class TFileCacheRead: public TObject


TFileCacheRead : a cache when reading 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 read cache system is used by the classes TNetFile,
TXNetFile and TWebFile (via TFile::ReadBuffers()).

When processing TTree, TChain, a specialized class TTreeCache that
derives from this class is automatically created.

Function Members (Methods)

public:

	TFileCacheRead()
	TFileCacheRead(TFile* file, Int_t buffersize)
virtual	~TFileCacheRead()
void	TObject::AbstractMethod(const char* method) const
virtual void	TObject::AppendPad(Option_t* option = "")
virtual void	TObject::Browse(TBrowser* b)
static TClass*	Class()
static TClass*	TObject::Class()
virtual const char*	TObject::ClassName() const
virtual void	TObject::Clear(Option_t* = "")
virtual TObject*	TObject::Clone(const char* newname = "") const
virtual Int_t	TObject::Compare(const TObject* obj) const
virtual void	TObject::Copy(TObject& object) const
virtual void	TObject::Delete(Option_t* option = "")MENU
virtual Int_t	TObject::DistancetoPrimitive(Int_t px, Int_t py)
virtual void	TObject::Draw(Option_t* option = "")
virtual void	TObject::DrawClass() constMENU
virtual TObject*	TObject::DrawClone(Option_t* option = "") constMENU
virtual void	TObject::Dump() constMENU
virtual void	TObject::Error(const char* method, const char* msgfmt) const
virtual void	TObject::Execute(const char* method, const char* params, Int_t* error = 0)
virtual void	TObject::Execute(TMethod* method, TObjArray* params, Int_t* error = 0)
virtual void	TObject::ExecuteEvent(Int_t event, Int_t px, Int_t py)
virtual void	TObject::Fatal(const char* method, const char* msgfmt) const
virtual TObject*	TObject::FindObject(const char* name) const
virtual TObject*	TObject::FindObject(const TObject* obj) const
virtual Int_t	GetBufferSize() const
virtual Option_t*	TObject::GetDrawOption() const
static Long_t	TObject::GetDtorOnly()
virtual const char*	TObject::GetIconName() const
virtual const char*	TObject::GetName() const
virtual char*	TObject::GetObjectInfo(Int_t px, Int_t py) const
static Bool_t	TObject::GetObjectStat()
virtual Option_t*	TObject::GetOption() const
virtual const char*	TObject::GetTitle() const
virtual UInt_t	TObject::GetUniqueID() const
virtual Bool_t	TObject::HandleTimer(TTimer* timer)
virtual ULong_t	TObject::Hash() const
virtual void	TObject::Info(const char* method, const char* msgfmt) const
virtual Bool_t	TObject::InheritsFrom(const char* classname) const
virtual Bool_t	TObject::InheritsFrom(const TClass* cl) const
virtual void	TObject::Inspect() constMENU
void	TObject::InvertBit(UInt_t f)
virtual TClass*	IsA() const
virtual TClass*	TObject::IsA() const
virtual Bool_t	IsAsyncReading() const
virtual Bool_t	TObject::IsEqual(const TObject* obj) const
virtual Bool_t	TObject::IsFolder() const
Bool_t	TObject::IsOnHeap() const
virtual Bool_t	TObject::IsSortable() const
Bool_t	TObject::IsZombie() const
virtual void	TObject::ls(Option_t* option = "") const
void	TObject::MayNotUse(const char* method) const
virtual Bool_t	TObject::Notify()
static void	TObject::operator delete(void* ptr)
static void	TObject::operator delete(void* ptr, void* vp)
static void	TObject::operator delete[](void* ptr)
static void	TObject::operator delete[](void* ptr, void* vp)
void*	TObject::operator new(size_t sz)
void*	TObject::operator new(size_t sz, void* vp)
void*	TObject::operator new[](size_t sz)
void*	TObject::operator new[](size_t sz, void* vp)
TObject&	TObject::operator=(const TObject& rhs)
virtual void	TObject::Paint(Option_t* option = "")
virtual void	TObject::Pop()
virtual void	Prefetch(Long64_t pos, Int_t len)
virtual void	Print(Option_t* option = "") const
virtual void	TObject::Print(Option_t* option = "") const
virtual Int_t	TObject::Read(const char* name)
virtual Int_t	ReadBuffer(char* buf, Long64_t pos, Int_t len)
virtual void	TObject::RecursiveRemove(TObject* obj)
void	TObject::ResetBit(UInt_t f)
virtual void	TObject::SaveAs(const char* filename = "", Option_t* option = "") constMENU
virtual void	TObject::SavePrimitive(basic_ostream<char,char_traits<char> >& out, Option_t* option = "")
void	TObject::SetBit(UInt_t f)
void	TObject::SetBit(UInt_t f, Bool_t set)
virtual void	TObject::SetDrawOption(Option_t* option = "")MENU
static void	TObject::SetDtorOnly(void* obj)
virtual void	SetFile(TFile* file)
static void	TObject::SetObjectStat(Bool_t stat)
virtual void	TObject::SetUniqueID(UInt_t uid)
virtual void	ShowMembers(TMemberInspector& insp, char* parent)
virtual void	TObject::ShowMembers(TMemberInspector& insp, char* parent)
virtual void	Sort()
virtual void	Streamer(TBuffer& b)
virtual void	TObject::Streamer(TBuffer& b)
void	StreamerNVirtual(TBuffer& b)
void	TObject::StreamerNVirtual(TBuffer& b)
virtual void	TObject::SysError(const char* method, const char* msgfmt) const
Bool_t	TObject::TestBit(UInt_t f) const
Int_t	TObject::TestBits(UInt_t f) const
virtual void	TObject::UseCurrentStyle()
virtual void	TObject::Warning(const char* method, const char* msgfmt) const
virtual Int_t	TObject::Write(const char* name = 0, Int_t option = 0, Int_t bufsize = 0)
virtual Int_t	TObject::Write(const char* name = 0, Int_t option = 0, Int_t bufsize = 0) const

