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Reference Guide
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TFileCacheRead Class Reference


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.

Definition at line 22 of file TFileCacheRead.h.

Public Member Functions

 TFileCacheRead ()
 Default Constructor.
 
 TFileCacheRead (TFile *file, Int_t buffersize, TObject *tree=0)
 Creates a TFileCacheRead data structure.
 
virtual ~TFileCacheRead ()
 Destructor.
 
virtual Int_t AddBranch (TBranch *, Bool_t=kFALSE)
 
virtual Int_t AddBranch (const char *, Bool_t=kFALSE)
 
virtual void AddNoCacheBytesRead (Long64_t len)
 
virtual void AddNoCacheReadCalls (Int_t reads)
 
virtual void Close (Option_t *option="")
 Close out any threads or asynchronous fetches used by the underlying implementation. More...
 
virtual Int_t GetBufferSize () const
 
virtual Long64_t GetBytesRead () const
 
virtual Long64_t GetBytesReadExtra () const
 
TFileGetFile () const
 
virtual Long64_t GetNoCacheBytesRead () const
 
virtual Int_t GetNoCacheReadCalls () const
 
Int_t GetNseek () const
 
Int_t GetNtot () const
 
Long64_t GetPrefetchedBlocks () const
 
virtual TFilePrefetchGetPrefetchObj ()
 
virtual Int_t GetReadCalls () const
 
virtual Int_t GetUnzipBuffer (char **, Long64_t, Int_t, Bool_t *)
 
virtual Bool_t IsAsyncReading () const
 
virtual Bool_t IsEnablePrefetching () const
 
virtual Bool_t IsLearning () const
 
virtual Int_t LearnBranch (TBranch *, Bool_t=kFALSE)
 
virtual void Prefetch (Long64_t pos, Int_t len)
 Add block of length len at position pos in the list of blocks to be prefetched. More...
 
virtual void Print (Option_t *option="") const
 Print cache statistics. More...
 
virtual Int_t ReadBuffer (char *buf, Long64_t pos, Int_t len)
 Read buffer at position pos. More...
 
virtual Int_t ReadBufferExt (char *buf, Long64_t pos, Int_t len, Int_t &loc)
 
virtual Int_t ReadBufferExtNormal (char *buf, Long64_t pos, Int_t len, Int_t &loc)
 Base function for ReadBuffer. More...
 
virtual Int_t ReadBufferExtPrefetch (char *buf, Long64_t pos, Int_t len, Int_t &loc)
 prefetch the first block
 
virtual void SecondPrefetch (Long64_t, Int_t)
 
virtual void SecondSort ()
 Sort buffers to be prefetched in increasing order of positions. More...
 
virtual Int_t SetBufferSize (Int_t buffersize)
 Sets the buffer size. More...
 
virtual void SetEnablePrefetching (Bool_t setPrefetching=kFALSE)
 Set the prefetching mode of this file. More...
 
virtual void SetFile (TFile *file, TFile::ECacheAction action=TFile::kDisconnect)
 Set the file using this cache and reset the current blocks (if any).
 
virtual void SetSkipZip (Bool_t=kTRUE)
 
virtual void Sort ()
 Sort buffers to be prefetched in increasing order of positions. More...
 
virtual void WaitFinishPrefetch ()
 
- Public Member Functions inherited from TObject
 TObject ()
 TObject constructor. More...
 
 TObject (const TObject &object)
 TObject copy ctor.
 
virtual ~TObject ()
 TObject destructor. More...
 
void AbstractMethod (const char *method) const
 Use this method to implement an "abstract" method that you don't want to leave purely abstract. More...
 
virtual void AppendPad (Option_t *option="")
 Append graphics object to current pad. More...
 
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. More...
 
virtual const char * ClassName () const
 Returns name of class to which the object belongs.
 
virtual void Clear (Option_t *="")
 
virtual TObjectClone (const char *newname="") const
 Make a clone of an object using the Streamer facility. More...
 
virtual Int_t Compare (const TObject *obj) const
 Compare abstract method. More...
 
virtual void Copy (TObject &object) const
 Copy this to obj.
 
virtual void Delete (Option_t *option="")
 Delete this object. More...
 
virtual Int_t DistancetoPrimitive (Int_t px, Int_t py)
 Computes distance from point (px,py) to the object. More...
 
