ROOT logo
ROOT » IO » IO » TFileCacheWrite

class TFileCacheWrite: public TObject

TFileCacheWrite : 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()).

Function Members (Methods)

TFileCacheWrite(TFile* file, Int_t buffersize)
voidTObject::AbstractMethod(const char* method) const
virtual voidTObject::AppendPad(Option_t* option = "")
virtual voidTObject::Browse(TBrowser* b)
static TClass*Class()
virtual const char*TObject::ClassName() const
virtual voidTObject::Clear(Option_t* = "")
virtual TObject*TObject::Clone(const char* newname = "") const
virtual Int_tTObject::Compare(const TObject* obj) const
virtual voidTObject::Copy(TObject& object) const
virtual voidTObject::Delete(Option_t* option = "")MENU
virtual Int_tTObject::DistancetoPrimitive(Int_t px, Int_t py)
virtual voidTObject::Draw(Option_t* option = "")
virtual voidTObject::DrawClass() constMENU
virtual TObject*TObject::DrawClone(Option_t* option = "") constMENU
virtual voidTObject::Dump() constMENU
virtual voidTObject::Error(const char* method, const char* msgfmt) const
virtual voidTObject::Execute(const char* method, const char* params, Int_t* error = 0)
virtual voidTObject::Execute(TMethod* method, TObjArray* params, Int_t* error = 0)
virtual voidTObject::ExecuteEvent(Int_t event, Int_t px, Int_t py)
virtual voidTObject::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 Bool_tFlush()
virtual Int_tGetBytesInCache() const
virtual Option_t*TObject::GetDrawOption() const
static Long_tTObject::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_tTObject::GetObjectStat()
virtual Option_t*TObject::GetOption() const
virtual const char*TObject::GetTitle() const
virtual UInt_tTObject::GetUniqueID() const
virtual Bool_tTObject::HandleTimer(TTimer* timer)
virtual ULong_tTObject::Hash() const
virtual voidTObject::Info(const char* method, const char* msgfmt) const
virtual Bool_tTObject::InheritsFrom(const char* classname) const
virtual Bool_tTObject::InheritsFrom(const TClass* cl) const
virtual voidTObject::Inspect() constMENU
voidTObject::InvertBit(UInt_t f)
virtual TClass*IsA() const
virtual Bool_tTObject::IsEqual(const TObject* obj) const
virtual Bool_tTObject::IsFolder() const
Bool_tTObject::IsOnHeap() const
virtual Bool_tTObject::IsSortable() const
Bool_tTObject::IsZombie() const
virtual voidTObject::ls(Option_t* option = "") const
voidTObject::MayNotUse(const char* method) const
virtual Bool_tTObject::Notify()
voidTObject::Obsolete(const char* method, const char* asOfVers, const char* removedFromVers) const
static voidTObject::operator delete(void* ptr)
static voidTObject::operator delete(void* ptr, void* vp)
static voidTObject::operator delete[](void* ptr)
static voidTObject::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)
virtual voidTObject::Paint(Option_t* option = "")
virtual voidTObject::Pop()
virtual voidPrint(Option_t* option = "") const
virtual Int_tTObject::Read(const char* name)
virtual Int_tReadBuffer(char* buf, Long64_t pos, Int_t len)
virtual voidTObject::RecursiveRemove(TObject* obj)
voidTObject::ResetBit(UInt_t f)
virtual voidTObject::SaveAs(const char* filename = "", Option_t* option = "") constMENU
virtual voidTObject::SavePrimitive(ostream& out, Option_t* option = "")
voidTObject::SetBit(UInt_t f)
voidTObject::SetBit(UInt_t f, Bool_t set)
virtual voidTObject::SetDrawOption(Option_t* option = "")MENU
static voidTObject::SetDtorOnly(void* obj)
virtual voidSetFile(TFile* file)
static voidTObject::SetObjectStat(Bool_t stat)
virtual voidTObject::SetUniqueID(UInt_t uid)
virtual voidShowMembers(TMemberInspector& insp)
virtual voidStreamer(TBuffer& b)
voidStreamerNVirtual(TBuffer& b)
virtual voidTObject::SysError(const char* method, const char* msgfmt) const
Bool_tTObject::TestBit(UInt_t f) const
Int_tTObject::TestBits(UInt_t f) const
virtual voidTObject::UseCurrentStyle()
virtual voidTObject::Warning(const char* method, const char* msgfmt) const
virtual Int_tTObject::Write(const char* name = 0, Int_t option = 0, Int_t bufsize = 0)
virtual Int_tTObject::Write(const char* name = 0, Int_t option = 0, Int_t bufsize = 0) const
virtual Int_tWriteBuffer(const char* buf, Long64_t pos, Int_t len)
virtual voidTObject::DoError(int level, const char* location, const char* fmt, va_list va) const

Data Members

char*fBuffer[fBufferSize] buffer of contiguous prefetched blocks
Int_tfBufferSizeAllocated size of fBuffer
TFile*fFilePointer to file
Int_tfNtotTotal size of cached blocks
Bool_tfRecursiveflag to avoid recursive calls
Long64_tfSeekStartSeek value of first block in cache

Class Charts

Inheritance Inherited Members Includes Libraries
Class Charts

Function documentation

 Default Constructor.
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
Bool_t Flush()
 Flush the current write buffer to the file.
 Returns kTRUE in case of error.
void Print(Option_t* option = "") const
 Print class internal structure.
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.
        Returns -1 if data not in write cache,
        0 otherwise.
Int_t WriteBuffer(const char* buf, Long64_t pos, Int_t len)
 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.
void SetFile(TFile* file)
 Set the file using this cache.
 Any write not yet flushed will be lost.
TFileCacheWrite(const TFileCacheWrite& )
TFileCacheWrite& operator=(const TFileCacheWrite& )
Int_t GetBytesInCache() const
{ return fNtot; }