Abstract interface to read data from an ntuple.

The page source is initialized with the columns of interest. Pages from those columns can then be mapped into memory. The page source also gives access to the ntuple's meta-data.

Definition at line 193 of file RPageStorage.hxx.

Public Types
using	ColumnSet_t = std::unordered_set< DescriptorId_t >
	Derived from the model (fields) that are actually being requested at a given point in time.

Public Types inherited from ROOT::Experimental::Detail::RPageStorage
using	ColumnHandle_t = RColumnHandle
	The column handle identifies a column with the current open page storage.

Public Member Functions
	RPageSource (const RPageSource &)=delete

	RPageSource (RPageSource &&)=default

	RPageSource (std::string_view ntupleName, const RNTupleReadOptions &fOptions)

virtual	~RPageSource ()

ColumnHandle_t	AddColumn (DescriptorId_t fieldId, const RColumn &column) final
	Register a new column.

void	Attach ()
	Open the physical storage container for the tree.

virtual std::unique_ptr< RPageSource >	Clone () const =0
	Open the same storage multiple time, e.g. for reading in multiple threads.

void	DropColumn (ColumnHandle_t columnHandle) final
	Unregisters a column.

ColumnId_t	GetColumnId (ColumnHandle_t columnHandle)

const RNTupleDescriptor &	GetDescriptor () const

NTupleSize_t	GetNElements (ColumnHandle_t columnHandle)

NTupleSize_t	GetNEntries ()

EPageStorageType	GetType () final
	Whether the concrete implementation is a sink or a source.

virtual std::unique_ptr< RCluster >	LoadCluster (DescriptorId_t clusterId, const ColumnSet_t &columns)=0
	Populates all the pages of the given cluster id and columns; it is possible that some columns do not contain any pages.

RPageSource &	operator= (const RPageSource &)=delete

RPageSource &	operator= (RPageSource &&)=default

virtual RPage	PopulatePage (ColumnHandle_t columnHandle, const RClusterIndex &clusterIndex)=0
	Another version of PopulatePage that allows to specify cluster-relative indexes.

virtual RPage	PopulatePage (ColumnHandle_t columnHandle, NTupleSize_t globalIndex)=0
	Allocates and fills a page that contains the index-th element.

void	UnzipCluster (RCluster *cluster)
	Parallel decompression and unpacking of the pages in the given cluster.

Public Member Functions inherited from ROOT::Experimental::Detail::RPageStorage
	RPageStorage (const RPageStorage &other)=delete

	RPageStorage (RPageStorage &&other)=default

	RPageStorage (std::string_view name)

virtual	~RPageStorage ()

virtual RNTupleMetrics &	GetMetrics ()
	Returns an empty metrics. Page storage implementations usually have their own metrics.

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

RPageStorage &	operator= (RPageStorage &&other)=default

virtual void	ReleasePage (RPage &page)=0
	Every page store needs to be able to free pages it handed out.

void	SetTaskScheduler (RTaskScheduler *taskScheduler)

Static Public Member Functions
static std::unique_ptr< RPageSource >	Create (std::string_view ntupleName, std::string_view location, const RNTupleReadOptions &options=RNTupleReadOptions())
	Guess the concrete derived page source from the file name (location)

Protected Member Functions
virtual RNTupleDescriptor	AttachImpl ()=0

virtual void	UnzipClusterImpl (RCluster *)

Protected Attributes
ColumnSet_t	fActiveColumns
	The active columns are implicitly defined by the model fields or views.

RNTupleDescriptor	fDescriptor

RNTupleReadOptions	fOptions

Protected Attributes inherited from ROOT::Experimental::Detail::RPageStorage
std::string	fNTupleName

RTaskScheduler *	fTaskScheduler = nullptr

#include <ROOT/RPageStorage.hxx>

Inheritance diagram for ROOT::Experimental::Detail::RPageSource:

[legend]

Member Typedef Documentation

◆ ColumnSet_t

using ROOT::Experimental::Detail::RPageSource::ColumnSet_t = std::unordered_set<DescriptorId_t>

Derived from the model (fields) that are actually being requested at a given point in time.

Definition at line 196 of file RPageStorage.hxx.

