feat(sim): Allow branch registration in FairGenerator

examples/simulation/rutherford/macros/CMakeLists.txt

@@ -13,7 +13,7 @@ set(maxTestTime 60)
 
 foreach(mcEngine IN LISTS mcEngine_list)
   add_test(NAME ex_sim_rutherford_${mcEngine}
-           COMMAND ${CMAKE_CURRENT_BINARY_DIR}/run_rutherford.sh 10 \"${mcEngine}\")
+           COMMAND ${CMAKE_CURRENT_BINARY_DIR}/run_rutherford.sh 10 \"${mcEngine}\" false)
   set_tests_properties(ex_sim_rutherford_${mcEngine} PROPERTIES
     TIMEOUT ${maxTestTime}
     PASS_REGULAR_EXPRESSION "Macro finished successfully"

fairroot/base/sim/FairMCApplication.cxx

@@ -92,7 +92,6 @@ FairMCApplication::FairMCApplication(const char* name, const char* title, TObjAr
     , fMC(nullptr)
     , fRun(FairRunSim::Instance())
     , fSaveCurrentEvent(kTRUE)
-    , fState(FairMCApplicationState::kUnknownState)
     , fRunInfo()
     , fGeometryIsInitialized(kFALSE)
     , fOwnedModules()
@@ -153,7 +152,6 @@ FairMCApplication::FairMCApplication(const FairMCApplication& rhs, std::unique_p
     , listDetectors()
     , fMC(nullptr)
     , fSaveCurrentEvent(kTRUE)
-    , fState(FairMCApplicationState::kUnknownState)
     , fRunInfo()
     , fGeometryIsInitialized(kFALSE)
     , fOwnedModules()
@@ -227,7 +225,6 @@ FairMCApplication::FairMCApplication()
     , listDetectors()
     , fMC(nullptr)
     , fSaveCurrentEvent(kTRUE)
-    , fState(FairMCApplicationState::kUnknownState)
     , fRunInfo()
     , fGeometryIsInitialized(kFALSE)
     , fOwnedModules()
@@ -283,12 +280,17 @@ void FairMCApplication::InitMC(const char*, const char*)
         fTrajFilter = std::make_unique<FairTrajFilter>();
     }
 
+    InitFinalizer();
+    fState = FairMCApplicationState::kPostInit;
+
     LOG(info) << "Monte Carlo Engine Initialisation with: " << MCName.Data();
 }
 
 //_____________________________________________________________________________
 void FairMCApplication::RunMC(Int_t nofEvents)
 {
+    fState = FairMCApplicationState::kRun;
+
     // Reset the time for FairRunInfo. Otherwise the time of the
     // first event will include the time needed for initilization.
     fRunInfo.Reset();
@@ -459,7 +461,6 @@ void FairMCApplication::InitOnWorker()
         std::lock_guard guard(mtx);
         fRootManager->InitSink();
         RegisterOutput();
-        fRootManager->WriteFolder();
     }
 
     // Cache thread-local gMC
@@ -469,6 +470,8 @@ void FairMCApplication::InitOnWorker()
     fMC->SetStack(fStack.get());
     fMC->SetMagField(fxField);
 
+    InitFinalizer();
+
     LOG(info) << "Monte Carlo Engine Worker Initialisation  with: " << fMC->GetName();
 }
 
@@ -634,8 +637,8 @@ void FairMCApplication::FinishEvent()
     LOG(debug) << "[" << fRootManager->GetInstanceId()
                << " FairMCMCApplication::FinishEvent: " << fMCEventHeader->GetEventID() << " (MC "
                << gMC->CurrentEvent() << ")";
-    if (gMC->IsMT()
-        && fRun->GetSink()->GetSinkType() == kONLINESINK) {   // fix the rare case when running G4 multithreaded on MQ
+    if (gMC->IsMT() && fRun->GetSink()->GetSinkType() == kONLINESINK)
+    {   // fix the rare case when running G4 multithreaded on MQ
         fMCEventHeader->SetEventID(gMC->CurrentEvent() + 1);
     }
 
@@ -817,7 +820,7 @@ void FairMCApplication::ConstructGeometry()
 
     gGeoManager->RefreshPhysicalNodes(kFALSE);
 
-    fState = FairMCApplicationState::kUnknownState;
+    fState = FairMCApplicationState::kInit;
 }
 
