Alignment/CommonAlignmentAlgorithm/plugins/SiStripBackplaneCalibration.cc - master - githubmirror/cmssw

Alignment/CommonAlignmentAlgorithm/plugins/SiStripBackplaneCalibration.cc
554 строки26 KB
Shahzad Malik Muzaffar
[ALCA-DB] Drop Geometry/CommonDetUnit package
28 май 2026, 12:57
28 май 2026, 12:57993d9d5
/// \class SiStripBackplaneCalibration
///
/// Calibration of back plane corrections for the strip tracker, integrated in the
/// alignment algorithms. Note that not all algorithms support this...
///
/// Usally use one instance for deco mode data since peak mode should give the
//  reference - but the strip local reco foresees also calibration parameters
//  for peak data like for the Lorentz angle.
///
///  \author    : Gero Flucke
///  date       : November 2012
///  $Revision: 1.1.2.13 $
///  $Date: 2013/05/31 08:37:12 $
///  (last update by $Author: flucke $)

#include "Alignment/CommonAlignmentAlgorithm/interface/IntegratedCalibrationBase.h"
#include "Alignment/CommonAlignmentAlgorithm/interface/TkModuleGroupSelector.h"
// include 'locally':
#include "SiStripReadoutModeEnums.h"
#include "TreeStruct.h"

#include "CondCore/DBOutputService/interface/PoolDBOutputService.h"
#include "CondFormats/DataRecord/interface/SiStripCondDataRecords.h"
#include "CondFormats/SiStripObjects/interface/SiStripLatency.h"
#include "CondFormats/SiStripObjects/interface/SiStripLorentzAngle.h"
// #include "CalibTracker/Records/interface/SiStripDependentRecords.h"
#include "CondFormats/SiStripObjects/interface/SiStripBackPlaneCorrection.h"

#include "DataFormats/DetId/interface/DetId.h"
#include "DataFormats/SiStripDetId/interface/SiStripDetId.h"

#include "FWCore/Framework/interface/ESWatcher.h"
#include "FWCore/MessageLogger/interface/MessageLogger.h"
#include "FWCore/ServiceRegistry/interface/Service.h"
#include "FWCore/ParameterSet/interface/ParameterSet.h"

#include "Geometry/CommonTopologies/interface/GeomDet.h"
#include "MagneticField/Engine/interface/MagneticField.h"
#include "MagneticField/Records/interface/IdealMagneticFieldRecord.h"
#include "TrackingTools/TransientTrackingRecHit/interface/TransientTrackingRecHit.h"
#include "FWCore/Framework/interface/ConsumesCollector.h"

#include "TTree.h"
#include "TFile.h"
#include "TString.h"

// #include <iostream>
#include <vector>
#include <map>
#include <sstream>
#include <cstdio>
#include <functional>

class SiStripBackplaneCalibration : public IntegratedCalibrationBase {
public:
  /// Constructor
  explicit SiStripBackplaneCalibration(const edm::ParameterSet &cfg, edm::ConsumesCollector &iC);

  /// Destructor
  ~SiStripBackplaneCalibration() override;

  /// How many parameters does this calibration define?
  unsigned int numParameters() const override;

  // /// Return all derivatives,
  // /// default implementation uses other derivatives(..) method,
  // /// but can be overwritten in derived class for efficiency.
  // virtual std::vector<double> derivatives(const TransientTrackingRecHit &hit,
  // 					  const TrajectoryStateOnSurface &tsos,
  // 					  const edm::EventSetup &setup,
  // 					  const EventInfo &eventInfo) const;

  /// Return non-zero derivatives for x- and y-measurements with their indices by reference.
  /// Return value is their number.
  unsigned int derivatives(std::vector<ValuesIndexPair> &outDerivInds,
                           const TransientTrackingRecHit &hit,
                           const TrajectoryStateOnSurface &tsos,
                           const edm::EventSetup &setup,
                           const EventInfo &eventInfo) const override;