Constructor & Destructor Documentation

◆ RPageSource() [1/3]

ROOT::Experimental::Detail::RPageSource::RPageSource	(	std::string_view	ntupleName,
		const RNTupleReadOptions &	fOptions
	)

Definition at line 52 of file RPageStorage.cxx.

◆ RPageSource() [2/3]

ROOT::Experimental::Detail::RPageSource::RPageSource ( const RPageSource & )

delete

◆ RPageSource() [3/3]

ROOT::Experimental::Detail::RPageSource::RPageSource ( RPageSource && )

default

◆ ~RPageSource()

ROOT::Experimental::Detail::RPageSource::~RPageSource ( )

virtual

Definition at line 57 of file RPageStorage.cxx.

Member Function Documentation

◆ AddColumn()

ROOT::Experimental::Detail::RPageStorage::ColumnHandle_t ROOT::Experimental::Detail::RPageSource::AddColumn	(	DescriptorId_t	fieldId,
		const RColumn &	column
	)

finalvirtual

Register a new column.

When reading, the column must exist in the ntuple on disk corresponding to the meta-data. When writing, every column can only be attached once.

Implements ROOT::Experimental::Detail::RPageStorage.

Definition at line 68 of file RPageStorage.cxx.

◆ Attach()

void ROOT::Experimental::Detail::RPageSource::Attach ( )

inline

Open the physical storage container for the tree.

Definition at line 228 of file RPageStorage.hxx.

◆ AttachImpl()

virtual RNTupleDescriptor ROOT::Experimental::Detail::RPageSource::AttachImpl ( )

protectedpure virtual

Implemented in ROOT::Experimental::Detail::RPageSourceFile.

◆ Clone()

virtual std::unique_ptr< RPageSource > ROOT::Experimental::Detail::RPageSource::Clone ( ) const

pure virtual

Open the same storage multiple time, e.g. for reading in multiple threads.

Implemented in ROOT::Experimental::Detail::RPageSourceFile.

◆ Create()

std::unique_ptr< ROOT::Experimental::Detail::RPageSource > ROOT::Experimental::Detail::RPageSource::Create	(	std::string_view	ntupleName,
		std::string_view	location,
		const RNTupleReadOptions &	options = `RNTupleReadOptions()`
	)

static

Guess the concrete derived page source from the file name (location)

Definition at line 61 of file RPageStorage.cxx.

◆ DropColumn()

void ROOT::Experimental::Detail::RPageSource::DropColumn ( ColumnHandle_t columnHandle )

finalvirtual

Unregisters a column.

A page source decreases the reference counter for the corresponding active column. For a page sink, dropping columns is currently a no-op.

Implements ROOT::Experimental::Detail::RPageStorage.

Definition at line 77 of file RPageStorage.cxx.

◆ GetColumnId()

ROOT::Experimental::ColumnId_t ROOT::Experimental::Detail::RPageSource::GetColumnId ( ColumnHandle_t columnHandle )

Definition at line 92 of file RPageStorage.cxx.

◆ GetDescriptor()

const RNTupleDescriptor & ROOT::Experimental::Detail::RPageSource::GetDescriptor ( ) const

inline

Definition at line 223 of file RPageStorage.hxx.

◆ GetNElements()

ROOT::Experimental::NTupleSize_t ROOT::Experimental::Detail::RPageSource::GetNElements ( ColumnHandle_t columnHandle )

Definition at line 87 of file RPageStorage.cxx.

◆ GetNEntries()

ROOT::Experimental::NTupleSize_t ROOT::Experimental::Detail::RPageSource::GetNEntries ( )

Definition at line 82 of file RPageStorage.cxx.

◆ GetType()

EPageStorageType ROOT::Experimental::Detail::RPageSource::GetType ( )

inlinefinalvirtual

Whether the concrete implementation is a sink or a source.

Implements ROOT::Experimental::Detail::RPageStorage.

Definition at line 222 of file RPageStorage.hxx.

◆ LoadCluster()

virtual std::unique_ptr< RCluster > ROOT::Experimental::Detail::RPageSource::LoadCluster	(	DescriptorId_t	clusterId,
		const ColumnSet_t &	columns
	)

pure virtual

Populates all the pages of the given cluster id and columns; it is possible that some columns do not contain any pages.

