Merge branch 'SimulationEnergiesThreadSafetyPt1_21.0' into '21.0'

Replace static bool variables with std::call_once (ATLASSIM-3568)

See merge request atlas/athena!9651

Calorimeter/CaloG4Sim/src/SimulationEnergies.cc

@@ -120,7 +120,10 @@
 #include "G4TouchableHistory.hh"
 
 #include "G4ios.hh"
+#include <mutex>
 
+static std::once_flag warning1OnceFlag;
+static std::once_flag warning2OnceFlag;
 
 namespace CaloG4
 {
@@ -564,17 +567,13 @@ namespace CaloG4
       }
 
       // If we get here, the registry was never initialized for LAr.
-      // FIXME: thread-unsafe statics!!!
-      static G4bool errorDisplayed = false;
-      if ( ! errorDisplayed ) {
-        errorDisplayed = true;
-        G4cout << "SimulationEnergies::ProcessEscapedEnergy - " << G4endl
-               << "   WARNING! CaloG4::EscapedEnergyRegistry was never initialized for 'LArG4::'" << G4endl
-               << "   and LArG4Sim is the package with the code that handles CalibrationHits" << G4endl
-               << "   in non-sensitive volumes.  Not all energies deposited in this simulation" << G4endl
-               << "   will be recorded." << G4endl;
-      }
-
+      std::call_once(warning1OnceFlag, [](){
+          G4cout << "SimulationEnergies::ProcessEscapedEnergy - " << G4endl
+                 << "   WARNING! CaloG4::EscapedEnergyRegistry was never initialized for 'LArG4::'" << G4endl
+                 << "   and LArG4Sim is the package with the code that handles CalibrationHits" << G4endl
+                 << "   in non-sensitive volumes.  Not all energies deposited in this simulation" << G4endl
+                 << "   will be recorded." << G4endl;
+        });
       return false;
     }
     else {
@@ -588,17 +587,14 @@ namespace CaloG4
       }
 
       // If we get here, the registry was never initialized for LAr.
-      // FIXME: thread-unsafe statics!!!
-      static G4bool errorDisplayed1 = false;
-      if ( ! errorDisplayed1 ) {
-        errorDisplayed1 = true;
-        G4cout << "SimulationEnergies::ProcessEscapedEnergy - " << G4endl
-               <<"   WARNING! touchableHandle->GetVolume()==0  geometry problem ?  and also" << G4endl
-               << "   WARNING! CaloG4::EscapedEnergyRegistry was never initialized for 'LArG4::'" << G4endl
-               << "   and LArG4Sim is the package with the code that handles CalibrationHits" << G4endl
-               << "   in non-sensitive volumes.  Not all energies deposited in this simulation" << G4endl
-               << "   will be recorded." << G4endl;
-      }
+      std::call_once(warning2OnceFlag, [](){
+          G4cout << "SimulationEnergies::ProcessEscapedEnergy - " << G4endl
+                 <<"   WARNING! touchableHandle->GetVolume()==0  geometry problem ?  and also" << G4endl
+                 << "   WARNING! CaloG4::EscapedEnergyRegistry was never initialized for 'LArG4::'" << G4endl
+                 << "   and LArG4Sim is the package with the code that handles CalibrationHits" << G4endl
+                 << "   in non-sensitive volumes.  Not all energies deposited in this simulation" << G4endl
+                 << "   will be recorded." << G4endl;
+        });
       return false;
     }
   }