 // ____________________________________________________________________________
@@ -831,6 +834,8 @@ Bool_t FairMCApplication::MisalignGeometry()
 //_____________________________________________________________________________
 void FairMCApplication::InitGeometry()
 {
+    if (FairMCApplicationState::kInit != fState)
+        LOG(fatal) << "InitGeometry possible in kInit state only";
     fState = FairMCApplicationState::kInitGeometry;
 
     LOG(info) << "FairMCApplication::InitGeometry: " << fRootManager->GetInstanceId();
@@ -868,16 +873,9 @@ void FairMCApplication::InitGeometry()
     /// save Geo Params in Output file
     if (fRootManager && !fParent) {
         RegisterOutput();
-
-        /**Tasks has to be initialized here, they have access to the detector branches and still can create objects in
-         * the tree*/
-        /// There is always a Main Task  !
-        /// so .. always a InitTasks() is called <D.B>
-        if (fFairTaskList) {
-            InitTasks();
+        if (GetIsMT()) {
+            fRootManager->RemoveOutputFolderForMtMode();
         }
-
-        fRootManager->WriteFolder();
     }
     fMCEventHeader->SetRunID(runId);
 
@@ -921,7 +919,26 @@ void FairMCApplication::InitGeometry()
 
     fGeometryIsInitialized = kTRUE;
 
-    fState = FairMCApplicationState::kUnknownState;
+    fState = FairMCApplicationState::kInit;
+}
+
+//_____________________________________________________________________________
+void FairMCApplication::InitFinalizer()
+{
+    /** Initialize the event generator */
+    if (fEvGen) {
+        fEvGen->Init();
+    }
+    /**Tasks has to be initialized here, they have access to the detector branches and still can create objects in
+     * the tree*/
+    if (fFairTaskList) {
+        InitTasks();
+    }
+    {
+        std::lock_guard guard(mtx);
+        fRootManager->WriteFolder();
+        fRootManager->RemoveOutputFolderForMtMode();
+    }
 }
 
 //_____________________________________________________________________________
@@ -1009,10 +1026,6 @@ void FairMCApplication::AddIons()
                       << pdgDatabase->GetParticle(ion->GetName())->PdgCode();
         }
     }
-    /** Initialize the event generator */
-    if (fEvGen) {
-        fEvGen->Init();
-    }
 }
 //_____________________________________________________________________________
 void FairMCApplication::AddParticles()

fairroot/base/sim/FairMCApplication.h

@@ -1,5 +1,5 @@
 /********************************************************************************
- * Copyright (C) 2014-2023 GSI Helmholtzzentrum fuer Schwerionenforschung GmbH  *
+ * Copyright (C) 2014-2024 GSI Helmholtzzentrum fuer Schwerionenforschung GmbH  *
  *                                                                              *
  *              This software is distributed under the terms of the             *
  *              GNU Lesser General Public Licence (LGPL) version 3,             *
@@ -46,9 +46,12 @@ class TTask;
 
 enum class FairMCApplicationState
 {
-    kUnknownState,
+    kPreInit,
     kConstructGeometry,
-    kInitGeometry
+    kInit,
+    kInitGeometry,
+    kPostInit,
+    kRun
 };
 
 /**
@@ -88,8 +91,7 @@ class FairMCApplication : public TVirtualMCApplication
     /** Add user defined ions (optional)
         Called by TVirtualMC.
         TGeant3 calls AddIons() first, then InitGeometry().
-        TGeant4 calls InitGeometry() first, then AddIons().
-        This function also initializes event generators.*/
+        TGeant4 calls InitGeometry() first, then AddIons().*/
     void AddIons() override;   // MC Application
     /**
      *Add user defined Tasks to be executed after each event (optional)
@@ -127,8 +129,7 @@ class FairMCApplication : public TVirtualMCApplication
     /** Initialize geometry
         Called by TVirtualMC.
         TGeant3 calls AddIons() first, then InitGeometry().
-        TGeant4 calls InitGeometry() first, then AddIons().
-        This function also registers detectors.*/
+        TGeant4 calls InitGeometry() first, then AddIons().*/
     void InitGeometry() override;   // MC Application
     /** Initialize MC engine */
     void InitMC(const char* setup, const char* cuts);
@@ -241,6 +242,11 @@ class FairMCApplication : public TVirtualMCApplication
 
     /** Register output */
     void RegisterOutput();
+    /** Finalize the init stage:
+        initialize event generator,
+        initialize tasks,
+        write output folder.*/
+    void InitFinalizer();
 
     void UndoGeometryModifications();
 
@@ -320,7 +326,7 @@ class FairMCApplication : public TVirtualMCApplication
     Bool_t fSaveCurrentEvent;
 
     /** Current state */
-    FairMCApplicationState fState;   //!
+    FairMCApplicationState fState{FairMCApplicationState::kPreInit};   //!
 
