StripClusteringTool.cxx

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/*
  Copyright (C) 2002-2026 CERN for the benefit of the ATLAS collaboration
*/
 
#include "StripClusteringTool.h"
 
 
#include <Acts/Clusterization/Clusterization.hpp>
 
#include <InDetRawData/SCT3_RawData.h>
#include <SCT_ReadoutGeometry/SCT_ModuleSideDesign.h>
#include <SCT_ReadoutGeometry/StripStereoAnnulusDesign.h>
#include <TrkSurfaces/Surface.h>
 
#include <algorithm>
#include <stdexcept>
 
 
namespace ActsTrk {
constexpr double ONE_TWELFTH = 1./12.;
constexpr float oneStripSF = 1.1025;
constexpr float twoStripSF = 0.0729; 
  
  // Required by ACTS clusterization
static
int getCellColumn(const StripClusteringTool::Cell& cell)
{
    return cell.index;
}
 
// Required by ACTS clusterization
static inline void clusterReserve(StripClusteringTool::Cluster& cl,
                                  std::size_t n)
{
  cl.ids.reserve(n);
} 
 
// Required by ACTS clusterization
static
void clusterAddCell(StripClusteringTool::Cluster& cl, const StripClusteringTool::Cell& cell)
{
    cl.ids.push_back(cell.id.get_compact());
    if (cl.ids.size() < (sizeof(cl.hitsInThirdTimeBin) * 8)) {
      cl.hitsInThirdTimeBin |= cell.timeBits.test(0) << cl.ids.size();
    }
}
 
StripClusteringTool::StripClusteringTool(
    const std::string& type, const std::string& name, const IInterface* parent)
    : base_class(type,name,parent)
{
}
 
StatusCode StripClusteringTool::initialize()
{
    ATH_MSG_DEBUG("Initializing " << name() << "...");
 
    ATH_MSG_DEBUG(m_stripDetElStatus);
    ATH_MSG_DEBUG(m_checkBadModules);
    ATH_MSG_DEBUG(m_maxFiredStrips);
    ATH_MSG_DEBUG(m_stripDetEleCollKey);
    ATH_MSG_DEBUG(m_isITk);
    ATH_MSG_DEBUG(m_errorStrategy);
 
 
    ATH_CHECK(m_conditionsTool.retrieve(DisableTool{!m_stripDetElStatus.empty()} ));
    ATH_CHECK(m_lorentzAngleTool.retrieve());
    ATH_CHECK(decodeTimeBins());    
 
    ATH_CHECK(m_stripDetElStatus.initialize(not m_stripDetElStatus.empty()));
    ATH_CHECK(m_stripDetEleCollKey.initialize());
 
    ATH_CHECK( detStore()->retrieve(m_stripID, "SCT_ID") );
    
    return StatusCode::SUCCESS;
}
 
StatusCode StripClusteringTool::decodeTimeBins()
{
    for (size_t i = 0; i < m_timeBinStr.size(); i++) {
    if (i >= 3) {
        ATH_MSG_WARNING("Time bin string has excess characters");
        break;
    }
    switch (std::toupper(m_timeBinStr[i])) {
    case 'X': m_timeBinBits[i] = -1; break;
    case '0': m_timeBinBits[i] =  0; break;
    case '1': m_timeBinBits[i] =  1; break;
    default:
        ATH_MSG_FATAL("Invalid time bin string: " << m_timeBinStr);
        return StatusCode::FAILURE;
    }
    }
    return StatusCode::SUCCESS;
}
 
StatusCode
StripClusteringTool::clusterize(const EventContext& ctx,
                const RawDataCollection& RDOs,
                const InDet::SiDetectorElementStatus& stripDetElStatus,
                const InDetDD::SiDetectorElement& element,
        Acts::Ccl::ClusteringData& data,
                std::vector<typename IStripClusteringTool::ClusterCollection>& collection) const
{
    IdentifierHash idHash = RDOs.identifyHash();
    // At least an empty cluster collection needs to be always added because the
    // assumption is that there is one element per element RawDataCollection.
    collection.emplace_back();
    bool goodModule = true;
    if (m_checkBadModules.value()) {
      goodModule = stripDetElStatus.isGood(idHash);
    }
 
    VALIDATE_STATUS_ARRAY(
      m_checkBadModules.value() && !m_stripDetElStatus.empty(),
      stripDetElStatus.isGood(idHash), m_conditionsTool->isGood(idHash));
 
    if (!goodModule) {
      ATH_MSG_DEBUG("Strip module failed status check");
      return StatusCode::SUCCESS;
    }
    
    // If more than a certain number of RDOs set module to bad
    // in this case we skip clusterization
    if (m_maxFiredStrips != 0u) {
      unsigned int nFiredStrips = 0u;
      for (const SCT_RDORawData* rdo : RDOs) {
        nFiredStrips += rdo->getGroupSize();
      }
      if (nFiredStrips > m_maxFiredStrips)
    return StatusCode::SUCCESS;
    }
        
    std::optional<std::pair<typename IStripClusteringTool::CellCollection,bool>> unpckd
      = unpackRDOs(ctx, RDOs, stripDetElStatus, element);
 
    if (not unpckd.has_value()) {
    ATH_MSG_FATAL("Error encountered while unpacking strip RDOs!");
    return StatusCode::FAILURE;
    }
 
    auto& [cells, badStripOnModule] = *unpckd;
    // Bad strips on a module invalidates the hitsInThirdTimeBin word.
    // Therefore set it to 0 if that's the case.
    // We are currently not using this, but keeping it here should we need it in the future
 
    Acts::Ccl::createClusters<CellCollection, typename IStripClusteringTool::ClusterCollection, 1>(data, cells, collection.back());
 
    return StatusCode::SUCCESS;
}
 
  
StatusCode
StripClusteringTool::makeClusters(const EventContext& ctx,
                  typename IStripClusteringTool::ClusterCollection& clusters,
                  const InDetDD::SiDetectorElement& element,
                                  size_t /*icluster*/,
                                  std::any& /*vars*/,
                  typename ClusterContainer::iterator itrContainer) const
{
    const IdentifierHash idHash = element.identifyHash();
    double lorentzShift = m_lorentzAngleTool->getLorentzShift(idHash, ctx);
 
    const InDetDD::SiDetectorDesign& design = element.design();
    // get the pitch, this will be the local covariance for the cluster
 
    assert((not m_isITk) || element.isBarrel() ||  dynamic_cast<const InDetDD::StripStereoAnnulusDesign*>(&element.design()) !=nullptr);
    float pitch = (element.isBarrel() or (not m_isITk))
      ? design.phiPitch()
      : static_cast<const InDetDD::StripStereoAnnulusDesign&>(element.design()).phiPitchPhi();
    Eigen::Matrix<float,1,1> localCov(pitch * pitch * ONE_TWELFTH);
 
    for (typename IStripClusteringTool::Cluster& cl : clusters) {
      try {
    xAOD::StripCluster *xaodCluster = *itrContainer;
    ATH_CHECK(makeCluster(cl,
                  lorentzShift,
                  localCov,
                  *m_stripID,
                  element,
                  design,
                  *xaodCluster));
    ++itrContainer;
      } catch (const std::exception& e) {
    ATH_MSG_FATAL("Exception thrown while creating xAOD::StripCluster:"
              << e.what());
    ATH_MSG_FATAL("Detector Element identifier: " << element.identify());
    ATH_MSG_FATAL("Strip Identifiers in cluster:");
    for (const auto& id : cl.ids)
      ATH_MSG_FATAL("  " << id);
    return StatusCode::FAILURE;
      }
    }
 
    return StatusCode::SUCCESS;
}
 
static
std::pair<
    Eigen::Matrix<float,1,1>,
    Eigen::Matrix<float,3,1>>
computePosition(const StripClusteringTool::Cluster& cluster,
        std::size_t size,
        double lorentzShift,
        const IStripClusteringTool::IDHelper& stripID,
        const InDetDD::SiDetectorElement& element,
        const InDetDD::SiDetectorDesign& design,
        bool isITk )
{
 
