BeamEffectsAlg.cxx

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/*
  Copyright (C) 2002-2022 CERN for the benefit of the ATLAS collaboration
*/
 
// class header
#include "BeamEffectsAlg.h"
 
// Athena headers
#include "GeneratorObjects/McEventCollection.h"
#include "StoreGate/ReadHandle.h"
#include "StoreGate/WriteHandle.h"
 
// HepMC includes
#include "AtlasHepMC/GenEvent.h"
#include "AtlasHepMC/GenVertex.h"
 
// CLHEP includes
#include "CLHEP/Vector/LorentzVector.h"
 
namespace Simulation
{
 
  BeamEffectsAlg::BeamEffectsAlg( const std::string& name, ISvcLocator* pSvcLocator )
    : AthReentrantAlgorithm( name, pSvcLocator )
  {
  }

  StatusCode BeamEffectsAlg::initialize()
  {
    // the Tools for event manipulation
    if (!m_genEventManipulators.empty()) {
      ATH_CHECK( m_genEventManipulators.retrieve() );
    }
    // This will check that the properties were initialized
    // properly by job configuration.
    ATH_CHECK( m_inputMcEventCollection.initialize() );
    ATH_CHECK( m_outputMcEventCollection.initialize() );
    ATH_CHECK( m_eventInfoKey.initialize() );
    return StatusCode::SUCCESS;
  }
 
  StatusCode BeamEffectsAlg::execute(const EventContext& ctx) const
  {
    // Construct handles from the keys.
    SG::ReadHandle<McEventCollection> h_inputMcEventCollection (m_inputMcEventCollection, ctx);
    SG::WriteHandle<McEventCollection> h_outputMcEventCollection (m_outputMcEventCollection, ctx);
    if(!h_inputMcEventCollection.isValid()) {
      ATH_MSG_FATAL("No input McEventCollection called " << h_inputMcEventCollection.name() << " in " << h_inputMcEventCollection.store());
      return StatusCode::FAILURE;
    }
    auto outputMcEventCollection = std::make_unique<McEventCollection>(*h_inputMcEventCollection);
    ATH_CHECK( h_outputMcEventCollection.record ( std::move (outputMcEventCollection)) );
    // loop over the events in the mc collection
    for (HepMC::GenEvent* currentGenEvent : *h_outputMcEventCollection) {
      // skip empty events
      if ( !currentGenEvent ) continue;
      ATH_CHECK(this->patchSignalProcessVertex(*currentGenEvent));
      // manipulate the GenEvent if needed : validating, filtering, smearing, dispersion, ...
      for (const auto& manipulator : m_genEventManipulators) {
        // call manipulate(..) in the current GenEventManipulator
        ATH_CHECK(manipulator->manipulate(*currentGenEvent, ctx));
      }
    }
 
    return StatusCode::SUCCESS;
  }
 
  StatusCode BeamEffectsAlg::patchSignalProcessVertex(HepMC::GenEvent& ge) const
  {
    //Ensure that we have a valid signal_process_vertex
    if( !HepMC::signal_process_vertex(&ge) ) {
      if(m_ISFRun) {
        ATH_MSG_DEBUG("No signal_process_vertex found - creating a dummy GenVertex.");
        HepMC::FourVector signalPos( 0.0, 0.0, 0.0, 0.0);
        HepMC::GenVertexPtr signalVertex = HepMC::newGenVertexPtr( signalPos );
        // ge will now take ownership of the signal process vertex
        HepMC::set_signal_process_vertex(&ge, signalVertex );
      }
      else {
        if (!ge.vertices().empty()) {
          ATH_MSG_DEBUG("No signal_process_vertex found - using the first GenVertex in the event.");
          HepMC::GenVertexPtr signalVertex = ge.vertices().front();
          HepMC::set_signal_process_vertex(&ge,signalVertex );
        }
      }
      if( !HepMC::signal_process_vertex(&ge) ) { // Insanity check
        if (!ge.vertices().empty()) {
          ATH_MSG_ERROR("Failed to set signal_process_vertex for GenEvent!!");
          return StatusCode::FAILURE;
        }
        ATH_MSG_WARNING("No signal_process_vertex found. Empty GenEvent!");
      }
    }
    else {
      ATH_MSG_DEBUG("signal_process_vertex set by Generator.");
    }
    return StatusCode::SUCCESS;
  }
 
} // namespace Simulation