Add a sensor property cache to speed up evaluation of virtual sensors by ~25%.

DCDBLib/include_internal/sensorconfig_internal.h

@@ -7,6 +7,7 @@
 
 #include <list>
 #include <string>
+#include <unordered_map>
 
 #include "cassandra.h"
 
@@ -27,6 +28,9 @@ protected:
   Connection* connection;
   CassSession* session;
 
+  typedef std::unordered_map<std::string, PublicSensor> SensorPropertyCache_t;
+  static SensorPropertyCache_t sensorPropertyCache;
+
   bool validateSensorPattern(const char* sensorPattern);
   bool validateSensorPublicName(std::string publicName);
 

DCDBLib/src/sensorconfig.cpp

@@ -11,6 +11,7 @@
 #include <string>
 #include <list>
 #include <unordered_set>
+#include <utility>
 
 #include "cassandra.h"
 
@@ -150,8 +151,9 @@ SensorConfig::~SensorConfig()
 }
 
 /*
- * SensorConfigImpl protected functions
+ * SensorConfigImpl protected members and functions
  */
+SensorConfigImpl::SensorPropertyCache_t SensorConfigImpl::sensorPropertyCache;
 
 /*
  * Validate the pattern for a Sensor to be published
@@ -600,6 +602,14 @@ SCError SensorConfigImpl::getPublicSensorsVerbose(std::list<PublicSensor>& publi
 
 SCError SensorConfigImpl::getPublicSensorByName(PublicSensor& sensor, const char* publicName)
 {
+  /* Check if the sensor definition is already in the cache */
+  SensorPropertyCache_t::const_iterator got = sensorPropertyCache.find(publicName);
+  if (got != sensorPropertyCache.end()) {
+      sensor = got->second;
+      return SC_OK;
+  }
+
+  /* Not in cache - query the data base */
   /* Check if the session is valid */
   if (!session) {
       return SC_INVALIDSESSION;
@@ -702,6 +712,8 @@ SCError SensorConfigImpl::getPublicSensorByName(PublicSensor& sensor, const char
           sensor.t_zero = tzero;
           sensor.frequency = frequency;
 
+          /* Add to sensorPropertyCache for later use */
+          sensorPropertyCache.insert(std::make_pair(publicName, sensor));
       }
       else {
           cass_result_free(result);