  /// Setting the determined parameter identified by index,
  /// returns false if out-of-bounds, true otherwise.
  bool setParameter(unsigned int index, double value) override;

  /// Setting the determined parameter uncertainty identified by index,
  /// returns false if out-of-bounds, true otherwise.
  bool setParameterError(unsigned int index, double error) override;

  /// Return current value of parameter identified by index.
  /// Returns 0. if index out-of-bounds.
  double getParameter(unsigned int index) const override;

  /// Return current value of parameter identified by index.
  /// Returns 0. if index out-of-bounds or if errors undetermined.
  double getParameterError(unsigned int index) const override;

  // /// Call at beginning of job:
  void beginOfJob(AlignableTracker *tracker, AlignableMuon *muon, AlignableExtras *extras) override;

  /// Called at end of a the job of the AlignmentProducer.
  /// Write out determined parameters.
  void endOfJob() override;

private:
  /// If called the first time, fill 'siStripBackPlaneCorrInput_',
  /// later check that Backplane has not changed.
  bool checkBackPlaneCorrectionInput(const edm::EventSetup &setup, const EventInfo &eventInfo);
  /// Input BackPlaneCorrection values:
  /// - either from EventSetup of first call to derivatives(..)
  /// - or created from files of passed by configuration (i.e. from parallel processing)
  const SiStripBackPlaneCorrection *getBackPlaneCorrectionInput();

  /// Determined parameter value for this detId (detId not treated => 0.)
  /// and the given run.
  double getParameterForDetId(unsigned int detId, edm::RunNumber_t run) const;

  void writeTree(const SiStripBackPlaneCorrection &backPlaneCorr,
                 const std::map<unsigned int, TreeStruct> &treeInfo,
                 const char *treeName) const;
  SiStripBackPlaneCorrection *createFromTree(const char *fileName, const char *treeName) const;

  const std::string readoutModeName_;
  int16_t readoutMode_;
  const bool saveToDB_;
  const std::string recordNameDBwrite_;
  const std::string outFileName_;
  const std::vector<std::string> mergeFileNames_;

  edm::ESWatcher<SiStripBackPlaneCorrectionRcd> watchBackPlaneCorrRcd_;

  SiStripBackPlaneCorrection *siStripBackPlaneCorrInput_;

  std::vector<double> parameters_;
  std::vector<double> paramUncertainties_;

  TkModuleGroupSelector *moduleGroupSelector_;
  const edm::ParameterSet moduleGroupSelCfg_;
  const edm::ESGetToken<SiStripLatency, SiStripLatencyRcd> latencyToken_;
  const edm::ESGetToken<SiStripLorentzAngle, SiStripLorentzAngleRcd> lorentzAngleToken_;
  const edm::ESGetToken<MagneticField, IdealMagneticFieldRecord> magFieldToken_;
  const edm::ESGetToken<SiStripBackPlaneCorrection, SiStripBackPlaneCorrectionRcd> backPlaneCorrToken_;
};

//======================================================================
//======================================================================
//======================================================================

SiStripBackplaneCalibration::SiStripBackplaneCalibration(const edm::ParameterSet &cfg, edm::ConsumesCollector &iC)
    : IntegratedCalibrationBase(cfg),
      readoutModeName_(cfg.getParameter<std::string>("readoutMode")),
      saveToDB_(cfg.getParameter<bool>("saveToDB")),
      recordNameDBwrite_(cfg.getParameter<std::string>("recordNameDBwrite")),
      outFileName_(cfg.getParameter<std::string>("treeFile")),
      mergeFileNames_(cfg.getParameter<std::vector<std::string> >("mergeTreeFiles")),
      siStripBackPlaneCorrInput_(nullptr),
      moduleGroupSelector_(nullptr),
      moduleGroupSelCfg_(cfg.getParameter<edm::ParameterSet>("BackplaneModuleGroups")),
      latencyToken_(iC.esConsumes()),
      lorentzAngleToken_(iC.esConsumes<edm::Transition::BeginRun>(edm::ESInputTag("", readoutModeName_))),
      magFieldToken_(iC.esConsumes()),
      backPlaneCorrToken_(iC.esConsumes(edm::ESInputTag("", readoutModeName_))) {
  // SiStripLatency::singleReadOutMode() returns
  // 1: all in peak, 0: all in deco, -1: mixed state
  // (in principle one could treat even mixed state APV by APV...)
  if (readoutModeName_ == "peak") {
    readoutMode_ = kPeakMode;
  } else if (readoutModeName_ == "deconvolution") {
    readoutMode_ = kDeconvolutionMode;
  } else {
    throw cms::Exception("BadConfig") << "SiStripBackplaneCalibration:\n"
                                      << "Unknown mode '" << readoutModeName_
                                      << "', should be 'peak' or 'deconvolution' .\n";
  }
}