The pages source may load more columns than the minimal necessary set from columns. To indicate which columns have been loaded, LoadCluster() must mark them with SetColumnAvailable(). That includes the ones from the columns that don't have pages; otherwise subsequent requests for the cluster would assume an incomplete cluster and trigger loading again. LoadCluster() is typically called from the I/O thread of a cluster pool, i.e. the method runs concurrently to other methods of the page source.

Implemented in ROOT::Experimental::Detail::RPageSourceFile.

◆ operator=() [1/2]

RPageSource & ROOT::Experimental::Detail::RPageSource::operator= ( const RPageSource & )

delete

◆ operator=() [2/2]

RPageSource & ROOT::Experimental::Detail::RPageSource::operator= ( RPageSource && )

default

◆ PopulatePage() [1/2]

virtual RPage ROOT::Experimental::Detail::RPageSource::PopulatePage	(	ColumnHandle_t	columnHandle,
		const RClusterIndex &	clusterIndex
	)

pure virtual

Another version of PopulatePage that allows to specify cluster-relative indexes.

Implemented in ROOT::Experimental::Detail::RPageSourceFile.

◆ PopulatePage() [2/2]

virtual RPage ROOT::Experimental::Detail::RPageSource::PopulatePage	(	ColumnHandle_t	columnHandle,
		NTupleSize_t	globalIndex
	)

pure virtual

Allocates and fills a page that contains the index-th element.

Implemented in ROOT::Experimental::Detail::RPageSourceFile.

◆ UnzipCluster()

void ROOT::Experimental::Detail::RPageSource::UnzipCluster ( RCluster * cluster )

Parallel decompression and unpacking of the pages in the given cluster.

The unzipped pages are supposed to be preloaded in a page pool attached to the source. The method is triggered by the cluster pool's unzip thread. It is an optional optimization, the method can safely do nothing. In particular, the actual implementation will only run if a task scheduler is set. In practice, a task scheduler is set if implicit multi-threading is turned on.

Definition at line 98 of file RPageStorage.cxx.

◆ UnzipClusterImpl()

virtual void ROOT::Experimental::Detail::RPageSource::UnzipClusterImpl ( RCluster * )

inlineprotectedvirtual

Reimplemented in ROOT::Experimental::Detail::RPageSourceFile.

Definition at line 206 of file RPageStorage.hxx.

Member Data Documentation

◆ fActiveColumns

ColumnSet_t ROOT::Experimental::Detail::RPageSource::fActiveColumns

protected

The active columns are implicitly defined by the model fields or views.

Definition at line 202 of file RPageStorage.hxx.

◆ fDescriptor

RNTupleDescriptor ROOT::Experimental::Detail::RPageSource::fDescriptor

protected

Definition at line 200 of file RPageStorage.hxx.

◆ fOptions

RNTupleReadOptions ROOT::Experimental::Detail::RPageSource::fOptions

protected

Definition at line 199 of file RPageStorage.hxx.

Libraries for ROOT::Experimental::Detail::RPageSource:

[legend]

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

tree/ntuple/v7/inc/ROOT/RPageStorage.hxx
tree/ntuple/v7/src/RPageStorage.cxx

Public Types

Public Member Functions

Static Public Member Functions

Protected Member Functions

Protected Attributes

Member Typedef Documentation

◆ ColumnSet_t

Constructor & Destructor Documentation

◆ RPageSource() [1/3]

◆ RPageSource() [2/3]

◆ RPageSource() [3/3]

◆ ~RPageSource()

Member Function Documentation

◆ AddColumn()

◆ Attach()

◆ AttachImpl()

◆ Clone()

◆ Create()

◆ DropColumn()

◆ GetColumnId()

◆ GetDescriptor()

◆ GetNElements()

◆ GetNEntries()

◆ GetType()

◆ LoadCluster()

◆ operator=() [1/2]

◆ operator=() [2/2]

◆ PopulatePage() [1/2]

◆ PopulatePage() [2/2]

◆ UnzipCluster()

◆ UnzipClusterImpl()

Member Data Documentation

◆ fActiveColumns

◆ fDescriptor

◆ fOptions