libdcdb: adding group queries in SensorDataStore

- overloaded query() and fuzzyQuery() methods that allow to query a set
of sensor IDs at the same time
- also changed the behavior of fuzzuQuery(): only one query is performed
now, retrieving the most recent value BEFORE the specified timestamp

lib/include/dcdb/sensordatastore.h

@@ -158,6 +158,18 @@ public:
      */
     void query(std::list<SensorDataStoreReading>& result, SensorId& sid, TimeStamp& start, TimeStamp& end, QueryAggregate aggregate=AGGREGATE_NONE);
 
+    /**
+     * @brief This function queries a the values of
+     *        a set of sensors in the given time range.
+     *        The weekstamp being used is in this case that of the sensor ID 
+     *        at the front of the input list.
+     * @param result   The list where the results will be stored.
+     * @param sids     The list of SensorIds to query.
+     * @param start    Start of the time series.
+     * @param end      End of the time series.
+     */
+    void query(std::list<SensorDataStoreReading>& result, std::list<SensorId>& sids, TimeStamp& start, TimeStamp& end, QueryAggregate aggregate=AGGREGATE_NONE);
+    
     /**
      * @brief This function performs a fuzzy query and returns the 
      *        closest sensor reading to the input timestamp.
@@ -168,6 +180,18 @@ public:
      */
     void fuzzyQuery(std::list<SensorDataStoreReading>& result, SensorId& sid, TimeStamp& ts, uint64_t tol_ns=10000000000);
 
+    /**
+     * @brief This function performs a fuzzy query and returns the closest 
+     *        sensor reading to the input timestamp, one per queried sensor.
+     *        The weekstamp being used is in this case that of the sensor ID 
+     *        at the front of the input list.
+     * @param result   The list where the results will be stored.
+     * @param sids     The list of SensorIds to query.
+     * @param ts       The target timestamp.
+     * @param tol_ns   Tolerance of the fuzzy query in nanoseconds.
+     */
+    void fuzzyQuery(std::list<SensorDataStoreReading>& result, std::list<SensorId>& sids, TimeStamp& ts, uint64_t tol_ns=10000000000);
+
     typedef void (*QueryCbFunc)(SensorDataStoreReading& reading, void* userData);
     /**
      * @brief This function queries a sensor's values in

lib/include_internal/sensordatastore_internal.h

@@ -40,6 +40,8 @@
 #include "dcdb/sensordatastore.h"
 #include "dcdb/connection.h"
 
+#define QUERY_GROUP_LIMIT 1000
+
 namespace DCDB {
 static std::string const AggregateString[] = {"", "min", "max", "avg", "sum", "count"};
 
@@ -119,7 +121,7 @@ public:
   void setDebugLog(bool dl);
 
   /**
-   * @brief This function querie a sensor's values in
+   * @brief This function queries a sensor's values in
    *        the given time range.
    * @param result   The list where the results will be stored.
    * @param sid      The SensorId to query.
@@ -128,7 +130,19 @@ public:
    */
   void query(std::list<SensorDataStoreReading>& result, SensorId& sid, TimeStamp& start, TimeStamp& end, QueryAggregate aggregate);
 
-   /**
+  /**
+   * @brief This function queries a the values of
+   *        a set of sensors in the given time range.
+   *        The weekstamp being used is in this case that 
+   *        of the sensor ID at the front of the input list.
+   * @param result   The list where the results will be stored.
+   * @param sids     The list of SensorIds to query.
+   * @param start    Start of the time series.
+   * @param end      End of the time series.
+   */
+  void query(std::list<SensorDataStoreReading>& result, std::list<SensorId>& sids, TimeStamp& start, TimeStamp& end, QueryAggregate aggregate);
+
+  /**
    * @brief This function performs a fuzzy query and returns the 
    *        closest sensor reading to the input timestamp.
    * @param result   The list where the results will be stored.
@@ -136,7 +150,19 @@ public:
    * @param ts       The target timestamp.
    * @param tol_ns   Tolerance of the fuzzy query in nanoseconds.
    */
-   void fuzzyQuery(std::list<SensorDataStoreReading>& result, SensorId& sid, TimeStamp& ts, uint64_t tol_ns=10000000000);
+  void fuzzyQuery(std::list<SensorDataStoreReading>& result, SensorId& sid, TimeStamp& ts, uint64_t tol_ns=10000000000);
+   
+  /**
+   * @brief This function performs a fuzzy query and returns the closest 
+   *        sensor reading to the input timestamp, one per queried sensor.
+   *        The weekstamp being used is in this case that of the sensor ID 
+   *        at the front of the input list.
+   * @param result   The list where the results will be stored.
+   * @param sids     The list of SensorIds to query.
+   * @param ts       The target timestamp.
+   * @param tol_ns   Tolerance of the fuzzy query in nanoseconds.
+   */
+  void fuzzyQuery(std::list<SensorDataStoreReading>& result, std::list<SensorId>& sids, TimeStamp& ts, uint64_t tol_ns=10000000000);
 
   /**
    * @brief This function queries a sensor's values in