The on-storage meta-data of an ntuple.

Represents the on-disk (on storage) information about an ntuple. The meta-data consists of a header and one or several footers. The header carries the ntuple schema, i.e. the fields and the associated columns and their relationships. The footer(s) carry information about one or several clusters. For every cluster, a footer stores its location and size, and for every column the range of element indexes as well as a list of pages and page locations.

The descriptor provide machine-independent (de-)serialization of headers and footers, and it provides lookup routines for ntuple objects (pages, clusters, ...). It is supposed to be usable by all RPageStorage implementations.

The serialization does not use standard ROOT streamers in order to not let it depend on libCore. The serialization uses the concept of frames: header, footer, and substructures have a preamble with version numbers and the size of the writte struct. This allows for forward and backward compatibility when the meta-data evolves.

Definition at line 384 of file RNTupleDescriptor.hxx.

Classes
class	RClusterDescriptorIterable
	Used to loop over all the clusters of an ntuple (in unspecified order) More...

class	RClusterGroupDescriptorIterable
	Used to loop over all the cluster groups of an ntuple (in unspecified order) More...

class	RColumnDescriptorIterable
	Used to loop over a field's associated columns. More...

class	RFieldDescriptorIterable
	Used to loop over a field's child fields. More...

Public Member Functions
	RNTupleDescriptor ()=default

	RNTupleDescriptor (const RNTupleDescriptor &other)=delete

	RNTupleDescriptor (RNTupleDescriptor &&other)=default

RResult< void >	AddClusterDetails (RClusterDescriptor &&clusterDesc)
	Methods to load and drop cluster details.

std::unique_ptr< RNTupleDescriptor >	Clone () const

RResult< void >	DropClusterDetails (DescriptorId_t clusterId)

DescriptorId_t	FindClusterId (DescriptorId_t columnId, NTupleSize_t index) const

DescriptorId_t	FindColumnId (DescriptorId_t fieldId, std::uint32_t columnIndex) const

DescriptorId_t	FindFieldId (std::string_view fieldName) const
	Searches for a top-level field.

DescriptorId_t	FindFieldId (std::string_view fieldName, DescriptorId_t parentId) const

DescriptorId_t	FindNextClusterId (DescriptorId_t clusterId) const

DescriptorId_t	FindPrevClusterId (DescriptorId_t clusterId) const

std::unique_ptr< RNTupleModel >	GenerateModel () const
	Re-create the C++ model from the stored meta-data.

const RClusterDescriptor &	GetClusterDescriptor (DescriptorId_t clusterId) const

const RClusterGroupDescriptor &	GetClusterGroupDescriptor (DescriptorId_t clusterGroupId) const

RClusterGroupDescriptorIterable	GetClusterGroupIterable () const

RClusterDescriptorIterable	GetClusterIterable () const

const RColumnDescriptor &	GetColumnDescriptor (DescriptorId_t columnId) const

RColumnDescriptorIterable	GetColumnIterable (const RFieldDescriptor &fieldDesc) const

RColumnDescriptorIterable	GetColumnIterable (DescriptorId_t fieldId) const

std::string	GetDescription () const

const RFieldDescriptor &	GetFieldDescriptor (DescriptorId_t fieldId) const

RFieldDescriptorIterable	GetFieldIterable (const RFieldDescriptor &fieldDesc) const

RFieldDescriptorIterable	GetFieldIterable (const RFieldDescriptor &fieldDesc, const std::function< bool(DescriptorId_t, DescriptorId_t)> &comparator) const

RFieldDescriptorIterable	GetFieldIterable (DescriptorId_t fieldId) const

RFieldDescriptorIterable	GetFieldIterable (DescriptorId_t fieldId, const std::function< bool(DescriptorId_t, DescriptorId_t)> &comparator) const

const RFieldDescriptor &	GetFieldZero () const

DescriptorId_t	GetFieldZeroId () const
	Returns the logical parent of all top-level NTuple data fields.

