Fix issue with returning string_view (#215)

Author: awegrzyn

examples/2-TaggedMetrics.cxx

@@ -24,4 +24,6 @@ int main()
   // then add predefined tag
   monitoring->send(Metric{10, "myMetric"}.addTag(tags::Key::Detector, tags::Value::ACO));
   monitoring->send(Metric{10, "myMetric"}.addTag(tags::Key::CRU, 0));
+  monitoring->send(Metric{10, "myMetric"}.addTag(tags::Key::CRU, 12));
+  monitoring->send(Metric{10, "myMetric"}.addTag(tags::Key::CRU, 1234));
 }

include/Monitoring/Tags.h

@@ -154,7 +154,7 @@ static constexpr std::array<std::string_view, 39> TAG_VALUE = {{
 
 static constexpr std::string_view GetValue(const int value)
 {
-  return value > 0 ? TAG_VALUE[value] : std::to_string(0 - value);
+  return TAG_VALUE[value];
 }
 
 } // namespace tags

src/Backends/ApMonBackend.cxx

@@ -66,7 +66,7 @@ void ApMonBackend::send(const Metric& metric)
     entity += ',';
     entity += tags::TAG_KEY[key];
     entity += '=';
-    entity += tags::GetValue(value);
+    (value > 0) ? entity += tags::GetValue(value) : entity += std::to_string(0 - value);
   }
 
   int valueSize = metric.getValuesSize();

src/Backends/InfluxDB.cxx

@@ -89,7 +89,8 @@ std::string InfluxDB::toInfluxLineProtocol(const Metric& metric)
   convert << name << "," << tagSet;
 
   for (const auto& [key, value] : metric.getTags()) {
-    convert << "," << tags::TAG_KEY[key] << "=" << tags::GetValue(value);
+    convert << "," << tags::TAG_KEY[key] << "=";
+    (value > 0) ? convert << tags::GetValue(value) : convert << (0 - value);
   }
   convert << ' ';
   for (const auto& [name, value] : metric.getValues()) {

src/Backends/StdOut.cxx

@@ -65,26 +65,27 @@ void StdOut::send(std::vector<Metric>&& metrics)
 
 void StdOut::send(const Metric& metric)
 {
-  std::ostringstream mStream;
-  mStream << "[" << mPrefix << "] "  << metric.getName();
+  std::ostringstream convert;
+  convert << "[" << mPrefix << "] "  << metric.getName();
   for (auto& value : metric.getValues()) {
     auto stringValue = std::visit(overloaded{
       [](const std::string& value) -> std::string { return value; },
       [](auto value) -> std::string { return std::to_string(value); }
     }, value.second);
     if (metric.getValuesSize() == 1) {
-      mStream << ',' << metric.getFirstValueType() << ' ' << stringValue;
+      convert << ',' << metric.getFirstValueType() << ' ' << stringValue;
     } else {
-      mStream << ' ' << value.first << '=' << stringValue;
+      convert << ' ' << value.first << '=' << stringValue;
     }
   }
-  mStream << ' ' << convertTimestamp(metric.getTimestamp()) << ' ' << tagString;
+  convert << ' ' << convertTimestamp(metric.getTimestamp()) << ' ' << tagString;
 
   for (const auto& [key, value] : metric.getTags()) {
-    mStream << ',' << tags::TAG_KEY[key] << "=" << tags::GetValue(value);
+    convert << ',' << tags::TAG_KEY[key] << "=";
+    (value > 0) ? convert << tags::GetValue(value) : convert << (0 - value);
   }
-  mStream << '\n';
-  std::cout << mStream.str();
+  convert << '\n';
+  std::cout << convert.str();
 }
 
 } // namespace backends