A cache when writing files over the network.

A caching system to speed up network I/O, i.e. when there is no operating system caching support (like the buffer cache for local disk I/O). The cache makes sure that every I/O is done with a (large) fixed length buffer thereby avoiding many small I/O's. Currently the write cache system is used by the classes TNetFile, TXNetFile and TWebFile (via TFile::WriteBuffers()).

The write cache is automatically created when writing a remote file (created in TFile::Open()).

Definition at line 19 of file TFileCacheWrite.h.

Public Member Functions
	TFileCacheWrite ()
	Default Constructor.

	TFileCacheWrite (TFile *file, Int_t buffersize)
	Creates a TFileCacheWrite data structure.

virtual	~TFileCacheWrite ()
	Destructor.

virtual Bool_t	Flush ()
	Flush the current write buffer to the file.

virtual Int_t	GetBytesInCache () const

virtual void	Print (Option_t *option="") const
	Print class internal structure.

virtual Int_t	ReadBuffer (char *buf, Long64_t pos, Int_t len)
	Called by the read cache to check if the requested data is not in the write cache buffer.

virtual void	SetFile (TFile *file)
	Set the file using this cache.

virtual Int_t	WriteBuffer (const char *buf, Long64_t pos, Int_t len)
	Write buffer at position pos in the write buffer.

Public Member Functions inherited from TObject
	TObject ()
	TObject constructor.

	TObject (const TObject &object)
	TObject copy ctor.

virtual	~TObject ()
	TObject destructor.

void	AbstractMethod (const char *method) const
	Use this method to implement an "abstract" method that you don't want to leave purely abstract.

virtual void	AppendPad (Option_t *option="")
	Append graphics object to current pad.

virtual void	Browse (TBrowser *b)
	Browse object. May be overridden for another default action.

ULong_t	CheckedHash ()
	Check and record whether this class has a consistent Hash/RecursiveRemove setup (*) and then return the regular Hash value for this object.

virtual const char *	ClassName () const
	Returns name of class to which the object belongs.

virtual void	Clear (Option_t *="")

virtual TObject *	Clone (const char *newname="") const
	Make a clone of an object using the Streamer facility.

virtual Int_t	Compare (const TObject *obj) const
	Compare abstract method.

virtual void	Copy (TObject &object) const
	Copy this to obj.

virtual void	Delete (Option_t *option="")
	Delete this object.

virtual Int_t	DistancetoPrimitive (Int_t px, Int_t py)
	Computes distance from point (px,py) to the object.

virtual void	Draw (Option_t *option="")
	Default Draw method for all objects.

virtual void	DrawClass () const
	Draw class inheritance tree of the class to which this object belongs.

virtual TObject *	DrawClone (Option_t *option="") const
	Draw a clone of this object in the current selected pad for instance with: `gROOT->SetSelectedPad(gPad)`.

virtual void	Dump () const
	Dump contents of object on stdout.

virtual void	Error (const char method, const char msgfmt,...) const
	Issue error message.

virtual void	Execute (const char method, const char params, Int_t *error=0)
	Execute method on this object with the given parameter string, e.g.

virtual void	Execute (TMethod method, TObjArray params, Int_t *error=0)
	Execute method on this object with parameters stored in the TObjArray.

virtual void	ExecuteEvent (Int_t event, Int_t px, Int_t py)
	Execute action corresponding to an event at (px,py).

virtual void	Fatal (const char method, const char msgfmt,...) const
	Issue fatal error message.

virtual TObject *	FindObject (const char *name) const
	Must be redefined in derived classes.

virtual TObject *	FindObject (const TObject *obj) const
	Must be redefined in derived classes.

virtual Option_t *	GetDrawOption () const
	Get option used by the graphics system to draw this object.

virtual const char *	GetIconName () const
	Returns mime type name of object.

virtual const char *	GetName () const
	Returns name of object.

virtual char *	GetObjectInfo (Int_t px, Int_t py) const
	Returns string containing info about the object at position (px,py).

virtual Option_t *	GetOption () const

virtual const char *	GetTitle () const
	Returns title of object.

virtual UInt_t	GetUniqueID () const
	Return the unique object id.

virtual Bool_t	HandleTimer (TTimer *timer)
	Execute action in response of a timer timing out.

virtual ULong_t	Hash () const
	Return hash value for this object.

Bool_t	HasInconsistentHash () const
	Return true is the type of this object is known to have an inconsistent setup for Hash and RecursiveRemove (i.e.

virtual void	Info (const char method, const char msgfmt,...) const
	Issue info message.

virtual Bool_t	InheritsFrom (const char *classname) const
	Returns kTRUE if object inherits from class "classname".

virtual Bool_t	InheritsFrom (const TClass *cl) const
	Returns kTRUE if object inherits from TClass cl.

virtual void	Inspect () const
	Dump contents of this object in a graphics canvas.

void	InvertBit (UInt_t f)

virtual Bool_t	IsEqual (const TObject *obj) const
	Default equal comparison (objects are equal if they have the same address in memory).

virtual Bool_t	IsFolder () const
	Returns kTRUE in case object contains browsable objects (like containers or lists of other objects).

