TBufferMerger is a class to facilitate writing data in parallel from multiple threads, while writing to a single output file.

Its purpose is similar to TParallelMergingFile, but instead of using processes that connect to a network socket, TBufferMerger uses threads that each write to a TBufferMergerFile, which in turn push data into a queue managed by the TBufferMerger.

Definition at line 41 of file TBufferMerger.hxx.

Public Member Functions
	TBufferMerger (const char name, Option_t option="RECREATE", Int_t compress=ROOT::RCompressionSetting::EDefaults::kUseCompiledDefault)
	Constructor.
	TBufferMerger (std::unique_ptr< TFile > output)
	Constructor.
virtual	~TBufferMerger ()
	Destructor.
size_t	GetAutoSave () const
size_t	GetBuffered () const
Bool_t	GetCompressTemporaryKeys () const
std::shared_ptr< TBufferMergerFile >	GetFile ()
	Returns a TBufferMergerFile to which data can be written.
const char *	GetMergeOptions ()
	Returns the current merge options.
Bool_t	GetNotrees () const
	Returns whether the file has been marked as not containing any TTree objects and thus that steps that are specific to TTree can be skipped.
size_t	GetQueueSize () const
void	SetAutoSave (size_t)
void	SetCompressTemporaryKeys (Bool_t=true)
void	SetMergeOptions (const TString &options)
	Sets the merge options.
void	SetNotrees (Bool_t notrees=kFALSE)
	Indicates that any TTree objects in the file should be skipped and thus that steps that are specific to TTree can be skipped.

Private Member Functions
	TBufferMerger ()
	TBufferMerger has no default constructor.
	TBufferMerger (const TBufferMerger &)
	TBufferMerger has no copy constructor.
void	Init (std::unique_ptr< TFile >)
void	Merge (TBufferMergerFile *memfile)
TBufferMerger &	operator= (const TBufferMerger &)
	TBufferMerger has no copy operator.

Private Attributes
std::vector< std::weak_ptr< TBufferMergerFile > >	fAttachedFiles
std::mutex	fMergeMutex
TFileMerger	fMerger {false, false}

Friends
class	TBufferMergerFile

#include <ROOT/TBufferMerger.hxx>

Constructor & Destructor Documentation

◆ TBufferMerger() [1/4]

ROOT::TBufferMerger::TBufferMerger	(	const char *	name,
		Option_t *	option = "RECREATE",
		Int_t	compress = ROOT::RCompressionSetting::EDefaults::kUseCompiledDefault )

Constructor.

Parameters

name	Output file name
option	Output file creation options
compress	Output file compression level

Definition at line 23 of file TBufferMerger.cxx.

◆ TBufferMerger() [2/4]

ROOT::TBufferMerger::TBufferMerger ( std::unique_ptr< TFile > output )

Constructor.

Parameters

output Output TFile

Definition at line 31 of file TBufferMerger.cxx.

◆ ~TBufferMerger()

ROOT::TBufferMerger::~TBufferMerger ( )

virtual

Destructor.

Definition at line 44 of file TBufferMerger.cxx.

◆ TBufferMerger() [3/4]

ROOT::TBufferMerger::TBufferMerger ( )

private

TBufferMerger has no default constructor.

◆ TBufferMerger() [4/4]

ROOT::TBufferMerger::TBufferMerger ( const TBufferMerger & )

private

TBufferMerger has no copy constructor.

Member Function Documentation

◆ GetAutoSave()

size_t ROOT::TBufferMerger::GetAutoSave ( ) const

inline

Definition at line 78 of file TBufferMerger.hxx.

◆ GetBuffered()

size_t ROOT::TBufferMerger::GetBuffered ( ) const

inline

Definition at line 75 of file TBufferMerger.hxx.

◆ GetCompressTemporaryKeys()

Bool_t ROOT::TBufferMerger::GetCompressTemporaryKeys ( ) const

inline

Definition at line 111 of file TBufferMerger.hxx.

◆ GetFile()

std::shared_ptr< TBufferMergerFile > ROOT::TBufferMerger::GetFile ( )

Returns a TBufferMergerFile to which data can be written.

