Allow for using aggregate functions in queries

lib/include/dcdb/sensor.h

@@ -20,7 +20,7 @@ namespace DCDB {
     public:
       Sensor(DCDB::Connection* connection, std::string publicName);
       virtual ~Sensor();
-      void query(std::list<SensorDataStoreReading>& reading, TimeStamp& start, TimeStamp& end);
+      void query(std::list<SensorDataStoreReading>& reading, TimeStamp& start, TimeStamp& end, QueryAggregate aggregate = AGGREGATE_NONE);
 
       double getScalingFactor() const {
         return scalingFactor;

lib/include/dcdb/sensordatastore.h

@@ -50,6 +50,15 @@ typedef enum {
   SDS_OK,
   SDS_EMPTYSET
 } SDSQueryResult;
+  
+typedef enum {
+  AGGREGATE_NONE = 0,
+  AGGREGATE_MIN,
+  AGGREGATE_MAX,
+  AGGREGATE_AVG,
+  AGGREGATE_SUM,
+  AGGREGATE_COUNT
+} QueryAggregate;
 
 /* Forward-declaration of the implementation-internal classes */
 class SensorDataStoreImpl;
@@ -107,7 +116,7 @@ public:
      * @param start    Start of the time series.
      * @param end      End of the time series.
      */
-    void query(std::list<SensorDataStoreReading>& result, SensorId& sid, TimeStamp& start, TimeStamp& end);
+    void query(std::list<SensorDataStoreReading>& result, SensorId& sid, TimeStamp& start, TimeStamp& end, QueryAggregate aggregate=AGGREGATE_NONE);
 
     typedef void (*QueryCbFunc)(SensorDataStoreReading& reading, void* userData);
     /**
@@ -119,7 +128,7 @@ public:
      * @param start    Start of the time series.
      * @param end      End of the time series.
      */
-    void queryCB(QueryCbFunc cbFunc, void* userData, SensorId& sid, TimeStamp& start, TimeStamp& end);
+    void queryCB(QueryCbFunc cbFunc, void* userData, SensorId& sid, TimeStamp& start, TimeStamp& end, QueryAggregate aggregate=AGGREGATE_NONE);
 
     /**
      * @brief This function queries the integrated value (val * sec)

lib/include_internal/sensordatastore_internal.h

@@ -40,7 +40,8 @@
 #include "dcdb/connection.h"
 
 namespace DCDB {
-
+static std::string const AggregateString[] = {"", "min", "max", "avg", "sum", "count"};
+  
 /**
  * @brief The SensorDataStoreImpl class contains all protected
  *        functions belonging to SensorDataStore which are
@@ -82,7 +83,7 @@ public:
    * @param start    Start of the time series.
    * @param end      End of the time series.
    */
-  void query(std::list<SensorDataStoreReading>& result, SensorId& sid, TimeStamp& start, TimeStamp& end);
+  void query(std::list<SensorDataStoreReading>& result, SensorId& sid, TimeStamp& start, TimeStamp& end, QueryAggregate aggregate);
 
   /**
    * @brief This function queries a sensor's values in
@@ -93,7 +94,7 @@ public:
    * @param start    Start of the time series.
    * @param end      End of the time series.
    */
-  void queryCB(SensorDataStore::QueryCbFunc cbFunc, void* userData, SensorId& sid, TimeStamp& start, TimeStamp& end);
+  void queryCB(SensorDataStore::QueryCbFunc cbFunc, void* userData, SensorId& sid, TimeStamp& start, TimeStamp& end, QueryAggregate aggregate);
 
   /**
    * @brief This function queries the integrated value

lib/src/sensor.cpp

@@ -38,7 +38,7 @@ namespace DCDB {
     delete sensorConfig;
   }
 
-  void Sensor::query(std::list<SensorDataStoreReading>& result, TimeStamp& start, TimeStamp& end) {
+  void Sensor::query(std::list<SensorDataStoreReading>& result, TimeStamp& start, TimeStamp& end, QueryAggregate aggregate) {
     SensorDataStore sensorDataStore(connection);
 
     if (publicSensor.is_virtual) {
@@ -61,7 +61,7 @@ namespace DCDB {
 
         /* Iterate over the expanded list of sensorIds and output the results in CSV format */
         for (std::list<SensorId>::iterator sit = sensorIds.begin(); sit != sensorIds.end(); sit++) {
-            sensorDataStore.query(result, *sit, start, end);
+            sensorDataStore.query(result, *sit, start, end, aggregate);
         }
 
         if (scalingFactor != 1.0 || publicSensor.scaling_factor != 1.0) {

lib/src/sensordatastore.cpp

@@ -145,7 +145,7 @@ void SensorDataStoreImpl::insert(SensorId* sid, uint64_t ts, int64_t value)
   cass_statement_bind_bytes_by_name(statement, "sid", (cass_byte_t*)(key.c_str()), 16);
   cass_statement_bind_int64_by_name(statement, "ts", ts);
   cass_statement_bind_int64_by_name(statement, "value", value);
-
+  
   future = cass_session_execute(session, statement);
   cass_future_wait(future);
 
