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[ntuple] improve reading of std::vector<complex object> #21651

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Merged
jblomer merged 1 commit into from
Mar 24, 2026
Merged

[ntuple] improve reading of std::vector<complex object> #21651

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3 changes: 2 additions & 1 deletion tree/ntuple/src/RFieldSequenceContainer.cxx
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Original file line number Diff line number Diff line change
Expand Up @@ -615,7 +615,8 @@ void ROOT::RVectorField::ResizeVector(void *vec, std::size_t nItems, std::size_t
// See "semantics of reading non-trivial objects" in RNTuple's Architecture.md
R__ASSERT(itemSize > 0);
const auto oldNItems = typedValue->size() / itemSize;
const bool canRealloc = oldNItems < nItems;
const auto availNItems = typedValue->capacity() / itemSize;
const bool canRealloc = availNItems < nItems;
bool allDeallocated = false;
if (itemDeleter) {
allDeallocated = canRealloc;
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71 changes: 18 additions & 53 deletions tree/ntuple/test/rfield_vector.cxx
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Original file line number Diff line number Diff line change
Expand Up @@ -341,63 +341,14 @@ void FillComplexVector(const std::string &fname)
ntuple->Fill();
}

// Note: RVec and std::vector differ in the number of construction/destruction calls when reading through
// a file. The reason is that we can control the memory re-allocation prodedure for RVec, which allows
// us to save destruction/construction calls.

TEST(RNTuple, ComplexVector)
{
FileRaii fileGuard("test_ntuple_vec_complex.root");
FillComplexVector<Vector_t>(fileGuard.GetPath());

ComplexStruct::SetNCallConstructor(0);
ComplexStruct::SetNCallDestructor(0);
{
auto ntuple = RNTupleReader::Open("T", fileGuard.GetPath());
auto rdV = ntuple->GetModel().GetDefaultEntry().GetPtr<std::vector<ComplexStruct>>("v");

ntuple->LoadEntry(0);
EXPECT_EQ(0, ComplexStruct::GetNCallConstructor());
EXPECT_EQ(0, ComplexStruct::GetNCallDestructor());
EXPECT_TRUE(rdV->empty());
ntuple->LoadEntry(1);
EXPECT_EQ(10, ComplexStruct::GetNCallConstructor());
EXPECT_EQ(0, ComplexStruct::GetNCallDestructor());
EXPECT_EQ(10u, rdV->size());
ntuple->LoadEntry(2);
EXPECT_EQ(10010, ComplexStruct::GetNCallConstructor());
EXPECT_EQ(10, ComplexStruct::GetNCallDestructor());
EXPECT_EQ(10000u, rdV->size());
ntuple->LoadEntry(3);
EXPECT_EQ(10010, ComplexStruct::GetNCallConstructor());
EXPECT_EQ(9910, ComplexStruct::GetNCallDestructor());
EXPECT_EQ(100u, rdV->size());
ntuple->LoadEntry(4);
EXPECT_EQ(10210, ComplexStruct::GetNCallConstructor());
EXPECT_EQ(10010, ComplexStruct::GetNCallDestructor());
EXPECT_EQ(200u, rdV->size());
ntuple->LoadEntry(5);
EXPECT_EQ(10210, ComplexStruct::GetNCallConstructor());
EXPECT_EQ(10210, ComplexStruct::GetNCallDestructor());
EXPECT_EQ(0u, rdV->size());
ntuple->LoadEntry(6);
EXPECT_EQ(10211, ComplexStruct::GetNCallConstructor());
EXPECT_EQ(10210, ComplexStruct::GetNCallDestructor());
EXPECT_EQ(1u, rdV->size());
}
EXPECT_EQ(10211u, ComplexStruct::GetNCallDestructor());
}

TEST(RNTuple, ComplexRVec)
template <template <typename> class Coll_t>
void TestComplexVector(const std::string &fname)
{
FileRaii fileGuard("test_ntuple_rvec_complex.root");
FillComplexVector<ROOT::RVec>(fileGuard.GetPath());

ComplexStruct::SetNCallConstructor(0);
ComplexStruct::SetNCallDestructor(0);
{
auto ntuple = RNTupleReader::Open("T", fileGuard.GetPath());
auto rdV = ntuple->GetModel().GetDefaultEntry().GetPtr<ROOT::RVec<ComplexStruct>>("v");
auto ntuple = RNTupleReader::Open("T", fname);
auto rdV = ntuple->GetModel().GetDefaultEntry().GetPtr<Coll_t<ComplexStruct>>("v");

ntuple->LoadEntry(0);
EXPECT_EQ(0, ComplexStruct::GetNCallConstructor());
Expand Down Expand Up @@ -431,6 +382,20 @@ TEST(RNTuple, ComplexRVec)
EXPECT_EQ(10111u, ComplexStruct::GetNCallDestructor());
}

TEST(RNTuple, ComplexVector)
{
FileRaii fileGuard("test_ntuple_vec_complex.root");
FillComplexVector<Vector_t>(fileGuard.GetPath());
TestComplexVector<Vector_t>(fileGuard.GetPath());
}

TEST(RNTuple, ComplexRVec)
{
FileRaii fileGuard("test_ntuple_rvec_complex.root");
FillComplexVector<ROOT::RVec>(fileGuard.GetPath());
TestComplexVector<ROOT::RVec>(fileGuard.GetPath());
}

TEST(RNTuple, VectorOfString)
{
FileRaii fileGuard("test_ntuple_vector_of_string.root");
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