ProcessBankSplitTask.cpp

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// Mantid Repository : https://github.com/mantidproject/mantid
//
// Copyright © 2025 ISIS Rutherford Appleton Laboratory UKRI,
//   NScD Oak Ridge National Laboratory, European Spallation Source,
//   Institut Laue - Langevin & CSNS, Institute of High Energy Physics, CAS
// SPDX - License - Identifier: GPL - 3.0 +
 
#include "MantidDataHandling/AlignAndFocusPowderSlim/ProcessBankSplitTask.h"
#include "MantidDataHandling/AlignAndFocusPowderSlim/ProcessEventsTask.h"
#include "MantidKernel/Logger.h"
#include "MantidKernel/ParallelMinMax.h"
#include "MantidKernel/Timer.h"
#include "MantidKernel/Unit.h"
#include "MantidNexus/H5Util.h"
#include "tbb/parallel_for.h"
#include "tbb/parallel_reduce.h"
 
#include <ranges>
 
namespace Mantid::DataHandling::AlignAndFocusPowderSlim {
 
namespace {
 
const std::string MICROSEC("microseconds");
 
// Logger for this class
auto g_log = Kernel::Logger("ProcessBankSplitTask");
 
} // namespace
ProcessBankSplitTask::ProcessBankSplitTask(
    std::vector<std::string> &bankEntryNames, H5::H5File &h5file, const bool is_time_filtered,
    std::vector<int> &workspaceIndices, std::vector<API::MatrixWorkspace_sptr> &wksps,
    const std::map<detid_t, double> &calibration, const std::map<detid_t, double> &scale_at_sample,
    const std::set<detid_t> &masked, const size_t events_per_chunk, const size_t grainsize_event,
    std::vector<std::pair<int, PulseROI>> target_to_pulse_indices, std::shared_ptr<API::Progress> &progress)
    : m_h5file(h5file), m_bankEntries(bankEntryNames), m_loader(is_time_filtered, {}, target_to_pulse_indices),
      m_workspaceIndices(workspaceIndices), m_wksps(wksps), m_calibration(calibration),
      m_scale_at_sample(scale_at_sample), m_masked(masked), m_events_per_chunk(events_per_chunk),
      m_grainsize_event(grainsize_event), m_progress(progress) {}
 
void ProcessBankSplitTask::operator()(const tbb::blocked_range<size_t> &range) const {
  auto entry = m_h5file.openGroup("entry"); // type=NXentry
  for (size_t wksp_index = range.begin(); wksp_index < range.end(); ++wksp_index) {
    const auto &bankName = m_bankEntries[wksp_index];
    // empty bank names indicate spectra to skip; control should never get here, but just in case
    if (bankName.empty()) {
      continue;
    }
    Kernel::Timer timer;
    g_log.debug() << bankName << " start" << std::endl;
 
    // open the bank
    auto event_group = entry.openGroup(bankName); // type=NXevent_data
 
    // skip empty dataset
    auto tof_SDS = event_group.openDataSet(NxsFieldNames::TIME_OF_FLIGHT);
    const int64_t total_events = static_cast<size_t>(tof_SDS.getSpace().getSelectNpoints());
    if (total_events == 0) {
      m_progress->report();
      continue;
    }
 
    auto eventSplitRanges = m_loader.getEventIndexSplitRanges(event_group, total_events);
 
    // Get all spectra for this bank.
    // Create temporary y arrays for each workspace.
    std::vector<API::ISpectrum *> spectra;
    std::vector<std::vector<uint32_t>> y_temps;
    for (const auto &wksp : m_wksps) {
      spectra.push_back(&wksp->getSpectrum(wksp_index));
      y_temps.emplace_back(spectra.back()->dataY().size());
    }
 
    // create object so bank calibration can be re-used
    std::unique_ptr<BankCalibration> calibration = nullptr;
 
    // get handle to the data
    auto detID_SDS = event_group.openDataSet(NxsFieldNames::DETID);
    // auto tof_SDS = event_group.openDataSet(NxsFieldNames::TIME_OF_FLIGHT);
    // and the units
    std::string tof_unit;
    Nexus::H5Util::readStringAttribute(tof_SDS, "units", tof_unit);
    const double time_conversion = Kernel::Units::timeConversionValue(tof_unit, MICROSEC);
 
    // declare arrays once so memory can be reused
    auto event_detid = std::make_unique<std::vector<uint32_t>>();       // uint32 for ORNL nexus file
    auto event_time_of_flight = std::make_unique<std::vector<float>>(); // float for ORNL nexus files
 