@@ -174,15 +174,21 @@ void SensorDataStoreImpl::setTTL(uint64_t ttl)
  * and creates a SensorDataStoreReading object for each
  * entry which is stored in the result list.
  */
-void SensorDataStoreImpl::query(std::list<SensorDataStoreReading>& result, SensorId& sid, TimeStamp& start, TimeStamp& end)
+void SensorDataStoreImpl::query(std::list<SensorDataStoreReading>& result, SensorId& sid, TimeStamp& start, TimeStamp& end, QueryAggregate aggregate)
 {
   CassError rc = CASS_OK;
   CassStatement* statement = NULL;
   CassFuture *future = NULL;
   const CassPrepared* prepared = nullptr;
-  const char* query = "SELECT * FROM " KEYSPACE_NAME "." CF_SENSORDATA " WHERE sid = ? AND ts >= ? AND ts <= ? ;";
-
-  future = cass_session_prepare(session, query);
+  
+  std::string query = std::string("SELECT ts,");
+  if (aggregate == AGGREGATE_NONE) {
+    query.append("value");
+  } else {
+    query.append(AggregateString[aggregate] + std::string("(value) as value"));
+  }
+  query.append(" FROM " KEYSPACE_NAME "." CF_SENSORDATA " WHERE sid = ? AND ts >= ? AND ts <= ? ;");
+  future = cass_session_prepare(session, query.c_str());
   cass_future_wait(future);
 
   rc = cass_future_error_code(future);
@@ -198,7 +204,7 @@ void SensorDataStoreImpl::query(std::list<SensorDataStoreReading>& result, Senso
   const std::string key = sid.serialize();
 
 #if 0
-  std::cout << "Query: " << query << std::endl << "sid: " << key << " ts1: " << start.getRaw() << " ts2: " << end.getRaw() << std::endl;
+  std::cout << "Query: " << query << std::endl << "sid: " << sid.toString() << " ts1: " << start.getRaw() << " ts2: " << end.getRaw() << std::endl;
 #endif
 
   statement = cass_prepared_bind(prepared);
@@ -253,15 +259,21 @@ void SensorDataStoreImpl::query(std::list<SensorDataStoreReading>& result, Senso
  * This function issues a regular query to the data store
  * and calls cbFunc for every reading.
  */
-void SensorDataStoreImpl::queryCB(SensorDataStore::QueryCbFunc cbFunc, void* userData, SensorId& sid, TimeStamp& start, TimeStamp& end)
+void SensorDataStoreImpl::queryCB(SensorDataStore::QueryCbFunc cbFunc, void* userData, SensorId& sid, TimeStamp& start, TimeStamp& end, QueryAggregate aggregate)
 {
   CassError rc = CASS_OK;
   CassStatement* statement = NULL;
   CassFuture *future = NULL;
   const CassPrepared* prepared = nullptr;
-  const char* query = "SELECT * FROM " KEYSPACE_NAME "." CF_SENSORDATA " WHERE sid = ? AND ts >= ? AND ts <= ? ;";
-
-  future = cass_session_prepare(session, query);
+  
+  std::string query = std::string("SELECT ts,");
+  if (aggregate == AGGREGATE_NONE) {
+    query.append("value");
+  } else {
+    query.append(AggregateString[aggregate] + std::string("(value) as value"));
+  }
+  query.append(" FROM " KEYSPACE_NAME "." CF_SENSORDATA " WHERE sid = ? AND ts >= ? AND ts <= ? ;");
+  future = cass_session_prepare(session, query.c_str());
   cass_future_wait(future);
 
   rc = cass_future_error_code(future);
@@ -323,7 +335,7 @@ SDSQueryResult SensorDataStoreImpl::querySum(int64_t& result, SensorId& sid, Tim
   std::list<SensorDataStoreReading> queryResult;
 
   /* Issue a standard query */
-  query(queryResult, sid, start, end);
+  query(queryResult, sid, start, end, AGGREGATE_NONE);
 
   /* Check if at least 2 readings in result */
   if (queryResult.size() < 2)
@@ -514,9 +526,9 @@ void SensorDataStore::setTTL(uint64_t ttl)
  * forwards to the insert function of the SensorDataStoreImpl
  * class.
  */
-void SensorDataStore::query(std::list<SensorDataStoreReading>& result, SensorId& sid, TimeStamp& start, TimeStamp& end)
+void SensorDataStore::query(std::list<SensorDataStoreReading>& result, SensorId& sid, TimeStamp& start, TimeStamp& end, QueryAggregate aggregate)
 {
-    impl->query(result, sid, start, end);
+    impl->query(result, sid, start, end, aggregate);
 }
 
 /**
@@ -525,9 +537,9 @@ void SensorDataStore::query(std::list<SensorDataStoreReading>& result, SensorId&
  * forwards to the insert function of the SensorDataStoreImpl
  * class.
  */
-void SensorDataStore::queryCB(SensorDataStore::QueryCbFunc cbFunc, void* userData, SensorId& sid, TimeStamp& start, TimeStamp& end)
+void SensorDataStore::queryCB(SensorDataStore::QueryCbFunc cbFunc, void* userData, SensorId& sid, TimeStamp& start, TimeStamp& end, QueryAggregate aggregate)
 {
-    return impl->queryCB(cbFunc, userData, sid, start, end);
+    return impl->queryCB(cbFunc, userData, sid, start, end, aggregate);
 }
 
 /**