The RRawFileDavix class provides read-only access to remote non-ROOT files.

It uses the Davix library for the transport layer. It instructs the RRawFile base class to buffer in larger chunks than the default for local files, assuming that remote file access has high(er) latency.

Definition at line 35 of file RRawFileDavix.hxx.

Public Types
enum class	ELineBreaks { kAuto , kSystem , kUnix , kWindows }
	kAuto detects the line break from the first line, kSystem picks the system's default More...

Public Member Functions
	RRawFileDavix (std::string_view url, RRawFile::ROptions options)
	~RRawFileDavix ()
std::unique_ptr< RRawFile >	Clone () const final
	Create a new RawFile that accesses the same resource. The file pointer is reset to zero.
std::uint64_t	GetFilePos () const
	Returns the offset for the next Read/Readln call.
virtual RIOVecLimits	GetReadVLimits ()
	Returns the limits regarding the ioVec input to ReadV for this specific file; may open the file as a side-effect.
std::uint64_t	GetSize ()
	Returns the size of the file.
std::string	GetUrl () const
	Returns the url of the file.
bool	IsBuffering () const
bool	IsOpen () const
	Once opened, the file stay open until destruction of the RRawFile object.
size_t	Read (void *buffer, size_t nbytes)
	Read from fFilePos offset. Returns the actual number of bytes read.
size_t	ReadAt (void *buffer, size_t nbytes, std::uint64_t offset)
	Buffered read from a random position.
bool	Readln (std::string &line)
	Read the next line starting from the current value of fFilePos. Returns false if the end of the file is reached.
void	ReadV (RIOVec *ioVec, unsigned int nReq)
	Opens the file if necessary and calls ReadVImpl.
void	Seek (std::uint64_t offset)
	Change the cursor fFilePos.
void	SetBuffering (bool value)
	Turn on/off buffered reads; if off, all scalar read requests go directly to the implementation.

Static Public Member Functions
static std::unique_ptr< RRawFile >	Create (std::string_view url, ROptions options=ROptions())
	Factory method that returns a suitable concrete implementation according to the transport in the url.
static std::string	GetLocation (std::string_view url)
	Returns only the file location, e.g. "server/file" for http://server/file.
static std::string	GetTransport (std::string_view url)
	Returns only the transport protocol in lower case, e.g. "http" for HTTP://server/file.

Protected Member Functions
void	EnsureOpen ()
	Open the file if not already open. Otherwise noop.
std::uint64_t	GetSizeImpl () final
	Derived classes should return the file size.
void	OpenImpl () final
	OpenImpl() is called at most once and before any call to either DoReadAt or DoGetSize.
size_t	ReadAtImpl (void *buffer, size_t nbytes, std::uint64_t offset) final
	Derived classes should implement low-level reading without buffering.
void	ReadVImpl (RIOVec *ioVec, unsigned int nReq) final
	By default implemented as a loop of ReadAt calls but can be overwritten, e.g. XRootD or DAVIX implementations.
virtual void	SetDiscourageReadAheadImpl (bool)

Protected Attributes
std::uint64_t	fFilePos = 0
	The current position in the file, which can be changed by Seek, Read, and Readln.
ROptions	fOptions
std::string	fUrl

Private Attributes
unsigned int	fBlockBufferIdx = 0
	To be used modulo kNumBlockBuffers, points to the last used block buffer in fBlockBuffers.
RBlockBuffer	fBlockBuffers [kNumBlockBuffers]
	An active buffer and a shadow buffer, which supports "jumping back" to a previously used location in the file.
std::unique_ptr< unsigned char[]>	fBufferSpace
	Memory block containing the block buffers consecutively.
std::unique_ptr< Internal::RDavixFileDes >	fFileDes
std::uint64_t	fFileSize = kUnknownFileSize
	The cached file size.
bool	fIsBuffering = true
	Runtime switch to decide if reads are buffered or directly sent to ReadAtImpl().
bool	fIsOpen = false
	Files are opened lazily and only when required; the open state is kept by this flag.

