[ALICE3] Introduce flat LUT container for the TrackSmearer and rebase OTF code to use it (#15826)

Co-authored-by: ALICE Action Bot <alibuild@cern.ch>
Co-authored-by: jesgum <jesper.gumprecht@gmail.com>

Author: 3 people

ALICE3/Core/CMakeLists.txt

@@ -12,28 +12,30 @@
 o2physics_add_library(ALICE3Core
                       SOURCES TOFResoALICE3.cxx
                               TrackUtilities.cxx
-                              DelphesO2TrackSmearer.cxx
+                              FlatLutEntry.cxx
+                              FlatTrackSmearer.cxx
                               GeometryContainer.cxx
                       PUBLIC_LINK_LIBRARIES O2::Framework
                                             O2Physics::AnalysisCore)
 
 o2physics_target_root_dictionary(ALICE3Core
                       HEADERS TOFResoALICE3.h
                               TrackUtilities.h
-                              DelphesO2TrackSmearer.h
+                              FlatLutEntry.h
                               GeometryContainer.h
                       LINKDEF ALICE3CoreLinkDef.h)
 
 o2physics_add_library(FastTracker
                       SOURCES FastTracker.cxx
                               DetLayer.cxx
-                              DelphesO2LutWriter.cxx
+                              FlatLutEntry.cxx
+                              FlatLutWriter.cxx
                       PUBLIC_LINK_LIBRARIES O2::Framework
                                             O2Physics::AnalysisCore
                                             O2Physics::ALICE3Core)
 
 o2physics_target_root_dictionary(FastTracker
                       HEADERS FastTracker.h
                               DetLayer.h
-                              DelphesO2LutWriter.h
+                              FlatLutWriter.h
                       LINKDEF FastTrackerLinkDef.h)

ALICE3/Core/FastTrackerLinkDef.h

@@ -18,6 +18,6 @@
 
 #pragma link C++ class o2::fastsim::GeometryContainer + ;
 #pragma link C++ class o2::fastsim::FastTracker + ;
-#pragma link C++ class o2::fastsim::DelphesO2LutWriter + ;
+#pragma link C++ class o2::fastsim::FlatLutWriter + ;
 
