Reads RNTuple data from storage.

The RNTupleReader provides access to data stored in the RNTuple binary format as C++ objects, using an RNTupleModel. It infers this model from the RNTuple's on-disk metadata, or uses a model imposed by the user. The latter case allows users to read into a specialized RNTuple model that covers only a subset of the fields in the RNTuple. The RNTuple model is used when reading complete entries through LoadEntry(). Individual fields can be read as well by instantiating a tree view.

#include <ROOT/RNTupleReader.hxx>
#include <iostream>
 
auto reader = ROOT::RNTupleReader::Open("myNTuple", "some/file.root");
std::cout << "myNTuple has " << reader->GetNEntries() << " entries\n";

Definition at line 66 of file RNTupleReader.hxx.

Classes
class	RIterator

Public Member Functions
	~RNTupleReader ()

RIterator	begin ()

std::unique_ptr< RNTupleReader >	Clone ()

std::unique_ptr< ROOT::REntry >	CreateEntry ()

void	EnableMetrics ()
	Enable performance measurements (decompression time, bytes read from storage, etc.)

RIterator	end ()

ROOT::RNTupleCollectionView	GetCollectionView (ROOT::DescriptorId_t fieldId)
	Provides access to a collection field from its on-disk ID, that can itself generate new RNTupleViews for its nested fields.

ROOT::RNTupleCollectionView	GetCollectionView (std::string_view fieldName)
	Provides access to a collection field, that can itself generate new RNTupleViews for its nested fields.

const ROOT::RNTupleDescriptor &	GetDescriptor ()
	Returns a cached copy of the page source descriptor.

template<typename T >
ROOT::RNTupleDirectAccessView< T >	GetDirectAccessView (ROOT::DescriptorId_t fieldId)
	Provides direct access to the I/O buffers of a mappable (sub)field from its on-disk ID.

template<typename T >
ROOT::RNTupleDirectAccessView< T >	GetDirectAccessView (std::string_view fieldName)
	Provides direct access to the I/O buffers of a mappable (sub)field.

ROOT::RNTupleGlobalRange	GetEntryRange ()
	Returns an iterator over the entry indices of the RNTuple.

const Experimental::Detail::RNTupleMetrics &	GetMetrics () const

const ROOT::RNTupleModel &	GetModel ()

ROOT::NTupleSize_t	GetNEntries () const
	Returns the number of entries in this RNTuple.

template<typename T >
ROOT::RNTupleView< T >	GetView (ROOT::DescriptorId_t fieldId)
	Provides access to an individual (sub)field from its on-disk ID.

template<typename T >
ROOT::RNTupleView< T >	GetView (ROOT::DescriptorId_t fieldId, std::shared_ptr< T > objPtr)
	Provides access to an individual (sub)field from its on-disk ID, reading its values into `objPtr`.

template<typename T >
ROOT::RNTupleView< T >	GetView (ROOT::DescriptorId_t fieldId, T *rawPtr)
	Provides access to an individual (sub)field from its on-disk ID, reading its values into `rawPtr`.

ROOT::RNTupleView< void >	GetView (ROOT::DescriptorId_t fieldId, void *rawPtr, const std::type_info &ti)
	Provides access to an individual (sub)field from its on-disk ID, reading its values into `objPtr` as the type provided by `ti`.

ROOT::RNTupleView< void >	GetView (ROOT::DescriptorId_t fieldId, void *rawPtr, std::string_view typeName)
	Provides access to an individual (sub)field from its on-disk ID, reading its values into `rawPtr` as the type provided by `typeName`.

template<typename T >
ROOT::RNTupleView< T >	GetView (std::string_view fieldName)
	Provides access to an individual (sub)field, e.g.

template<typename T >
ROOT::RNTupleView< T >	GetView (std::string_view fieldName, std::shared_ptr< T > objPtr)
	Provides access to an individual (sub)field, reading its values into `objPtr`.

template<typename T >
ROOT::RNTupleView< T >	GetView (std::string_view fieldName, T *rawPtr)
	Provides access to an individual (sub)field, reading its values into `rawPtr`.

ROOT::RNTupleView< void >	GetView (std::string_view fieldName, void *rawPtr, const std::type_info &ti)
	Provides access to an individual (sub)field, reading its values into `rawPtr` as the type provided by `ti`.

