ROOT::Internal::RNTupleFileWriter::RImplSimple Struct Reference

Definition at line 149 of file RMiniFile.hxx.

Classes
struct	RSharedData
	Data that is shared between a "main" RImplSimple and all its clones. More...

Public Member Functions
	RImplSimple ()
	RImplSimple (const RImplSimple &other)=delete
	RImplSimple (RImplSimple &&other)=delete
void	AllocateBuffers (std::size_t bufferSize)
void	Flush ()
	operator bool () const
RImplSimple &	operator= (const RImplSimple &other)=delete
RImplSimple &	operator= (RImplSimple &&other)=delete
std::uint64_t	ReserveBlobKey (std::size_t nbytes, std::size_t len, unsigned char keyBuffer[kBlobKeyLen]=nullptr)
	Reserves an RBlob opaque key as data record and returns the offset of the record.
void	Write (const void *buffer, size_t nbytes, std::int64_t offset=-1)
	Writes bytes in the open stream, either at fFilePos or at the given offset.
std::uint64_t	WriteKey (const void *buffer, std::size_t nbytes, std::size_t len, std::int64_t offset=-1, std::uint64_t directoryOffset=100, const std::string &className="", const std::string &objectName="", const std::string &title="")
	Writes a TKey including the data record, given by buffer, into fFile; returns the file offset to the payload.

Public Attributes
std::shared_ptr< RSharedData >	fShared

Static Public Attributes
static constexpr int	kBlockAlign = 4096
	Direct I/O requires that all buffers and write lengths are aligned.
static constexpr std::size_t	kHeaderBlockSize = 4096
	During commit, WriteTFileKeysList() updates fNBytesKeys and fSeekKeys of the RTFFile located at fSeekFileRecord.

Constructor & Destructor Documentation

RImplSimple() [1/3]

ROOT::Internal::RNTupleFileWriter::RImplSimple::RImplSimple ( )

default

RImplSimple() [2/3]

ROOT::Internal::RNTupleFileWriter::RImplSimple::RImplSimple ( const RImplSimple & other )

delete

RImplSimple() [3/3]

ROOT::Internal::RNTupleFileWriter::RImplSimple::RImplSimple ( RImplSimple && other )

delete

Member Function Documentation

AllocateBuffers()

void ROOT::Internal::RNTupleFileWriter::RImplSimple::AllocateBuffers

(

std::size_t

bufferSize

)

Definition at line 982 of file RMiniFile.cxx.

Flush()

void ROOT::Internal::RNTupleFileWriter::RImplSimple::Flush

(

)

Definition at line 1027 of file RMiniFile.cxx.

operator bool()

ROOT::Internal::RNTupleFileWriter::RImplSimple::operator bool ( ) const

inline

Definition at line 206 of file RMiniFile.hxx.

operator=() [1/2]

RImplSimple & ROOT::Internal::RNTupleFileWriter::RImplSimple::operator= ( const RImplSimple & other )

delete

operator=() [2/2]

RImplSimple & ROOT::Internal::RNTupleFileWriter::RImplSimple::operator= ( RImplSimple && other )

delete

ReserveBlobKey()

std::uint64_t ROOT::Internal::RNTupleFileWriter::RImplSimple::ReserveBlobKey	(	std::size_t	nbytes,
		std::size_t	len,
		unsigned char	keyBuffer[kBlobKeyLen] = nullptr )

Reserves an RBlob opaque key as data record and returns the offset of the record.

If keyBuffer is specified, it must be written before the returned offset. (Note that the array type is purely documentation, the argument is actually just a pointer.)

Definition at line 1151 of file RMiniFile.cxx.

Write()

void ROOT::Internal::RNTupleFileWriter::RImplSimple::Write	(	const void *	buffer,
		size_t	nbytes,
		std::int64_t	offset = -1 )

Writes bytes in the open stream, either at fFilePos or at the given offset.

Definition at line 1073 of file RMiniFile.cxx.

WriteKey()

std::uint64_t ROOT::Internal::RNTupleFileWriter::RImplSimple::WriteKey	(	const void *	buffer,
		std::size_t	nbytes,
		std::size_t	len,
		std::int64_t	offset = -1,
		std::uint64_t	directoryOffset = 100,
		const std::string &	className = "",
		const std::string &	objectName = "",
		const std::string &	title = "" )

Writes a TKey including the data record, given by buffer, into fFile; returns the file offset to the payload.

The payload is already compressed

Definition at line 1124 of file RMiniFile.cxx.

Member Data Documentation

fShared

std::shared_ptr<RSharedData> ROOT::Internal::RNTupleFileWriter::RImplSimple::fShared

Definition at line 184 of file RMiniFile.hxx.

kBlockAlign

constexpr int ROOT::Internal::RNTupleFileWriter::RImplSimple::kBlockAlign = 4096

staticconstexpr

Direct I/O requires that all buffers and write lengths are aligned.

It seems 512 byte alignment is the minimum for Direct I/O to work, but further testing showed that it results in worse performance than 4kB.

Definition at line 152 of file RMiniFile.hxx.

kHeaderBlockSize

constexpr std::size_t ROOT::Internal::RNTupleFileWriter::RImplSimple::kHeaderBlockSize = 4096

staticconstexpr

During commit, WriteTFileKeysList() updates fNBytesKeys and fSeekKeys of the RTFFile located at fSeekFileRecord.

Given that the TFile key starts at offset 100 and the file name, which is written twice, is shorter than 255 characters, we should need at most ~600 bytes. However, the header also needs to be aligned to kBlockAlign...

Definition at line 157 of file RMiniFile.hxx.

Collaboration diagram for ROOT::Internal::RNTupleFileWriter::RImplSimple:

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

• tree/ntuple/inc/ROOT/RMiniFile.hxx
• tree/ntuple/src/RMiniFile.cxx