Common: improve reference run handling in checker (#2376)

* [Common] only verify the reference run validity when checking single plots

A valid reference run is not needed when checking canvas objects, because
the reference plot is already embedded in the canvas and does not need
to be retrieved again from QCDB

* [Common] cache reference plots in checker

The reference plots are retrieved only once the first time the corresponding
object is checked, and cached for all subsequent checks until the start
of a new activity.

* [Common] clang formatting

Author: aferrero2707

Modules/Common/include/Common/ReferenceComparatorCheck.h

@@ -22,6 +22,7 @@
 #include "Common/ObjectComparatorInterface.h"
 
 #include <sstream>
+#include <unordered_map>
 
 class TPaveText;
 
@@ -56,6 +57,7 @@ class ReferenceComparatorCheck : public o2::quality_control::checker::CheckInter
   std::map<std::string, std::shared_ptr<TPaveText>> mQualityLabels;
   quality_control::core::Activity mActivity /*current*/, mReferenceActivity;
   size_t mReferenceRun;
+  std::unordered_map<std::string, std::shared_ptr<MonitorObject>> mReferencePlots;
 };
 
 } // namespace o2::quality_control_modules::common

Modules/Common/src/ReferenceComparatorCheck.cxx

@@ -63,6 +63,9 @@ void ReferenceComparatorCheck::startOfActivity(const Activity& activity)
   mActivity = activity;
   mReferenceActivity = activity;
   mReferenceActivity.mId = mReferenceRun;
+
+  // clear the cache of reference plots
+  mReferencePlots.clear();
 }
 
 void ReferenceComparatorCheck::endOfActivity(const Activity& activity)
@@ -149,8 +152,18 @@ Quality ReferenceComparatorCheck::getSinglePlotQuality(std::shared_ptr<MonitorOb
 
   // get path of mo and ref (we have to remove the provenance)
   std::string path = RepoPathUtils::getPathNoProvenance(mo);
-  // todo we could cache the reference plot within a run
-  auto referencePlot = retrieveReference(path, mReferenceActivity);
+
+  if (mReferenceRun == 0) {
+    message = "No reference run provided";
+    return Quality::Null;
+  }
+
+  // retrieve the reference plot only once and cache it for later use
+  if (mReferencePlots.count(path) == 0) {
+    mReferencePlots[path] = retrieveReference(path, mReferenceActivity);
+  }
+
+  auto referencePlot = mReferencePlots[path];
   if (!referencePlot) {
     message = "Reference plot not found";
     return Quality::Null;
@@ -172,11 +185,6 @@ Quality ReferenceComparatorCheck::check(std::map<std::string, std::shared_ptr<Mo
 {
   Quality result = Quality::Null;
 
-  if (mReferenceRun == 0) {
-    result.addFlag(FlagTypeFactory::Unknown(), "No reference run provided");
-    return result;
-  }
-
   for (auto& [key, mo] : *moMap) {
     auto moName = mo->getName();
     Quality quality;