std::uint64_t	GetGeneration () const

std::string	GetName () const

std::size_t	GetNClusterGroups () const

std::size_t	GetNClusters () const

std::size_t	GetNColumns () const

NTupleSize_t	GetNElements (DescriptorId_t columnId) const

NTupleSize_t	GetNEntries () const
	We know the number of entries from adding the cluster summaries.

std::size_t	GetNFields () const

std::uint64_t	GetOnDiskFooterSize () const

std::uint64_t	GetOnDiskHeaderSize () const

std::string	GetQualifiedFieldName (DescriptorId_t fieldId) const
	Walks up the parents of the field ID and returns a field name of the form a.b.c.d In case of invalid field ID, an empty string is returned.

RFieldDescriptorIterable	GetTopLevelFields () const

RFieldDescriptorIterable	GetTopLevelFields (const std::function< bool(DescriptorId_t, DescriptorId_t)> &comparator) const

void	IncGeneration ()

RNTupleDescriptor &	operator= (const RNTupleDescriptor &other)=delete

RNTupleDescriptor &	operator= (RNTupleDescriptor &&other)=default

bool	operator== (const RNTupleDescriptor &other) const

void	PrintInfo (std::ostream &output) const

Private Attributes
std::unordered_map< DescriptorId_t, RClusterDescriptor >	fClusterDescriptors
	May contain only a subset of all the available clusters, e.g.

std::unordered_map< DescriptorId_t, RClusterGroupDescriptor >	fClusterGroupDescriptors

std::unordered_map< DescriptorId_t, RColumnDescriptor >	fColumnDescriptors

std::string	fDescription
	Free text from the user.

std::unordered_map< DescriptorId_t, RFieldDescriptor >	fFieldDescriptors

std::uint64_t	fGeneration = 0
	Once constructed by an RNTupleDescriptorBuilder, the descriptor is mostly immutable except for set of active the page locations.

std::string	fName
	The ntuple name needs to be unique in a given storage location (file)

std::uint64_t	fNEntries = 0
	Updated by the descriptor builder when the cluster summaries are added.

std::uint64_t	fOnDiskFooterSize = 0
	Like fOnDiskHeaderSize, contains both cluster summaries and page locations.

std::uint64_t	fOnDiskHeaderSize = 0
	Set by the descriptor builder when deserialized.

Friends
class	RNTupleDescriptorBuilder

#include <ROOT/RNTupleDescriptor.hxx>

Constructor & Destructor Documentation

◆ RNTupleDescriptor() [1/3]

ROOT::Experimental::RNTupleDescriptor::RNTupleDescriptor ( )

default

◆ RNTupleDescriptor() [2/3]

ROOT::Experimental::RNTupleDescriptor::RNTupleDescriptor ( const RNTupleDescriptor & other )

delete

◆ RNTupleDescriptor() [3/3]

ROOT::Experimental::RNTupleDescriptor::RNTupleDescriptor ( RNTupleDescriptor && other )

default

Member Function Documentation

◆ AddClusterDetails()

ROOT::Experimental::RResult< void > ROOT::Experimental::RNTupleDescriptor::AddClusterDetails ( RClusterDescriptor && clusterDesc )

Methods to load and drop cluster details.

Definition at line 319 of file RNTupleDescriptor.cxx.

◆ Clone()

std::unique_ptr< ROOT::Experimental::RNTupleDescriptor > ROOT::Experimental::RNTupleDescriptor::Clone ( ) const

Definition at line 353 of file RNTupleDescriptor.cxx.

◆ DropClusterDetails()

ROOT::Experimental::RResult< void > ROOT::Experimental::RNTupleDescriptor::DropClusterDetails ( DescriptorId_t clusterId )

Definition at line 332 of file RNTupleDescriptor.cxx.