R__ALWAYS_INLINE Bool_t	IsOnHeap () const

virtual Bool_t	IsSortable () const

R__ALWAYS_INLINE Bool_t	IsZombie () const

virtual void	ls (Option_t *option="") const
	The ls function lists the contents of a class on stdout.

void	MayNotUse (const char *method) const
	Use this method to signal that a method (defined in a base class) may not be called in a derived class (in principle against good design since a child class should not provide less functionality than its parent, however, sometimes it is necessary).

virtual Bool_t	Notify ()
	This method must be overridden to handle object notification.

void	Obsolete (const char method, const char asOfVers, const char *removedFromVers) const
	Use this method to declare a method obsolete.

void	operator delete (void *ptr)
	Operator delete.

void	operator delete[] (void *ptr)
	Operator delete [].

void *	operator new (size_t sz)

void *	operator new (size_t sz, void *vp)

void *	operator new[] (size_t sz)

void *	operator new[] (size_t sz, void *vp)

TObject &	operator= (const TObject &rhs)
	TObject assignment operator.

virtual void	Paint (Option_t *option="")
	This method must be overridden if a class wants to paint itself.

virtual void	Pop ()
	Pop on object drawn in a pad to the top of the display list.

virtual Int_t	Read (const char *name)
	Read contents of object with specified name from the current directory.

virtual void	RecursiveRemove (TObject *obj)
	Recursively remove this object from a list.

void	ResetBit (UInt_t f)

virtual void	SaveAs (const char filename="", Option_t option="") const
	Save this object in the file specified by filename.

virtual void	SavePrimitive (std::ostream &out, Option_t *option="")
	Save a primitive as a C++ statement(s) on output stream "out".

void	SetBit (UInt_t f)

void	SetBit (UInt_t f, Bool_t set)
	Set or unset the user status bits as specified in f.

virtual void	SetDrawOption (Option_t *option="")
	Set drawing option for object.

virtual void	SetUniqueID (UInt_t uid)
	Set the unique object id.

virtual void	SysError (const char method, const char msgfmt,...) const
	Issue system error message.

R__ALWAYS_INLINE Bool_t	TestBit (UInt_t f) const

Int_t	TestBits (UInt_t f) const

virtual void	UseCurrentStyle ()
	Set current style settings in this object This function is called when either TCanvas::UseCurrentStyle or TROOT::ForceStyle have been invoked.

virtual void	Warning (const char method, const char msgfmt,...) const
	Issue warning message.

virtual Int_t	Write (const char *name=0, Int_t option=0, Int_t bufsize=0)
	Write this object to the current directory.

virtual Int_t	Write (const char *name=0, Int_t option=0, Int_t bufsize=0) const
	Write this object to the current directory.

Protected Attributes
char *	fBuffer
	[fBufferSize] buffer of contiguous prefetched blocks

Int_t	fBufferSize
	Allocated size of fBuffer.

TFile *	fFile
	Pointer to file.

Int_t	fNtot
	Total size of cached blocks.

Bool_t	fRecursive
	flag to avoid recursive calls

Long64_t	fSeekStart
	Seek value of first block in cache.

Private Member Functions
	TFileCacheWrite (const TFileCacheWrite &)=delete

TFileCacheWrite &	operator= (const TFileCacheWrite &)=delete

Additional Inherited Members
Public Types inherited from TObject
enum	{ kIsOnHeap = 0x01000000 , kNotDeleted = 0x02000000 , kZombie = 0x04000000 , kInconsistent = 0x08000000 , kBitMask = 0x00ffffff }

enum	{ kSingleKey = BIT(0) , kOverwrite = BIT(1) , kWriteDelete = BIT(2) }

enum	EDeprecatedStatusBits { kObjInCanvas = BIT(3) }

enum	EStatusBits { kCanDelete = BIT(0) , kMustCleanup = BIT(3) , kIsReferenced = BIT(4) , kHasUUID = BIT(5) , kCannotPick = BIT(6) , kNoContextMenu = BIT(8) , kInvalidObject = BIT(13) }

Static Public Member Functions inherited from TObject
static Long_t	GetDtorOnly ()
	Return destructor only flag.

static Bool_t	GetObjectStat ()
	Get status of object stat flag.

static void	SetDtorOnly (void *obj)
	Set destructor only flag.

static void	SetObjectStat (Bool_t stat)
	Turn on/off tracking of objects in the TObjectTable.

