ROOT::Experimental::TBufferMerger Class Reference

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

A TBufferMergerFile is similar to a TMemFile, but when data is written to it, it is appended to the TBufferMerger queue.

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.

The TBufferMerger merges all data into the output file on disk.

Definition at line 44 of file TBufferMerger.hxx.

Public Member Functions
	TBufferMerger (const char *name, Option_t *option="RECREATE", Int_t compress=1)
	Constructor. More...
virtual	~TBufferMerger ()
	Destructor. More...
std::shared_ptr< TBufferMergerFile >	GetFile ()
	Returns a TBufferMergerFile to which data can be written. More...

Private Member Functions
	TBufferMerger ()
	TBufferMerger has no default constructor. More...
	TBufferMerger (const TBufferMerger &)
	TBufferMerger has no copy constructor. More...
TBufferMerger &	operator= (const TBufferMerger &)
	TBufferMerger has no copy operator. More...
void	Push (TBufferFile *buffer)
void	WriteOutputFile ()

Private Attributes
std::vector< std::weak_ptr< TBufferMergerFile > >	fAttachedFiles
const Int_t	fCompress
std::condition_variable	fDataAvailable
std::unique_ptr< std::thread >	fMergingThread
const std::string	fName
const std::string	fOption
std::queue< TBufferFile * >	fQueue
std::mutex	fQueueMutex

Friends
class	TBufferMergerFile

#include <ROOT/TBufferMerger.hxx>

Constructor & Destructor Documentation

TBufferMerger() [1/3]

ROOT::Experimental::TBufferMerger::TBufferMerger	(	const char *	name,
		Option_t *	option = "RECREATE",
		Int_t	compress = 1
	)

Constructor.

Parameters

name	Output file name
option	Output file creation options
ftitle	Output file title
compression	Output file compression level

Definition at line 23 of file TBufferMerger.cxx.

~TBufferMerger()

ROOT::Experimental::TBufferMerger::~TBufferMerger ( )

virtual

Destructor.

Definition at line 29 of file TBufferMerger.cxx.

TBufferMerger() [2/3]

ROOT::Experimental::TBufferMerger::TBufferMerger ( )

private

TBufferMerger has no default constructor.

TBufferMerger() [3/3]

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

private

TBufferMerger has no copy constructor.

Member Function Documentation

GetFile()

std::shared_ptr< TBufferMergerFile > ROOT::Experimental::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 38 of file TBufferMerger.cxx.

operator=()

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

private

TBufferMerger has no copy operator.

Push()

void ROOT::Experimental::TBufferMerger::Push ( TBufferFile *  buffer )

private

Definition at line 47 of file TBufferMerger.cxx.

WriteOutputFile()

void ROOT::Experimental::TBufferMerger::WriteOutputFile ( )

private

Definition at line 56 of file TBufferMerger.cxx.

Friends And Related Function Documentation

TBufferMergerFile

friend class TBufferMergerFile

friend

Definition at line 69 of file TBufferMerger.hxx.

Member Data Documentation

fAttachedFiles

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

private

Definition at line 91 of file TBufferMerger.hxx.

fCompress

const Int_t ROOT::Experimental::TBufferMerger::fCompress

private

Definition at line 86 of file TBufferMerger.hxx.

fDataAvailable

std::condition_variable ROOT::Experimental::TBufferMerger::fDataAvailable

private

Definition at line 88 of file TBufferMerger.hxx.

fMergingThread

std::unique_ptr<std::thread> ROOT::Experimental::TBufferMerger::fMergingThread

private

Definition at line 90 of file TBufferMerger.hxx.

fName

const std::string ROOT::Experimental::TBufferMerger::fName

private

Definition at line 84 of file TBufferMerger.hxx.

fOption

const std::string ROOT::Experimental::TBufferMerger::fOption

private

Definition at line 85 of file TBufferMerger.hxx.

fQueue

std::queue<TBufferFile *> ROOT::Experimental::TBufferMerger::fQueue

private

Definition at line 89 of file TBufferMerger.hxx.

fQueueMutex

std::mutex ROOT::Experimental::TBufferMerger::fQueueMutex

private

Definition at line 87 of file TBufferMerger.hxx.

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

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