◆ FindClusterId()

ROOT::Experimental::DescriptorId_t ROOT::Experimental::RNTupleDescriptor::FindClusterId	(	DescriptorId_t	columnId,
		NTupleSize_t	index
	)		const

Definition at line 276 of file RNTupleDescriptor.cxx.

◆ FindColumnId()

ROOT::Experimental::DescriptorId_t ROOT::Experimental::RNTupleDescriptor::FindColumnId	(	DescriptorId_t	fieldId,
		std::uint32_t	columnIndex
	)		const

Definition at line 266 of file RNTupleDescriptor.cxx.

◆ FindFieldId() [1/2]

ROOT::Experimental::DescriptorId_t ROOT::Experimental::RNTupleDescriptor::FindFieldId ( std::string_view fieldName ) const

Searches for a top-level field.

Definition at line 259 of file RNTupleDescriptor.cxx.

◆ FindFieldId() [2/2]

ROOT::Experimental::DescriptorId_t ROOT::Experimental::RNTupleDescriptor::FindFieldId	(	std::string_view	fieldName,
		DescriptorId_t	parentId
	)		const

Definition at line 221 of file RNTupleDescriptor.cxx.

◆ FindNextClusterId()

ROOT::Experimental::DescriptorId_t ROOT::Experimental::RNTupleDescriptor::FindNextClusterId ( DescriptorId_t clusterId ) const

Definition at line 292 of file RNTupleDescriptor.cxx.

◆ FindPrevClusterId()

ROOT::Experimental::DescriptorId_t ROOT::Experimental::RNTupleDescriptor::FindPrevClusterId ( DescriptorId_t clusterId ) const

Definition at line 307 of file RNTupleDescriptor.cxx.

◆ GenerateModel()

std::unique_ptr< ROOT::Experimental::RNTupleModel > ROOT::Experimental::RNTupleDescriptor::GenerateModel ( ) const

Re-create the C++ model from the stored meta-data.

Definition at line 343 of file RNTupleDescriptor.cxx.

◆ GetClusterDescriptor()

const RClusterDescriptor & ROOT::Experimental::RNTupleDescriptor::GetClusterDescriptor ( DescriptorId_t clusterId ) const

inline

Definition at line 642 of file RNTupleDescriptor.hxx.

◆ GetClusterGroupDescriptor()

const RClusterGroupDescriptor & ROOT::Experimental::RNTupleDescriptor::GetClusterGroupDescriptor ( DescriptorId_t clusterGroupId ) const

inline

Definition at line 638 of file RNTupleDescriptor.hxx.

◆ GetClusterGroupIterable()

RClusterGroupDescriptorIterable ROOT::Experimental::RNTupleDescriptor::GetClusterGroupIterable ( ) const

inline

Definition at line 680 of file RNTupleDescriptor.hxx.

◆ GetClusterIterable()

RClusterDescriptorIterable ROOT::Experimental::RNTupleDescriptor::GetClusterIterable ( ) const

inline

Definition at line 682 of file RNTupleDescriptor.hxx.

◆ GetColumnDescriptor()

const RColumnDescriptor & ROOT::Experimental::RNTupleDescriptor::GetColumnDescriptor ( DescriptorId_t columnId ) const

inline

Definition at line 635 of file RNTupleDescriptor.hxx.

◆ GetColumnIterable() [1/2]

RColumnDescriptorIterable ROOT::Experimental::RNTupleDescriptor::GetColumnIterable ( const RFieldDescriptor & fieldDesc ) const

inline

Definition at line 671 of file RNTupleDescriptor.hxx.

◆ GetColumnIterable() [2/2]

RColumnDescriptorIterable ROOT::Experimental::RNTupleDescriptor::GetColumnIterable ( DescriptorId_t fieldId ) const

inline

Definition at line 675 of file RNTupleDescriptor.hxx.

◆ GetDescription()

std::string ROOT::Experimental::RNTupleDescriptor::GetDescription ( ) const

inline

Definition at line 688 of file RNTupleDescriptor.hxx.

