The prefetching mechanism uses two classes (TFilePrefetch and TFPBlock) to prefetch in advance a block of tree entries.
There is a thread which takes care of actually transferring the blocks and making them available to the main requesting thread. Therefore, the time spent by the main thread waiting for the data before processing considerably decreases. Besides the prefetching mechanisms there is also a local caching option which can be enabled by the user. Both capabilities are disabled by default and must be explicitly enabled by the user.
Definition at line 33 of file TFilePrefetch.h.
Public Member Functions | |
TFilePrefetch (TFile *) | |
Constructor. | |
~TFilePrefetch () override | |
Destructor. | |
void | AddPendingBlock (TFPBlock *) |
Safe method to add a block to the pendingList. | |
void | AddReadBlock (TFPBlock *) |
Safe method to add a block to the readList. | |
Bool_t | BinarySearchReadList (TFPBlock *, Long64_t, Int_t, Int_t *) |
Search for a requested element in a block and return the index. | |
Bool_t | CheckBlockInCache (char *&, TFPBlock *) |
Test if the block is in cache. | |
TFPBlock * | CreateBlockObj (Long64_t *, Int_t *, Int_t) |
Create a new block or recycle an old one. | |
char * | GetBlockFromCache (const char *, Int_t) |
Return a buffer from cache. | |
std::condition_variable & | GetCondNewBlock () |
TFPBlock * | GetPendingBlock () |
Safe method to remove a block from the pendingList. | |
TThread * | GetThread () const |
Return reference to the consumer thread. | |
Long64_t | GetWaitTime () |
Return the time spent wating for buffer to be read in microseconds. | |
TClass * | IsA () const override |
Bool_t | IsPrefetchFinished () const |
void | ReadAsync (TFPBlock *, Bool_t &) |
Read one block and insert it in prefetchBuffers list. | |
void | ReadBlock (Long64_t *, Int_t *, Int_t) |
Create a TFPBlock object or recycle one and add it to the prefetchBlocks list. | |
Bool_t | ReadBuffer (char *, Long64_t, Int_t) |
Return a prefetched element. | |
void | ReadListOfBlocks () |
Get blocks specified in prefetchBlocks. | |
void | SaveBlockInCache (TFPBlock *) |
Save the block content in cache. | |
Bool_t | SetCache (const char *) |
Set the path of the cache directory. | |
void | SetFile (TFile *file, TFile::ECacheAction action=TFile::kDisconnect) |
Change the file. | |
void | Streamer (TBuffer &) override |
Stream an object of class TObject. | |
void | StreamerNVirtual (TBuffer &ClassDef_StreamerNVirtual_b) |
Int_t | SumHex (const char *) |
Sum up individual hex values to obtain a decimal value. | |
Int_t | ThreadStart () |
Used to start the consumer thread. | |
void | WaitFinishPrefetch () |
Killing the async prefetching thread. | |
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 with: gROOT->SetSelectedPad(c1) . | |
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=nullptr) |
Execute method on this object with the given parameter string, e.g. | |
virtual void | Execute (TMethod *method, TObjArray *params, Int_t *error=nullptr) |
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) |
Bool_t | IsDestructed () const |
IsDestructed. | |
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 (the base implementation is no-op). | |
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, void *vp) |
Only called by placement new when throwing an exception. | |
void | operator delete[] (void *ptr) |
Operator delete []. | |
void | operator delete[] (void *ptr, void *vp) |
Only called by placement new[] when throwing an exception. | |
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 void | Print (Option_t *option="") const |
This method must be overridden when a class wants to print itself. | |
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. | |
void | StreamerNVirtual (TBuffer &ClassDef_StreamerNVirtual_b) |
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=nullptr, Int_t option=0, Int_t bufsize=0) |