ROOT::RNTupleView< void >	GetView (std::string_view fieldName, void *rawPtr, std::string_view typeName)
	Provides access to an individual (sub)field, reading its values into `rawPtr` as the type provided by `typeName`.

void	LoadEntry (ROOT::NTupleSize_t index)
	Fills the default entry of the model.

void	LoadEntry (ROOT::NTupleSize_t index, ROOT::REntry &entry)
	Fills a user provided entry after checking that the entry has been instantiated from the RNTuple model.

void	PrintInfo (const ENTupleInfo what=ENTupleInfo::kSummary, std::ostream &output=std::cout) const
	Prints a detailed summary of the RNTuple, including a list of fields.

void	Show (ROOT::NTupleSize_t index, std::ostream &output=std::cout)
	Shows the values of the i-th entry/row, starting with 0 for the first entry.

Static Public Member Functions
static std::unique_ptr< RNTupleReader >	Open (const RNTuple &ntuple, const ROOT::RNTupleReadOptions &options=ROOT::RNTupleReadOptions())

static std::unique_ptr< RNTupleReader >	Open (const ROOT::RNTupleDescriptor::RCreateModelOptions &createModelOpts, const RNTuple &ntuple, const ROOT::RNTupleReadOptions &options=ROOT::RNTupleReadOptions())

static std::unique_ptr< RNTupleReader >	Open (const ROOT::RNTupleDescriptor::RCreateModelOptions &createModelOpts, std::string_view ntupleName, std::string_view storage, const ROOT::RNTupleReadOptions &options=ROOT::RNTupleReadOptions())
	The caller imposes the way the model is reconstructed.

static std::unique_ptr< RNTupleReader >	Open (std::string_view ntupleName, std::string_view storage, const ROOT::RNTupleReadOptions &options=ROOT::RNTupleReadOptions())
	Open an RNTuple for reading.

static std::unique_ptr< RNTupleReader >	Open (std::unique_ptr< ROOT::RNTupleModel > model, const RNTuple &ntuple, const ROOT::RNTupleReadOptions &options=ROOT::RNTupleReadOptions())

static std::unique_ptr< RNTupleReader >	Open (std::unique_ptr< ROOT::RNTupleModel > model, std::string_view ntupleName, std::string_view storage, const ROOT::RNTupleReadOptions &options=ROOT::RNTupleReadOptions())
	The caller imposes a model, which must be compatible with the model found in the data on storage.

Private Member Functions
	RNTupleReader (std::unique_ptr< Internal::RPageSource > source, const ROOT::RNTupleReadOptions &options)
	The model is generated from the RNTuple metadata on storage.

	RNTupleReader (std::unique_ptr< ROOT::RNTupleModel > model, std::unique_ptr< Internal::RPageSource > source, const ROOT::RNTupleReadOptions &options)

void	ConnectModel (ROOT::RNTupleModel &model)

RNTupleReader *	GetDisplayReader ()

void	InitPageSource (bool enableMetrics)

ROOT::DescriptorId_t	RetrieveFieldId (std::string_view fieldName) const

Private Attributes
std::optional< ROOT::RNTupleDescriptor >	fCachedDescriptor
	The RNTuple descriptor in the page source is protected by a read-write lock.

std::optional< ROOT::RNTupleDescriptor::RCreateModelOptions >	fCreateModelOptions
	If not nullopt, these will be used when creating the model.

std::unique_ptr< RNTupleReader >	fDisplayReader
	We use a dedicated on-demand reader for Show().

Experimental::Detail::RNTupleMetrics	fMetrics

std::unique_ptr< ROOT::RNTupleModel >	fModel
	Needs to be destructed before fSource.

ROOT::NTupleSize_t	fNEntries = 0
	We know that the RNTupleReader is always reading a single RNTuple, so the number of entries is fixed.

std::unique_ptr< Internal::RPageSource >	fSource

std::unique_ptr< Internal::RPageStorage::RTaskScheduler >	fUnzipTasks
	Set as the page source's scheduler for parallel page decompression if implicit multi-threading (IMT) is on.