◆ GetFieldDescriptor()

const RFieldDescriptor & ROOT::Experimental::RNTupleDescriptor::GetFieldDescriptor ( DescriptorId_t fieldId ) const

inline

Definition at line 632 of file RNTupleDescriptor.hxx.

◆ GetFieldIterable() [1/4]

RFieldDescriptorIterable ROOT::Experimental::RNTupleDescriptor::GetFieldIterable ( const RFieldDescriptor & fieldDesc ) const

inline

Definition at line 646 of file RNTupleDescriptor.hxx.

◆ GetFieldIterable() [2/4]

RFieldDescriptorIterable ROOT::Experimental::RNTupleDescriptor::GetFieldIterable	(	const RFieldDescriptor &	fieldDesc,
		const std::function< bool(DescriptorId_t, DescriptorId_t)> &	comparator
	)		const

inline

Definition at line 649 of file RNTupleDescriptor.hxx.

◆ GetFieldIterable() [3/4]

RFieldDescriptorIterable ROOT::Experimental::RNTupleDescriptor::GetFieldIterable ( DescriptorId_t fieldId ) const

inline

Definition at line 654 of file RNTupleDescriptor.hxx.

◆ GetFieldIterable() [4/4]

RFieldDescriptorIterable ROOT::Experimental::RNTupleDescriptor::GetFieldIterable	(	DescriptorId_t	fieldId,
		const std::function< bool(DescriptorId_t, DescriptorId_t)> &	comparator
	)		const

inline

Definition at line 657 of file RNTupleDescriptor.hxx.

◆ GetFieldZero()

const RFieldDescriptor & ROOT::Experimental::RNTupleDescriptor::GetFieldZero ( ) const

inline

Definition at line 701 of file RNTupleDescriptor.hxx.

◆ GetFieldZeroId()

ROOT::Experimental::DescriptorId_t ROOT::Experimental::RNTupleDescriptor::GetFieldZeroId ( ) const

Returns the logical parent of all top-level NTuple data fields.

Definition at line 252 of file RNTupleDescriptor.cxx.

◆ GetGeneration()

std::uint64_t ROOT::Experimental::RNTupleDescriptor::GetGeneration ( ) const

inline

Definition at line 718 of file RNTupleDescriptor.hxx.

◆ GetName()

std::string ROOT::Experimental::RNTupleDescriptor::GetName ( ) const

inline

Definition at line 687 of file RNTupleDescriptor.hxx.

◆ GetNClusterGroups()

std::size_t ROOT::Experimental::RNTupleDescriptor::GetNClusterGroups ( ) const

inline

Definition at line 692 of file RNTupleDescriptor.hxx.

◆ GetNClusters()

std::size_t ROOT::Experimental::RNTupleDescriptor::GetNClusters ( ) const

inline

Definition at line 693 of file RNTupleDescriptor.hxx.

◆ GetNColumns()

std::size_t ROOT::Experimental::RNTupleDescriptor::GetNColumns ( ) const

inline

Definition at line 691 of file RNTupleDescriptor.hxx.

◆ GetNElements()

ROOT::Experimental::NTupleSize_t ROOT::Experimental::RNTupleDescriptor::GetNElements ( DescriptorId_t columnId ) const

Definition at line 207 of file RNTupleDescriptor.cxx.

◆ GetNEntries()

NTupleSize_t ROOT::Experimental::RNTupleDescriptor::GetNEntries ( ) const

inline

We know the number of entries from adding the cluster summaries.

Definition at line 696 of file RNTupleDescriptor.hxx.

◆ GetNFields()

std::size_t ROOT::Experimental::RNTupleDescriptor::GetNFields ( ) const

inline

Definition at line 690 of file RNTupleDescriptor.hxx.