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. More...
 
virtual TObjectDrawClone (Option_t *option="") const
 Draw a clone of this object in the current selected pad for instance with: gROOT->SetSelectedPad(gPad). More...
 
virtual void Dump () const
 Dump contents of object on stdout. More...
 
virtual void Error (const char *method, const char *msgfmt,...) const
 Issue error message. More...
 
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. More...
 
virtual void Execute (TMethod *method, TObjArray *params, Int_t *error=0)
 Execute method on this object with parameters stored in the TObjArray. More...
 
virtual void ExecuteEvent (Int_t event, Int_t px, Int_t py)
 Execute action corresponding to an event at (px,py). More...
 
virtual void Fatal (const char *method, const char *msgfmt,...) const
 Issue fatal error message. More...
 
virtual TObjectFindObject (const char *name) const
 Must be redefined in derived classes. More...
 
virtual TObjectFindObject (const TObject *obj) const
 Must be redefined in derived classes. More...
 
virtual Option_t * GetDrawOption () const
 Get option used by the graphics system to draw this object. More...
 
virtual const char * GetIconName () const
 Returns mime type name of object. More...
 
virtual const char * GetName () const
 Returns name of object. More...
 
virtual char * GetObjectInfo (Int_t px, Int_t py) const
 Returns string containing info about the object at position (px,py). More...
 
virtual Option_t * GetOption () const
 
virtual const char * GetTitle () const
 Returns title of object. More...
 
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. More...
 
virtual ULong_t Hash () const
 Return hash value for this object. More...
 
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. More...
 
virtual void Info (const char *method, const char *msgfmt,...) const
 Issue info message. More...
 
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. More...
 
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). More...
 
virtual Bool_t IsFolder () const
 Returns kTRUE in case object contains browsable objects (like containers or lists of other objects). More...
 
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. More...
 
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). More...
 
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. More...
 
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)
 
TObjectoperator= (const TObject &rhs)
 TObject assignment operator.
 
virtual void Paint (Option_t *option="")
 This method must be overridden if a class wants to paint itself. More...
 
virtual void Pop ()
 Pop on object drawn in a pad to the top of the display list. More...
 
virtual Int_t Read (const char *name)
 Read contents of object with specified name from the current directory. More...
 
virtual void RecursiveRemove (TObject *obj)
 Recursively remove this object from a list. More...
 
void ResetBit (UInt_t f)
 
virtual void SaveAs (const char *filename="", Option_t *option="") const
 Save this object in the file specified by filename. More...
 
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, Bool_t set)
 Set or unset the user status bits as specified in f.
 
void SetBit (UInt_t f)
 
virtual void SetDrawOption (Option_t *option="")
 Set drawing option for object. More...
 
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. More...
 
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. More...
 
virtual void Warning (const char *method, const char *msgfmt,...) const
 Issue warning message. More...
 
virtual Int_t Write (const char *name=0, Int_t option=0, Int_t bufsize=0)
 Write this object to the current directory. More...
 
virtual Int_t Write (const char *name=0, Int_t option=0, Int_t bufsize=0) const
 Write this object to the current directory. More...
 

Protected Member Functions

void SetEnablePrefetchingImpl (Bool_t setPrefetching=kFALSE)
 TFileCacheRead implementation of SetEnablePrefetching. More...
 
- 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 ()
 

Protected Attributes

Bool_t fAsyncReading
 
Bool_t fBIsSorted
 
Bool_t fBIsTransferred
 
Int_t * fBLen
 [fBNb]
 
Int_t fBNb
 
Int_t fBNseek
 
Int_t fBNtot
 
Long64_t * fBPos
 [fBNb]
 
Long64_t * fBSeek
 [fBNseek]
 
Int_t * fBSeekIndex
 [fBNseek]
 
Int_t * fBSeekLen
 [fBNseek]
 
Int_t * fBSeekPos
 [fBNseek]
 
Int_t fBSeekSize
 
Long64_t * fBSeekSort
 [fBNseek]
 
Int_t * fBSeekSortLen
 [fBNseek]
 
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.
 
Long64_t fBytesRead
 Number of bytes read for this cache.
 
Long64_t fBytesReadExtra
 Number of extra bytes (overhead) read by the readahead buffer.
 
Bool_t fEnablePrefetching
 reading by prefetching asynchronously
 
TFilefFile
 Pointer to file.
 
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.
 