#include <ROOT/RNTupleReader.hxx>

Constructor & Destructor Documentation

◆ RNTupleReader() [1/2]

ROOT::RNTupleReader::RNTupleReader	(	std::unique_ptr< ROOT::RNTupleModel >	model,
		std::unique_ptr< Internal::RPageSource >	source,
		const ROOT::RNTupleReadOptions &	options )

private

Definition at line 59 of file RNTupleReader.cxx.

◆ RNTupleReader() [2/2]

ROOT::RNTupleReader::RNTupleReader	(	std::unique_ptr< Internal::RPageSource >	source,
		const ROOT::RNTupleReadOptions &	options )

explicitprivate

The model is generated from the RNTuple metadata on storage.

Definition at line 74 of file RNTupleReader.cxx.

◆ ~RNTupleReader()

ROOT::RNTupleReader::~RNTupleReader ( )

default

Member Function Documentation

◆ begin()

RIterator ROOT::RNTupleReader::begin ( )

inline

Definition at line 446 of file RNTupleReader.hxx.

◆ Clone()

std::unique_ptr< RNTupleReader > ROOT::RNTupleReader::Clone ( )

inline

Definition at line 168 of file RNTupleReader.hxx.

◆ ConnectModel()

void ROOT::RNTupleReader::ConnectModel ( ROOT::RNTupleModel & model )

private

Definition at line 25 of file RNTupleReader.cxx.

◆ CreateEntry()

std::unique_ptr< ROOT::REntry > ROOT::RNTupleReader::CreateEntry ( )

Definition at line 144 of file RNTupleReader.cxx.

◆ EnableMetrics()

void ROOT::RNTupleReader::EnableMetrics ( )

inline

Enable performance measurements (decompression time, bytes read from storage, etc.)

Example: inspect the reader metrics after loading every entry

#include <ROOT/RNTupleReader.hxx>
#include <iostream>
 
auto ntuple = ROOT::RNTupleReader::Open("myNTuple", "some/file.root");
// metrics must be turned on beforehand
reader->EnableMetrics();
 
for (auto i : ntuple->GetEntryRange()) {
   reader->LoadEntry(i);
}
reader->PrintInfo(ROOT::ENTupleInfo::kMetrics);

Definition at line 465 of file RNTupleReader.hxx.

◆ end()

RIterator ROOT::RNTupleReader::end ( )

inline

Definition at line 447 of file RNTupleReader.hxx.

◆ GetCollectionView() [1/2]

ROOT::RNTupleCollectionView ROOT::RNTupleReader::GetCollectionView ( ROOT::DescriptorId_t fieldId )

inline

Provides access to a collection field from its on-disk ID, that can itself generate new RNTupleViews for its nested fields.

See also: GetCollectionView(std::string_view)

Definition at line 441 of file RNTupleReader.hxx.

◆ GetCollectionView() [2/2]

ROOT::RNTupleCollectionView ROOT::RNTupleReader::GetCollectionView ( std::string_view fieldName )

inline

Provides access to a collection field, that can itself generate new RNTupleViews for its nested fields.

Raises an exception if:

there is no field with the given name or,
the field is not a collection

See also: GetView(std::string_view)

Definition at line 427 of file RNTupleReader.hxx.

◆ GetDescriptor()

const ROOT::RNTupleDescriptor & ROOT::RNTupleReader::GetDescriptor ( )

Returns a cached copy of the page source descriptor.

The returned pointer remains valid until the next call to LoadEntry() or to any of the views returned from the reader.

Definition at line 254 of file RNTupleReader.cxx.

◆ GetDirectAccessView() [1/2]

template<typename T >

ROOT::RNTupleDirectAccessView< T > ROOT::RNTupleReader::GetDirectAccessView ( ROOT::DescriptorId_t fieldId )

inline

Provides direct access to the I/O buffers of a mappable (sub)field from its on-disk ID.

See also: GetDirectAccessView(std::string_view)

Definition at line 413 of file RNTupleReader.hxx.

◆ GetDirectAccessView() [2/2]

template<typename T >

ROOT::RNTupleDirectAccessView< T > ROOT::RNTupleReader::GetDirectAccessView ( std::string_view fieldName )

inline

Provides direct access to the I/O buffers of a mappable (sub)field.

Raises an exception if there is no field with the given name. Attempting to access the values of a direct-access view for non-mappable fields will yield compilation errors.

See also: GetView(std::string_view)

Definition at line 404 of file RNTupleReader.hxx.

