TruthParticleCnvTool.cxx

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/*
  Copyright (C) 2002-2026 CERN for the benefit of the ATLAS collaboration
*/

// TruthParticleCnvTool.cxx 
// Implementation file for class TruthParticleCnvTool
// Author: S.Binet<binet@cern.ch>
//         P.A Delsart <delsart in2p3 dot fr> (pile-up compatibility)
 
// STL includes
#include <sstream>
 
// FrameWork includes
#include "GaudiKernel/ThreadLocalContext.h"
 
// CLHEP/HepMC includes
#include "AtlasHepMC/GenEvent.h"
#include "AtlasHepMC/GenParticle.h"
#include "AtlasHepMC/GenVertex.h"
#include "AtlasHepMC/Polarization.h"
#include "TruthUtils/HepMCHelpers.h"
 
// McParticleKernel includes
#include "McParticleKernel/ITruthIsolationTool.h"
 
// McParticleEvent includes
#include "McParticleEvent/TruthParticle.h"
 
// McParticleTools includes
#include "TruthParticleCnvTool.h"
 
// GeneratorObjects includes
#include "GeneratorObjects/HepMcParticleLink.h"
 


TruthParticleCnvTool::TruthParticleCnvTool( const std::string& type, 
                        const std::string& name, 
                        const IInterface* parent ) : 
  base_class( type, name, parent ),
  m_dataType         ( ParticleDataType::True ),
  m_vxCandidatesName ( ),
  m_selectSignalTypeProp ( 0 )
{
  //
  // Property declaration
  // 
  
  declareProperty( "DataType", 
           m_dataType_int = 4,
           "Type of data we are dealing with (Full/Fast/Truth...)" );
 
  declareProperty( "TruthIsolationTool",
           m_isolationTool = IsolTool_t( "TruthIsolationTool" ),
           "Pointer to the TruthIsolationTool to be able to compute "
           "transverse energy isolations for various isolation cones cuts. "
           "See McParticleEvent/TruthParticleParameters.h for cone cuts." );
 
 
  declareProperty( "DoEtIsolations",
           m_doEtIsolation = false,
           "Switch to compute or not the Et-isolations for TruthParticle "
           "(and their underlying @c HepMC::GenParticle).\n"
           "Default is to not compute these Et-isolations (and save CPU)." );
 
  setDataType( m_dataType_int );
 
  declareProperty( "SelectSignalType",
           m_selectSignalTypeProp,
           "Switch to select different type of signal\n"
           " hard scatter               0\n"
           " hard scatter plus minbias  1\n" 
           " only minbias              -1\n" 
           "Default is hard scatter only." );
 
  declareInterface<ITruthParticleCnvTool>(this);
}

TruthParticleCnvTool::~TruthParticleCnvTool()
{ 
  ATH_MSG_DEBUG("Calling destructor");
}

StatusCode TruthParticleCnvTool::initialize()
{
  ATH_MSG_INFO("Initializing " << name() << "...");
 
  // retrieve the TruthIsolation tool only if asked for.
  if ( m_doEtIsolation.value() ) {
    ATH_CHECK(m_isolationTool.retrieve());
  }
  else {
    m_isolationTool.disable();
  }
 
  //initialize DataHandleKeys
  ATH_CHECK(m_mcPartsOutputWriteHandleKey.initialize());
  ATH_CHECK(m_mcEventsReadHandleKey.initialize());
 
  // for compatibility with earlier version we accept <0 values :
  if(m_selectSignalTypeProp<0) m_selectSignalType = PileUpClassification::ALLMINBIAS;
  else m_selectSignalType = (PileUpClassification::PileuType_t) m_selectSignalTypeProp;
  