Write this object to the current directory. | |
virtual Int_t | Write (const char *name=nullptr, Int_t option=0, Int_t bufsize=0) const |
Write this object to the current directory. | |
Static Public Member Functions | |
static TClass * | Class () |
static const char * | Class_Name () |
static constexpr Version_t | Class_Version () |
static const char * | DeclFileName () |
Static Public Member Functions inherited from TObject | |
static TClass * | Class () |
static const char * | Class_Name () |
static constexpr Version_t | Class_Version () |
static const char * | DeclFileName () |
static Longptr_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. | |
Static Private Member Functions | |
static TThread::VoidRtnFunc_t | ThreadProc (void *) |
Execution loop of the consumer thread. | |
Private Attributes | |
TThread * | fConsumer |
consumer thread | |
TFile * | fFile |
reference to the file | |
std::mutex | fMutexPendingList |
mutex for the pending list | |
std::mutex | fMutexReadList |
mutex for the list of read blocks | |
std::condition_variable | fNewBlockAdded |
signal the addition of a new pending block | |
TString | fPathCache |
path to the cache directory | |
TList * | fPendingBlocks |
list of pending blocks to be read | |
std::atomic< Bool_t > | fPrefetchFinished |
true if prefetching is over | |
std::condition_variable | fReadBlockAdded |
signal the addition of a new red block | |
TList * | fReadBlocks |
list of blocks read | |
TSemaphore * | fSemChangeFile |
semaphore used when changing a file in TChain | |
Bool_t | fThreadJoined |
mark if async thread was joined | |
TStopwatch | fWaitTime |
time waiting to prefetch a buffer (in usec) | |
Additional Inherited Members | |
Public Types inherited from TObject | |
enum | { kIsOnHeap = 0x01000000 , kNotDeleted = 0x02000000 , kZombie = 0x04000000 , kInconsistent = 0x08000000 , kBitMask = 0x00ffffff } |
enum | { kSingleKey = (1ULL << ( 0 )) , kOverwrite = (1ULL << ( 1 )) , kWriteDelete = (1ULL << ( 2 )) } |
enum | EDeprecatedStatusBits { kObjInCanvas = (1ULL << ( 3 )) } |
enum | EStatusBits { kCanDelete = (1ULL << ( 0 )) , kMustCleanup = (1ULL << ( 3 )) , kIsReferenced = (1ULL << ( 4 )) , kHasUUID = (1ULL << ( 5 )) , kCannotPick = (1ULL << ( 6 )) , kNoContextMenu = (1ULL << ( 8 )) , kInvalidObject = (1ULL << ( 13 )) } |
Protected Types inherited from TObject | |
enum | { kOnlyPrepStep = (1ULL << ( 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 <TFilePrefetch.h>
TFilePrefetch::TFilePrefetch | ( | TFile * | file | ) |
Constructor.
Definition at line 56 of file TFilePrefetch.cxx.
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override |
Destructor.
Definition at line 74 of file TFilePrefetch.cxx.
void TFilePrefetch::AddPendingBlock | ( | TFPBlock * | block | ) |
Safe method to add a block to the pendingList.
Definition at line 225 of file TFilePrefetch.cxx.
void TFilePrefetch::AddReadBlock | ( | TFPBlock * | block | ) |
Safe method to add a block to the readList.
Definition at line 261 of file TFilePrefetch.cxx.
Bool_t TFilePrefetch::BinarySearchReadList | ( | TFPBlock * | blockObj, |
Long64_t | offset, | ||
Int_t | len, | ||
Int_t * | index | ||
) |
Search for a requested element in a block and return the index.
Definition at line 146 of file TFilePrefetch.cxx.
Test if the block is in cache.
Definition at line 397 of file TFilePrefetch.cxx.
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static |
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inlinestaticconstexpr |
Definition at line 84 of file TFilePrefetch.h.
Create a new block or recycle an old one.
Definition at line 283 of file TFilePrefetch.cxx.
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inlinestatic |
Definition at line 84 of file TFilePrefetch.h.
char * TFilePrefetch::GetBlockFromCache | ( | const char * | path, |
Int_t | length | ||
) |
Return a buffer from cache.
