MagneticField.h

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#ifndef MagneticField_MagneticField_h
#define MagneticField_MagneticField_h
 
#include <atomic>
 
#include "DataFormats/GeometryVector/interface/GlobalVector.h"
#include "DataFormats/GeometryVector/interface/GlobalPoint.h"
#include "FWCore/Utilities/interface/Visibility.h"
#include "FWCore/Utilities/interface/Likely.h"
#include "FWCore/Utilities/interface/thread_safety_macros.h"
 
class MagneticField {
public:
  MagneticField();
  MagneticField(const MagneticField& orig);
  virtual ~MagneticField();
 
  virtual MagneticField* clone() const { return nullptr; }
 
  virtual GlobalVector inTesla(const GlobalPoint& gp) const = 0;
 
  GlobalVector inKGauss(const GlobalPoint& gp) const { return inTesla(gp) * 10.F; }
 
  GlobalVector inInverseGeV(const GlobalPoint& gp) const { return inTesla(gp) * 2.99792458e-3F; }
 
  // engine is defined.
  virtual bool isDefined(const GlobalPoint& /*gp*/) const { return true; }
 
  virtual GlobalVector inTeslaUnchecked(const GlobalPoint& gp) const {
    return inTesla(gp);  // default dummy implementation
  }
 
  int nominalValue() const {
    if (kSet == nominalValueCompiuted.load())
      return theNominalValue;
    return computeNominalValue();
  }
 
private:
  //nominal field value
  virtual int computeNominalValue() const;
  mutable std::atomic<char> nominalValueCompiuted;
  //  CMS_THREAD_GUARD(nominalValueCompiuted) mutable int theNominalValue;
  //  PG temporary fix for clang 3.4 which is not parsing thread_guard correctly
  CMS_THREAD_SAFE mutable int theNominalValue;
  enum FooStates { kUnset, kSetting, kSet };
};
 
#endif