Cleanups.

DCDBLib/include/c_api.h

@@ -25,6 +25,7 @@ typedef enum {
   DCDB_C_OK,
   DCDB_C_CONNERR,
   DCDB_C_SENSORNOTFOUND,
+  DCDB_C_EMPTYSET,
   DCDB_C_UNKNOWN
 } DCDB_C_RESULT;
 

DCDBLib/include/sensordatastore.h

@@ -24,6 +24,11 @@
 #ifndef SENSORDATASTORE_H_
 #define SENSORDATASTORE_H_
 
+typedef enum {
+  SDS_OK,
+  SDS_EMPTYSET
+} SDSQueryResult;
+
 /* Forward-declaration of the implementation-internal classes */
 class SensorDataStoreImpl;
 
@@ -89,8 +94,9 @@ public:
      * @param sid      The SensorId to query.
      * @param start    Start of the time series.
      * @param end      End of the time series.
+     * @return         SDS_OK if ok, SDS_EMPTYSET if not at least 2 readings in interval.
      */
-    void querySum(int64_t& result, SensorId sid, DCDBTimeStamp start, DCDBTimeStamp end);
+    SDSQueryResult querySum(int64_t& result, SensorId sid, DCDBTimeStamp start, DCDBTimeStamp end);
 
     /**
      * @brief A shortcut constructor for a SensorDataStore object

DCDBLib/include_internal/sensordatastore_internal.h

@@ -70,8 +70,9 @@ public:
    * @param sid      The SensorId to query.
    * @param start    Start of the time series.
    * @param end      End of the time series.
+   * @return         SDS_OK if ok, SDS_EMPTYSET if not at least 2 readings in interval.
    */
-  void querySum(int64_t& result, SensorId sid, DCDBTimeStamp start, DCDBTimeStamp end);
+  SDSQueryResult querySum(int64_t& result, SensorId sid, DCDBTimeStamp start, DCDBTimeStamp end);
 
   /**
    * @brief This is the standard constructor of the SensorDataStoreImpl class.

DCDBLib/src/c_api.cpp

@@ -81,7 +81,11 @@ DCDB_C_RESULT dcdbQuerySum(
   /* Iterate over the expanded list of sensorIds and sum up the results */
   for (std::list<SensorId>::iterator sit = sensorIds.begin(); sit != sensorIds.end(); sit++) {
       int64_t tmp_result = 0;
-      sensorDataStore.querySum(tmp_result, *sit, start, end);
+      if (sensorDataStore.querySum(tmp_result, *sit, start, end) == SDS_EMPTYSET) {
+          /* In case there is no reading for this sensor, invalidate everything */
+          *result = 0;
+          return DCDB_C_EMPTYSET;
+      }
       *result += tmp_result;
   }
 

DCDBLib/src/sensordatastore.cpp

@@ -233,13 +233,17 @@ void SensorDataStoreImpl::query(std::list<SensorDataStoreReading>& result, Senso
  * by first querying for the result set list using query() and then
  * summing up the result.
  */
-void SensorDataStoreImpl::querySum(int64_t& result, SensorId sid, DCDBTimeStamp start, DCDBTimeStamp end)
+SDSQueryResult SensorDataStoreImpl::querySum(int64_t& result, SensorId sid, DCDBTimeStamp start, DCDBTimeStamp end)
 {
   std::list<SensorDataStoreReading> queryResult;
 
   /* Issue a standard query */
   query(queryResult, sid, start, end);
 
+  /* Check if at least 2 readings in result */
+  if (queryResult.size() < 2)
+    return SDS_EMPTYSET;
+
   /* Integrate the result */
   result = 0;
 
@@ -268,6 +272,7 @@ void SensorDataStoreImpl::querySum(int64_t& result, SensorId sid, DCDBTimeStamp
       }
       prev = *it;
   }
+  return SDS_OK;
 }
 
 /**
@@ -337,9 +342,9 @@ void SensorDataStore::query(std::list<SensorDataStoreReading>& result, SensorId
  * forwards to the insert function of the SensorDataStoreImpl
  * class.
  */
-void SensorDataStore::querySum(int64_t& result, SensorId sid, DCDBTimeStamp start, DCDBTimeStamp end)
+SDSQueryResult SensorDataStore::querySum(int64_t& result, SensorId sid, DCDBTimeStamp start, DCDBTimeStamp end)
 {
-    impl->querySum(result, sid, start, end);
+    return impl->querySum(result, sid, start, end);
 }
 
 /**