Static Private Attributes
static constexpr unsigned int	kNumBlockBuffers = 2
	Don't change without adapting ReadAt().
static constexpr std::uint64_t	kUnknownFileSize = std::uint64_t(-1)
	Used as a marker that the file size was not yet queried.

#include <ROOT/RRawFileDavix.hxx>

Inheritance diagram for ROOT::Internal::RRawFileDavix:

Member Enumeration Documentation

◆ ELineBreaks

enum class ROOT::Internal::RRawFile::ELineBreaks

stronginherited

kAuto detects the line break from the first line, kSystem picks the system's default

Enumerator
kAuto
kSystem
kUnix
kWindows

Definition at line 46 of file RRawFile.hxx.

Constructor & Destructor Documentation

◆ RRawFileDavix()

ROOT::Internal::RRawFileDavix::RRawFileDavix	(	std::string_view	url,
		RRawFile::ROptions	options )

Definition at line 55 of file RRawFileDavix.cxx.

◆ ~RRawFileDavix()

ROOT::Internal::RRawFileDavix::~RRawFileDavix ( )

Definition at line 60 of file RRawFileDavix.cxx.

Member Function Documentation

◆ Clone()

std::unique_ptr< ROOT::Internal::RRawFile > ROOT::Internal::RRawFileDavix::Clone ( ) const

finalvirtual

Create a new RawFile that accesses the same resource. The file pointer is reset to zero.

Implements ROOT::Internal::RRawFile.

Definition at line 66 of file RRawFileDavix.cxx.

◆ Create()

std::unique_ptr< ROOT::Internal::RRawFile > ROOT::Internal::RRawFile::Create	(	std::string_view	url,
		ROptions	options = ROptions() )

staticinherited

Factory method that returns a suitable concrete implementation according to the transport in the url.

Definition at line 64 of file RRawFile.cxx.

◆ EnsureOpen()

void ROOT::Internal::RRawFile::EnsureOpen ( )

protectedinherited

Open the file if not already open. Otherwise noop.

Definition at line 88 of file RRawFile.cxx.

◆ GetFilePos()

std::uint64_t ROOT::Internal::RRawFile::GetFilePos ( ) const

inlineinherited

Returns the offset for the next Read/Readln call.

Definition at line 173 of file RRawFile.hxx.

◆ GetLocation()

std::string ROOT::Internal::RRawFile::GetLocation ( std::string_view url )

staticinherited

Returns only the file location, e.g. "server/file" for http://server/file.

Definition at line 105 of file RRawFile.cxx.

◆ GetReadVLimits()

virtual RIOVecLimits ROOT::Internal::RRawFile::GetReadVLimits ( )

inlinevirtualinherited

Returns the limits regarding the ioVec input to ReadV for this specific file; may open the file as a side-effect.

Reimplemented in ROOT::Internal::RRawFileNetXNG.

Definition at line 182 of file RRawFile.hxx.

◆ GetSize()

std::uint64_t ROOT::Internal::RRawFile::GetSize ( )

inherited

Returns the size of the file.

Definition at line 113 of file RRawFile.cxx.

◆ GetSizeImpl()

std::uint64_t ROOT::Internal::RRawFileDavix::GetSizeImpl ( )

finalprotectedvirtual

Derived classes should return the file size.

Implements ROOT::Internal::RRawFile.

Definition at line 71 of file RRawFileDavix.cxx.

◆ GetTransport()

std::string ROOT::Internal::RRawFile::GetTransport ( std::string_view url )

staticinherited

Returns only the transport protocol in lower case, e.g. "http" for HTTP://server/file.

Definition at line 127 of file RRawFile.cxx.

◆ GetUrl()

std::string ROOT::Internal::RRawFile::GetUrl ( ) const

inherited

Returns the url of the file.

Definition at line 123 of file RRawFile.cxx.

