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ROOT::RDF::RTrivialDS Class Referencefinal

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::RColumnReaderBaseGetColumnReaders (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_tfCounter
 
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]colNameThe 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]colNameThe 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]slotThe data processing slot that needs to be considered
[in]entryThe 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:

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