◆ GetDisplayReader()

ROOT::RNTupleReader * ROOT::RNTupleReader::GetDisplayReader ( )

private

Definition at line 220 of file RNTupleReader.cxx.

◆ GetEntryRange()

ROOT::RNTupleGlobalRange ROOT::RNTupleReader::GetEntryRange ( )

inline

Returns an iterator over the entry indices of the RNTuple.

Example: iterate over all entries and print each entry in JSON format

#include <ROOT/RNTupleReader.hxx>
#include <iostream>
 
auto reader = ROOT::RNTupleReader::Open("myNTuple", "some/file.root");
for (auto i : ntuple->GetEntryRange()) {
   reader->Show(i);
}

Definition at line 258 of file RNTupleReader.hxx.

◆ GetMetrics()

const Experimental::Detail::RNTupleMetrics & ROOT::RNTupleReader::GetMetrics ( ) const

inline

Definition at line 466 of file RNTupleReader.hxx.

◆ GetModel()

const ROOT::RNTupleModel & ROOT::RNTupleReader::GetModel ( )

Definition at line 134 of file RNTupleReader.cxx.

◆ GetNEntries()

ROOT::NTupleSize_t ROOT::RNTupleReader::GetNEntries ( ) const

inline

Returns the number of entries in this RNTuple.

Note that the recommended way to iterate the RNTuple is using

// RECOMMENDED way to iterate an ntuple

for (auto i : reader->GetEntryRange()) { ... }

instead of

// DISCOURAGED way to iterate an ntuple

for (auto i = 0u; i < reader->GetNEntries(); ++i) { ... }

The reason is that determining the number of entries, while currently cheap, may in the future be an expensive operation.

Definition at line 189 of file RNTupleReader.hxx.

◆ GetView() [1/10]

template<typename T >

ROOT::RNTupleView< T > ROOT::RNTupleReader::GetView ( ROOT::DescriptorId_t fieldId )

inline

Provides access to an individual (sub)field from its on-disk ID.

See also: GetView(std::string_view)

Definition at line 348 of file RNTupleReader.hxx.

◆ GetView() [2/10]

template<typename T >

ROOT::RNTupleView< T > ROOT::RNTupleReader::GetView	(	ROOT::DescriptorId_t	fieldId,
		std::shared_ptr< T >	objPtr )

inline

Provides access to an individual (sub)field from its on-disk ID, reading its values into objPtr.

See also: GetView(std::string_view, std::shared_ptr<T>)

Definition at line 359 of file RNTupleReader.hxx.

◆ GetView() [3/10]

template<typename T >

ROOT::RNTupleView< T > ROOT::RNTupleReader::GetView	(	ROOT::DescriptorId_t	fieldId,
		T *	rawPtr )

inline

Provides access to an individual (sub)field from its on-disk ID, reading its values into rawPtr.

See also: GetView(std::string_view, std::shared_ptr<T>)

Definition at line 370 of file RNTupleReader.hxx.

◆ GetView() [4/10]

ROOT::RNTupleView< void > ROOT::RNTupleReader::GetView	(	ROOT::DescriptorId_t	fieldId,
		void *	rawPtr,
		const std::type_info &	ti )

inline

Provides access to an individual (sub)field from its on-disk ID, reading its values into objPtr as the type provided by ti.

See also: GetView(std::string_view, std::shared_ptr<T>)

Definition at line 392 of file RNTupleReader.hxx.

◆ GetView() [5/10]

ROOT::RNTupleView< void > ROOT::RNTupleReader::GetView	(	ROOT::DescriptorId_t	fieldId,
		void *	rawPtr,
		std::string_view	typeName )

inline

Provides access to an individual (sub)field from its on-disk ID, reading its values into rawPtr as the type provided by typeName.

See also: GetView(std::string_view, std::shared_ptr<T>)

Definition at line 381 of file RNTupleReader.hxx.

◆ GetView() [6/10]

template<typename T >

ROOT::RNTupleView< T > ROOT::RNTupleReader::GetView ( std::string_view fieldName )

inline

Provides access to an individual (sub)field, e.g.