◆ IsBuffering()

bool ROOT::Internal::RRawFile::IsBuffering ( ) const

inlineinherited

Definition at line 188 of file RRawFile.hxx.

◆ IsOpen()

bool ROOT::Internal::RRawFile::IsOpen ( ) const

inlineinherited

Once opened, the file stay open until destruction of the RRawFile object.

Definition at line 194 of file RRawFile.hxx.

◆ OpenImpl()

void ROOT::Internal::RRawFileDavix::OpenImpl ( )

finalprotectedvirtual

OpenImpl() is called at most once and before any call to either DoReadAt or DoGetSize.

If fOptions.fBlocksize is negative, derived classes are responsible to set a sensible value. After a call to OpenImpl(), fOptions.fBlocksize must be larger or equal to zero.

Implements ROOT::Internal::RRawFile.

Definition at line 81 of file RRawFileDavix.cxx.

◆ Read()

size_t ROOT::Internal::RRawFile::Read	(	void *	buffer,
		size_t	nbytes )

inherited

Read from fFilePos offset. Returns the actual number of bytes read.

Definition at line 137 of file RRawFile.cxx.

◆ ReadAt()

size_t ROOT::Internal::RRawFile::ReadAt	(	void *	buffer,
		size_t	nbytes,
		std::uint64_t	offset )

inherited

Buffered read from a random position.

Returns the actual number of bytes read. Short reads indicate the end of the file

Definition at line 144 of file RRawFile.cxx.

◆ ReadAtImpl()

size_t ROOT::Internal::RRawFileDavix::ReadAtImpl	(	void *	buffer,
		size_t	nbytes,
		std::uint64_t	offset )

finalprotectedvirtual

Derived classes should implement low-level reading without buffering.

Short reads indicate the end of the file, therefore derived classes should return nbytes bytes if available.

Implements ROOT::Internal::RRawFile.

Definition at line 92 of file RRawFileDavix.cxx.

◆ Readln()

bool ROOT::Internal::RRawFile::Readln ( std::string & line )

inherited

Read the next line starting from the current value of fFilePos. Returns false if the end of the file is reached.

Definition at line 208 of file RRawFile.cxx.

◆ ReadV()

void ROOT::Internal::RRawFile::ReadV	(	RIOVec *	ioVec,
		unsigned int	nReq )

inherited

Opens the file if necessary and calls ReadVImpl.

Definition at line 193 of file RRawFile.cxx.

◆ ReadVImpl()

void ROOT::Internal::RRawFileDavix::ReadVImpl	(	RIOVec *	ioVec,
		unsigned int	nReq )

finalprotectedvirtual

By default implemented as a loop of ReadAt calls but can be overwritten, e.g. XRootD or DAVIX implementations.

Reimplemented from ROOT::Internal::RRawFile.

Definition at line 102 of file RRawFileDavix.cxx.

◆ Seek()

void ROOT::Internal::RRawFile::Seek ( std::uint64_t offset )

inherited

Change the cursor fFilePos.

Definition at line 241 of file RRawFile.cxx.

◆ SetBuffering()

void ROOT::Internal::RRawFile::SetBuffering ( bool value )

inherited

Turn on/off buffered reads; if off, all scalar read requests go directly to the implementation.

Buffering also turns on and off OS read-ahead where supported: if buffering is switched, SetDiscourageReadAheadImpl() will be called accordingly.

Definition at line 199 of file RRawFile.cxx.

◆ SetDiscourageReadAheadImpl()

virtual void ROOT::Internal::RRawFile::SetDiscourageReadAheadImpl ( bool )

inlineprotectedvirtualinherited

Reimplemented in ROOT::Internal::RRawFileUnix.

Definition at line 144 of file RRawFile.hxx.

Member Data Documentation

◆ fBlockBufferIdx

unsigned int ROOT::Internal::RRawFile::fBlockBufferIdx = 0

privateinherited

To be used modulo kNumBlockBuffers, points to the last used block buffer in fBlockBuffers.