◆ GetOnDiskFooterSize()

std::uint64_t ROOT::Experimental::RNTupleDescriptor::GetOnDiskFooterSize ( ) const

inline

Definition at line 630 of file RNTupleDescriptor.hxx.

◆ GetOnDiskHeaderSize()

std::uint64_t ROOT::Experimental::RNTupleDescriptor::GetOnDiskHeaderSize ( ) const

inline

Definition at line 629 of file RNTupleDescriptor.hxx.

◆ GetQualifiedFieldName()

std::string ROOT::Experimental::RNTupleDescriptor::GetQualifiedFieldName ( DescriptorId_t fieldId ) const

Walks up the parents of the field ID and returns a field name of the form a.b.c.d In case of invalid field ID, an empty string is returned.

Definition at line 238 of file RNTupleDescriptor.cxx.

◆ GetTopLevelFields() [1/2]

RFieldDescriptorIterable ROOT::Experimental::RNTupleDescriptor::GetTopLevelFields ( ) const

inline

Definition at line 662 of file RNTupleDescriptor.hxx.

◆ GetTopLevelFields() [2/2]

RFieldDescriptorIterable ROOT::Experimental::RNTupleDescriptor::GetTopLevelFields ( const std::function< bool(DescriptorId_t, DescriptorId_t)> & comparator ) const

inline

Definition at line 665 of file RNTupleDescriptor.hxx.

◆ IncGeneration()

void ROOT::Experimental::RNTupleDescriptor::IncGeneration ( )

inline

Definition at line 719 of file RNTupleDescriptor.hxx.

◆ operator=() [1/2]

RNTupleDescriptor & ROOT::Experimental::RNTupleDescriptor::operator= ( const RNTupleDescriptor & other )

delete

◆ operator=() [2/2]

RNTupleDescriptor & ROOT::Experimental::RNTupleDescriptor::operator= ( RNTupleDescriptor && other )

default

◆ operator==()

bool ROOT::Experimental::RNTupleDescriptor::operator== ( const RNTupleDescriptor & other ) const

Definition at line 197 of file RNTupleDescriptor.cxx.

◆ PrintInfo()

void ROOT::Experimental::RNTupleDescriptor::PrintInfo ( std::ostream & output ) const

Definition at line 82 of file RNTupleDescriptorFmt.cxx.

Friends And Related Symbol Documentation

◆ RNTupleDescriptorBuilder

friend class RNTupleDescriptorBuilder

friend

Definition at line 385 of file RNTupleDescriptor.hxx.

Member Data Documentation

◆ fClusterDescriptors

std::unordered_map<DescriptorId_t, RClusterDescriptor> ROOT::Experimental::RNTupleDescriptor::fClusterDescriptors

private

May contain only a subset of all the available clusters, e.g.

the clusters of the current file from a chain of files

Definition at line 412 of file RNTupleDescriptor.hxx.

◆ fClusterGroupDescriptors

std::unordered_map<DescriptorId_t, RClusterGroupDescriptor> ROOT::Experimental::RNTupleDescriptor::fClusterGroupDescriptors

private

Definition at line 409 of file RNTupleDescriptor.hxx.

◆ fColumnDescriptors

std::unordered_map<DescriptorId_t, RColumnDescriptor> ROOT::Experimental::RNTupleDescriptor::fColumnDescriptors

private

Definition at line 408 of file RNTupleDescriptor.hxx.

◆ fDescription

std::string ROOT::Experimental::RNTupleDescriptor::fDescription

private

Free text from the user.

Definition at line 391 of file RNTupleDescriptor.hxx.

◆ fFieldDescriptors

std::unordered_map<DescriptorId_t, RFieldDescriptor> ROOT::Experimental::RNTupleDescriptor::fFieldDescriptors

private

Definition at line 407 of file RNTupleDescriptor.hxx.

◆ fGeneration

std::uint64_t ROOT::Experimental::RNTupleDescriptor::fGeneration = 0

private

Once constructed by an RNTupleDescriptorBuilder, the descriptor is mostly immutable except for set of active the page locations.

