ITS: findRoads reduce resizing of seeds

Author: f3sch

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

@@ -776,6 +776,9 @@ void TrackerTraits<nLayers>::findRoads(const int iteration)
 
   for (int startLevel{mTrkParams[iteration].CellsPerRoad()}; startLevel >= mTrkParams[iteration].CellMinimumLevel(); --startLevel) {
     CA_DEBUGGER(std::cout << "\t > Processing level " << startLevel << std::endl);
+    auto seedFilter = [&](const CellSeed& seed) {
+      return seed.getQ2Pt() <= 1.e3 && seed.getChi2() <= mTrkParams[0].MaxChi2NDF * ((startLevel + 2) * 2 - 5);
+    };
     bounded_vector<CellSeed> trackSeeds(mMemoryPool.get());
     for (int startLayer{mTrkParams[iteration].CellsPerRoad() - 1}; startLayer >= startLevel - 1; --startLayer) {
       if ((mTrkParams[iteration].StartLayerMask & (1 << (startLayer + 2))) == 0) {
@@ -798,9 +801,10 @@ void TrackerTraits<nLayers>::findRoads(const int iteration)
       deepVectorClear(lastCellId);   /// tame the memory peaks
       deepVectorClear(lastCellSeed); /// tame the memory peaks
 
-      std::copy_if(updatedCellSeed.begin(), updatedCellSeed.end(), std::back_inserter(trackSeeds), [&](const CellSeed& seed) {
-        return seed.getQ2Pt() <= 1.e3 && seed.getChi2() <= mTrkParams[0].MaxChi2NDF * ((startLevel + 2) * 2 - 5);
-      });
+      if (!updatedCellSeed.empty()) {
+        trackSeeds.reserve(trackSeeds.size() + std::count_if(updatedCellSeed.begin(), updatedCellSeed.end(), seedFilter));
+        std::copy_if(updatedCellSeed.begin(), updatedCellSeed.end(), std::back_inserter(trackSeeds), seedFilter);
+      }
     }
 
     if (trackSeeds.empty()) {