Definition at line 110 of file RRawFile.hxx.

◆ fBlockBuffers

RBlockBuffer ROOT::Internal::RRawFile::fBlockBuffers[kNumBlockBuffers]

privateinherited

An active buffer and a shadow buffer, which supports "jumping back" to a previously used location in the file.

Definition at line 112 of file RRawFile.hxx.

◆ fBufferSpace

std::unique_ptr<unsigned char[]> ROOT::Internal::RRawFile::fBufferSpace

privateinherited

Memory block containing the block buffers consecutively.

Definition at line 114 of file RRawFile.hxx.

◆ fFileDes

std::unique_ptr<Internal::RDavixFileDes> ROOT::Internal::RRawFileDavix::fFileDes

private

Definition at line 37 of file RRawFileDavix.hxx.

◆ fFilePos

std::uint64_t ROOT::Internal::RRawFile::fFilePos = 0

protectedinherited

The current position in the file, which can be changed by Seek, Read, and Readln.

Definition at line 128 of file RRawFile.hxx.

◆ fFileSize

std::uint64_t ROOT::Internal::RRawFile::fFileSize = kUnknownFileSize

privateinherited

The cached file size.

Definition at line 118 of file RRawFile.hxx.

◆ fIsBuffering

bool ROOT::Internal::RRawFile::fIsBuffering = true

privateinherited

Runtime switch to decide if reads are buffered or directly sent to ReadAtImpl().

Definition at line 122 of file RRawFile.hxx.

◆ fIsOpen

bool ROOT::Internal::RRawFile::fIsOpen = false

privateinherited

Files are opened lazily and only when required; the open state is kept by this flag.

Definition at line 120 of file RRawFile.hxx.

◆ fOptions

ROptions ROOT::Internal::RRawFile::fOptions

protectedinherited

Definition at line 126 of file RRawFile.hxx.

◆ fUrl

std::string ROOT::Internal::RRawFile::fUrl

protectedinherited

Definition at line 125 of file RRawFile.hxx.

◆ kNumBlockBuffers

unsigned int ROOT::Internal::RRawFile::kNumBlockBuffers = 2

staticconstexprprivateinherited

Don't change without adapting ReadAt().

Definition at line 92 of file RRawFile.hxx.

◆ kUnknownFileSize

std::uint64_t ROOT::Internal::RRawFile::kUnknownFileSize = std::uint64_t(-1)

staticconstexprprivateinherited

Used as a marker that the file size was not yet queried.

Definition at line 116 of file RRawFile.hxx.

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

net/davix/inc/ROOT/RRawFileDavix.hxx
net/davix/src/RRawFileDavix.cxx

Public Types

Public Member Functions

Static Public Member Functions

Protected Member Functions

Protected Attributes

Private Attributes

Static Private Attributes

Member Enumeration Documentation

◆ ELineBreaks

Constructor & Destructor Documentation

◆ RRawFileDavix()

◆ ~RRawFileDavix()

Member Function Documentation

◆ Clone()

◆ Create()

◆ EnsureOpen()

◆ GetFilePos()

◆ GetLocation()

◆ GetReadVLimits()

◆ GetSize()

◆ GetSizeImpl()

◆ GetTransport()

◆ GetUrl()

◆ IsBuffering()

◆ IsOpen()

◆ OpenImpl()

◆ Read()

◆ ReadAt()

◆ ReadAtImpl()

◆ Readln()

◆ ReadV()

◆ ReadVImpl()

◆ Seek()

◆ SetBuffering()

◆ SetDiscourageReadAheadImpl()

Member Data Documentation

◆ fBlockBufferIdx

◆ fBlockBuffers

◆ fBufferSpace

◆ fFileDes

◆ fFilePos

◆ fFileSize

◆ fIsBuffering

◆ fIsOpen

◆ fOptions

◆ fUrl

◆ kNumBlockBuffers

◆ kUnknownFileSize