Definition at line 443 of file TFilePrefetch.cxx.
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inline |
Definition at line 80 of file TFilePrefetch.h.
TFPBlock * TFilePrefetch::GetPendingBlock | ( | ) |
Safe method to remove a block from the pendingList.
Definition at line 237 of file TFilePrefetch.cxx.
TThread * TFilePrefetch::GetThread | ( | ) | const |
Return reference to the consumer thread.
Definition at line 305 of file TFilePrefetch.cxx.
Long64_t TFilePrefetch::GetWaitTime | ( | ) |
Return the time spent wating for buffer to be read in microseconds.
Definition at line 172 of file TFilePrefetch.cxx.
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inlineoverridevirtual |
Reimplemented from TObject.
Definition at line 84 of file TFilePrefetch.h.
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inline |
Definition at line 82 of file TFilePrefetch.h.
Read one block and insert it in prefetchBuffers list.
Definition at line 108 of file TFilePrefetch.cxx.
Create a TFPBlock object or recycle one and add it to the prefetchBlocks list.
Definition at line 216 of file TFilePrefetch.cxx.
Return a prefetched element.
Definition at line 180 of file TFilePrefetch.cxx.
void TFilePrefetch::ReadListOfBlocks | ( | ) |
Get blocks specified in prefetchBlocks.
Definition at line 130 of file TFilePrefetch.cxx.
void TFilePrefetch::SaveBlockInCache | ( | TFPBlock * | block | ) |
Save the block content in cache.
Definition at line 476 of file TFilePrefetch.cxx.
Bool_t TFilePrefetch::SetCache | ( | const char * | path | ) |
Set the path of the cache directory.
Definition at line 528 of file TFilePrefetch.cxx.
void TFilePrefetch::SetFile | ( | TFile * | file, |
TFile::ECacheAction | action = TFile::kDisconnect |
||
) |
Change the file.
When prefetching is enabled we also need to:
Definition at line 319 of file TFilePrefetch.cxx.
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overridevirtual |
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inline |
Definition at line 84 of file TFilePrefetch.h.
Int_t TFilePrefetch::SumHex | ( | const char * | hex | ) |
Sum up individual hex values to obtain a decimal value.
Definition at line 383 of file TFilePrefetch.cxx.
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staticprivate |
Execution loop of the consumer thread.
Definition at line 367 of file TFilePrefetch.cxx.
Int_t TFilePrefetch::ThreadStart | ( | ) |
Used to start the consumer thread.
Definition at line 351 of file TFilePrefetch.cxx.
void TFilePrefetch::WaitFinishPrefetch | ( | ) |
Killing the async prefetching thread.
Definition at line 90 of file TFilePrefetch.cxx.
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private |
consumer thread
Definition at line 39 of file TFilePrefetch.h.
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private |
reference to the file
Definition at line 36 of file TFilePrefetch.h.
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private |
mutex for the pending list
Definition at line 40 of file TFilePrefetch.h.
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private |
mutex for the list of read blocks
Definition at line 41 of file TFilePrefetch.h.
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private |
signal the addition of a new pending block
Definition at line 42 of file TFilePrefetch.h.
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private |
path to the cache directory
Definition at line 45 of file TFilePrefetch.h.
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private |
list of pending blocks to be read
Definition at line 37 of file TFilePrefetch.h.
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private |
true if prefetching is over
Definition at line 48 of file TFilePrefetch.h.
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private |
signal the addition of a new red block
Definition at line 43 of file TFilePrefetch.h.
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private |
list of blocks read
Definition at line 38 of file TFilePrefetch.h.
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private |
semaphore used when changing a file in TChain
Definition at line 44 of file TFilePrefetch.h.
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private |
mark if async thread was joined
Definition at line 47 of file TFilePrefetch.h.
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private |
time waiting to prefetch a buffer (in usec)
Definition at line 46 of file TFilePrefetch.h.