ITS: compactify findRoads

Author: f3sch

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

@@ -823,19 +823,12 @@ void TrackerTraits<nLayers>::findRoads(const int iteration)
     }
 
     bounded_vector<TrackITSExt> tracks(mMemoryPool.get());
-    tracks.reserve(trackSeeds.size());
     mTaskArena.execute([&] {
-      tbb::combinable<bounded_vector<TrackITSExt>> locTracksData([&] {
-        return bounded_vector<TrackITSExt>(mMemoryPool.get());
-      });
-
+      bounded_vector<int> perSeedCount(trackSeeds.size() + 1, 0, mMemoryPool.get());
       tbb::parallel_for(
         tbb::blocked_range<int>(0, (int)trackSeeds.size()),
         [&](const tbb::blocked_range<int>& Seeds) {
           for (int iSeed = Seeds.begin(); iSeed < Seeds.end(); ++iSeed) {
-            auto& localTracks = locTracksData.local();
-            localTracks.reserve(Seeds.size());
-
             const CellSeed& seed{trackSeeds[iSeed]};
             TrackITSExt temporaryTrack{seed};
             temporaryTrack.resetCovariance();
@@ -855,14 +848,41 @@ void TrackerTraits<nLayers>::findRoads(const int iteration)
             if (!fitSuccess || temporaryTrack.getPt() < mTrkParams[iteration].MinPt[mTrkParams[iteration].NLayers - temporaryTrack.getNClusters()]) {
               continue;
             }
-            localTracks.push_back(temporaryTrack);
+            ++perSeedCount[iSeed];
           }
         });
+      std::exclusive_scan(perSeedCount.begin(), perSeedCount.end(), perSeedCount.begin(), 0);
+      auto totalTracks{perSeedCount.back()};
+      if (totalTracks == 0) {
+        return;
+      }
+      tracks.resize(totalTracks);
 
-      locTracksData.combine_each([&](const bounded_vector<TrackITSExt>& localTracks) {
-        tracks.insert(tracks.end(), localTracks.begin(), localTracks.end());
-      });
-      tracks.shrink_to_fit();
+      tbb::parallel_for(
+        tbb::blocked_range<int>(0, (int)trackSeeds.size()),
+        [&](const tbb::blocked_range<int>& Seeds) {
+          for (int iSeed = Seeds.begin(); iSeed < Seeds.end(); ++iSeed) {
+            if (perSeedCount[iSeed] == perSeedCount[iSeed + 1]) {
+              continue;
+            }
+            const CellSeed& seed{trackSeeds[iSeed]};
+            auto& trk = tracks[perSeedCount[iSeed]] = TrackITSExt(seed);
+            trk.resetCovariance();
+            trk.setChi2(0);
+            for (int iL{0}; iL < 7; ++iL) {
+              trk.setExternalClusterIndex(iL, seed.getCluster(iL), seed.getCluster(iL) != constants::its::UnusedIndex);
+            }
+
+            bool fitSuccess = fitTrack(trk, 0, mTrkParams[0].NLayers, 1, mTrkParams[0].MaxChi2ClusterAttachment, mTrkParams[0].MaxChi2NDF);
+            if (!fitSuccess) {
+              continue;
+            }
+            trk.getParamOut() = trk.getParamIn();
+            trk.resetCovariance();
+            trk.setChi2(0);
+            fitTrack(trk, mTrkParams[0].NLayers - 1, -1, -1, mTrkParams[0].MaxChi2ClusterAttachment, mTrkParams[0].MaxChi2NDF, 50.f);
+          }
+        });
 
       tbb::parallel_sort(tracks.begin(), tracks.end(), [](const auto& a, const auto& b) {
         return a.getChi2() < b.getChi2();