GetView<Particle>("particle"), GetView<double>("particle.pt") or GetView<std::vector<Particle>>("particles"). It is possible to directly get the size of a collection (without reading the collection itself) using RNTupleCardinality: GetView<ROOT::RNTupleCardinality<std::uint64_t>>("particles").

Raises an exception if there is no field with the given name.

Example: iterate over a field named "pt" of type float

#include <ROOT/RNTupleReader.hxx>
#include <iostream>
 
auto reader = ROOT::RNTupleReader::Open("myNTuple", "some/file.root");
auto pt = reader->GetView<float>("pt");
 
for (auto i : reader->GetEntryRange()) {
   std::cout << i << ": " << pt(i) << "\n";
}

Note: if T = void, type checks are disabled. This is not really useful for this overload because RNTupleView<void> does not give access to the pointer. If required, it is possible to provide an objPtr of a dynamic type, for example via GetView(std::string_view, void *, std::string_view).

Definition at line 285 of file RNTupleReader.hxx.

◆ GetView() [7/10]

template<typename T >

ROOT::RNTupleView< T > ROOT::RNTupleReader::GetView	(	std::string_view	fieldName,
		std::shared_ptr< T >	objPtr )

inline

Provides access to an individual (sub)field, reading its values into objPtr.

Raises an exception if there is no field with the given name.

Example: iterate over a field named "pt" of type float

#include <ROOT/RNTupleReader.hxx>
#include <iostream>
 
auto reader = ROOT::RNTupleReader::Open("myNTuple", "some/file.root");
auto pt = std::make_shared<float>();
auto ptView = reader->GetView("pt", pt);
 
for (auto i : reader->GetEntryRange()) {
   ptView(i);
   std::cout << i << ": " << *pt << "\n";
}

Note: if T = void, type checks are disabled. It is the caller's responsibility to match the field and object types. It is strongly recommended to use an overload that allows passing the typeName, such as GetView(std::string_view, void *, std::string_view). This allows type checks with the on-disk metadata and enables automatic schema evolution and conversion rules.

Definition at line 314 of file RNTupleReader.hxx.

◆ GetView() [8/10]

template<typename T >

ROOT::RNTupleView< T > ROOT::RNTupleReader::GetView	(	std::string_view	fieldName,
		T *	rawPtr )

inline

Provides access to an individual (sub)field, reading its values into rawPtr.

See also: GetView(std::string_view, std::shared_ptr<T>)

Definition at line 323 of file RNTupleReader.hxx.

◆ GetView() [9/10]

ROOT::RNTupleView< void > ROOT::RNTupleReader::GetView	(	std::string_view	fieldName,
		void *	rawPtr,
		const std::type_info &	ti )

inline

Provides access to an individual (sub)field, reading its values into rawPtr as the type provided by ti.

See also: GetView(std::string_view, std::shared_ptr<T>)

Definition at line 339 of file RNTupleReader.hxx.

◆ GetView() [10/10]

ROOT::RNTupleView< void > ROOT::RNTupleReader::GetView	(	std::string_view	fieldName,
		void *	rawPtr,
		std::string_view	typeName )

inline

Provides access to an individual (sub)field, reading its values into rawPtr as the type provided by typeName.

See also: GetView(std::string_view, std::shared_ptr<T>)

Definition at line 331 of file RNTupleReader.hxx.

◆ InitPageSource()

void ROOT::RNTupleReader::InitPageSource ( bool enableMetrics )

private

Definition at line 43 of file RNTupleReader.cxx.

◆ LoadEntry() [1/2]

void ROOT::RNTupleReader::LoadEntry ( ROOT::NTupleSize_t index )

inline

Fills the default entry of the model.

Raises an exception when index is greater than the number of entries present in the RNTuple

Definition at line 228 of file RNTupleReader.hxx.

◆ LoadEntry() [2/2]

void ROOT::RNTupleReader::LoadEntry	(	ROOT::NTupleSize_t	index,
		ROOT::REntry &	entry )

inline

Fills a user provided entry after checking that the entry has been instantiated from the RNTuple model.

Definition at line 238 of file RNTupleReader.hxx.

◆ Open() [1/6]

std::unique_ptr< ROOT::RNTupleReader > ROOT::RNTupleReader::Open	(	const RNTuple &	ntuple,
		const ROOT::RNTupleReadOptions &	options = ROOT::RNTupleReadOptions() )

static

Definition at line 99 of file RNTupleReader.cxx.

