Make O2DatabasePDG::Instance() thread-safe and remove duplicate PDG warnings

Author: jackal1-66

DataFormats/simulation/include/SimulationDataFormat/O2DatabasePDG.h

@@ -34,12 +34,13 @@ class O2DatabasePDG
  public:
   static TDatabasePDG* Instance()
   {
-    static bool initialized = false; // initialize this --> adds particles to TDatabasePDG;
-    auto db = TDatabasePDG::Instance();
-    if (!initialized) {
+    // adds the ALICE particles to TDatabasePDG on first use.
+    // Initialisation is done through a local static database to make the Instance() function thread-safe
+    static TDatabasePDG* db = [] {
+      auto db = TDatabasePDG::Instance();
       addALICEParticles(db);
-      initialized = true;
-    }
+      return db;
+    }();
     return db;
   }
 

Detectors/gconfig/data/extra_ions_pdg_table.dat

@@ -706,7 +706,6 @@
  1352 W174                  1000741740 1 100 Ion  222 1.61992e+02 0.00000e+00 0 0 0 -1 0 0
  1353 Hg198                 1000801980 1 100 Ion  240 1.84365e+02 0.00000e+00 0 0 0 -1 0 0
  1354 Pd115                 1000461150 1 100 Ion  138 1.07018e+02 0.00000e+00 0 0 0 -1 0 0
- 1355 Li4                   1000030040 1 100 Ion  9 3.74977e+00 0.00000e+00 0 0 0 -1 0 0
  1356 Lu170                 1000711700 1 100 Ion  213 1.58261e+02 0.00000e+00 0 0 0 -1 0 0
  1357 Ho163                 1000671630 1 100 Ion  201 1.51733e+02 0.00000e+00 0 0 0 -1 0 0
  1358 Tm153                 1000691530 1 100 Ion  207 1.42430e+02 0.00000e+00 0 0 0 -1 0 0

Generators/src/GeneratorFactory.cxx

@@ -60,11 +60,6 @@ namespace eventgen
 // using the configured GeneratorExternalParam. This makes the simulation parallelisation automatic
 // on Hyperloop.
 // To-do: Define the behaviour with ini configuration which are already definining a hybrid gen
-//
-// Note on GeneratorHybrid.num_workers: expanding to 8 sub-generators does not by itself raise
-// the number of TBB workers that actually run them in parallel. This is controlled by
-// the parameter GeneratorHybrid.num_workers. On Hyperloop this will be part
-// of the standard train configuration
 std::string buildHyperloopExternalHybridConfig(GeneratorExternalParam const& extparams)
 {
   rapidjson::Document doc;
@@ -89,12 +84,10 @@ std::string buildHyperloopExternalHybridConfig(GeneratorExternalParam const& ext
   doc.AddMember("generators", generators, alloc);
   doc.AddMember("fractions", fractions, alloc);
 
-  // The generated config file is deliberatelly left on disk for possible inspection after the process ran.
   std::string path = "hyperloop_exttohybrid_" + std::to_string(getpid()) + ".json";
   std::ofstream ofs(path);
   if (!ofs.is_open()) {
     LOG(fatal) << "Failed to open " << path << " for writing the Hyperloop hybrid generator configuration";
-    exit(1);
   }
   rapidjson::OStreamWrapper osw(ofs);
   rapidjson::Writer<rapidjson::OStreamWrapper> writer(osw);
@@ -140,7 +133,7 @@ void GeneratorFactory::setPrimaryGenerator(o2::conf::SimConfig const& conf, Fair
 
   /** generators **/
 
-  o2::O2DatabasePDG::addALICEParticles(TDatabasePDG::Instance());
+  o2::O2DatabasePDG::Instance(); //--> ALICE particles are added once in this call
   auto genconfig = conf.getGenerator();
 #if defined(GENERATORS_WITH_PYTHIA8) && defined(GENERATORS_WITH_HEPMC3)
   std::string hyperloopExtHybridConfigFile; // set when IS_HYPERLOOP is defined