 #endif // ALICE3_CORE_FASTTRACKERLINKDEF_H_

ALICE3/Core/FlatLutEntry.cxx

@@ -0,0 +1,270 @@
+// Copyright 2019-2020 CERN and copyright holders of ALICE O2.
+// See https://alice-o2.web.cern.ch/copyright for details of the copyright holders.
+// All rights not expressly granted are reserved.
+//
+// This software is distributed under the terms of the GNU General Public
+// License v3 (GPL Version 3), copied verbatim in the file "COPYING".
+//
+// In applying this license CERN does not waive the privileges and immunities
+// granted to it by virtue of its status as an Intergovernmental Organization
+// or submit itself to any jurisdiction.
+
+#include "FlatLutEntry.h"
+
+#include <Framework/Logger.h>
+#include <Framework/RuntimeError.h>
+
+#include <cstring>
+
+namespace o2::delphes
+{
+
+float map_t::fracPositionWithinBin(float val) const
+{
+  float width = (max - min) / nbins;
+  int bin;
+  float returnVal = 0.5f;
+  if (log) {
+    bin = static_cast<int>((std::log10(val) - min) / width);
+    returnVal = ((std::log10(val) - min) / width) - bin;
+  } else {
+    bin = static_cast<int>((val - min) / width);
+    returnVal = val / width - bin;
+  }
+  return returnVal;
+}
+
+int map_t::find(float val) const
+{
+  float width = (max - min) / nbins;
+  int bin;
+  if (log) {
+    bin = static_cast<int>((std::log10(val) - min) / width);
+  } else {
+    bin = static_cast<int>((val - min) / width);
+  }
+  if (bin < 0) {
+    return 0;
+  }
+  if (bin > nbins - 1) {
+    return nbins - 1;
+  }
+  return bin;
+}
+
+void map_t::print() const
+{
+  LOGF(info, "nbins = %d, min = %f, max = %f, log = %s \n", nbins, min, max, log ? "on" : "off");
+}
+
+bool lutHeader_t::check_version() const
+{
+  return (version == LUTCOVM_VERSION);
+}
+
+void lutHeader_t::print() const
+{
+  LOGF(info, " version: %d \n", version);
+  LOGF(info, "     pdg: %d \n", pdg);
+  LOGF(info, "   field: %f \n", field);
+  LOGF(info, "  nchmap: ");
+  nchmap.print();
+  LOGF(info, "  radmap: ");
+  radmap.print();
+  LOGF(info, "  etamap: ");
+  etamap.print();
+  LOGF(info, "   ptmap: ");
+  ptmap.print();
+}
+
+void FlatLutData::initialize(const lutHeader_t& header)
+{
+  mNchBins = header.nchmap.nbins;
+  mRadBins = header.radmap.nbins;
+  mEtaBins = header.etamap.nbins;
+  mPtBins = header.ptmap.nbins;
+
+  size_t headerSize = sizeof(lutHeader_t);
+  size_t numEntries = static_cast<size_t>(mNchBins) * mRadBins * mEtaBins * mPtBins;
+  size_t entriesSize = numEntries * sizeof(lutEntry_t);
+  size_t totalSize = headerSize + entriesSize;
+
+  mData.resize(totalSize);
+  // Write header at the beginning
+  std::memcpy(mData.data(), &header, headerSize);
+  updateRef();
+}
+
+size_t FlatLutData::getEntryOffset(int nch_bin, int rad_bin, int eta_bin, int pt_bin) const
+{
+  size_t headerSize = sizeof(lutHeader_t);
+
+  // Linear index: nch varies slowest, pt varies fastest
+  // idx = nch * (rad*eta*pt) + rad * (eta*pt) + eta * pt + pt
+  size_t linearIdx = static_cast<size_t>(nch_bin) * (mRadBins * mEtaBins * mPtBins) + static_cast<size_t>(rad_bin) * (mEtaBins * mPtBins) + static_cast<size_t>(eta_bin) * mPtBins + static_cast<size_t>(pt_bin);
+
+  return headerSize + linearIdx * sizeof(lutEntry_t);
+}
+
+const lutEntry_t* FlatLutData::getEntryRef(int nch_bin, int rad_bin, int eta_bin, int pt_bin) const
+{
+  size_t offset = getEntryOffset(nch_bin, rad_bin, eta_bin, pt_bin);
+  return reinterpret_cast<const lutEntry_t*>(mDataRef.data() + offset);
+}
+
+lutEntry_t* FlatLutData::getEntry(int nch_bin, int rad_bin, int eta_bin, int pt_bin)
+{
+  size_t offset = getEntryOffset(nch_bin, rad_bin, eta_bin, pt_bin);
+  return reinterpret_cast<lutEntry_t*>(mData.data() + offset);
+}
+
+const lutHeader_t& FlatLutData::getHeaderRef() const
+{
+  return *reinterpret_cast<const lutHeader_t*>(mDataRef.data());
+}
+
+lutHeader_t& FlatLutData::getHeader()
+{
+  return *reinterpret_cast<lutHeader_t*>(mData.data());
+}
+
+void FlatLutData::updateRef()
+{
+  mDataRef = std::span{mData.data(), mData.size()};
+}
+
+void FlatLutData::cacheDimensions()
+{
