A simple data-source implementation, for demo purposes.

Constructing an RDataFrame as RDataFrame(nEntries) is a superior alternative. If size is std::numeric_limits<ULong64_t>::max(), this acts as an infinite data-source: it returns entries from GetEntryRanges forever or until a Range stops the event loop (for test purposes).

Definition at line 26 of file RTrivialDS.hxx.

Public Member Functions
	RTrivialDS ()
	This ctor produces a data-source that returns infinite entries.

	RTrivialDS (ULong64_t size, bool skipEvenEntries=false)

	~RTrivialDS ()

const std::vector< std::string > &	GetColumnNames () const final
	Returns a reference to the collection of the dataset's column names.

std::vector< std::pair< ULong64_t, ULong64_t > >	GetEntryRanges () final
	Return ranges of entries to distribute to tasks.

std::string	GetLabel () final
	Return a string representation of the datasource type.

std::string	GetTypeName (std::string_view) const final
	Type of a column as a string, e.g.

bool	HasColumn (std::string_view colName) const final
	Checks if the dataset has a certain column.

void	Initialize () final
	Convenience method called before starting an event-loop.

bool	SetEntry (unsigned int slot, ULong64_t entry) final
	Advance the "cursors" returned by GetColumnReaders to the selected entry for a particular slot.

void	SetNSlots (unsigned int nSlots) final
	Inform RDataSource of the number of processing slots (i.e.

Public Member Functions inherited from ROOT::RDF::RDataSource
virtual	~RDataSource ()=default

virtual void	Finalize ()
	Convenience method called after concluding an event-loop.

virtual void	FinalizeSlot (unsigned int)
	Convenience method called at the end of the data processing associated to a slot.

template<typename T >
std::vector< T ** >	GetColumnReaders (std::string_view columnName)
	Called at most once per column by RDF.

virtual std::unique_ptr< ROOT::Detail::RDF::RColumnReaderBase >	GetColumnReaders (unsigned int, std::string_view, const std::type_info &)
	If the other GetColumnReaders overload returns an empty vector, this overload will be called instead.

virtual void	InitSlot (unsigned int, ULong64_t)
	Convenience method called at the start of the data processing associated to a slot.

Protected Member Functions
std::string	AsString () final

Private Member Functions
std::vector< void * >	GetColumnReadersImpl (std::string_view name, const std::type_info &) final
	type-erased vector of pointers to pointers to column values - one per slot

Private Attributes
std::vector< std::string >	fColNames {"col0"}

std::vector< ULong64_t >	fCounter

std::vector< ULong64_t * >	fCounterAddr

std::vector< std::pair< ULong64_t, ULong64_t > >	fEntryRanges

unsigned int	fNSlots = 0U

ULong64_t	fSize = 0ULL

bool	fSkipEvenEntries = false

Additional Inherited Members
Protected Types inherited from ROOT::RDF::RDataSource
using	Record_t = std::vector< void * >

#include <ROOT/RTrivialDS.hxx>

Inheritance diagram for ROOT::RDF::RTrivialDS:

[legend]

Constructor & Destructor Documentation

◆ RTrivialDS() [1/2]

ROOT::RDF::RTrivialDS::RTrivialDS	(	ULong64_t	size,
		bool	skipEvenEntries = `false`
	)

Definition at line 34 of file RTrivialDS.cxx.

◆ RTrivialDS() [2/2]

ROOT::RDF::RTrivialDS::RTrivialDS ( )

This ctor produces a data-source that returns infinite entries.

Definition at line 38 of file RTrivialDS.cxx.

◆ ~RTrivialDS()

ROOT::RDF::RTrivialDS::~RTrivialDS ( )

Definition at line 42 of file RTrivialDS.cxx.

Member Function Documentation

◆ AsString()

std::string ROOT::RDF::RTrivialDS::AsString ( )

inlinefinalprotectedvirtual

Reimplemented from ROOT::RDF::RDataSource.

Definition at line 38 of file RTrivialDS.hxx.

◆ GetColumnNames()

const std::vector< std::string > & ROOT::RDF::RTrivialDS::GetColumnNames ( ) const

finalvirtual

Returns a reference to the collection of the dataset's column names.

Implements ROOT::RDF::RDataSource.

Definition at line 46 of file RTrivialDS.cxx.

◆ GetColumnReadersImpl()

std::vector< void * > ROOT::RDF::RTrivialDS::GetColumnReadersImpl	(	std::string_view	name,
		const std::type_info &
	)

finalprivatevirtual

type-erased vector of pointers to pointers to column values - one per slot

Implements ROOT::RDF::RDataSource.

Definition at line 20 of file RTrivialDS.cxx.

◆ GetEntryRanges()

std::vector< std::pair< ULong64_t, ULong64_t > > ROOT::RDF::RTrivialDS::GetEntryRanges ( )

finalvirtual

Return ranges of entries to distribute to tasks.

They are required to be contiguous intervals with no entries skipped. Supposing a dataset with nEntries, the intervals must start at 0 and end at nEntries, e.g. [0-5],[5-10] for 10 entries. This function will be invoked repeatedly by RDataFrame as it needs additional entries to process. The same entry range should not be returned more than once. Returning an empty collection of ranges signals to RDataFrame that the processing can stop.