Protected Types inherited from TObject
enum	{ kOnlyPrepStep = BIT(3) }

Protected Member Functions inherited from TObject
virtual void	DoError (int level, const char location, const char fmt, va_list va) const
	Interface to ErrorHandler (protected).

void	MakeZombie ()

#include <TFileCacheWrite.h>

Inheritance diagram for TFileCacheWrite:

[legend]

Constructor & Destructor Documentation

◆ TFileCacheWrite() [1/3]

TFileCacheWrite::TFileCacheWrite ( const TFileCacheWrite & )

privatedelete

◆ TFileCacheWrite() [2/3]

TFileCacheWrite::TFileCacheWrite ( )

Default Constructor.

Definition at line 37 of file TFileCacheWrite.cxx.

◆ TFileCacheWrite() [3/3]

TFileCacheWrite::TFileCacheWrite	(	TFile *	file,
		Int_t	buffersize
	)

Creates a TFileCacheWrite data structure.

The write cache will be connected to file. The size of the cache will be buffersize, if buffersize < 10000 a default size of 512 Kbytes is used

Definition at line 53 of file TFileCacheWrite.cxx.

◆ ~TFileCacheWrite()

TFileCacheWrite::~TFileCacheWrite ( )

virtual

Destructor.

Definition at line 70 of file TFileCacheWrite.cxx.

Member Function Documentation

◆ Flush()

Bool_t TFileCacheWrite::Flush ( )

virtual

Flush the current write buffer to the file.

Returns kTRUE in case of error.

Definition at line 79 of file TFileCacheWrite.cxx.

◆ GetBytesInCache()

virtual Int_t TFileCacheWrite::GetBytesInCache ( ) const

inlinevirtual

Definition at line 38 of file TFileCacheWrite.h.

◆ operator=()

TFileCacheWrite & TFileCacheWrite::operator= ( const TFileCacheWrite & )

privatedelete

◆ Print()

void TFileCacheWrite::Print ( Option_t * option = "" ) const

virtual

Print class internal structure.

Reimplemented from TObject.

Definition at line 94 of file TFileCacheWrite.cxx.

◆ ReadBuffer()

Int_t TFileCacheWrite::ReadBuffer	(	char *	buf,
		Long64_t	pos,
		Int_t	len
	)

virtual

Called by the read cache to check if the requested data is not in the write cache buffer.

Returns -1 if data not in write cache, 0 otherwise.

Definition at line 108 of file TFileCacheWrite.cxx.

◆ SetFile()

void TFileCacheWrite::SetFile ( TFile * file )

virtual

Set the file using this cache.

Any write not yet flushed will be lost.

Definition at line 153 of file TFileCacheWrite.cxx.

◆ WriteBuffer()

Int_t TFileCacheWrite::WriteBuffer	(	const char *	buf,
		Long64_t	pos,
		Int_t	len
	)

virtual

Write buffer at position pos in the write buffer.

The function returns 1 if the buffer has been successfully entered into the write buffer. The function returns 0 in case WriteBuffer() was recusively called via Flush(). The function returns -1 in case of error.

Definition at line 121 of file TFileCacheWrite.cxx.

Member Data Documentation

◆ fBuffer

char* TFileCacheWrite::fBuffer

protected

[fBufferSize] buffer of contiguous prefetched blocks

Definition at line 26 of file TFileCacheWrite.h.

◆ fBufferSize

Int_t TFileCacheWrite::fBufferSize

protected

Allocated size of fBuffer.

Definition at line 23 of file TFileCacheWrite.h.

◆ fFile

TFile* TFileCacheWrite::fFile

protected

Pointer to file.

Definition at line 25 of file TFileCacheWrite.h.

◆ fNtot

Int_t TFileCacheWrite::fNtot

protected

Total size of cached blocks.

Definition at line 24 of file TFileCacheWrite.h.

◆ fRecursive

Bool_t TFileCacheWrite::fRecursive

protected

flag to avoid recursive calls

Definition at line 27 of file TFileCacheWrite.h.

◆ fSeekStart

Long64_t TFileCacheWrite::fSeekStart

protected

Seek value of first block in cache.

Definition at line 22 of file TFileCacheWrite.h.

Libraries for TFileCacheWrite:

[legend]

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

io/io/inc/TFileCacheWrite.h
io/io/src/TFileCacheWrite.cxx

Public Member Functions

Protected Attributes

Private Member Functions

Additional Inherited Members

Constructor & Destructor Documentation

◆ TFileCacheWrite() [1/3]

◆ TFileCacheWrite() [2/3]

◆ TFileCacheWrite() [3/3]

◆ ~TFileCacheWrite()

Member Function Documentation

◆ Flush()

◆ GetBytesInCache()

◆ operator=()

◆ Print()

◆ ReadBuffer()

◆ SetFile()

◆ WriteBuffer()

Member Data Documentation

◆ fBuffer

◆ fBufferSize

◆ fFile

◆ fNtot

◆ fRecursive

◆ fSeekStart