Long64_t fNoCacheBytesRead
 Number of bytes read by basket to fill cached tree.
 
Int_t fNoCacheReadCalls
 Number of read calls by basket to fill cached tree.
 
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
 
TFilePrefetchfPrefetch
 ! Object that does the asynchronous reading in another thread
 
Long64_t fPrefetchedBlocks
 Number of blocks prefetched.
 
Int_t fReadCalls
 Number of read calls for this cache.
 
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)
 

Private Member Functions

 TFileCacheRead (const TFileCacheRead &)
 
TFileCacheReadoperator= (const TFileCacheRead &)
 

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.
 
Inheritance diagram for TFileCacheRead:
[legend]

Member Function Documentation

◆ Close()

void TFileCacheRead::Close ( Option_t *  option = "")
virtual

Close out any threads or asynchronous fetches used by the underlying implementation.

This is called by TFile::Close to prevent usage of the file handles after the closing of the file.

Definition at line 188 of file TFileCacheRead.cxx.

◆ Prefetch()

void TFileCacheRead::Prefetch ( Long64_t  pos,
Int_t  len 
)
virtual

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.

Definition at line 201 of file TFileCacheRead.cxx.

◆ Print()

void TFileCacheRead::Print ( Option_t *  option = "") const
virtual

Print cache statistics.

The format is: ******TreeCache statistics for file: cms2.root ****** Reading............................: 72761843 bytes in 7 transactions Readahead..........................: 256000 bytes with overhead = 0 bytes Average transaction................: 10394.549000 Kbytes Number of blocks in current cache..: 210, total size: 6280352

If option = "a" the list of blocks in the cache is printed NB: this function is automatically called by TTreeCache::Print

Reimplemented from TObject.

Reimplemented in TTreeCache, and TTreeCacheUnzip.

Definition at line 325 of file TFileCacheRead.cxx.

◆ ReadBuffer()

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

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.

Reimplemented in TTreeCache.

Definition at line 363 of file TFileCacheRead.cxx.

◆ ReadBufferExtNormal()

Int_t TFileCacheRead::ReadBufferExtNormal ( char *  buf,
Long64_t  pos,
Int_t  len,
Int_t &  loc 
)
virtual

Base function for ReadBuffer.

Also gives out the position of the block in the internal buffer. This helps TTreeCacheUnzip to avoid doing twice the binary search.

Definition at line 453 of file TFileCacheRead.cxx.

◆ SecondSort()

void TFileCacheRead::SecondSort ( )
virtual

Sort buffers to be prefetched in increasing order of positions.

Merge consecutive blocks if necessary.

Definition at line 629 of file TFileCacheRead.cxx.

◆ SetBufferSize()

Int_t TFileCacheRead::SetBufferSize ( Int_t  buffersize)
virtual

Sets the buffer size.

If the current prefetch list is too large to fit in the new buffer some or all of the prefetch blocks are dropped. The requested buffersize must be greater than zero. Return values:

  • 0 if the prefetch block lists remain unchanged
  • 1 if some or all blocks have been removed from the prefetch list
  • -1 on error

Reimplemented in TTreeCache, and TTreeCacheUnzip.

Definition at line 709 of file TFileCacheRead.cxx.

◆ SetEnablePrefetching()

void TFileCacheRead::SetEnablePrefetching ( Bool_t  setPrefetching = kFALSE)
virtual

Set the prefetching mode of this file.

If 'setPrefetching', enable the asynchronous prefetching (using TFilePrefetch) and if the gEnv and rootrc variable Cache.Directory is set, also enable the local caching of the prefetched blocks. if 'setPrefetching', the old prefetcher is enabled is the gEnv and rootrc variable is TFile.AsyncReading

Definition at line 771 of file TFileCacheRead.cxx.

◆ SetEnablePrefetchingImpl()

void TFileCacheRead::SetEnablePrefetchingImpl ( Bool_t  setPrefetching = kFALSE)
protected

TFileCacheRead implementation of SetEnablePrefetching.

This function is called from the constructor and should not be virtual.

Definition at line 781 of file TFileCacheRead.cxx.

◆ Sort()

void TFileCacheRead::Sort ( )
virtual

Sort buffers to be prefetched in increasing order of positions.

Merge consecutive blocks if necessary.

Definition at line 571 of file TFileCacheRead.cxx.

Libraries for TFileCacheRead:
[legend]

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