//======================================================================
SiStripBackplaneCalibration::~SiStripBackplaneCalibration() {
  delete moduleGroupSelector_;
  //  std::cout << "Destroy SiStripBackplaneCalibration named " << this->name() << std::endl;
  delete siStripBackPlaneCorrInput_;
}

//======================================================================
unsigned int SiStripBackplaneCalibration::numParameters() const { return parameters_.size(); }

//======================================================================
unsigned int SiStripBackplaneCalibration::derivatives(std::vector<ValuesIndexPair> &outDerivInds,
                                                      const TransientTrackingRecHit &hit,
                                                      const TrajectoryStateOnSurface &tsos,
                                                      const edm::EventSetup &setup,
                                                      const EventInfo &eventInfo) const {
  // ugly const-cast:
  // But it is either only first initialisation or throwing an exception...
  const_cast<SiStripBackplaneCalibration *>(this)->checkBackPlaneCorrectionInput(setup, eventInfo);

  outDerivInds.clear();

  const SiStripLatency *latency = &setup.getData(latencyToken_);
  const int16_t mode = latency->singleReadOutMode();

  if (mode == readoutMode_) {
    if (hit.det()) {  // otherwise 'constraint hit' or whatever

      const int index =
          moduleGroupSelector_->getParameterIndexFromDetId(hit.det()->geographicalId(), eventInfo.eventId().run());
      if (index >= 0) {  // otherwise not treated
        const MagneticField *magneticField = &setup.getData(magFieldToken_);
        const GlobalVector bField(magneticField->inTesla(hit.det()->surface().position()));
        const LocalVector bFieldLocal(hit.det()->surface().toLocal(bField));
        //std::cout << "SiStripBackplaneCalibration derivatives " << readoutModeName_ << std::endl;
        const double dZ = hit.det()->surface().bounds().thickness();          // it's a float only...
        const double tanPsi = tsos.localParameters().mixedFormatVector()[1];  //float...

        const SiStripLorentzAngle *lorentzAngleHandle = &setup.getData(lorentzAngleToken_);
        // Yes, mobility (= LA/By) stored in object called LA...
        const double mobility = lorentzAngleHandle->getLorentzAngle(hit.det()->geographicalId());
        // shift due to dead back plane has two parts:
        // 1) Lorentz Angle correction formula gets reduced thickness dz*(1-bp)
        // 2) 'Direct' effect is shift of effective module position in local z by bp*dz/2
        //   (see GF's presentation in alignment meeting 25.10.2012,
        //    https://indico.cern.ch/conferenceDisplay.py?confId=174266#2012-10-25)
        //        const double xDerivative = 0.5 * dZ * (mobility * bFieldLocal.y() - tanPsi);
        //FIXME: +tanPsi? At least that fits the sign of the dr/dw residual
        //       in KarimakiDerivatives...
        const double xDerivative = 0.5 * dZ * (mobility * bFieldLocal.y() + tanPsi);
        // std::cout << "derivative is " << xDerivative << " for index " << index
        // 	  << std::endl;
        //         if (index >= 10) {
        //           std::cout << "mobility * y-field " << mobility * bFieldLocal.y()
        //                     << ", \n tanPsi " << tanPsi /*<< ", dZ " << dZ */ << std::endl;
        //           std::cout << "|tanPsi| - |mobility * y-field| "
        //                     << fabs(tanPsi) - fabs(mobility * bFieldLocal.y())
        //                     << std::endl;
        //         }
        const Values derivs(xDerivative, 0.);  // yDerivative = 0.
        outDerivInds.push_back(ValuesIndexPair(derivs, index));
      }
    } else {
      edm::LogWarning("Alignment") << "@SUB=SiStripBackplaneCalibration::derivatives1"
                                   << "Hit without GeomDet, skip!";
    }
  } else if (mode != kDeconvolutionMode && mode != kPeakMode) {
    // warn only if unknown/mixed mode
    edm::LogWarning("Alignment") << "@SUB=SiStripBackplaneCalibration::derivatives2"
                                 << "Readout mode is " << mode << ", but looking for " << readoutMode_ << " ("
                                 << readoutModeName_ << ").";
  }

  return outDerivInds.size();
}

//======================================================================
bool SiStripBackplaneCalibration::setParameter(unsigned int index, double value) {
  if (index >= parameters_.size()) {
    return false;
  } else {
    parameters_[index] = value;
    return true;
  }
}

//======================================================================
bool SiStripBackplaneCalibration::setParameterError(unsigned int index, double error) {
  if (index >= paramUncertainties_.size()) {
    return false;
  } else {
    paramUncertainties_[index] = error;
    return true;
  }
}

//======================================================================
double SiStripBackplaneCalibration::getParameter(unsigned int index) const {
  return (index >= parameters_.size() ? 0. : parameters_[index]);
}

//======================================================================
double SiStripBackplaneCalibration::getParameterError(unsigned int index) const {
  return (index >= paramUncertainties_.size() ? 0. : paramUncertainties_[index]);
}

//======================================================================
void SiStripBackplaneCalibration::beginOfJob(AlignableTracker *aliTracker,
                                             AlignableMuon * /*aliMuon*/,
                                             AlignableExtras * /*aliExtras*/) {
  //specify the sub-detectors for which the back plane correction is determined: all strips
  const std::vector<int> sdets = {SiStripDetId::TIB, SiStripDetId::TID, SiStripDetId::TOB, SiStripDetId::TEC};

  moduleGroupSelector_ = new TkModuleGroupSelector(aliTracker, moduleGroupSelCfg_, sdets);

  parameters_.resize(moduleGroupSelector_->getNumberOfParameters(), 0.);
  paramUncertainties_.resize(moduleGroupSelector_->getNumberOfParameters(), 0.);

  edm::LogInfo("Alignment") << "@SUB=SiStripBackplaneCalibration"
                            << "Created with name " << this->name() << " for readout mode '" << readoutModeName_
                            << "',\n"
                            << this->numParameters() << " parameters to be determined."
                            << "\nsaveToDB = " << saveToDB_ << "\n outFileName = " << outFileName_
                            << "\n N(merge files) = " << mergeFileNames_.size()
                            << "\n number of IOVs = " << moduleGroupSelector_->numIovs();

  if (!mergeFileNames_.empty()) {
    edm::LogInfo("Alignment") << "@SUB=SiStripBackplaneCalibration"
                              << "First file to merge: " << mergeFileNames_[0];
  }
}

//======================================================================
void SiStripBackplaneCalibration::endOfJob() {
  // loginfo output
  std::ostringstream out;
  out << "Parameter results for readout mode '" << readoutModeName_ << "'\n";
  for (unsigned int iPar = 0; iPar < parameters_.size(); ++iPar) {
    out << iPar << ": " << parameters_[iPar] << " +- " << paramUncertainties_[iPar] << "\n";
  }
  edm::LogInfo("Alignment") << "@SUB=SiStripBackplaneCalibration::endOfJob" << out.str();

  std::map<unsigned int, TreeStruct> treeInfo;  // map of TreeStruct for each detId

  // now write 'input' tree
  const SiStripBackPlaneCorrection *input = this->getBackPlaneCorrectionInput();  // never NULL
  const std::string treeName(this->name() + '_' + readoutModeName_ + '_');
  this->writeTree(*input, treeInfo, (treeName + "input").c_str());  // empty treeInfo for input...

  if (input->getBackPlaneCorrections().empty()) {
    edm::LogError("Alignment") << "@SUB=SiStripBackplaneCalibration::endOfJob"
                               << "Input back plane correction map is empty ('" << readoutModeName_
                               << "' mode), skip writing output!";
    return;
  }

  const unsigned int nonZeroParamsOrErrors =  // Any determined value?
      count_if(parameters_.begin(), parameters_.end(), [](auto c) { return c != 0.; }) +
      count_if(paramUncertainties_.begin(), paramUncertainties_.end(), [](auto c) { return c != 0.; });

  for (unsigned int iIOV = 0; iIOV < moduleGroupSelector_->numIovs(); ++iIOV) {
    cond::Time_t firstRunOfIOV = moduleGroupSelector_->firstRunOfIOV(iIOV);
    SiStripBackPlaneCorrection output{};
    // Loop on map of values from input and add (possible) parameter results
    for (auto iterIdValue = input->getBackPlaneCorrections().begin();
         iterIdValue != input->getBackPlaneCorrections().end();
         ++iterIdValue) {
      // type of (*iterIdValue) is pair<unsigned int, float>
      const unsigned int detId = iterIdValue->first;  // key of map is DetId
      // Some code one could use to miscalibrate wrt input:
      // double param = 0.;
      // const DetId id(detId);
      // switch (id.subdetId()) {
      // case 3:
      //   // delta = 0.025;
      //   {
      //     TIBDetId tibId(detId);
      //     param = tibId.layer() * 0.01;
      //   }
      //   break;
      // case 5:
      //   //delta = 0.050;
      //   {
      //     TOBDetId tobId(detId);
      //     param = tobId.layer() * 0.015;
      //   }
      //   break;
      // case 4: // TID
      //   param = 0.03; break;
      // case 6: // TEC
      //   param = 0.05; break;
      //   break;
      // default:
      //   std::cout << "unknown subdet " << id.subdetId() << std::endl;
      // }
      const double param = this->getParameterForDetId(detId, firstRunOfIOV);
      // put result in output, i.e. sum of input and determined parameter:
      output.putBackPlaneCorrection(detId, iterIdValue->second + param);
      const int paramIndex = moduleGroupSelector_->getParameterIndexFromDetId(detId, firstRunOfIOV);
      treeInfo[detId] = TreeStruct(param, this->getParameterError(paramIndex), paramIndex);
    }

    if (saveToDB_ || nonZeroParamsOrErrors != 0) {  // Skip writing mille jobs...
      this->writeTree(output, treeInfo, (treeName + Form("result_%lld", firstRunOfIOV)).c_str());
    }

    if (saveToDB_) {  // If requested, write out to DB
      edm::Service<cond::service::PoolDBOutputService> dbService;
      if (dbService.isAvailable()) {
        dbService->writeOneIOV(output, firstRunOfIOV, recordNameDBwrite_);
        // no 'delete output;': writeOne(..) took over ownership
      } else {
        edm::LogError("BadConfig") << "@SUB=SiStripBackplaneCalibration::endOfJob"
                                   << "No PoolDBOutputService available, but saveToDB true!";
      }
    }
  }  // end loop on IOVs
}

//======================================================================
bool SiStripBackplaneCalibration::checkBackPlaneCorrectionInput(const edm::EventSetup &setup,
                                                                const EventInfo &eventInfo) {
  const SiStripBackPlaneCorrection *backPlaneCorrHandle = nullptr;
  if (!siStripBackPlaneCorrInput_) {
    backPlaneCorrHandle = &setup.getData(backPlaneCorrToken_);
    siStripBackPlaneCorrInput_ = new SiStripBackPlaneCorrection(*backPlaneCorrHandle);
    // FIXME: Should we call 'watchBackPlaneCorrRcd_.check(setup)' as well?
    //        Otherwise could be that next check has to check via following 'else', though
    //        no new IOV has started... (to be checked)
  } else {
    if (watchBackPlaneCorrRcd_.check(setup)) {  // new IOV of input - but how to check peak vs deco?
      backPlaneCorrHandle = &setup.getData(backPlaneCorrToken_);

      if (backPlaneCorrHandle->getBackPlaneCorrections()               // but only bad if non-identical values
          != siStripBackPlaneCorrInput_->getBackPlaneCorrections()) {  // (comparing maps)
        // Maps are containers sorted by key, but comparison problems may arise from
        // 'floating point comparison' problems (FIXME?)
        throw cms::Exception("BadInput") << "SiStripBackplaneCalibration::checkBackPlaneCorrectionInput:\n"
                                         << "Content of SiStripBackPlaneCorrection changed at run "
                                         << eventInfo.eventId().run() << ", but algorithm expects constant input!\n";
        return false;  // not reached...
      }
    }
  }

  return true;
}

//======================================================================
const SiStripBackPlaneCorrection *SiStripBackplaneCalibration::getBackPlaneCorrectionInput() {
  // For parallel processing in Millepede II, create SiStripBackPlaneCorrection
  // from info stored in files of parallel jobs and check that they are identical.
  // If this job has run on events, still check that back plane corrections are
  // identical to the ones from mergeFileNames_.
  const std::string treeName(((this->name() + '_') += readoutModeName_) += "_input");
  for (auto iFile = mergeFileNames_.begin(); iFile != mergeFileNames_.end(); ++iFile) {
    SiStripBackPlaneCorrection *bpCorr = this->createFromTree(iFile->c_str(), treeName.c_str());
    // siStripBackPlaneCorrInput_ could be non-null from previous file of this loop
    // or from checkBackPlaneCorrectionInput(..) when running on data in this job as well
    if (!siStripBackPlaneCorrInput_ || siStripBackPlaneCorrInput_->getBackPlaneCorrections().empty()) {
      delete siStripBackPlaneCorrInput_;  // NULL or empty
      siStripBackPlaneCorrInput_ = bpCorr;
    } else {
      // about comparison of maps see comments in checkBackPlaneCorrectionInput
      if (bpCorr && !bpCorr->getBackPlaneCorrections().empty() &&  // single job might not have got events
          bpCorr->getBackPlaneCorrections() != siStripBackPlaneCorrInput_->getBackPlaneCorrections()) {
        // Throw exception instead of error?
        edm::LogError("NoInput") << "@SUB=SiStripBackplaneCalibration::getBackPlaneCorrectionInput"
                                 << "Different input values from tree " << treeName << " in file " << *iFile << ".";
      }
      delete bpCorr;
    }
  }

  if (!siStripBackPlaneCorrInput_) {  // no files nor ran on events
    siStripBackPlaneCorrInput_ = new SiStripBackPlaneCorrection;
    edm::LogError("NoInput") << "@SUB=SiStripBackplaneCalibration::getBackPlaneCorrectionInput"
                             << "No input, create an empty one ('" << readoutModeName_ << "' mode)!";
  } else if (siStripBackPlaneCorrInput_->getBackPlaneCorrections().empty()) {
    edm::LogError("NoInput") << "@SUB=SiStripBackplaneCalibration::getBackPlaneCorrectionInput"
                             << "Empty result ('" << readoutModeName_ << "' mode)!";
  }

  return siStripBackPlaneCorrInput_;
}

//======================================================================
double SiStripBackplaneCalibration::getParameterForDetId(unsigned int detId, edm::RunNumber_t run) const {
  const int index = moduleGroupSelector_->getParameterIndexFromDetId(detId, run);

  return (index < 0 ? 0. : parameters_[index]);
}

//======================================================================
void SiStripBackplaneCalibration::writeTree(const SiStripBackPlaneCorrection &backPlaneCorrection,
                                            const std::map<unsigned int, TreeStruct> &treeInfo,
                                            const char *treeName) const {
  TFile *file = TFile::Open(outFileName_.c_str(), "UPDATE");
  if (!file) {
    edm::LogError("BadConfig") << "@SUB=SiStripBackplaneCalibration::writeTree"
                               << "Could not open file '" << outFileName_ << "'.";
    return;
  }

  TTree *tree = new TTree(treeName, treeName);
  unsigned int id = 0;
  float value = 0.;
  TreeStruct treeStruct;
  tree->Branch("detId", &id, "detId/i");
  tree->Branch("value", &value, "value/F");
  tree->Branch("treeStruct", &treeStruct, TreeStruct::LeafList());

  for (auto iterIdValue = backPlaneCorrection.getBackPlaneCorrections().begin();
       iterIdValue != backPlaneCorrection.getBackPlaneCorrections().end();
       ++iterIdValue) {
    // type of (*iterIdValue) is pair<unsigned int, float>
    id = iterIdValue->first;  // key of map is DetId
    value = iterIdValue->second;
    // type of (*treeStructIter) is pair<unsigned int, TreeStruct>
    auto treeStructIter = treeInfo.find(id);  // find info for this id
    if (treeStructIter != treeInfo.end()) {
      treeStruct = treeStructIter->second;  // info from input map
    } else {                                // if none found, fill at least parameter index (using 1st IOV...)
      const cond::Time_t run1of1stIov = moduleGroupSelector_->firstRunOfIOV(0);
      const int ind = moduleGroupSelector_->getParameterIndexFromDetId(id, run1of1stIov);
      treeStruct = TreeStruct(ind);
    }
    tree->Fill();
  }
  tree->Write();
  delete file;  // tree vanishes with the file...
}

//======================================================================
SiStripBackPlaneCorrection *SiStripBackplaneCalibration::createFromTree(const char *fileName,
                                                                        const char *treeName) const {
  // Check for file existence on your own to work around
  // https://hypernews.cern.ch/HyperNews/CMS/get/swDevelopment/2715.html:
  TFile *file = nullptr;
  FILE *testFile = fopen(fileName, "r");
  if (testFile) {
    fclose(testFile);
    file = TFile::Open(fileName, "READ");
  }  // else not existing, see error below

  TTree *tree = nullptr;
  if (file)
    file->GetObject(treeName, tree);

  SiStripBackPlaneCorrection *result = nullptr;
  if (tree) {
    unsigned int id = 0;
    float value = 0.;
    tree->SetBranchAddress("detId", &id);
    tree->SetBranchAddress("value", &value);

    result = new SiStripBackPlaneCorrection;
    const Long64_t nEntries = tree->GetEntries();
    for (Long64_t iEntry = 0; iEntry < nEntries; ++iEntry) {
      tree->GetEntry(iEntry);
      result->putBackPlaneCorrection(id, value);
    }
  } else {  // Warning only since could be parallel job on no events.
    edm::LogWarning("Alignment") << "@SUB=SiStripBackplaneCalibration::createFromTree"
                                 << "Could not get TTree '" << treeName << "' from file '" << fileName
                                 << (file ? "'." : "' (file does not exist).");
  }

  delete file;  // tree will vanish with file
  return result;
}

//======================================================================
//======================================================================
// Plugin definition

#include "Alignment/CommonAlignmentAlgorithm/interface/IntegratedCalibrationPluginFactory.h"

DEFINE_EDM_PLUGIN(IntegratedCalibrationPluginFactory, SiStripBackplaneCalibration, "SiStripBackplaneCalibration");