At the end, all TBufferMergerFiles get merged into the output file. The user is responsible to "cd" into the file to associate objects such as histograms or trees to it.

After the creation of this file, the user must reset the kMustCleanup bit on any objects attached to it and take care of their deletion, as there is a possibility that a race condition will happen that causes a crash if ROOT manages these objects.

Definition at line 56 of file TBufferMerger.cxx.

◆ GetMergeOptions()

const char * ROOT::TBufferMerger::GetMergeOptions ( )

Returns the current merge options.

Definition at line 65 of file TBufferMerger.cxx.

◆ GetNotrees()

Bool_t ROOT::TBufferMerger::GetNotrees ( ) const

inline

Returns whether the file has been marked as not containing any TTree objects and thus that steps that are specific to TTree can be skipped.

Definition at line 102 of file TBufferMerger.hxx.

◆ GetQueueSize()

size_t ROOT::TBufferMerger::GetQueueSize ( ) const

inline

Definition at line 72 of file TBufferMerger.hxx.

◆ Init()

void ROOT::TBufferMerger::Init ( std::unique_ptr< TFile > output )

private

Definition at line 36 of file TBufferMerger.cxx.

◆ Merge()

void ROOT::TBufferMerger::Merge ( ROOT::TBufferMergerFile * memfile )

private

Definition at line 76 of file TBufferMerger.cxx.

◆ operator=()

TBufferMerger & ROOT::TBufferMerger::operator= ( const TBufferMerger & )

private

TBufferMerger has no copy operator.

◆ SetAutoSave()

void ROOT::TBufferMerger::SetAutoSave ( size_t )

inline

Definition at line 84 of file TBufferMerger.hxx.

◆ SetCompressTemporaryKeys()

void ROOT::TBufferMerger::SetCompressTemporaryKeys ( Bool_t = true )

inline

Definition at line 108 of file TBufferMerger.hxx.

◆ SetMergeOptions()

void ROOT::TBufferMerger::SetMergeOptions ( const TString & options )

Sets the merge options.

SetMergeOptions("fast") will disable recompression of input data into the output if they have different compression settings.

Parameters

options TFileMerger/TFileMergeInfo merge options

Definition at line 71 of file TBufferMerger.cxx.

◆ SetNotrees()

void ROOT::TBufferMerger::SetNotrees ( Bool_t notrees = kFALSE )

inline

Indicates that any TTree objects in the file should be skipped and thus that steps that are specific to TTree can be skipped.

Definition at line 95 of file TBufferMerger.hxx.

◆ TBufferMergerFile

friend class TBufferMergerFile

friend

Definition at line 113 of file TBufferMerger.hxx.

Member Data Documentation

◆ fAttachedFiles

std::vector<std::weak_ptr<TBufferMergerFile> > ROOT::TBufferMerger::fAttachedFiles

private

Definition at line 131 of file TBufferMerger.hxx.

◆ fMergeMutex

std::mutex ROOT::TBufferMerger::fMergeMutex

private

Definition at line 130 of file TBufferMerger.hxx.

◆ fMerger

TFileMerger ROOT::TBufferMerger::fMerger {false, false}

private

Definition at line 129 of file TBufferMerger.hxx.

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

io/io/inc/ROOT/TBufferMerger.hxx
io/io/src/TBufferMerger.cxx

Public Member Functions

Private Member Functions

Private Attributes

Friends

Constructor & Destructor Documentation

◆ TBufferMerger() [1/4]

◆ TBufferMerger() [2/4]

◆ ~TBufferMerger()

◆ TBufferMerger() [3/4]

◆ TBufferMerger() [4/4]

Member Function Documentation

◆ GetAutoSave()

◆ GetBuffered()

◆ GetCompressTemporaryKeys()

◆ GetFile()

◆ GetMergeOptions()

◆ GetNotrees()

◆ GetQueueSize()

◆ Init()

◆ Merge()

◆ operator=()

◆ SetAutoSave()

◆ SetCompressTemporaryKeys()

◆ SetMergeOptions()

◆ SetNotrees()

Friends And Related Symbol Documentation

◆ TBufferMergerFile

Member Data Documentation

◆ fAttachedFiles

◆ fMergeMutex

◆ fMerger