    Identifier ids_front(cluster.ids.front());
    Identifier ids_back(cluster.ids.back());
    InDetDD::SiCellId frontId = stripID.strip(ids_front);
    InDetDD::SiLocalPosition pos = design.localPositionOfCell(frontId);
    if (size > 1) {
      InDetDD::SiCellId backId = stripID.strip(ids_back);
    InDetDD::SiLocalPosition backPos =
        design.localPositionOfCell(backId);
    pos = 0.5 * (pos + backPos);
    }
 
    // update the xPhi position
    pos.xPhi( pos.xPhi() + lorentzShift );
    Eigen::Matrix<float,3,1> posG(element.surface().localToGlobal(pos).cast<float>());
    
    if ((not element.isBarrel()) and isITk) {
        assert(dynamic_cast<const InDetDD::StripStereoAnnulusDesign*>(&design) != nullptr);
    const InDetDD::StripStereoAnnulusDesign& annulusDesign =
        static_cast<const InDetDD::StripStereoAnnulusDesign&>
        (design);
    pos = annulusDesign.localPositionOfCellPC(element.cellIdOfPosition(pos));
    }
 
    return std::make_pair(Eigen::Matrix<float,1,1>(pos.xPhi()),
              std::move(posG));
}
 
 
// N.B. the cluster is added to the container
StatusCode
StripClusteringTool::makeCluster(Cluster &cluster,
                 double lorentzShift,
                 Eigen::Matrix<float,1,1>& localCov,
                 const StripID& stripID,
                 const InDetDD::SiDetectorElement& element,
                 const InDetDD::SiDetectorDesign& design,
                 xAOD::StripCluster& cl) const
{
    std::size_t size = cluster.ids.size();
    
    auto [localPos, globalPos]
      = computePosition(cluster, size, lorentzShift, stripID, element, design, m_isITk);
 
    // For Strip Clusters the identifier is taken from the front rod list object
    // This is the same strategy used in Athena:
    // Since clusterId is arbitary (it only needs to be unique) just use ID of first strip
    // For strip Cluster it has been found that "identifierOfPosition" does not produces unique values
 
 
    // If requiring broad errors, use the cluster size as error -
    // TODO use SiWidth to get the right cluster size as I'm assuming equal strip pitch
    
    if (m_errorStrategy == 1)   {// use width
      
      localCov *= size*size;
      
    } else if (m_errorStrategy == 2) { //use tuned error as function of size
      
      if (size == 1)
        localCov *= oneStripSF;
      else if (size == 2)
        localCov *= twoStripSF*size*size;
      else
        localCov *= size*size;
      
    }
    
    cl.setMeasurement<1>(element.identifyHash(), localPos, localCov);
    cl.setIdentifier( cluster.ids.front() );
 
    // Do I really need the global position in fast tracking?
    cl.globalPosition() = globalPos;     
    
    cl.setChannelsInPhi(size);
    cl.setRDOlist(std::move(cluster.ids));
    
    return StatusCode::SUCCESS;
}
 
 
bool StripClusteringTool::passTiming(const std::bitset<3>& timePattern) const {
    // Convert the given timebin to a bit set and test each bit
    // if bit is -1 (i.e. X) it always passes, other wise require exact match of 0/1
    // N.B bitset has opposite order to the bit pattern we define
    if (m_timeBinBits[0] != -1 and timePattern.test(2) != static_cast<bool>(m_timeBinBits[0])) return false;
    if (m_timeBinBits[1] != -1 and timePattern.test(1) != static_cast<bool>(m_timeBinBits[1])) return false;
    if (m_timeBinBits[2] != -1 and timePattern.test(0) != static_cast<bool>(m_timeBinBits[2])) return false;
    return true;
}
 
