documented Variant Visitor rate class

Author: awegrzyn

examples/4-RateDerivedMetric.cxx

@@ -16,7 +16,7 @@ int main(int argc, char *argv[]) {
   Monitoring::Get().addDerivedMetric("myMetric", AliceO2::Monitoring::DerivedMetricMode::RATE);
 
   // now send at least two metrics to see the result
-  for (int i = 0; i < 101; i+=10) {
+  for (int i = 0; i < 101; i += 10) {
     Monitoring::Get().send(i, "myMetric");
     std::this_thread::sleep_for(std::chrono::milliseconds(250));
   }

src/Backends/InfluxDB.cxx

@@ -71,7 +71,7 @@ void InfluxDB::send(const Metric& metric)
 
   std::stringstream convert;
   convert << name << "," << tagSet << metricTags << " value=" << value << " " << convertTimestamp(metric.getTimestamp());
-  
+
   try {
     transport->send(convert.str());
   } catch (MonitoringInternalException&) {

src/DerivedMetrics.cxx

@@ -61,7 +61,7 @@ Metric DerivedMetrics::calculateRate(std::string name)
     throw MonitoringInternalException("DerivedMetrics/Calculate rate", "Division by 0");
   }
 
-  boost::variant< int, std::string, double, int64_t > rate =  boost::apply_visitor(VariantVisitor(timestampCount), current, previous);
+  boost::variant< int, std::string, double, int64_t > rate =  boost::apply_visitor(VariantVisitorRate(timestampCount), current, previous);
   return Metric{rate, name + "Rate"};
 }
 

src/VariantVisitorRate.h

@@ -4,29 +4,38 @@ namespace AliceO2
 namespace Monitoring 
 {
 
-class VariantVisitor : public boost::static_visitor<boost::variant<int, std::string, double, int64_t>>
+class VariantVisitorRate : public boost::static_visitor<boost::variant<int, std::string, double, int64_t>>
 {
 private:
+  /// Timestamp difference in milliseconds
   int timestampCount;
+
 public:
-  VariantVisitor(int count) {
-    timestampCount = count;
+  /// Creates variant visitor functor
+  /// \param count  timestamp difference in milliseconds
+  VariantVisitorRate(int count) : timestampCount(count) {
   }
 
+  /// Overloads operator() to avoid operating on strings
+  /// \throws MonitoringInternalException
   boost::variant<int, std::string, double, int64_t> operator()(const std::string& a, const std::string& b) const {
-    std::cout << "skipping string" << std::endl;
+    throw MonitoringInternalException("DerivedMetrics/VariantRateVisitor", "Cannot operate on string values");
   }
 
+  /// Calculates rate only when two arguments of the same type are passed
+  /// \return calculated rate in Hz
   template<typename T>
   boost::variant<int, std::string, double, int64_t> operator()(const T& a, const T& b) const {
     return (1000*(a - b)) / timestampCount;
   }
 
+  /// If arguments have different type an exception is raised
+  /// \throws MonitoringInternalException
   template<typename T, typename U>
   boost::variant<int, std::string, double, int64_t> operator()(const T& a, const U& b) const {
-    throw std::invalid_argument("can't operate on different types");
+    throw MonitoringInternalException("DerivedMetrics/VariantRateVisitor", "Cannot operate on different types");
   }
 };
 
-}
-}
+} // namespace Monitoring
+} // namespace AliceO2