From 9cd86cde62033fca7f127ad7e3f1869198de1261 Mon Sep 17 00:00:00 2001
From: Giulio Eulisse <10544+ktf@users.noreply.github.com>
Date: Tue, 29 Sep 2020 13:30:59 +0200
Subject: [PATCH] DPL: avoid copying shared pointers while reading

---
 Framework/Core/include/Framework/TableTreeHelpers.h |  2 +-
 Framework/Core/src/TableTreeHelpers.cxx             | 10 +++++-----
 2 files changed, 6 insertions(+), 6 deletions(-)

diff --git a/Framework/Core/include/Framework/TableTreeHelpers.h b/Framework/Core/include/Framework/TableTreeHelpers.h
index 91adac34bae3a..9a9bcd9200255 100644
--- a/Framework/Core/include/Framework/TableTreeHelpers.h
+++ b/Framework/Core/include/Framework/TableTreeHelpers.h
@@ -212,7 +212,7 @@ class TreeToTable
   TTreeReader* mTreeReader;
 
   // a list of ColumnIterator*
-  std::vector<std::shared_ptr<ColumnIterator>> mColumnIterators;
+  std::vector<std::unique_ptr<ColumnIterator>> mColumnIterators;
 
   // Append next set of branch values to the
   // corresponding table columns
diff --git a/Framework/Core/src/TableTreeHelpers.cxx b/Framework/Core/src/TableTreeHelpers.cxx
index ea8699e490d3c..b7de8bf802aad 100644
--- a/Framework/Core/src/TableTreeHelpers.cxx
+++ b/Framework/Core/src/TableTreeHelpers.cxx
@@ -738,7 +738,7 @@ TreeToTable::~TreeToTable()
 
 bool TreeToTable::addColumn(const char* colname)
 {
-  auto colit = std::make_shared<ColumnIterator>(mTreeReader, colname);
+  auto colit = std::make_unique<ColumnIterator>(mTreeReader, colname);
   auto stat = colit->getStatus();
   if (stat) {
     mColumnIterators.push_back(std::move(colit));
@@ -763,7 +763,7 @@ bool TreeToTable::addAllColumns()
     auto br = (TBranch*)branchList->At(ii);
 
     // IMPROVE: make sure that a column is not added more than one time
-    auto colit = std::make_shared<ColumnIterator>(mTreeReader, br->GetName());
+    auto colit = std::make_unique<ColumnIterator>(mTreeReader, br->GetName());
     if (colit->getStatus()) {
       mColumnIterators.push_back(std::move(colit));
     } else {
@@ -776,14 +776,14 @@ bool TreeToTable::addAllColumns()
 
 void TreeToTable::push()
 {
-  for (auto colit : mColumnIterators) {
+  for (auto&& colit : mColumnIterators) {
     colit->push();
   }
 }
 
 void TreeToTable::reserve(size_t s)
 {
-  for (auto column : mColumnIterators) {
+  for (auto&& column : mColumnIterators) {
     column->reserve(s);
   }
 }
@@ -805,7 +805,7 @@ std::shared_ptr<arrow::Table> TreeToTable::finalize()
   // prepare the elements needed to create the final table
   std::vector<std::shared_ptr<arrow::Array>> array_vector;
   std::vector<std::shared_ptr<arrow::Field>> schema_vector;
-  for (auto colit : mColumnIterators) {
+  for (auto&& colit : mColumnIterators) {
     colit->finish();
     array_vector.push_back(colit->getArray());
     schema_vector.push_back(colit->getSchema());