data[], int length)

src/ArduinoIoTCloudTCP.cpp

@@ -283,18 +283,20 @@ void ArduinoIoTCloudTCP::handleMessage(int length)
 
 void ArduinoIoTCloudTCP::sendPropertiesToCloud()
 {
+  int bytes_encoded = 0;
   uint8_t data[MQTT_TRANSMIT_BUFFER_SIZE];
-  int const length = CBOREncoder::encode(_property_container, data, sizeof(data));
-  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 */
-    write(_dataTopicOut, _mqtt_data_buf, _mqtt_data_len);
-  }
+
+  if (CBOREncoder::encode(_property_container, data, sizeof(data), bytes_encoded, false) == CborNoError)
+    if (bytes_encoded > 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 = bytes_encoded;
+      memcpy(_mqtt_data_buf, data, _mqtt_data_len);
+      /* Transmit the properties to the MQTT broker */
+      write(_dataTopicOut, _mqtt_data_buf, _mqtt_data_len);
+    }
 }
 
 void ArduinoIoTCloudTCP::requestLastValue()

src/cbor/CBOREncoder.cpp

@@ -30,39 +30,48 @@
 /******************************************************************************
  * PUBLIC MEMBER FUNCTIONS
  ******************************************************************************/
-
-int CBOREncoder::encode(PropertyContainer & property_container, uint8_t * data, size_t const size, bool lightPayload)
+#include <iostream>
+CborError CBOREncoder::encode(PropertyContainer & property_container, uint8_t * data, size_t const size, int & bytes_encoded, bool lightPayload)
 {
+  CborError error = CborNoError;
   CborEncoder encoder, arrayEncoder;
 
   cbor_encoder_init(&encoder, data, size, 0);
 
-  if (cbor_encoder_create_array(&encoder, &arrayEncoder, CborIndefiniteLength) != CborNoError)
-    return -1;
+  error = cbor_encoder_create_array(&encoder, &arrayEncoder, CborIndefiniteLength);
+  if (CborNoError != error)
+    return error;
 
   /* Check if backing storage and cloud has diverged
    * time interval may be elapsed or property may be changed
    * and if that's the case encode the property into the CBOR.
    */
-  CborError err = CborNoError;
+  int num_encoded_properties = 0;
   std::for_each(property_container.begin(),
                 property_container.end(),
-                [lightPayload, &arrayEncoder, &err](Property * p)
+                [lightPayload, &arrayEncoder, &error, &num_encoded_properties](Property * p)
                 {
                   if (p->shouldBeUpdated() && p->isReadableByCloud())
                   {
-                    err = p->append(&arrayEncoder, lightPayload);
-                    if(err != CborNoError)
+                    error = p->append(&arrayEncoder, lightPayload);
+                    if(error == CborNoError)
+                      num_encoded_properties++;
+                    else
                       return;
                   }
                 });
-  if ((err != CborNoError) && (err != CborErrorOutOfMemory))
-    return -1;
+  if ((CborNoError != error) && 
+      (CborErrorOutOfMemory != error))
+    return error;
 
+  error = cbor_encoder_close_container(&encoder, &arrayEncoder);
+  if (CborNoError != error)
+    return error;
 
-  if (cbor_encoder_close_container(&encoder, &arrayEncoder) != CborNoError)
-    return -1;
+  if (num_encoded_properties > 0)
+    bytes_encoded = cbor_encoder_get_buffer_size(&encoder, data);
+  else
+    bytes_encoded = 0;
 
-  int const bytes_encoded = cbor_encoder_get_buffer_size(&encoder, data);
-  return bytes_encoded;
+  return CborNoError;
 }

src/cbor/CBOREncoder.h

@@ -35,7 +35,7 @@ class CBOREncoder
 
     /* encode return > 0 if a property has changed and encodes the changed properties in CBOR format into the provided buffer */
     /* if lightPayload is true the integer identifier of the property will be encoded in the message instead of the property name in order to reduce the size of the message payload*/
-    static int encode(PropertyContainer & property_container, uint8_t * data, size_t const size, bool lightPayload = false);
+    static CborError encode(PropertyContainer & property_container, uint8_t * data, size_t const size, int & bytes_encoded, bool lightPayload = false);
 
 private: