o2-sim: Better VMC shutdown (via plugin code)

Introducing the ability to close/terminate the
VMC simulation engines.

* for instance to print final statistics about
  steps, magnetic field calls etc.

Detectors/gconfig/g4Config.C

@@ -133,3 +133,17 @@ void Config()
 
   std::cout << "g4Config.C finished" << std::endl;
 }
+
+void Terminate()
+{
+  static bool terminated = false;
+  if (!terminated) {
+    std::cout << "Executing G4 terminate\n";
+    TGeant4* geant4 = dynamic_cast<TGeant4*>(TVirtualMC::GetMC());
+    if (geant4) {
+      // we need to call finish run for Geant4 ... Since we use ProcessEvent() interface;
+      geant4->FinishRun();
+    }
+    terminated = true;
+  }
+}

Detectors/gconfig/include/SimSetup/SimSetup.h

@@ -10,11 +10,15 @@
 // or submit itself to any jurisdiction.
 
 #ifndef O2_SIMSETUP_H
+#define O2_SIMSETUP_H
 
 namespace o2
 {
 struct SimSetup {
   static void setup(const char* engine);
+
+  // a static entrypoint to shutdown the VMC system
+  static void shutdown();
 };
 } // namespace o2
 

Detectors/gconfig/src/G4Config.cxx

@@ -29,16 +29,23 @@ using std::endl;
 // these are used in commonConfig.C
 using o2::eventgen::DecayerPythia8;
 
+#include "../g4Config.C"
+
 namespace o2
 {
 namespace g4config
 {
-#include "../g4Config.C"
 
 void G4Config()
 {
   LOG(info) << "Setting up G4 sim from library code";
   Config();
 }
+
+void G4Terminate()
+{
+  Terminate();
+}
+
 } // namespace g4config
 } // namespace o2

Detectors/gconfig/src/SimSetup.cxx

@@ -11,6 +11,7 @@
 
 #include <cstring>
 #include "SimSetup/SimSetup.h"
+#include "TVirtualMC.h"
 #include <fairlogger/Logger.h>
 #include "SetCuts.h"
 #include <dlfcn.h>
@@ -25,9 +26,8 @@ namespace o2
 
 typedef void (*setup_fnc)();
 
-void setupFromPlugin(const char* libname, const char* setupfuncname)
+void execFromPlugin(const char* libname, const char* funcname)
 {
-  LOG(info) << "Loading simulation plugin " << libname;
   auto libHandle = dlopen(libname, RTLD_NOW);
   // try to make the library loading a bit more portable:
   if (!libHandle) {
@@ -43,26 +43,43 @@ void setupFromPlugin(const char* libname, const char* setupfuncname)
     libHandle = dlopen(stream.str().c_str(), RTLD_NOW);
   }
   assert(libHandle);
-  auto setup = (setup_fnc)dlsym(libHandle, setupfuncname);
-  assert(setup);
-  setup();
+  auto func = (setup_fnc)dlsym(libHandle, funcname);
+  assert(func);
+  func();
+}
+
+void execSetupFromPlugin(const char* libname, const char* funcname)
+{
+  LOG(info) << "Seting up transport engine from library " << libname;
+  execFromPlugin(libname, funcname);
 }
 
 void SimSetup::setup(const char* engine)
 {
   if (strcmp(engine, "TGeant3") == 0) {
-    setupFromPlugin("libO2G3Setup", "_ZN2o28g3config8G3ConfigEv");
+    execSetupFromPlugin("libO2G3Setup", "_ZN2o28g3config8G3ConfigEv");
   } else if (strcmp(engine, "TGeant4") == 0) {
-    setupFromPlugin("libO2G4Setup", "_ZN2o28g4config8G4ConfigEv");
+    execSetupFromPlugin("libO2G4Setup", "_ZN2o28g4config8G4ConfigEv");
   } else if (strcmp(engine, "TFluka") == 0) {
-    setupFromPlugin("libO2FLUKASetup", "_ZN2o211flukaconfig11FlukaConfigEv");
+    execSetupFromPlugin("libO2FLUKASetup", "_ZN2o211flukaconfig11FlukaConfigEv");
   } else if (strcmp(engine, "MCReplay") == 0) {
-    setupFromPlugin("libO2MCReplaySetup", "_ZN2o214mcreplayconfig14MCReplayConfigEv");
+    execSetupFromPlugin("libO2MCReplaySetup", "_ZN2o214mcreplayconfig14MCReplayConfigEv");
   } else if (strcmp(engine, "O2TrivialMCEngine") == 0) {
-    setupFromPlugin("libO2O2TrivialMCEngineSetup", "_ZN2o223o2trivialmcengineconfig23O2TrivialMCEngineConfigEv");
+    execSetupFromPlugin("libO2O2TrivialMCEngineSetup", "_ZN2o223o2trivialmcengineconfig23O2TrivialMCEngineConfigEv");
   } else {
     LOG(fatal) << "Unsupported engine " << engine;
   }
   o2::SetCuts();
 }
+
+// function to shutdown the engines and do some necessary
+// finalisation work
+void SimSetup::shutdown()
+{
+  auto vmc = TVirtualMC::GetMC();
+  if (strcmp(vmc->GetName(), "TGeant4") == 0) {
+    execFromPlugin("libO2G4Setup", "_ZN2o28g4config11G4TerminateEv");
+  }
+}
+
 } // namespace o2

run/O2SimDeviceRunner.cxx

@@ -12,6 +12,7 @@
 /// @author Sandro Wenzel
 
 #include "O2SimDevice.h"
+#include "SimSetup/SimSetup.h"
 #include <fairmq/DeviceRunner.h>
 #include <boost/program_options.hpp>
 #include <memory>
@@ -66,7 +67,7 @@ void sigaction_handler(int signal, siginfo_t* signal_info, void*)
         break;
       }
     }
-
+    o2::SimSetup::shutdown();
     _exit(0);
   }
 
@@ -177,6 +178,7 @@ int runSim(KernelSetup setup)
   while (setup.sim->Kernel(setup.workerID, *setup.primchannel, *setup.datachannel, setup.primstatuschannel)) {
   }
   doLogInfo(setup.workerID, "simulation is done");
+  o2::SimSetup::shutdown();
   return 0;
 }