MagneticField.cc

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#include "MagneticField/Engine/interface/MagneticField.h"

MagneticField::MagneticField() : nominalValueCompiuted(kUnset), theNominalValue(0) {}

MagneticField::MagneticField(const MagneticField& orig) : nominalValueCompiuted(kUnset), theNominalValue(0) {
  if (orig.nominalValueCompiuted.load() == kSet) {
    theNominalValue = orig.theNominalValue;
    nominalValueCompiuted.store(kSet);
  }
}

MagneticField::~MagneticField() {}

int MagneticField::computeNominalValue() const {
  int tmp = int((inTesla(GlobalPoint(0.f, 0.f, 0.f))).z() * 10.f + 0.5f);

  //Try to cache
  char expected = kUnset;
  if (nominalValueCompiuted.compare_exchange_strong(expected, kSetting)) {
    //it is our job to set the value
    std::swap(theNominalValue, tmp);

    //this must be after the swap
    nominalValueCompiuted.store(kSet);
    return theNominalValue;
  }
  //another thread beat us to trying to set theNominalValue
  // since we don't know when the other thread will finish
  // we just return tmp
  return tmp;
}