 
  ATH_MSG_INFO
    (" DoEtIsolations:       [" << std::boolalpha 
     << m_doEtIsolation.value() << "]" << endmsg
     << " McEvents:             [" << m_mcEventsReadHandleKey.key() << "]" << endmsg
     << " TruthParticlesOutput: [" << m_mcPartsOutputWriteHandleKey.key() << "]"
     << endmsg
     << " SelectSignalType:     [" << m_selectSignalType << "]");
 
  return StatusCode::SUCCESS;
}
 
StatusCode TruthParticleCnvTool::execute() const
{
  return execute (Gaudi::Hive::currentContext());
}
 
 
StatusCode TruthParticleCnvTool::execute (const EventContext& ctx) const
{  
  ATH_MSG_DEBUG("Executing " << name() << "...");
 
  //Setup WriteHandle, and record new TruthParticleContainer
  SG::WriteHandle<TruthParticleContainer> mcPartsOutputWriteHandle(m_mcPartsOutputWriteHandleKey, ctx);
  ATH_CHECK(mcPartsOutputWriteHandle.record(std::make_unique<TruthParticleContainer>()));  
  
  if (!mcPartsOutputWriteHandle.isValid()){
    ATH_MSG_ERROR("Invalid WriteHandle for TruthParticleContainer with key: " << m_mcPartsOutputWriteHandleKey.key());
    return StatusCode::FAILURE;
  }
 
  //Setup ReadHandle for input McEventCollection
  SG::ReadHandle<McEventCollection> mcEventsReadHandle(m_mcEventsReadHandleKey, ctx);
 
  if (!mcEventsReadHandle.isValid()){
     ATH_MSG_WARNING("Invalid ReadHandle for McEventCollection with key ["
             << m_mcEventsReadHandleKey.key() << "] !!"
             << endmsg
             << "TruthParticleContainer [" << m_mcPartsOutputWriteHandleKey.key()
             << "] will be EMPTY !!");
     return StatusCode::RECOVERABLE;
  }
  
  ATH_MSG_DEBUG(" Found McEventCollection of size = "<< mcEventsReadHandle->size() );
  // do the actual convertion (it is merely an interface adaptation now...)
  //  selection for particles from minbias copied from the JetsFromTruthTool
 
  std::size_t genEventIndex = 0;
  const ITruthParticleVisitor* dummyVisitor = nullptr;
  bool all_good = true;
 
  McEventCollection::const_iterator fEvt = mcEventsReadHandle->begin();
  McEventCollection::const_iterator lEvt = mcEventsReadHandle->end();
  PileUpClassification::findEventIterators(m_selectSignalType, fEvt,lEvt);
 
  ATH_MSG_DEBUG(" Found McEventCollection iterators : "<< (fEvt-mcEventsReadHandle->begin()) << " to "<< (lEvt-mcEventsReadHandle->begin()) );
 
  for(McEventCollection::const_iterator it=fEvt ; it != lEvt; ++it){
    const HepMC::GenEvent* evt = *it;
    // there are holes in a McEventCollection when pile-up is enabled
    // so deal with it
    if (nullptr == evt) {
      continue;
    }
    genEventIndex = (it - mcEventsReadHandle->begin());
    ATH_MSG_DEBUG(" adding event id="<< HepMC::signal_process_id(evt)<<"  genEventIndex="<< genEventIndex );
 
    if( HepMC::signal_process_id(evt) == 0 ) continue;
    if (!this->convert( mcEventsReadHandle.ptr(), genEventIndex, mcPartsOutputWriteHandle.ptr(), dummyVisitor ).isSuccess()) {
      ATH_MSG_DEBUG("Failed to convert an event...");
      all_good = false;
    }
  }
 