During the lifetime of the descriptor, page location information for clusters can be added or removed. When this happens, the generation should be increased, so that users of the descriptor know that the information changed. The generation is increased, e.g., by the page source's exclusive lock guard around the descriptor. It is used, e.g., by the descriptor cache in RNTupleReader.

Definition at line 405 of file RNTupleDescriptor.hxx.

◆ fName

std::string ROOT::Experimental::RNTupleDescriptor::fName

private

The ntuple name needs to be unique in a given storage location (file)

Definition at line 389 of file RNTupleDescriptor.hxx.

◆ fNEntries

std::uint64_t ROOT::Experimental::RNTupleDescriptor::fNEntries = 0

private

Updated by the descriptor builder when the cluster summaries are added.

Definition at line 396 of file RNTupleDescriptor.hxx.

◆ fOnDiskFooterSize

std::uint64_t ROOT::Experimental::RNTupleDescriptor::fOnDiskFooterSize = 0

private

Like fOnDiskHeaderSize, contains both cluster summaries and page locations.

Definition at line 394 of file RNTupleDescriptor.hxx.

◆ fOnDiskHeaderSize

std::uint64_t ROOT::Experimental::RNTupleDescriptor::fOnDiskHeaderSize = 0

private

Set by the descriptor builder when deserialized.

Definition at line 393 of file RNTupleDescriptor.hxx.

Libraries for ROOT::Experimental::RNTupleDescriptor:

[legend]

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

tree/ntuple/v7/inc/ROOT/RNTupleDescriptor.hxx
tree/ntuple/v7/src/RNTupleDescriptor.cxx
tree/ntuple/v7/src/RNTupleDescriptorFmt.cxx

Classes

Public Member Functions

Private Attributes

Friends

Constructor & Destructor Documentation

◆ RNTupleDescriptor() [1/3]

◆ RNTupleDescriptor() [2/3]

◆ RNTupleDescriptor() [3/3]

Member Function Documentation

◆ AddClusterDetails()

◆ Clone()

◆ DropClusterDetails()

◆ FindClusterId()

◆ FindColumnId()

◆ FindFieldId() [1/2]

◆ FindFieldId() [2/2]

◆ FindNextClusterId()

◆ FindPrevClusterId()

◆ GenerateModel()

◆ GetClusterDescriptor()

◆ GetClusterGroupDescriptor()

◆ GetClusterGroupIterable()

◆ GetClusterIterable()

◆ GetColumnDescriptor()

◆ GetColumnIterable() [1/2]

◆ GetColumnIterable() [2/2]

◆ GetDescription()

◆ GetFieldDescriptor()

◆ GetFieldIterable() [1/4]

◆ GetFieldIterable() [2/4]

◆ GetFieldIterable() [3/4]

◆ GetFieldIterable() [4/4]

◆ GetFieldZero()

◆ GetFieldZeroId()

◆ GetGeneration()

◆ GetName()

◆ GetNClusterGroups()

◆ GetNClusters()

◆ GetNColumns()

◆ GetNElements()

◆ GetNEntries()

◆ GetNFields()

◆ GetOnDiskFooterSize()

◆ GetOnDiskHeaderSize()

◆ GetQualifiedFieldName()

◆ GetTopLevelFields() [1/2]

◆ GetTopLevelFields() [2/2]

◆ IncGeneration()

◆ operator=() [1/2]

◆ operator=() [2/2]

◆ operator==()

◆ PrintInfo()

Friends And Related Symbol Documentation

◆ RNTupleDescriptorBuilder

Member Data Documentation

◆ fClusterDescriptors

◆ fClusterGroupDescriptors

◆ fColumnDescriptors

◆ fDescription

◆ fFieldDescriptors

◆ fGeneration

◆ fName

◆ fNEntries

◆ fOnDiskFooterSize

◆ fOnDiskHeaderSize