ITS: second round of comments

Author: mpuccio

Detectors/ITSMFT/ITS/tracking/GPU/cuda/TrackingKernels.cu

@@ -1094,7 +1094,7 @@ void processNeighboursHandler(const int startLevel,
   }
   GPUChkErrS(cudaStreamSynchronize(gpu::Stream::DefaultStream));
   thrust::device_vector<TrackSeed<NLayers>, gpu::TypedAllocator<TrackSeed<NLayers>>> outSeeds(updatedCellSeed.size(), allocTrackSeed);
-  auto end = thrust::copy_if(nosync_policy, updatedCellSeed.begin(), updatedCellSeed.end(), outSeeds.begin(), track::TrackSeedSelector<NLayers>{1.e3f, maxChi2NDF, startLevel, maxHoles, minSeedingClusters, holeLayerMask, nonSeedingLayerMask});
+  auto end = thrust::copy_if(nosync_policy, updatedCellSeed.begin(), updatedCellSeed.end(), outSeeds.begin(), track::TrackSeedSelector<NLayers>{constants::MaxTrackSeedQ2Pt, maxChi2NDF, startLevel, maxHoles, minSeedingClusters, holeLayerMask, nonSeedingLayerMask});
   auto s{end - outSeeds.begin()};
   seedsHost.reserve(seedsHost.size() + s);
   thrust::copy(outSeeds.begin(), outSeeds.begin() + s, std::back_inserter(seedsHost));

Detectors/ITSMFT/ITS/tracking/include/ITStracking/Constants.h

@@ -29,6 +29,7 @@ constexpr bool DoTimeBenchmarks = true;
 constexpr bool SaveTimeBenchmarks = false;
 constexpr float Tolerance = 1e-12;                  // numerical tolerance
 constexpr int ClustersPerCell = 3;                  // number of clusters for a cell
+constexpr float MaxTrackSeedQ2Pt = 1.e3f;           // maximum q/pt for track seeds
 constexpr int UnusedIndex = -1;                     // global unused flag
 constexpr float UnsetValue = -999.f;                // global unset value
 constexpr float Radl = 9.36f;                       // Radiation length of Si [cm]

Detectors/ITSMFT/ITS/tracking/src/TrackerTraits.cxx

@@ -686,12 +686,21 @@ bool TrackerTraits<NLayers>::finaliseTrackSeed(const TrackSeedN& seed,
                                       trkParams.ReseedIfShorter)) {
     return false;
   }
+  const auto passesFinalLengthCut = [&trkParams](const TrackITSExt& candidate) {
+    LayerMask hitLayerMask{0};
+    for (int iLayer{0}; iLayer < trkParams.NLayers; ++iLayer) {
+      if (candidate.getClusterIndex(iLayer) != constants::UnusedIndex) {
+        hitLayerMask.set(iLayer);
+      }
+    }
+    return track::TrackSeedSelector<NLayers>::getEffectiveTrackLength(hitLayerMask, trkParams.InactiveLayerMask) >= trkParams.MinTrackLength;
+  };
 
   const bool extendTop = trkParams.PassFlags[IterationStep::TrackFollowerTop];
   const bool extendBot = trkParams.PassFlags[IterationStep::TrackFollowerBot];
   if (!extendTop && !extendBot) {
     track = makeTrackITSExt(internalTrack);
-    return true;
+    return passesFinalLengthCut(track);
   }
 
   const int maxHypotheses = std::max(1, trkParams.TrackFollowerMaxHypotheses);
@@ -743,7 +752,7 @@ bool TrackerTraits<NLayers>::finaliseTrackSeed(const TrackSeedN& seed,
   if (bestDiff) {
     track.setExtendedLayerPattern<NLayers>(bestDiff);
   }
-  return true;
+  return passesFinalLengthCut(track);
 }
 
 template <int NLayers>
@@ -763,7 +772,7 @@ void TrackerTraits<NLayers>::findRoads(const int iteration)
   const auto minSeedingClusters = mTrkParams[iteration].getMinSeedingClusters();
   for (int startLevel{mTrkParams[iteration].CellsPerRoad()}; startLevel >= mTrkParams[iteration].CellMinimumLevel(); --startLevel) {
 
-    const track::TrackSeedSelector<NLayers> seedFilter{1.e3f, mTrkParams[iteration].MaxChi2NDF, startLevel, mTrkParams[iteration].MaxHoles, minSeedingClusters, mTrkParams[iteration].HoleLayerMask, nonSeedingLayerMask};
+    const track::TrackSeedSelector<NLayers> seedFilter{constants::MaxTrackSeedQ2Pt, mTrkParams[iteration].MaxChi2NDF, startLevel, mTrkParams[iteration].MaxHoles, minSeedingClusters, mTrkParams[iteration].HoleLayerMask, nonSeedingLayerMask};
 
     bounded_vector<TrackSeedN> trackSeeds(mMemoryPool.get());
     for (int startCellTopologyId{0}; startCellTopologyId < topology.nCells; ++startCellTopologyId) {
@@ -853,18 +862,14 @@ void TrackerTraits<NLayers>::acceptTracks(int iteration,
   auto& trks = mTimeFrame->getTracks();
   trks.reserve(trks.size() + tracks.size());
   const float smallestROFHalf = mTimeFrame->getROFOverlapTableView().getClockLayer().mROFLength * 0.5f;
-  const int minTrackLength = mTrkParams[iteration].MinTrackLength;
-  const LayerMask inactiveLayerMask = mTrkParams[iteration].InactiveLayerMask;
   for (auto& track : tracks) {
     int nShared = 0;
     bool isFirstShared{false};
     int firstLayer{-1}, firstCluster{-1};
-    LayerMask hitLayerMask{0};
     for (int iLayer{0}; iLayer < mTrkParams[iteration].NLayers; ++iLayer) {
       if (track.getClusterIndex(iLayer) == constants::UnusedIndex) {
         continue;
       }
-      hitLayerMask.set(iLayer);
       bool isShared = mTimeFrame->isClusterUsed(iLayer, track.getClusterIndex(iLayer));
       nShared += int(isShared);
       if (firstLayer < 0) {
@@ -874,11 +879,6 @@ void TrackerTraits<NLayers>::acceptTracks(int iteration,
       }
     }
 
-    /// seeds are selected with a length cut relaxed to the seeding layers: enforce the full minimum length before accepting the final track
-    if (track::TrackSeedSelector<NLayers>::getEffectiveTrackLength(hitLayerMask, inactiveLayerMask) < minTrackLength) {
-      continue;
-    }
-
     /// do not account for the first cluster in the shared clusters number if it is allowed
     if (nShared - int(isFirstShared && mTrkParams[iteration].AllowSharingFirstCluster) > mTrkParams[iteration].SharedMaxClusters) {
       continue;