[OMON-327] Provide metric type as int in StdOut backend (#194)

* Provide metric type as int in StdOut backend

* Add metric type tests

Author: awegrzyn

include/Monitoring/Metric.h

@@ -143,6 +143,9 @@ class Metric
   /// Whether timestamp should be included or not
   static bool includeTimestamp;
 
+  /// This is required for backward compability with boost::variant and old StdOut format
+  int getFirstValueType() const;
+
  protected:
   /// Allow DerivedMetrics access to setTags
   friend class o2::monitoring::DerivedMetrics;

src/Backends/StdOut.cxx

@@ -72,7 +72,7 @@ void StdOut::send(const Metric& metric)
       [](auto value) -> std::string { return std::to_string(value); }
     }, value.second);
     if (metric.getValuesSize() == 1) {
-      mStream << ",0 " << stringValue;
+      mStream << ',' << metric.getFirstValueType() << ' ' << stringValue;
     } else {
       mStream << ' ' << value.first << '=' << stringValue;
     }

src/Metric.cxx

@@ -159,6 +159,18 @@ std::size_t Metric::getValuesSize() const noexcept
   return mValues.size();
 }
 
+int Metric::getFirstValueType() const
+{
+  if (std::holds_alternative<int>(mValues.front().second))
+    return 0;
+  else if (std::holds_alternative<std::string>(mValues.front().second))
+    return 1;
+  else if (std::holds_alternative<double>(mValues.front().second))
+    return 2;
+  else
+    return 3;
+}
+
 bool Metric::includeTimestamp = true;
 Verbosity Metric::DefaultVerbosity = Verbosity::Info;
 std::map<std::underlying_type<Verbosity>::type, std::regex> Metric::mRegexPolicy;

test/testMetric.cxx

@@ -111,6 +111,46 @@ BOOST_AUTO_TEST_CASE(tags)
   BOOST_CHECK_EQUAL(sum, 45);
 }
 
+BOOST_AUTO_TEST_CASE(retrieveIntType)
+{
+  int value = 10;
+  std::string name("metric name");
+  Metric metricInstance(value, name);
+
+  BOOST_CHECK_EQUAL(std::get<int>(metricInstance.getFirstValue().second), 10);
+  BOOST_CHECK_EQUAL(metricInstance.getFirstValueType(), 0);
+}
+
+BOOST_AUTO_TEST_CASE(retrieveDoubleType)
+{
+  double value = 1.11;
+  std::string name("metric name");
+  Metric metricInstance(value, name);
+
+  BOOST_CHECK_EQUAL(std::get<double>(metricInstance.getFirstValue().second), 1.11);
+  BOOST_CHECK_EQUAL(metricInstance.getFirstValueType(), 2);
+}
+
+BOOST_AUTO_TEST_CASE(retrieveStringType)
+{
+  std::string value = "testString";
+  std::string name("metric name");
+  Metric metricInstance(value, name);
+
+  BOOST_CHECK_EQUAL(std::get<std::string>(metricInstance.getFirstValue().second), "testString");
+  BOOST_CHECK_EQUAL(metricInstance.getFirstValueType(), 1);
+}
+
+BOOST_AUTO_TEST_CASE(retrieveUnsignedLongLongType)
+{
+  uint64_t value = 10000000000000LL;
+  std::string name("metric name");
+  Metric metricInstance(value, name);
+
+  BOOST_CHECK_EQUAL(std::get<uint64_t>(metricInstance.getFirstValue().second), 10000000000000LL);
+  BOOST_CHECK_EQUAL(metricInstance.getFirstValueType(), 3);
+}
+
 BOOST_AUTO_TEST_CASE(regexVerbosityPolicy)
 {
   Metric::setVerbosityPolicy(Verbosity::Prod, std::regex("myMetric", std::regex::optimize));