◆ Open() [2/6]

std::unique_ptr< ROOT::RNTupleReader > ROOT::RNTupleReader::Open	(	const ROOT::RNTupleDescriptor::RCreateModelOptions &	createModelOpts,
		const RNTuple &	ntuple,
		const ROOT::RNTupleReadOptions &	options = ROOT::RNTupleReadOptions() )

static

Definition at line 125 of file RNTupleReader.cxx.

◆ Open() [3/6]

std::unique_ptr< ROOT::RNTupleReader > ROOT::RNTupleReader::Open	(	const ROOT::RNTupleDescriptor::RCreateModelOptions &	createModelOpts,
		std::string_view	ntupleName,
		std::string_view	storage,
		const ROOT::RNTupleReadOptions &	options = ROOT::RNTupleReadOptions() )

static

The caller imposes the way the model is reconstructed.

Definition at line 114 of file RNTupleReader.cxx.

◆ Open() [4/6]

std::unique_ptr< ROOT::RNTupleReader > ROOT::RNTupleReader::Open	(	std::string_view	ntupleName,
		std::string_view	storage,
		const ROOT::RNTupleReadOptions &	options = ROOT::RNTupleReadOptions() )

static

Open an RNTuple for reading.

Throws an RException if there is no RNTuple with the given name.

Example: open an RNTuple and print the number of entries

#include <ROOT/RNTupleReader.hxx>
#include <iostream>
 
auto reader = ROOT::RNTupleReader::Open("myNTuple", "some/file.root");
std::cout << "myNTuple has " << reader->GetNEntries() << " entries\n";

Definition at line 91 of file RNTupleReader.cxx.

◆ Open() [5/6]

std::unique_ptr< ROOT::RNTupleReader > ROOT::RNTupleReader::Open	(	std::unique_ptr< ROOT::RNTupleModel >	model,
		const RNTuple &	ntuple,
		const ROOT::RNTupleReadOptions &	options = ROOT::RNTupleReadOptions() )

static

Definition at line 105 of file RNTupleReader.cxx.

◆ Open() [6/6]

std::unique_ptr< ROOT::RNTupleReader > ROOT::RNTupleReader::Open	(	std::unique_ptr< ROOT::RNTupleModel >	model,
		std::string_view	ntupleName,
		std::string_view	storage,
		const ROOT::RNTupleReadOptions &	options = ROOT::RNTupleReadOptions() )

static

The caller imposes a model, which must be compatible with the model found in the data on storage.

Definition at line 83 of file RNTupleReader.cxx.

◆ PrintInfo()

void ROOT::RNTupleReader::PrintInfo	(	const ENTupleInfo	what = ENTupleInfo::kSummary,
		std::ostream &	output = std::cout ) const

Prints a detailed summary of the RNTuple, including a list of fields.

Example: print summary information to stdout

#include <ROOT/RNTupleReader.hxx>
#include <iostream>
 
auto reader = ROOT::RNTupleReader::Open("myNTuple", "some/file.root");
reader->PrintInfo();
// or, equivalently:
reader->PrintInfo(ROOT::ENTupleInfo::kSummary, std::cout);

Example: print detailed column storage data to stderr

#include <ROOT/RNTupleReader.hxx>
#include <iostream>
 
auto reader = ROOT::RNTupleReader::Open("myNTuple", "some/file.root");
reader->PrintInfo(ROOT::ENTupleInfo::kStorageDetails, std::cerr);

For use of ENTupleInfo::kMetrics, see EnableMetrics.

Definition at line 149 of file RNTupleReader.cxx.

◆ RetrieveFieldId()

ROOT::DescriptorId_t ROOT::RNTupleReader::RetrieveFieldId ( std::string_view fieldName ) const

private

Definition at line 262 of file RNTupleReader.cxx.

◆ Show()

void ROOT::RNTupleReader::Show	(	ROOT::NTupleSize_t	index,
		std::ostream &	output = std::cout )

Shows the values of the i-th entry/row, starting with 0 for the first entry.

By default, prints the output in JSON format. Uses the visitor pattern to traverse through each field of the given entry.

Definition at line 232 of file RNTupleReader.cxx.