     ClassDefOverride(FairMCApplication, 5);
 

fairroot/base/sink/FairRootFileSink.cxx

@@ -245,9 +245,6 @@ void FairRootFileSink::WriteFolder()
         fOutTree = new TTree(FairRootManager::GetTreeName(), Form("/%s", FairRootManager::GetFolderName()), 99);
         TruncateBranchNames();
         CreatePersistentBranchesAny();
-
-        // Delete the folder to make place in the gROOT for fOutFolder created by the Geant4MT threads
-        gROOT->GetRootFolder()->Remove(fOutFolder);
     }
 }
 

fairroot/base/steer/FairRootManager.cxx

@@ -38,6 +38,7 @@
 #include <TNamed.h>
 #include <TObjArray.h>    // for TObjArray
 #include <TObjString.h>   // for TObjString
+#include <TROOT.h>        // for gROOT
 #include <TTree.h>        // for TTree
 #include <algorithm>      // for find
 #include <atomic>
@@ -221,8 +222,8 @@ TClonesArray* FairRootManager::Register(TString branchName, TString className, T
 
 TClonesArray* FairRootManager::GetEmptyTClonesArray(TString branchName)
 {
-    if (fActiveContainer.find(branchName)
-        != fActiveContainer.end()) {               // if a TClonesArray is registered in the active container
+    if (fActiveContainer.find(branchName) != fActiveContainer.end())
+    {                                              // if a TClonesArray is registered in the active container
         if (fActiveContainer[branchName] == 0) {   // the address of the TClonesArray is still valid
             std::cout << "-E- FairRootManager::GetEmptyTClonesArray: Container deleted outside FairRootManager!"
                       << std::endl;
@@ -383,6 +384,12 @@ void FairRootManager::WriteFolder()
     }
 }
 
+void FairRootManager::RemoveOutputFolderForMtMode()
+{
+    auto rootFolder = static_cast<TFolder*>(gROOT->GetRootFolder());
+    rootFolder->Remove(rootFolder->FindObject(GetFolderName()));
+}
+
 Bool_t FairRootManager::SpecifyRunId()
 {
     if (!fSource) {

fairroot/base/steer/FairRootManager.h

@@ -18,12 +18,12 @@
 #include <TRefArray.h>   // for TRefArray
 #include <TString.h>     // for TString, operator<
 #include <fairlogger/Logger.h>
+#include <list>
 #include <map>   // for map, multimap, etc
 #include <memory>
 #include <string>
 #include <type_traits>   // is_pointer, remove_pointer, is_const, remove...
 #include <typeinfo>
-#include <list>
 
 class BinaryFunctor;
 class FairEventHeader;
@@ -218,6 +218,11 @@ class FairRootManager : public TObject
     void WriteFileHeader(FairFileHeader* f);
     /**Write the folder structure used to create the tree to the output file */
     void WriteFolder();
+    /**
+     * \brief Internal: Remove the folder describing the output tree structure from gROOT, called in TGeant4 MT
+     * simulation mode
+     */
+    void RemoveOutputFolderForMtMode();
 
     /**Check the maximum event number we can run to*/
     Int_t CheckMaxEventNo(Int_t EvtEnd = 0);

fairroot/base/steer/FairRunSim.h

@@ -226,6 +226,12 @@ class FairRunSim : public FairRun
   private:
     FairRunSim(const FairRunSim& M);
     FairRunSim& operator=(const FairRunSim&) { return *this; }
+    /**
+     * Performs simulation initialization:
+     * - runs simulation config (construct TGeant3/TGeant4, configure TGeant3/TGeant4, create stack),
+     * - runs FairMCApplication->InitMC() (set stack, run fMC->Init(), run fMC->BuildPhysics()),
+     * - runs postinit config (sets some VMC properties, which are only allowed after init).
+     */
     void SetMCConfig();
     void CheckFlukaExec();