  // VERY IMPORTANT ! Reset the index to the first GenEvent included
  // in this TruthParticleContainer. This will be used when read back from disk.
  mcPartsOutputWriteHandle->setGenEvent( mcEventsReadHandle.ptr(), (fEvt - mcEventsReadHandle->begin() ) );
 
  
  return all_good 
    ? StatusCode::SUCCESS
    : StatusCode::RECOVERABLE;
}
 

 
StatusCode
TruthParticleCnvTool::convert( const McEventCollection * mcCollection, 
                               const unsigned int genEventIndex,
                               TruthParticleContainer * container,
                               const ITruthParticleVisitor* visitor ) const 
{
  ATH_MSG_DEBUG("Converting McEventCollection to TruthParticleContainer");
 
  
  if ( nullptr == mcCollection ) {
    ATH_MSG_WARNING("Null pointer to McEventCollection !");
    return StatusCode::RECOVERABLE;
  }
 
  if ( mcCollection->size() <= genEventIndex ) {
    ATH_MSG_WARNING("McEventCollection size: " << mcCollection->size() 
            << endmsg
            << "Requested element nbr : " << genEventIndex << " !!");
    return StatusCode::RECOVERABLE;
  }
 
  const EventContext& ctx = Gaudi::Hive::currentContext();

  ATH_MSG_DEBUG("Retrieve the GenEvent from given McEventCollection");
  const HepMC::GenEvent * evt = (*mcCollection)[genEventIndex];
  container->setGenEvent( mcCollection, genEventIndex, ctx );
 
  // reserve enough space for the container so we don't have to relocate it
  container->reserve( container->size() + evt->particles_size() );

  TruthParticleContainer::Map_t bcToMcPart = container->m_particles;
 
  
  // Process particles in barcode order.
  auto bcmapatt = evt->attribute<HepMC::GenEventBarcodes>(HepMCStr::barcodes);
  if (!bcmapatt){
    ATH_MSG_ERROR("TruthParticleCnvTool.cxx: Event does not contain barcodes attribute");
    return StatusCode::FAILURE;
  } 
  std::map<int, HepMC3::ConstGenParticlePtr> bcmap = bcmapatt->barcode_to_particle_map();
  for (const auto &[bc,hepMcPart]: bcmap) {
 
    TruthParticle * mcPart = new TruthParticle( hepMcPart, container );
    container->push_back( mcPart );
    
    if ( visitor ) {
      visitor->visit( mcPart );
    }
 
    mcPart->setCharge( MC::charge( int(mcPart->pdgId())) );
    mcPart->setGenEventIndex( genEventIndex);
 
    if ( hepMcPart != mcPart->genParticle() ) {
      ATH_MSG_ERROR("TruthParticle is not wrapping the GenParticle : " 
            << hepMcPart << " !!");
    }
    HepMcParticleLink mcLink( bc, genEventIndex, HepMcParticleLink::IS_POSITION, HepMcParticleLink::IS_BARCODE, ctx ); // FIXME barcode-based
    bcToMcPart[ mcLink.compress() ] = mcPart;
 
  }//> end loop over particles
 
  // at this point the whole GenEvent has been proxied.
  // so we can setup its VectorMap
  container->setParticles( bcToMcPart );
 
  // connect the TruthParticleContainer to the container of TruthEtIsolations
  // if it exists and if we are asked for
  if ( m_doEtIsolation.value() ) {
    const std::string& etIsolName 
      = m_isolationTool->etIsolationsName( container->genEventName() );
    if ( etIsolName.empty() ) {
      ATH_MSG_WARNING("Could not retrieve the name of the "
              "TruthEtIsolations container (requested: [" 
              << container->genEventName() << "])");
      return StatusCode::RECOVERABLE;
    }
 
    const TruthEtIsolationsContainer* etIsols = nullptr;
    if ( !evtStore()->retrieve( etIsols, etIsolName ).isSuccess() ) {
      ATH_MSG_WARNING("Could not retrieve the TruthEtIsolations container at ["
              << etIsolName << "] !!");
      return StatusCode::RECOVERABLE;
    }
 
    // index of HepMC::GenEvent within the McEventCollection is the same
    // than the one of the TruthEtIsolations within the TruthEtIsolationsCont.
    container->setEtIsolations( etIsols, genEventIndex );
  }
 
  return StatusCode::SUCCESS;
}