Member Data Documentation

◆ fCachedDescriptor

std::optional<ROOT::RNTupleDescriptor> ROOT::RNTupleReader::fCachedDescriptor

private

The RNTuple descriptor in the page source is protected by a read-write lock.

We don't expose that to the users of RNTupleReader::GetDescriptor(). Instead, if descriptor information is needed, we clone the descriptor. Using the descriptor's generation number, we know if the cached descriptor is stale. Retrieving descriptor data from an RNTupleReader is supposed to be for testing and information purposes, not on a hot code path.

Definition at line 84 of file RNTupleReader.hxx.

◆ fCreateModelOptions

std::optional<ROOT::RNTupleDescriptor::RCreateModelOptions> ROOT::RNTupleReader::fCreateModelOptions

private

If not nullopt, these will be used when creating the model.

Definition at line 89 of file RNTupleReader.hxx.

◆ fDisplayReader

std::unique_ptr<RNTupleReader> ROOT::RNTupleReader::fDisplayReader

private

We use a dedicated on-demand reader for Show().

Printing data uses all the fields from the full model even if the analysis code uses only a subset of fields. The display reader is a clone of the original reader.

Definition at line 78 of file RNTupleReader.hxx.

◆ fMetrics

Experimental::Detail::RNTupleMetrics ROOT::RNTupleReader::fMetrics

private

Definition at line 87 of file RNTupleReader.hxx.

◆ fModel

std::unique_ptr<ROOT::RNTupleModel> ROOT::RNTupleReader::fModel

private

Needs to be destructed before fSource.

Definition at line 74 of file RNTupleReader.hxx.

◆ fNEntries

ROOT::NTupleSize_t ROOT::RNTupleReader::fNEntries = 0

private

We know that the RNTupleReader is always reading a single RNTuple, so the number of entries is fixed.

Definition at line 86 of file RNTupleReader.hxx.

◆ fSource

std::unique_ptr<Internal::RPageSource> ROOT::RNTupleReader::fSource

private

Definition at line 72 of file RNTupleReader.hxx.

◆ fUnzipTasks

std::unique_ptr<Internal::RPageStorage::RTaskScheduler> ROOT::RNTupleReader::fUnzipTasks

private

Set as the page source's scheduler for parallel page decompression if implicit multi-threading (IMT) is on.

Needs to be destructed after the page source is destructed (and thus be declared before)

Definition at line 70 of file RNTupleReader.hxx.

Libraries for ROOT::RNTupleReader:

[legend]

The documentation for this class was generated from the following files:

tree/ntuple/inc/ROOT/RNTupleReader.hxx
tree/ntuple/src/RNTupleReader.cxx

Classes

Public Member Functions

Static Public Member Functions

Private Member Functions

Private Attributes

Constructor & Destructor Documentation

◆ RNTupleReader() [1/2]

◆ RNTupleReader() [2/2]

◆ ~RNTupleReader()

Member Function Documentation

◆ begin()

◆ Clone()

◆ ConnectModel()

◆ CreateEntry()

◆ EnableMetrics()

◆ end()

◆ GetCollectionView() [1/2]

◆ GetCollectionView() [2/2]

◆ GetDescriptor()

◆ GetDirectAccessView() [1/2]

◆ GetDirectAccessView() [2/2]

◆ GetDisplayReader()

◆ GetEntryRange()

◆ GetMetrics()

◆ GetModel()

◆ GetNEntries()

◆ GetView() [1/10]

◆ GetView() [2/10]

◆ GetView() [3/10]

◆ GetView() [4/10]

◆ GetView() [5/10]

◆ GetView() [6/10]

◆ GetView() [7/10]

◆ GetView() [8/10]

◆ GetView() [9/10]

◆ GetView() [10/10]

◆ InitPageSource()

◆ LoadEntry() [1/2]

◆ LoadEntry() [2/2]

◆ Open() [1/6]

◆ Open() [2/6]

◆ Open() [3/6]

◆ Open() [4/6]

◆ Open() [5/6]

◆ Open() [6/6]

◆ PrintInfo()

◆ RetrieveFieldId()

◆ Show()

Member Data Documentation

◆ fCachedDescriptor

◆ fCreateModelOptions

◆ fDisplayReader

◆ fMetrics

◆ fModel

◆ fNEntries

◆ fSource

◆ fUnzipTasks