RMGGeneratorGPS.hh

// Copyright (C) 2022 Luigi Pertoldi <https://orcid.org/0000-0002-0467-2571>
//
// This program is free software: you can redistribute it and/or modify it under
// the terms of the GNU Lesser General Public License as published by the Free
// Software Foundation, either version 3 of the License, or (at your option) any
// later version.
//
// This program is distributed in the hope that it will be useful, but WITHOUT
// ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
// FOR A PARTICULAR PURPOSE.  See the GNU Lesser General Public License for more
// details.
//
// You should have received a copy of the GNU Lesser General Public License
// along with this program.  If not, see <https://www.gnu.org/licenses/>.
 
#ifndef _RMG_GENERATOR_GPS_HH_
#define _RMG_GENERATOR_GPS_HH_
 
#include <memory>
 
#include "G4AutoLock.hh"
#include "G4GeneralParticleSource.hh"
#include "G4ThreeVector.hh"
 
#include "RMGVGenerator.hh"
 
class G4Event;
class RMGGeneratorGPS : public RMGVGenerator {
 
  public:
 
    RMGGeneratorGPS() : RMGVGenerator("GPS") {
      fParticleSource = std::make_unique<G4GeneralParticleSource>();
    }
 
    ~RMGGeneratorGPS() = default;

    void GeneratePrimaries(G4Event* event) override {
      G4AutoLock lock(&fMutex);
 
      // the GPS is inherently thread-unsafe. only one source can be manipulated/used at a time.
      // all threads share the same internal global state.
      if (fVertexPositionSet) {
        auto n_source = fParticleSource->GetNumberofSource();
        for (auto i = 0; i < n_source; i++) {
          fParticleSource->SetCurrentSourceto(i);
          fParticleSource->GetCurrentSource()->GetPosDist()->SetCentreCoords(fVertexPosition);
        }
      }
      fParticleSource->GeneratePrimaryVertex(event);
    }

    void SetParticlePosition(G4ThreeVector vec) override {
      fVertexPosition = vec;
      fVertexPositionSet = true;
    }
 
  private:
 
    inline static G4Mutex fMutex = G4MUTEX_INITIALIZER;
 
    bool fVertexPositionSet = false;
    G4ThreeVector fVertexPosition;
 
    std::unique_ptr<G4GeneralParticleSource> fParticleSource = nullptr;
};
 
#endif
 
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