protected:

virtual void	TObject::DoError(int level, const char* location, const char* fmt, va_list va) const
void	TObject::MakeZombie()

private:

	TFileCacheRead(const TFileCacheRead&)
TFileCacheRead&	operator=(const TFileCacheRead&)

Data Members

private:

enum TObject::EStatusBits {	kCanDelete
	kMustCleanup
	kObjInCanvas
	kIsReferenced
	kHasUUID
	kCannotPick
	kNoContextMenu
	kInvalidObject
};
enum TObject::[unnamed] {	kIsOnHeap
	kNotDeleted
	kZombie
	kBitMask
	kSingleKey
	kOverwrite
	kWriteDelete
};

protected:

Bool_t	fAsyncReading
char*	fBuffer	[fBufferSize] buffer of contiguous prefetched blocks
Int_t	fBufferLen	Current buffer length (<= fBufferSize)
Int_t	fBufferSize	Allocated size of fBuffer (at a given time)
Int_t	fBufferSizeMin	Original size of fBuffer
Int_t	fBytesToPrefetch	Helpers to allow the incremental async prefetch
TFile*	fFile	Pointer to file
Int_t	fFirstIndexToPrefetch
Bool_t	fIsSorted	True if fSeek array is sorted
Bool_t	fIsTransferred	True when fBuffer contains something valid
Int_t*	fLen	[fNb] Length of long buffers
Int_t	fNb	Number of long buffers
Int_t	fNseek	Number of blocks to be prefetched
Int_t	fNtot	Total size of prefetched blocks
Long64_t*	fPos	[fNb] start of long buffers
Long64_t*	fSeek	[fNseek] Position on file of buffers to be prefetched
Int_t*	fSeekIndex	[fNseek] sorted index table of fSeek
Int_t*	fSeekLen	[fNseek] Length of buffers to be prefetched
Int_t*	fSeekPos	[fNseek] Position of sorted blocks in fBuffer
Int_t	fSeekSize	Allocated size of fSeek
Long64_t*	fSeekSort	[fNseek] Position on file of buffers to be prefetched (sorted)
Int_t*	fSeekSortLen	[fNseek] Length of buffers to be prefetched (sorted)

Class Charts

Inheritance Inherited Members Includes Libraries

Function documentation

TFileCacheRead()

 Default Constructor.

TFileCacheRead(TFile* file, Int_t buffersize)

 Creates a TFileCacheRead data structure.

~TFileCacheRead()

 Destructor.

void Prefetch(Long64_t pos, Int_t len)

 Add block of length len at position pos in the list of blocks to
 be prefetched. If pos <= 0 the current blocks (if any) are reset.

void Print(Option_t* option = "") const

 Print class internal structure.

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

 Read buffer at position pos.
 If pos is in the list of prefetched blocks read from fBuffer,
 otherwise need to make a normal read from file. Returns -1 in case of
 read error, 0 in case not in cache, 1 in case read from cache.

void SetFile(TFile* file)

 Set the file using this cache and reset the current blocks (if any).

void Sort()

 Sort buffers to be prefetched in increasing order of positions.
 Merge consecutive blocks if necessary.

TFileCacheRead(const TFileCacheRead& )

TFileCacheRead& operator=(const TFileCacheRead& )

Int_t GetBufferSize() const

{ return fBufferSize; }

Bool_t IsAsyncReading() const

{ return fAsyncReading; }