    // read parts of the bank at a time until all events are processed
    while (!eventSplitRanges.empty()) {
      // Create offsets and slab sizes for the next chunk of events.
      // This will read at most m_events_per_chunk events from the file
      // and will split the ranges if necessary for the next iteration.
      std::vector<size_t> offsets;
      std::vector<size_t> slabsizes;
      std::vector<std::pair<int, EventROI>> relative_target_ranges;
 
      size_t total_events_to_read = 0;
      // Process the event ranges until we reach the desired number of events to read or run out of ranges
      while (!eventSplitRanges.empty() && total_events_to_read < m_events_per_chunk) {
        // Get the next event range from the stack
        auto [target, eventRange] = eventSplitRanges.top();
        eventSplitRanges.pop();
 
        size_t range_size = eventRange.second - eventRange.first;
        size_t remaining_chunk = m_events_per_chunk - total_events_to_read;
 
        // If the range size is larger than the remaining chunk, we need to split it
        if (range_size > remaining_chunk) {
          // Split the range: process only part of it now, push the rest back for later
          relative_target_ranges.emplace_back(target,
                                              EventROI(total_events_to_read, total_events_to_read + remaining_chunk));
          offsets.push_back(eventRange.first);
          slabsizes.push_back(remaining_chunk);
          total_events_to_read += remaining_chunk;
          // Push the remainder of the range back to the front for next iteration
          eventSplitRanges.emplace(target, EventROI(eventRange.first + remaining_chunk, eventRange.second));
          break;
        } else {
          relative_target_ranges.emplace_back(target,
                                              EventROI(total_events_to_read, total_events_to_read + range_size));
          offsets.push_back(eventRange.first);
          slabsizes.push_back(range_size);
          total_events_to_read += range_size;
          // Continue to next range
        }
      }
 
      // log the event ranges being processed
      std::ostringstream oss;
      oss << "Processing " << bankName << " with " << total_events_to_read << " events in the ranges: ";
      for (size_t i = 0; i < offsets.size(); ++i) {
        oss << "[" << offsets[i] << ", " << (offsets[i] + slabsizes[i]) << "), ";
      }
      oss << "\n";
      g_log.debug() << oss.str();
 
      // load detid and tof at the same time
      tbb::parallel_invoke(
          [&] { // load detid
            // event_detid->clear();
            m_loader.loadData(detID_SDS, event_detid, offsets, slabsizes);
            // immediately find min/max to allow for other things to read disk
            const auto [minval, maxval] = Mantid::Kernel::parallel_minmax(event_detid, m_grainsize_event);
            // only recreate calibration if it doesn't already have the useful information
            if ((!calibration) || (calibration->idmin() > static_cast<detid_t>(minval)) ||
                (calibration->idmax() < static_cast<detid_t>(maxval))) {
              calibration =
                  std::make_unique<BankCalibration>(static_cast<detid_t>(minval), static_cast<detid_t>(maxval),
                                                    time_conversion, m_calibration, m_scale_at_sample, m_masked);
            }
          },
          [&] { // load time-of-flight
            // event_time_of_flight->clear();
            m_loader.loadData(tof_SDS, event_time_of_flight, offsets, slabsizes);
          });
 
      // loop over targets
      tbb::parallel_for(
          tbb::blocked_range<size_t>(0, m_workspaceIndices.size()), [&](const tbb::blocked_range<size_t> &r) {
            for (size_t idx = r.begin(); idx != r.end(); ++idx) {
              int i = m_workspaceIndices[idx];
 
              // Precompute indices for this target
              std::vector<size_t> indices;
              for (const auto &pair : relative_target_ranges) {
                if (pair.first == static_cast<int>(i)) {
                  auto [start, end] = pair.second;
                  for (size_t k = start; k < end; ++k) {
                    indices.push_back(k);
                  }
                }
              }
 
              auto event_id_view_for_target =
                  indices | std::views::transform([&event_detid](const auto &k) { return (*event_detid)[k]; });
              auto event_tof_view_for_target = indices | std::views::transform([&event_time_of_flight](const auto &k) {
                                                 return (*event_time_of_flight)[k];
                                               });
 
              ProcessEventsTask task(&event_id_view_for_target, &event_tof_view_for_target, calibration.get(),
                                     &spectra[idx]->readX());
 
              const tbb::blocked_range<size_t> range_info(0, indices.size(), m_grainsize_event);
              tbb::parallel_reduce(range_info, task);
 
              std::transform(y_temps[idx].begin(), y_temps[idx].end(), task.y_temp.begin(), y_temps[idx].begin(),
                             std::plus<uint32_t>());
            }
          });
    }
 
    // copy the data out into the correct spectrum
    tbb::parallel_for(size_t(0), m_wksps.size(), [&](size_t i) {
      auto &y_values = spectra[i]->dataY();
      std::copy(y_temps[i].cbegin(), y_temps[i].cend(), y_values.begin());
    });
 
    g_log.debug() << bankName << " stop " << timer << std::endl;
    m_progress->report();
  }
}
}; // namespace Mantid::DataHandling::AlignAndFocusPowderSlim