[OMON-503] Add possibility to increase metric value (#269)

Author: awegrzyn

include/Monitoring/Metric.h

@@ -97,6 +97,11 @@ class Metric
   /// \param name
   Metric&& addValue(const std::variant<int, std::string, double, uint64_t>& value, const std::string& name);
 
+  /// Increases metric value by provided value
+  /// \param value   value that metric will be increased
+  /// \param name    value name
+  Metric&& increaseValue(const std::variant<int, std::string, double, uint64_t>& value, const std::string& name = "value");
+
   /// Default destructor
   ~Metric() = default;
 

src/Metric.cxx

@@ -15,6 +15,7 @@
 ///
 
 #include "Monitoring/Metric.h"
+#include "VariantVisitorAdd.h"
 
 #include <iostream>
 #include <chrono>
@@ -76,6 +77,20 @@ Metric&& Metric::addValue(uint64_t value, const std::string& name)
   return std::move(*this);
 }
 
+Metric&& Metric::increaseValue(const std::variant<int, std::string, double, uint64_t>& value, const std::string& name)
+{
+    auto find = std::find_if(
+      mValues.begin(), mValues.end(),
+      [&](std::pair<std::string, std::variant<int, std::string, double, uint64_t>>& el) { return el.first == name; }
+    );
+    if (find != mValues.end()) {
+      find->second = std::visit(VariantVisitorAdd{}, find->second, value);
+    } else {
+      addValue(value, name);
+    }
+    return std::move(*this);
+}
+
 Metric&& Metric::addValue(std::string value, const std::string& name)
 {
   mValues.push_back({name, value});

src/VariantVisitorAdd.h

@@ -10,6 +10,7 @@
 // or submit itself to any jurisdiction.
 
 #include <variant>
+#include "Exceptions/MonitoringException.h"
 
 namespace o2
 {

test/testMetric.cxx

@@ -151,6 +151,24 @@ BOOST_AUTO_TEST_CASE(retrieveUnsignedLongLongType)
   BOOST_CHECK_EQUAL(metricInstance.getFirstValueType(), 3);
 }
 
+BOOST_AUTO_TEST_CASE(increaseMetric)
+{
+  Metric metric = Metric{10, "myMetric"};
+  metric.increaseValue(20);
+  BOOST_CHECK_EQUAL(std::get<int>(metric.getFirstValue().second), 30);
+
+  Metric metric2 = Metric{"myValue"};
+  metric2.addValue(3, "sum");
+  metric2.increaseValue(10, "sum");
+  BOOST_CHECK_EQUAL(std::get<int>(metric2.getFirstValue().second), 13);
+
+  Metric metric3 = Metric{"summed"};
+  for (int i = 0; i < 5; i++) {
+    metric3.increaseValue(i);
+  }
+  BOOST_CHECK_EQUAL(std::get<int>(metric3.getFirstValue().second), 10);
+}
+
 BOOST_AUTO_TEST_CASE(regexVerbosityPolicy)
 {
   Metric::setVerbosityPolicy(Verbosity::Prod, std::regex("myMetric", std::regex::optimize));