 
bool StripClusteringTool::isBadStrip(const EventContext& ctx,
                     const InDet::SiDetectorElementStatus *stripDetElStatus,
                     const StripID& stripID,
                     IdentifierHash waferHash,
                     Identifier stripId) const
{
    if (stripDetElStatus) {
        const int strip_i{stripID.strip(stripId)};
    VALIDATE_STATUS_ARRAY(
        stripDetElStatus,
        stripDetElStatus->isCellGood(waferHash.value(), strip_i),
        m_conditionsTool->isGood(stripId, InDetConditions::SCT_STRIP));
    return not stripDetElStatus->isCellGood(waferHash.value(), strip_i) ;
    }
    return not m_conditionsTool->isGood(stripId, InDetConditions::SCT_STRIP, ctx);
}
 
 
std::optional<std::pair<typename IStripClusteringTool::CellCollection, bool>>
StripClusteringTool::unpackRDOs(const EventContext& ctx,
                const RawDataCollection& RDOs,
                const InDet::SiDetectorElementStatus& stripDetElStatus,
                const InDetDD::SiDetectorElement& element) const
{
     const InDetDD::SiDetectorDesign& design = element.design();
  
     CellCollection cells;
     // reserve memory. number evaluated on ttbar pu200
     cells.reserve(60);
     bool badStripOnModule{false};
     //Check type in debug build otherwise assume it is correct
     assert(dynamic_cast<const InDetDD::SCT_ModuleSideDesign*>(&design)!=nullptr);
     std::size_t ncells = static_cast<size_t>(static_cast<const InDetDD::SCT_ModuleSideDesign&>(design).cells());
     
     // Simple single-entry cache
    Identifier::value_type waferId_compact_cache = 0;
    IdentifierHash waferHash_cache(0);
    bool cache_valid = false;
 
    for (const StripRDORawData * raw : RDOs) {
 
        //Check type in debug build otherwise assume it is correct
        assert(static_cast<const SCT3_RawData*>(raw)!=nullptr);
    const SCT3_RawData* raw3 = static_cast<const SCT3_RawData*>(raw);
 
    std::bitset<3> timePattern(raw3->getTimeBin());
    if (!passTiming(timePattern)) {
        ATH_MSG_DEBUG("Strip failed timing check");
        continue;
    }
 
    Identifier firstStripId = raw->identify();
    Identifier waferId = m_stripID->wafer_id(firstStripId);
 
    Identifier::value_type waferId_compact = waferId.get_compact();
 
    
    // Check cache - will be invalid when switching wafer groups
    if (!cache_valid || waferId_compact != waferId_compact_cache) {
      waferId_compact_cache = waferId_compact;
      waferHash_cache = m_stripID->wafer_hash(waferId);
      cache_valid = true;
    }
    
    std::size_t iFirstStrip = static_cast<size_t>(m_stripID->strip(firstStripId));
 
    std::size_t iMaxStrip = std::min(
        iFirstStrip + raw->getGroupSize(),
        ncells
        );
    
    for (size_t i = iFirstStrip; i < iMaxStrip; i++) {
        Identifier stripIdent = m_stripID->strip_id(waferId, i);
        if (isBadStrip(ctx, &stripDetElStatus, *m_stripID, waferHash_cache, stripIdent)) {
        // Bad strip, throw it out to minimize useless work.
        ATH_MSG_DEBUG("Bad strip encountered:" << stripIdent
                  << ", wafer is: " << waferId);
        badStripOnModule = true;
        } else {
        // Good strip!
        cells.emplace_back(i, stripIdent, std::move(timePattern));
        }
    }
    }
 
    return std::make_pair(std::move(cells), badStripOnModule);
}
 
} // namespace ActsTrk