From 5b35618604c09ccb1d14f261c4c3de01784fc20b Mon Sep 17 00:00:00 2001
From: Adam Wegrzynek <awegrzyn@users.noreply.github.com>
Date: Thu, 8 Aug 2019 11:44:59 +0200
Subject: [PATCH] Reset rate to 0 when new run starts (#159)

---
 src/DerivedMetrics.cxx | 17 ++++++++++++++++-
 test/testDerived.cxx   | 25 ++++++++++++++++++++++++-
 2 files changed, 40 insertions(+), 2 deletions(-)

diff --git a/src/DerivedMetrics.cxx b/src/DerivedMetrics.cxx
index 46b277d95..f4b61c738 100644
--- a/src/DerivedMetrics.cxx
+++ b/src/DerivedMetrics.cxx
@@ -19,11 +19,17 @@
 #include <map>
 #include <memory>
 #include <string>
-#include <variant>
 #include <vector>
 #include "VariantVisitorAdd.h"
 #include "VariantVisitorRate.h"
 
+template <class... Ts>
+struct overloaded : Ts... {
+  using Ts::operator()...;
+};
+template <class... Ts>
+overloaded(Ts...)->overloaded<Ts...>;
+
 namespace o2
 {
 /// ALICE O2 Monitoring system
@@ -82,6 +88,15 @@ Metric DerivedMetrics::process(Metric& metric, DerivedMetricMode mode)
        auto previous = search->second.getValue();
        auto rate = std::visit(VariantVisitorRate(timestampCount), current, previous);
 
+       // handle situation when a new run starts
+       auto isZero = std::visit(overloaded{
+                                  [](auto arg) { return arg == 0; },
+                                  [](const std::string& arg) { return arg == ""; }},
+                                current);
+       if (rate < 0 && isZero) {
+         rate = 0;
+       }
+
        // swap metrics
        mStorage.erase(key);
        mStorage.insert(std::make_pair(key, metric));
diff --git a/test/testDerived.cxx b/test/testDerived.cxx
index a49f03af8..fca73a867 100644
--- a/test/testDerived.cxx
+++ b/test/testDerived.cxx
@@ -51,6 +51,29 @@ BOOST_AUTO_TEST_CASE(derivedRateInt)
   }
 }
 
+BOOST_AUTO_TEST_CASE(derivedRateInt_newRun)
+{
+  struct RateResults {
+    int value;
+    int rate;
+  };
+  std::vector<RateResults> results = {{10, 0}, {20, 100}, {30, 100}, {50, 200}, {0, 0}, {10, 100}, {20, 100}, {30, 100}, {50, 200}};
+  o2::monitoring::DerivedMetrics derivedHandler;
+  std::string name("metricInt");
+
+  for (auto const result : results) {
+    try {
+      std::this_thread::sleep_for(std::chrono::milliseconds(100));
+      o2::monitoring::Metric metric(result.value, name);
+      o2::monitoring::Metric derived = derivedHandler.process(metric, DerivedMetricMode::RATE);
+      BOOST_CHECK_EQUAL(derived.getName(), "metricIntRate");
+      BOOST_WARN_CLOSE(std::get<double>(derived.getValue()), result.rate, 1.0);
+    } catch (MonitoringException& e) {
+      BOOST_CHECK_EQUAL(e.what(), std::string("Not enough values"));
+    }
+  }
+}
+
 BOOST_AUTO_TEST_CASE(derivedRateDouble)
 {
   struct RateResults {
@@ -70,7 +93,7 @@ BOOST_AUTO_TEST_CASE(derivedRateDouble)
       o2::monitoring::Metric derivedTagged = derivedHandler.process(metricTagged, DerivedMetricMode::RATE);
       BOOST_CHECK_EQUAL(derived.getName(), "metricDoubleRate");
       BOOST_WARN_CLOSE(std::get<double>(derived.getValue()), results[i].rate, 1.0);
-      BOOST_WARN_CLOSE(std::get<double>(derivedTagged.getValue()), resultsTagged[i].rate, 5.0);
+      BOOST_WARN_CLOSE(std::get<double>(derivedTagged.getValue()), resultsTagged[i].rate, 1.0);
     } catch (MonitoringException& e) {
       BOOST_CHECK_EQUAL(e.what(), std::string("Not enough values"));
     }