+  auto const& header = getHeaderRef();
+  mNchBins = header.nchmap.nbins;
+  mRadBins = header.radmap.nbins;
+  mEtaBins = header.etamap.nbins;
+  mPtBins = header.ptmap.nbins;
+}
+
+void FlatLutData::resetDimensions()
+{
+  mNchBins = 0;
+  mRadBins = 0;
+  mEtaBins = 0;
+  mPtBins = 0;
+}
+
+void FlatLutData::adopt(const uint8_t* buffer, size_t size)
+{
+  mData.resize(size);
+  std::memcpy(mData.data(), buffer, size);
+  updateRef();
+  cacheDimensions();
+}
+
+void FlatLutData::view(const uint8_t* buffer, size_t size)
+{
+  mData.clear();
+  mDataRef = std::span{buffer, size};
+  cacheDimensions();
+}
+
+void FlatLutData::validateBuffer(const uint8_t* buffer, size_t size)
+{
+  auto header = PreviewHeader(buffer, size);
+  auto mNchBins = header.nchmap.nbins;
+  auto mRadBins = header.radmap.nbins;
+  auto mEtaBins = header.etamap.nbins;
+  auto mPtBins = header.ptmap.nbins;
+
+  size_t expectedSize = sizeof(lutHeader_t) + static_cast<size_t>(mNchBins) * mRadBins * mEtaBins * mPtBins * sizeof(lutEntry_t);
+
+  if (size < expectedSize) {
+    throw framework::runtime_error_f("Buffer size mismatch: expected %zu, got %zu", expectedSize, size);
+  }
+}
+
+lutHeader_t FlatLutData::PreviewHeader(const uint8_t* buffer, size_t size)
+{
+  if (size < sizeof(lutHeader_t)) {
+    throw framework::runtime_error_f("Buffer too small for LUT header: expected at least %zu, got %zu", sizeof(lutHeader_t), size);
+  }
+  const auto* header = reinterpret_cast<const lutHeader_t*>(buffer);
+  if (!header->check_version()) {
+    throw framework::runtime_error_f("LUT header version mismatch: expected %d, got %d", LUTCOVM_VERSION, header->version);
+  }
+  return *header;
+}
+
+FlatLutData FlatLutData::AdoptFromBuffer(const uint8_t* buffer, size_t size)
+{
+  validateBuffer(buffer, size);
+  FlatLutData data;
+
+  // Copy buffer
+  data.adopt(buffer, size);
+  return data;
+}
+
+FlatLutData FlatLutData::ViewFromBuffer(const uint8_t* buffer, size_t size)
+{
+  validateBuffer(buffer, size);
+  FlatLutData data;
+
+  // Store reference to external buffer
+  // WARNING: Caller must ensure buffer lifetime exceeds FlatLutData usage
+  data.view(buffer, size);
+  return data;
+}
+
+FlatLutData FlatLutData::ViewFromBuffer(std::span<std::byte> const& span)
+{
+  return ViewFromBuffer(reinterpret_cast<const uint8_t*>(span.data()), span.size_bytes());
+}
+
+bool FlatLutData::isLoaded() const
+{
+  return ((!mData.empty()) || (!mDataRef.empty()));
+}
+
+lutHeader_t FlatLutData::PreviewHeader(std::ifstream& file, const char* filename)
+{
+  lutHeader_t tempHeader;
+  file.read(reinterpret_cast<char*>(&tempHeader), sizeof(lutHeader_t));
+  if (file.gcount() != static_cast<std::streamsize>(sizeof(lutHeader_t))) {
+    throw framework::runtime_error_f("Failed to read LUT header from %s", filename);
+  }
+  if (!tempHeader.check_version()) {
+    throw framework::runtime_error_f("LUT header version mismatch: expected %d, got %d", LUTCOVM_VERSION, tempHeader.version);
+  }
+  return tempHeader;
+}
+
+FlatLutData FlatLutData::loadFromFile(std::ifstream& file, const char* filename)
+{
+  // Read header first
+  lutHeader_t tempHeader = PreviewHeader(file, filename);
+
+  FlatLutData data;
+
+  // Initialize flat data structure
+  data.initialize(tempHeader);
+
+  // Read all entries sequentially into flat buffer
+  size_t headerSize = sizeof(lutHeader_t);
+  size_t numEntries = static_cast<size_t>(data.mNchBins) * data.mRadBins * data.mEtaBins * data.mPtBins;
+  size_t entriesSize = numEntries * sizeof(lutEntry_t);
+
+  file.read(reinterpret_cast<char*>(data.data() + headerSize), entriesSize);
+  if (file.gcount() != static_cast<std::streamsize>(entriesSize)) {
+    throw framework::runtime_error_f("Failed to read LUT entries from %s: expected %zu bytes, got %zu", filename, entriesSize, static_cast<size_t>(file.gcount()));
+  }
+
+  LOGF(info, "Successfully loaded LUT from %s: %zu entries", filename, numEntries);
+  return data;
+}
+
+void FlatLutData::reset()
+{
+  mData.clear();
+  updateRef();
+  resetDimensions();
+}
+
+} // namespace o2::delphes