Implements ROOT::RDF::RDataSource.

Definition at line 61 of file RTrivialDS.cxx.

◆ GetLabel()

std::string ROOT::RDF::RTrivialDS::GetLabel ( )

finalvirtual

Return a string representation of the datasource type.

The returned string will be used by ROOT::RDF::SaveGraph() to represent the datasource in the visualization of the computation graph. Concrete datasources can override the default implementation.

Reimplemented from ROOT::RDF::RDataSource.

Definition at line 118 of file RTrivialDS.cxx.

◆ GetTypeName()

std::string ROOT::RDF::RTrivialDS::GetTypeName ( std::string_view colName ) const

finalvirtual

Type of a column as a string, e.g.

GetTypeName("x") == "double". Required for jitting e.g. df.Filter("x>0").

Parameters

[in] colName The name of the column

Implements ROOT::RDF::RDataSource.

Definition at line 56 of file RTrivialDS.cxx.

◆ HasColumn()

bool ROOT::RDF::RTrivialDS::HasColumn ( std::string_view colName ) const

finalvirtual

Checks if the dataset has a certain column.

Parameters

[in] colName The name of the column

Implements ROOT::RDF::RDataSource.

Definition at line 51 of file RTrivialDS.cxx.

◆ Initialize()

void ROOT::RDF::RTrivialDS::Initialize ( )

finalvirtual

Convenience method called before starting an event-loop.

This method might be called multiple times over the lifetime of a RDataSource, since users can run multiple event-loops with the same RDataFrame. Ideally, Initialize should set the state of the RDataSource so that multiple identical event-loops will produce identical results.

Reimplemented from ROOT::RDF::RDataSource.

Definition at line 97 of file RTrivialDS.cxx.

◆ SetEntry()

bool ROOT::RDF::RTrivialDS::SetEntry	(	unsigned int	slot,
		ULong64_t	entry
	)

finalvirtual

Advance the "cursors" returned by GetColumnReaders to the selected entry for a particular slot.

Parameters

[in]	slot	The data processing slot that needs to be considered
[in]	entry	The entry which needs to be pointed to by the reader pointers Slots are adopted to accommodate parallel data processing. Different workers will loop over different ranges and will be labelled by different "slot" values. Returns true if the entry has to be processed, false otherwise.

Implements ROOT::RDF::RDataSource.

Definition at line 79 of file RTrivialDS.cxx.

◆ SetNSlots()

void ROOT::RDF::RTrivialDS::SetNSlots ( unsigned int nSlots )

finalvirtual

Inform RDataSource of the number of processing slots (i.e.

worker threads) used by the associated RDataFrame. Slots numbers are used to simplify parallel execution: RDataFrame guarantees that different threads will always pass different slot values when calling methods concurrently.

Implements ROOT::RDF::RDataSource.

Definition at line 88 of file RTrivialDS.cxx.

Member Data Documentation

◆ fColNames

std::vector<std::string> ROOT::RDF::RTrivialDS::fColNames {"col0"}

private

Definition at line 32 of file RTrivialDS.hxx.

◆ fCounter

std::vector<ULong64_t> ROOT::RDF::RTrivialDS::fCounter

private

Definition at line 33 of file RTrivialDS.hxx.

◆ fCounterAddr

std::vector<ULong64_t *> ROOT::RDF::RTrivialDS::fCounterAddr

private

Definition at line 34 of file RTrivialDS.hxx.

◆ fEntryRanges

std::vector<std::pair<ULong64_t, ULong64_t> > ROOT::RDF::RTrivialDS::fEntryRanges

private

Definition at line 31 of file RTrivialDS.hxx.

◆ fNSlots

unsigned int ROOT::RDF::RTrivialDS::fNSlots = 0U

private

Definition at line 28 of file RTrivialDS.hxx.

◆ fSize

ULong64_t ROOT::RDF::RTrivialDS::fSize = 0ULL

private

Definition at line 29 of file RTrivialDS.hxx.

◆ fSkipEvenEntries

bool ROOT::RDF::RTrivialDS::fSkipEvenEntries = false

private

Definition at line 30 of file RTrivialDS.hxx.

Libraries for ROOT::RDF::RTrivialDS:

[legend]

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

tree/dataframe/inc/ROOT/RTrivialDS.hxx
tree/dataframe/src/RTrivialDS.cxx

Public Member Functions

Protected Member Functions

Private Member Functions

Private Attributes

Additional Inherited Members

Constructor & Destructor Documentation

◆ RTrivialDS() [1/2]

◆ RTrivialDS() [2/2]

◆ ~RTrivialDS()

Member Function Documentation

◆ AsString()

◆ GetColumnNames()

◆ GetColumnReadersImpl()

◆ GetEntryRanges()

◆ GetLabel()

◆ GetTypeName()

◆ HasColumn()

◆ Initialize()

◆ SetEntry()

◆ SetNSlots()

Member Data Documentation

◆ fColNames

◆ fCounter

◆ fCounterAddr

◆ fEntryRanges

◆ fNSlots

◆ fSize

◆ fSkipEvenEntries